Pests and the plant defenses against them drive diversity in tropical rainforests

Date: March 14, 2019 Source: University of Utah Summary: Researchers have been baffled by tropical rainforest diversity for over a century; 650 different tree species can exist in an area covering two football fields, yet similar species never grow next to each other. It seems like it's good to be different than your neighbors, but why?

A group of caterpillars congregate on a leaf on an Inga tree species. Caterpillars can do extraordinary damage to tree leaves. Different species of Inga trees have various defenses against herbivore species. Some herbivores have adapted ways to overcome tree defenses.

Credit: Thomas Kursar

Researchers have been baffled by tropical rainforest diversity for over a century; 650 different tree species can exist in an area covering two football fields, yet similar species never grow next to each other. It seems like it's good to be different than your neighbors, but why?

To grow in a tropical rainforest is to engage in constant warfare. Plants battle for resources, such as sunlight, water and minerals. Similar tree species compete for resources in the same ways, so they may inhibit each other's growth. Plants also battle against herbivore pests. Related trees share the same pests and diseases -- if one gets it, the infestation can spread. Scientists have asked, "What is the primary driver in tropical forest diversity-competition for resources, or herbivore pests?"

For the first time, University of Utah biologists compared the two mechanisms in a single study.

The team analyzed how neighboring trees influence the growth and survival of nine coexisting species of the tree genus Inga in the Panama rainforest. They compared tree traits for resource acquisition, anti-herbivore defenses and the herbivores that live on the plants. They found that neighboring trees were basically the same in terms of acquiring resources, but had very different defenses and herbivores. Indeed, the defensive traits and shared pests impacted growth and survival, while resource acquisition traits had no effect on the plants' success. These findings indicate that anything impacting pest populations, such as climate change or habitat fragmentation, will have an impact on the health of the rainforest.

"Working in these hyper-diverse tropical rainforests makes it abundantly clear just how complex the web of interacting species really is. No species or individual lives in isolation. At all levels within the food chain species are competing with one another for precious resources and contributing a huge amount of their energy to defending themselves from the barrage of enemies they face, said Dale Forrister, doctoral candidate in the School of Biological Sciences at the University of Utah and lead author of the study. "We are excited about this study because it highlights some of the important ways these antagonistic interactions might influence tropical diversity."

This study published on March 14, 2019, in the journal Science.

It's a jungle out there

The team conducted their analysis over five years within a 50-hectare forest plot in Barro Colorado Island, Panama. The site has growth and survival data for over 423,000 trees from a previous long-term study. The researchers analyzed every individual tree sapling from the focal Inga species and calculated the similarity of their Inga neighbors' traits within a 10-meter "neighborhood." They measured four resource acquisition traits, five anti-herbivore defenses and recorded which herbivores were eating which plants.

Forrister developed a complicated model to determine how neighboring trees influence sapling growth and survival. They found that resource acquisition traits had no effect on survival, while defensive traits and herbivores had a big impact.

There are only so many ways to acquire resources. Defensive traits, however, are nearly endless. Plants and herbivores are in a constant arms race to outsmart each other. Plants develop traits to deter hungry mandibles, and herbivores adapt to deal with the leaf's defenses. The Inga genus has a quiver of anti-herbivore traits, including tiny hairs, nectar cups that attract pugnacious ant protectors, and most notably, leaves filled with poisonous compounds. Each Inga species can make hundreds or sometimes thousands of different toxins.

"People may think of a jungle like it's a giant salad bowl. It should be paradise for pests because they're surrounded by leaves. But plants have an infinite number of defense combinations -- half the weight of a young leaf is poison," said Phyllis Coley, Distinguished Professor of Biology at the University of Utah, research affiliate at the Smithsonian Tropical Research Institute and co-author of the study. "As a consequence of the diversity of defenses, each species of herbivore can only eat a few species of plants that they have adaptations for."

Closely related plants have similar defensive traits, and therefore similar pests. If a plant differs from its neighbor in terms of defenses, their herbivores aren't a threat, Coley continued. "You'll have your own herbivores, but at least you won't have all the critters in the neighborhood eating you."

Confounding chemical compounds

Plant toxins are the most important weapons for tropical plants, but testing the similarity of each species' chemicals proved problematic. Over five years, the researchers collected leaf samples in the field, dried them in a makeshift desiccator suitcase (no easy feat in 100 percent humidity) and then brought them to the U for analysis. Using high performance liquid chromatography, they separated all of the distinct compounds inside the leaves. However, only 4 percent of the Inga compounds were known to science. So, the team got creative and came up with a new metric. They used a mass spectrometer to determine the chemical structure of each compound, and established that compounds with similar structures were likely affecting herbivores in a similar way.

"Metabolomics, a relatively new field of science, offers scientist a powerful new toolbox for examining the vast amount of chemical diversity that exists out there. Chemicals play a huge role in nature, from defenses to communication they are the medium by which species interact. Being able to quantify this in a meaningful way provides a truly unique perspective," said Forrister.

But do the herbivores "care" about the traits the team was measuring and do Inga species with similar traits share herbivores? To test this, they collected caterpillars that were eating Inga leaves and sequenced their DNA to classify each as species A, species B, etc. They were unable to name the species because most of the caterpillars were new to science. They cataloged which herbivores were eating which plants, correlated the suite of compounds in the plants and inferred which plant species shared herbivore communities.

Both old-school field research and modern techniques were indispensable to this project's success.

"Despite state-of-the-art laboratory facilities, there's no substitute for spending months and months in the rainforest," said Coley. "It took us several years to collect data, and samples of leaves and herbivores. It's hot, humid and buggy, but attempting to understand the diversity of species is a biologist's dream."

The study reveals the significant role of herbivores in driving diversity in tropical ecosystems, with stark implications -- the loss of those populations could have catastrophic consequence on these important habitats.

"If climate change continues to increase the length of the dry season in the Americas, then the dynamics of the herbivore populations will change as well," said Coley. "That could have implications down the road."

Story Source:

Materials provided by University of Utah. Note: Content may be edited for style and length.

Journal Reference:

Dale L. Forrister, María-José Endara, Gordon C. Younkin, Phyllis D. Coley, Thomas A. Kursar. Herbivores as drivers of negative density dependence in tropical forest saplings. Science, 2019; 363 (6432): 1213 DOI: 10.1126/science.aau9460

Cite This Page:

MLA

APA

Chicago

University of Utah. "Pests and the plant defenses against them drive diversity in tropical rainforests." ScienceDaily. ScienceDaily, 14 March 2019. <www.sciencedaily.com/releases/2019/03/190314151548.htm>.

Parasitoid larvae in caterpillars affect behaviour of moths

Date: November 15, 2011

Source: Wageningen University and Research Centre

Summary:

Parasitoid larvae that feed within caterpillars that eat cabbage plants influence the plant via the caterpillar, making the cabbage plant an unattractive prospect for moths looking for a spot to lay their eggs.

Saliva from caterpillars of the large cabbage white (top row) and the small cabbage white (bottom row). The caterpillars were uncolonized (left) or colonized by either the Cotesia glomera parasitoid (middle) or the Hyposoter ebeninus parasitoid (right). The colour of the saliva differs depending on the caterpillar and the species of parasitoid that attacks the caterpillar.

Credit: Erik Poelman

Parasitoid larvae that feed within caterpillars that eat cabbage plants influence the plant via the caterpillar, making the cabbage plant an unattractive prospect for moths looking for a spot to lay their eggs. Together with French colleagues, researchers from the Entomology Laboratory at Wageningen University, part of Wageningen UR, will be publishing their discovery this week in the journal PNAS.

Plants that are gnawed at by caterpillars produce blends of volatiles that attract parasitic wasps, parasitoids. These wasps lay eggs in the caterpillars, after which the parasitoid larvae devour their host. So rather than turning into butterflies, the caterpillars are actually helping to produce a new generation of wasps. So in fact, the parasitoids are rescuing the plants from their attackers. During their development, the parasitoid larvae influence the caterpillars they are developing in and in turn, the caterpillars influence the cabbage plant; and all with far-reaching consequences for the diamondback (or cabbage) moth.

Cabbage plants eaten by cabbage white caterpillars are particularly attractive to female diamondback moths in search of a plant on which to lay their eggs. However, if the caterpillars have been colonized by parasitoids, the plants become less attractive to the diamondback moths. The level of impact depends on the species of parasitoid that is developing within the caterpillars.

To find out exactly how the parasitic wasps alter the cabbage plants, the researchers monitored the activity of 9 genes that are activated when the caterpillars of the small and large cabbage white gnaw the cabbage plant. The researchers used caterpillars that were parasitized with one of three different species of parasitoids. The plants appear to respond differently to two types of caterpillars, but the actual species of parasitoid that is developing within the caterpillar makes a much bigger difference. It is the saliva of the caterpillars that affects the plant's response. Interestingly enough, each individual species of parasitoid has a different effect on the quality of the caterpillars' saliva, which is reflected in the colour of the saliva.

This research carried out by researchers from the Universities of Wageningen and Rennes shows that parasitic wasps that infest cabbage white caterpillars do not only kill the caterpillars, but also make the cabbage plants less attractive to another enemy, the diamondback moth. Diamondback moths throughout the world have become resistant to countless insecticides, and there is an urgent need for alternative pesticides. In the case of cabbage whites, biological pest control gives the cabbage plants extra protection against diamondback moths. Researcher Erik Poelman calls this a 'spectacular' discovery, and adds: "This could help us to develop an environmentally-friendly way of protecting cabbage plants from diamondback moths."

Story Source:

Materials provided by Wageningen University and Research Centre. Note: Content may be edited for style and length.

Journal Reference:

E. H. Poelman, S.-J. Zheng, Z. Zhang, N. M. Heemskerk, A.-M. Cortesero, M. Dicke. Parasitoid-specific induction of plant responses to parasitized herbivores affects colonization by subsequent herbivores. Proceedings of the National Academy of Sciences, 2011; DOI:10.1073/pnas.1110748108

Cite This Page:

Wageningen University and Research Centre. "Parasitoid larvae in caterpillars affect behaviour of moths." ScienceDaily. ScienceDaily, 15 November 2011. <www.sciencedaily.com/releases/2011/11/111115132902.htm>.

How plants sniff out unhealthy neighbors to fight off infection

Date: March 5, 2012

Source: Springer Science+Business Media

Summary:

A new study sheds light on how plants sniff out unhealthy neighbors to fight off infection. People and animals are not the only ones who can smell. Plants are also able to perceive odors, but they process them in a very different way . While insects or mammals smell odors within a second of exposure, plants require much longer exposure times to respond. Then using this information, they react effectively to the odors emitted by infected or infested neighboring plants in order to increase their resistance to pest insects or disease.

People and animals are not the only ones who can smell. Plants are also able to perceive odors, but they process them in a very different way . While insects or mammals smell odors within a second of exposure, plants require much longer exposure times to respond. Then using this information, they react effectively to the odors emitted by infected or infested neighboring plants in order to increase their resistance to pest insects or disease.

The new study by Sarai Giron-Calva, from the Department of Genetic Engineering at CINVESTAV-Irapuato in Mexico, and colleagues is published online in Springer's Journal of Chemical Ecology. Odors emitted by stressed plants can induce resistance to disease in healthy neighbors. While this so-called 'talking trees' phenomenon was identified more than 20 years ago, the mechanism by which plants smell and process odors remains unclear.

To establish both the dose of odors and length of exposure which are required to induce resistance against bacterial infection in plants, the authors exposed lima bean plants to different concentrations of two odor compounds -- nonanal and methyl salicylate (MeSA). Both compounds are known to enhance resistance to bacterial disease in lima beans. They then measured the plants' resistance to the pathogen, after both 6 and 24 hours.

In the case of nonanal, plant resistance was significantly increased after both 6 and 24 hours. Furthermore, there was no difference in induced resistance between the two concentrations of the odor. In contrast, the authors found that the lima bean plants mounted a high level of resistance to bacterial infection after exposure to MeSA over an entire day, but not after short exposure of 6 hours. After 24 hours of exposure, the low concentration of MeSA was as effective at inducing resistance to the pathogen as the higher concentrations.

The researchers conclude: "In contrast to insect or mammals which can respond to odors within a second of exposure, the 'nose' of plants works in a fundamentally different way to perceive odors. Plant to plant signaling in this instance is likely to involve the accumulation of odors in the receiving plant over a long period of time."

Story Source:

Materials provided by Springer Science+Business Media.Note: Content may be edited for style and length.

Journal Reference:

P. Saraí Girón-Calva, Jorge Molina-Torres, Martin Heil.Volatile Dose and Exposure Time Impact Perception in Neighboring Plants. Journal of Chemical Ecology, 2012; 38 (2): 226 DOI: 10.1007/s10886-012-0072-3

Cite This Page:

Springer Science+Business Media. "How plants sniff out unhealthy neighbors to fight off infection." ScienceDaily. ScienceDaily, 5 March 2012. <www.sciencedaily.com/releases/2012/03/120305081256.htm>.

Voicemail discovered in nature: Insects receive soil messages from the past

Date: June 12, 2012

Source: Netherlands Institute of Ecology (NIOO-KNAW)

Summary:

Insects can use plants as "green phones" for communication with other bugs. A new study now shows that through those same plants insects are also able to leave "voicemail" messages in the soil. Herbivorous insects store their voicemails via their effects on soil fungi. Researchers discovered this unique messaging service in the ragwort plant.

Insect cage.

Credit: Image courtesy of Netherlands Institute of Ecology (NIOO-KNAW)

Insects can use plants as 'green phones' for communication with other bugs. A new study now shows that through those same plants insects are also able to leave 'voicemail' messages in the soil. Herbivorous insects store their voicemails via their effects on soil fungi. Researchers from the Netherlands Institute of Ecology (NIOO-KNAW) and Wageningen University (WUR) discovered this unique messaging service in the ragwort plant.

The journal Ecology Letters will soon publish these results.

A few years ago, NIOO scientists discovered that soil-dwelling and above-ground insects are able to communicate with each other using the plant as a telephone. Insects eating plant roots change the chemical composition of the leaves, causing the plant to release volatile signals into the air. This can convince above-ground insects to select another food plant in order to avoid competition and to escape from poisonous defense compounds in the plant. But the impact doesn't stop there.

The new research shows that insects leave a specific legacy that remains in the soil after they have fed on a plant. And future plants growing on that same spot can pick up these signals from the soil and pass them on to other insects. Those messages are really specific: the new plant can tell whether the former one was suffering from leaf-eating caterpillars or from root-eating insects. "The new plants are actually decoding a 'voicemail' message from the past to the next generation of plant-feeding insects, and their enemies," recaps NIOO researcher and first author Olga Kostenko. "The insects are re-living the past." This message from the past strongly influences the growth and possibly also the behavior of these bugs. Today's insect community is influenced by the messages from past seasons.

Kostenko and her colleagues grew ragwort plants in a greenhouse and exposed them to leaf-eating caterpillars or root-feeding beetle larvae. Then they grew new plants in the same soil and exposed them to insects again. "What we discovered is that the composition of fungi in the soil changed greatly and depended on whether the insect had been feeding on roots or leaves," explains Kostenko. "These changes in fungal community, in turn, affected the growth and chemistry of the next batch of plants and therefore the insects on those plants." Growth and palatability of new plants in the same soil thus mirrored the condition of the previous plant. In this way, a new plant can pass down the soil legacy or message from the past to caterpillars and their enemies.

"How long are these voicemail messages kept in the soil? That's what I also would like to know!" adds Kostenko. "We're working on this, and on the question of how widespread this phenomenon is in nature."

The research project was financed by a personal innovation grant of the Netherlands Organisation for Scientific Research (NWO) to Martijn Bezemer from the NIOO.

Story Source:

Materials provided by Netherlands Institute of Ecology (NIOO-KNAW). Note: Content may be edited for style and length.

Journal Reference:

Olga Kostenko, Tess F. J. Voorde, Patrick P. J. Mulder, Wim H. Putten, T. Martijn Bezemer. Legacy effects of aboveground-belowground interactions. Ecology Letters, 2012; DOI: 10.1111/j.1461-0248.2012.01801.x

Cite This Page:

Netherlands Institute of Ecology (NIOO-KNAW). "Voicemail discovered in nature: Insects receive soil messages from the past." ScienceDaily. ScienceDaily, 12 June 2012. <www.sciencedaily.com/releases/2012/06/120612115946.htm>.

Urbanization affects diets of butterflies

Butterflies that are 'picky' about the flowers they feed from may become increasingly dependent on fewer native flower sources with urbanization

Date: August 18, 2016

Source: National University of Singapore

Summary:

Researchers have revealed that most tropical butterflies feed on a variety of flower types, but those that are 'picky' about their flower diets tend to prefer native plants and are more dependent on forests. These 'picky' butterflies also have wings that are more conspicuous and shorter proboscis.

Yellow vein lancer (Pyroneura latoia) butterfly, a flower specialist that feeds on a single native flower species, feeding on flowers of the Leea indica plant.

Credit: Tea Yi Kai

A study led by researchers from the National University of Singapore (NUS) revealed that most tropical butterflies feed on a variety of flower types, but those that are 'picky' about their flower diets tend to prefer native plants and are more dependent on forests. These 'picky' butterflies also have wings that are more conspicuous and shorter proboscis. The reduction in native plants due to urbanisation affects the diet of such butterflies, and researchers suggest that intervention may be needed to manage their preferred flower resources.

These findings are the outcome of a three-year study on how urbanisation affects the diets of tropical butterflies. "Butterfly species exhibit different levels of flower preferences and flower specialisation. Understanding the complex phenomenon of flower specialisation of butterflies is important as butterflies are known to be important pollinators of tropical forests. Changes in vegetation structure due to urbanisation could alter butterfly behavior, and in turn, result in changes in native plant pollination and reproduction," explained Mr Anuj Jain, who conducted the study as part of his doctoral research at the Department of Biological Sciences at NUS Faculty of Science.

"It is worrying that butterflies that are flower specialists may become increasingly dependent on fewer native flower sources. To conserve such butterflies, there is a need to develop intervention measures to maintain the availability of suitable flowering plants," Mr Anuj added.

Results of the study were published online in the journal Biological Conservation in July 2016.

Impact of urbanisation on tropical butterflies

When butterflies hunt for nectar, they collect pollen on their legs and body, which helps in pollination for the reproduction of plants. Studying the flowers that butterflies feed on is critical in understanding the reproduction and dispersal of different types of plants.

"So far, studies on the flower-feeding patterns of butterflies have been concentrated in temperate countries, such as the United Kingdom and Spain, but this area is not well-studied for the tropics. With massive landscape transformation that is happening in the tropics, there is a need to understand flower use by butterflies, to assess the implications on pollination and plant reproduction, as well as conservation of butterfly species," said Associate Professor Edward Webb from the Department of Biological Sciences at NUS Faculty of Science, who supervised the study.

To address this research gap, Mr Anuj collaborated with Assistant Professor Krushnamegh Kunte from the National Center for Biological Sciences in India, and butterfly experts from the Nature Society (Singapore) to look deeper into the flower-feeding patterns of tropical butterflies.

Over a period of three years, the research team surveyed 62 sites in Singapore, which included both forested areas and urban parks, and recorded 3,092 flower visits by 190 butterfly species feeding on 149 plant species.

Some tropical butterflies benefit from urban vegetation while others suffer

The researchers found that among the 190 butterfly species observed nectaring during the study, 30 were flower specialists who are 'picky' about their diets, feeding only on selected flower species, while the rest feed from a wide array of flowers.

A few forest butterflies were found to be critically dependent on single native flower species. One of them is the Yellow Vein Lancer (Pyroneura latoia) butterfly, which fed on flowers of the native plant Leea indica in 74 per cent of feeding observations. The team also found that the Lycaenidae family of butterflies, which is the most extinction prone and most habitat-specialised butterfly family in Singapore, is the most flower-specialised.

Of the 19 butterfly species that made at least 10 flower visits in both forests and urban parks, five species expanded their diet when they are in urban parks, which have more non-native plants compared to forested sites. This suggests that non-native flowering plants may be benefitting some butterflies by providing extra nectar resources.

"Native flowering plants in the forests of Singapore tend to be spatially dispersed and flowering events are short, sporadic and few, except during times of mass flowering. The presence of non-native plants may make up for this shortfall in native flowering events. The impacts of non-native flowering plants can be complex, potentially benefiting generalist species while being detrimental to specialists," explained Mr Anuj.

Flower specialisation and evolutionary adaptation of butterflies

The research team also studied the factors that made butterflies flower-specialists or generalists and found that butterflies that feed on fewer flower species (i.e. specialists) have wings that are more conspicuous.

Mr Anuj said, "Our results suggest that the conspicuousness of the butterflies may be an important evolutionary adaptation to escape predators during feeding. When butterflies are feeding, they tend to be vulnerable to predation. They will need to optimise foraging strategies or morphologies to reduce the time they spend on flowers, which may reduce exposure to predators and may lower predation."

It was also found that butterflies that are flower generalists had longer proboscis lengths than specialists. Possession of a long proboscis is beneficial to butterflies because it widens food choices by allowing access to nectar in deep flowers, which typically secrete more nectar than short flowers.

Future studies to focus on impact of tropical butterflies on plant reproduction

In their current study, the research team could only quantify flower use by butterflies, but did not investigate the impact that the butterflies have on seed production, seed dispersal and establishment of native plants.

To further their understanding on the true costs and benefits of non-native plant species to butterflies in tropical forests, the team hopes to carry out community-level experiments involving multiple plant species over the entire plant reproduction cycle.

Story Source:

The above post is reprinted from materials provided by National University of Singapore. Note: Content may be edited for style and length.

Journal Reference:

Anuj Jain, Krushnamegh Kunte, Edward L. Webb. Flower specialization of butterflies and impacts of non-native flower use in a transformed tropical landscape. Biological Conservation, 2016; 201: 184 DOI: 10.1016/j.biocon.2016.06.034

Cite This Page:

National University of Singapore. "Urbanization affects diets of butterflies: Butterflies that are 'picky' about the flowers they feed from may become increasingly dependent on fewer native flower sources with urbanization." ScienceDaily. ScienceDaily, 18 August 2016. <www.sciencedaily.com/releases/2016/08/160818093319.htm>.

Vagalumes iluminam cavernas e cupinzeiros na Amazônia para atrair presas

08 de julho de 2016

Elton Alisson | Agência FAPESP – Em regiões no Cerrado brasileiro, como no Parque Nacional das Emas, em Goiás (GO), é possível observar durante noites quentes e úmidas na primavera um fenômeno, chamado de “cupinzeiros luminosos”, em que ninhos de cupins irradiam uma luz esverdeada intensa.

A luz é emitida por larvas de vagalumes da espécie Pyrearinus termitilluminans, que expõem seus tórax luminescentes sobre a superfície dos cupinzeiros a fim de atrair insetos voadores para se tornarem suas presas.

Um grupo de pesquisadores da Universidade Federal de São Carlos (UFSCar), campus de Sorocaba, constatou que esses cupinzeiros luminosos também ocorrem no interior da floresta amazônica.

Os pesquisadores também observaram a existência de larvas de vagalumes dentro de cavernas de argila na Amazônia, que exibem luminescência semelhante e com a mesma função das que colonizam os cupinzeiros luminosos.

As descobertas, feitas por meio de projetos apoiados pela FAPESP, foram descritas em um artigo publicado na Annals of the Entomological Society of America.

“Até então só havia relatos de bioluminescência [emissão de luz fria e visível por organismos vivos] em cavernas na Nova Zelândia e na Austrália, onde larvas de uma espécie de mosquito luminescente constroem teias no teto de grutas”, disse Vadim Viviani, professor da UFSCar e coordenador do estudo, à Agência FAPESP.

“É a primeira vez que é relatada a ocorrência de larvas luminescentes de vagalumes no interior de cavernas no mundo”, disse Viviani, que acabou de ser eleito o novo presidente da International Society for Bioluminescence and Chemiluminescence (ISBC) durante o último simpósio anual da entidade, realizado entre os dias 29 de maio e 2 de junho em Tsukuba, no Japão.

De acordo com o pesquisador, havia relatos ocasionais da existência de cupinzeiros luminosos na floresta amazônica e em outros locais da América do Sul, mas esses casos nunca foram investigados.

A fim de certificar a veracidade desses relatos, os pesquisadores começaram a realizar, a partir de 2009, expedições de observação na Amazônia, iniciando por uma região de transição do Cerrado para a floresta amazônica, ao longo do rio Araguaia, até chegar ao norte de Tocantins.

Em seguida, eles visitaram o lado noroeste do estado de Mato Grosso, ao longo do rio Juruena. E, finalmente, foram ao interior do estado do Pará, na cidade de Canaã de Carajás, em razão de informações que obtiveram da pesquisadora Cleide Costa, do Museu de Zoologia da Universidade de São Paulo (MZ-USP), de relatos de geólogos sobre a ocorrência de larvas bioluminescentes em cavernas argilosas na Floresta Nacional de Carajás.

Durante essas viagens, os pesquisadores constataram a existência de cupinzeiros luminosos, habitados por larvas luminescentes de vagalumes das espécies Pyrearinus fragilis e Pyrearinus termitilluminans, em três localidades diferentes no interior da floresta amazônica – nos municípios de Caseara, no Tocantins, Canaã dos Carajás, no Pará, e Juruena, no Mato Grosso – e na cidade de Novo Santo Antônio, no Mato Grosso, situada em uma área de Cerrado.

Além disso, também confirmaram a presença de larvas luminescentes de vagalumes da espécie Pyrearinus pumilus no interior de cavernas argilosas e com solo rico em ferro – chamadas de canga – na Floresta Nacional de Carajás.

“Observamos que as larvas luminescentes de vagalumes encontradas nas cavernas argilosas emitem luz muito provavelmente com a função de atrair insetos voadores para servirem de presas, como fazem as larvas de vagalumes que ocorrem em cupinzeiros luminosos no Cerrado e os mosquitos da espécie Arachnocampa luminosa que povoam cavernas na Nova Zelândia”, comparou Viviani.

Fontes de alimentos

De acordo com o pesquisador, ainda não há uma explicação definitiva sobre a origem evolutiva da colonização dos cupinzeiros ou do interior de cavernas por vagalumes.

O que se sabe é que vagalumes adultos colocam ovos na base dos cupinzeiros e no interior de cavernas e que, ao eclodir, dão origem a centenas de larvas luminescentes que transformam esses ambientes em seus habitats.

A explicação mais provável, contudo, é que como as larvas de outras espécies do gênero Pyrearinus são normalmente encontradas em troncos em decomposição ou no solo e são carnívoras, a associação com cupinzeiro foi uma adaptação vantajosa, pois esses lugares são ricos em cupins e outros insetos pequenos que lhes servem de alimento.

“Nossa hipótese é que as larvas de vagalumes desde cedo se associaram a locais onde havia madeira em decomposição e, consequentemente, tinha cupins. Mais tarde, adaptaram-se aos cupinzeiros situados dentro de ambientes florestais, no interior da floresta amazônica”, estimou.

“É provável que a substituição de áreas de floresta por Cerrado, devido às mudanças climáticas, pode ter resultado na adaptação das larvas de vagalumes a ambientes abertos, onde passaram a exibir uma bioluminescência mais intensa para atrair insetos voadores de lugares mais distantes”, explicou.

Já a adaptação a cavernas pode ter acontecido porque, a exemplo dos cupinzeiros, esses ambientes também têm mosquitos e outros insetos pequenos que se desenvolvem no interior das cavernas ou entram nelas acidentalmente, e que podem servir de alimento às larvas de vagalumes, especula Viviani.

“Em algum momento, essas larvas devem ter se adaptado aos túneis das cavernas de canga, em Carajás, que estima-se que foram formadas por tatus gigantes que entraram em extinção”, disse o pesquisador.

Os pesquisadores fizeram uma análise filogenética molecular preliminar – da relação evolutiva – das larvas luminescentes de vagalumes encontradas nos cupinzeiros e nas cavernas de canga no interior da floresta amazônica.

Os resultados das análises, juntamente com dados ecológicos, indicaram que, além da espécie Pyrearinus fragilis, que habita exclusivamente florestas, existem duas linhagens distintas da espécie de vagalumes Pyrearinus termitilluminans que estão adaptadas para cupinzeiros de Cerrado e de floresta.

A espécie Pyrearinus termitilluminans, por exemplo, foi encontrada em cupinzeiros localizados no Parque Nacional das Emas, em Goiás, e na zona de transição do Cerrado para a Amazônia.

Já a Pyrearinus fragilis foi identificada em cupinzeiros localizados dentro da floresta amazônica. E a Pyrearinus pumilus localizada no interior das cavernas de canga em Carajás, no Pará.

Todas essas espécies de vagalumes Pyrearinus pertencem ao grupo pumilus. “Essas espécies de vagalumes Pyrearinus do grupo pumilus compartilham de um ancestral comum que se associou a áreas ricas em matéria orgânica, preferencialmente com cupins. Algumas espécies acabaram por se adaptar a cupinzeiros e outras a cavernas”, resumiu Viviani.

Banquete de insetos

Segundo o pesquisador, a intensidade da luminescência esverdeada emitida pelas larvas de vagalumes luminescentes encontradas nas cavernas de canga aparentemente é mais fraca do que a de seus parentes próximos, encontrados em cupinzeiros superficiais que, no Cerrado, podem atingir 1,7 metro (m).

Ao contrário dos vagalumes lampirídeos, que geralmente ocorrem em campo aberto e emitem flashes intensos de luz, as larvas luminescente de vagalumes encontradas em cupinzeiros e em cavernas argilosas – que pertencem à família dos elaterídeos, conhecidos popularmente como vagalumes tec-tec ou salta-martins – emitem luz muito intensa e contínua, comparou Viviani.

“Além de maior intensidade intermediária, a luz emitida pelas larvas luminescentes de vagalumes elaterídeos de cupinzeiros e de cavernas é mantida por um tempo muito prolongado”, afirmou.

As larvas de vagalumes de cupinzeiros começam a emitir luz – que é a mais esverdeada entre todos os besouros – no final do entardecer, quando o Sol se põe, e continuam durante as primeiras horas da noite, relatou o pesquisador.

Além da vantagem para si próprias de emitir luz para atrair insetos voadores, as larvas bioluminescentes de vagalumes também acabam por beneficiar todo o microecossistema de um cupinzeiro, por exemplo, e de seus arredores, apontou o pesquisador, conforme já havia sido observado por Etelvino Bechara, pesquisador do Instituto de Química da USP, e Cleide Costa, do MZUSP, com cupinzeiros de Cerrado na década de 1980.

Ao emitir luz, as larvas bioluminescentes de vagalumes também atraem outros animais, como aranhas, sapos e aves, que se beneficiam do banquete de cupins e outros insetos pequenos atraídos pelas pequenas luzes brilhantes.

Posteriormente, os excrementos produzidos pelos animais que se fartaram do banquete de insetos ajudam a fertilizar o solo ao redor do cupinzeiro, que normalmente exibe uma flora mais rica que a dos arredores, disse Viviani.

“Dentro das florestas os cupinzeiros já estão em um ambiente bastante rico em matéria orgânica, onde tem muitas folhas caídas. Mas certamente a atração de presas pelas larvas luminescentes de vagalumes enriquece ainda mais o ambiente em volta do cupinzeiro, criando um microecossistema”, estimou.

Aplicações biotecnológicas

Além do ecossistema, a bioluminescência apresentada por essas espécies de vagalumes que habitam cupinzeiros e cavernas também pode trazer benefícios para a sociedade por meio de enzimas luminescentes (luciferases) e seus substratos (luciferina) que são amplamente utilizados como reagentes bioanalíticos e marcadores celulares em biossensores de poluição e prospecção de drogas anticancerígenas e antibióticos, entre uma vastíssima gama de outras aplicações, apontou o pesquisador.

O grupo de pesquisa liderado por ele na UFSCar é especializado em estudos bioquímicos sobre a estrutura molecular e a função das enzimas luciferases (responsável pela emissão de luz) de vagalumes, sendo um dos líderes mundiais nesta área.

A clonagem e a modificação feitas Viviani de uma enzima luciferase de larvas luminescentes de vagalumes colonizadoras de cupinzeiros no Cerrado – que apresenta a bioluminescência mais azul e mais eficiente entre as luciferases de besouros – resultaram no desenvolvimento de um marcador de células de mamíferos por um grupo de pesquisadores no Japão com os quais colabora.

Várias outras luciferases de besouros clonadas pelo grupo também estão atualmente sendo testadas para o desenvolvimento de biossensores e marcadores celulares pelo grupo do pesquisador na UFSCar.

No último simpósio anual da International Society for Bioluminescence and Chemiluminescence (ISBC), a estudante Gabriele Verônica de Mello Gabriel, que atualmente faz doutorado sob orientação de Viviani e um estágio de pesquisa no National Institute of Advanced Industrial Science and Technology em Tsukuba, no Japão, com Bolsa da FAPESP, obteve uma menção honrosa por sua pesquisa com biossensores luminescentes de pH e metais pesados que mudam de cor de acordo com esses fatores.

“É muito importante estudarmos a biodiversidade de vagalumes porque, além de serem bioindicadores de qualidade ambiental como áreas palustres [pantanosas], cursos de água e florestas, cada espécie apresenta luminescência com características diferentes, como a cor e o tipo de emissão da luz, que também podem ter aplicações biotecnológicas, biomédicas e ambientais diferentes”, afirmou Viviani.

O artigo “First report of Pyrearinus larvae (Coleoptera: Elateridae) in clayish canga caves and luminous termite mounds in the amazon forest with a preliminary molecular-based phylogenetic analysis of the P. pumilus group” (doi: 10.1093/aesa/saw002), de Viviani e Amaral, publicado na Annals of the Entomological Society of America, pode ser lido por assinantes da revista em http://aesa.oxfordjournals.org/content/early/2016/05/30/aesa.saw002/. 

Pesquisadores da UFSCar fazem o primeiro registro no mundo da existência de larvas luminescentes de vagalumes em cavernas no Pará, e relatam a ocorrência de cupinzeiros luminosos no interior da floresta amazônica (Foto: Wikimedia Commons)Link:

Link:

http://agencia.fapesp.br/vagalumes_iluminam_cavernas_e_cupinzeiros_na_amazonia_para_atrair_presas_/23496/

Cidade das formigas

Texto: Victória Flório e Patrícia Mariuzzo | Arte: Charles Rubin
21/5/2014

O inseto dos ovos camaleões

Ovos que mudam de cor para se proteger da radiação UV solar. O inseto Podisus maculiventris é um predador abundante no hemisfério norte e trabalho inédito mostra que seus ovos produzem pigmentos para se adaptar à luminosidade do ambiente.

DESCOBERTA: foi o acaso que levou estudante de doutorado da Universidade de Montreal, Paul Abram, a esta descoberta. Ele forrou uma caixa onde mantinha os insetos com jornal. Em uma das folhas, havia um jogo de palavras cruzadas, com quadrados pretos e brancos.

Abram observou que os insetos puseram ovos brancos nos quadros pretos e ovos pretos nos quadrados brancos das palavras cruzadas do jornal. Intrigado, conduziu um experimento controlado, com folhas de Soja como substrato para os ovos.

As plantas expostas à luz receberam ovos pretos no topo das folhas, mas os insetos botavam ovos claros na parte inferior (menos iluminada) das folhas. Em plantas com pouca iluminação, houve predomínio de ovos claros.

De acordo com os resultados, o inseto sente a luminosidade do meio na hora em que põe os ovos, que recebem a dose necessária de pigmentos (tal como a melanina).

O artigo completo está em:

http://www.sciencedirect.com/science/article/pii/S0960982215006752

Canal Fala Química

http://falaquimica.com/?p=2503

Coleções entomológicas: legislação brasileira, coleta, curadoria e taxonomias para as principais ordens

http://www.alice.cnptia.embrapa.br/alice/bitstream/doc/1013586/1/amabilio01.pdf

Agricultural biodiversity and plant defense: the potential of varietal mixtures for insect pest management

 

 

http://www.bioversityinternational.org/e-library/publications/detail/agricultural-biodiversity-and-plant-defense-the-potential-of-varietal-mixtures-for-insect-pest-mana/

Coleção Entomológica do IOC/Fiocruz lança, online e com consulta gratuita, catálogo ilustrado de abelhas

A Coleção Entomológica do Instituto Oswaldo Cruz (IOC/Fiocruz), que possui um dos maiores acervos de insetos da América Latina, acaba de lançar seu segundo catálogo ilustrado com todos os espécimes-tipo de abelhas depositados em seu acervo. Disponível online e com consulta gratuita, a publicação reúne, em cerca de 140 páginas, informações de mais de 30 espécies coletadas na América do Sul. O catálogo inclui atualizações taxonômicas, fotos dos insetos em diversos ângulos, além de tabelas com as características morfométricas de cada espécie descritas detalhadamente.

“A riqueza de informações disponibilizada neste catálogo pode auxiliar na identificação de materiais coletados em diversas regiões. A divulgação do conteúdo impresso e online visa ampliar o acesso por profissionais e estudantes de instituições de ensino e pesquisa do Brasil e do mundo”, destacou o organizador da publicação e pesquisador visitante do Laboratório de Biodiversidade Entomológica do IOC, Sandor Buys. A iniciativa é fruto da parceria com os professores da Universidade Federal do Paraná (UFPR), Sebastião Laroca e Maria Christina de Almeida. Curadora da Coleção, Jane Costa acredita que “a produção do catálogo possibilita a ampliação da divulgação científica, agiliza o trabalho de pesquisa e valoriza o acervo da Coleção”.

Ainda de acordo com Sandor, o material acompanha as demandas da sociedade. “Tudo o que está relacionado à biodiversidade passa por uma etapa de identificação. Para preservar uma área, por exemplo, é preciso conhecer os organismos que atuam no local e fazer um levantamento do ambiente. Isso permite definir a construção de um parque ou de uma reserva”, afirmou.

Fonte: IOC/Fiocruz

EcoDebate, 01/09/2014

Link:

http://www.ecodebate.com.br/2014/09/01/colecao-entomologica-do-iocfiocruz-lanca-online-e-com-consulta-gratuita-catalogo-ilustrado-de-abelhas/

4 things you can do to help the monarchs

https://www.facebook.com/GMOFreeUSA?fref=photo

Planet of the insects

Explore more visuals like this one on the web's largest information design community - Visually.

7 Productivity Lessons from Ants

Explore more infographics like this one on the web's largest information design community - Visually.

Estudo com formigas avalia recuperação da Mata Atlântica

14/03/2014

Por Ivonete Lucirio

Agência FAPESP – Uma forma de verificar a saúde de um ecossistema é avaliar a variedade de espécies que nele vivem. Pesquisadores da Universidade de Mogi das Cruzes (UMC) valeram-se dessa premissa ao quantificar espécies de formigas de serapilheira em uma região entre as Bacias Hidrográficas do Alto Tietê e do Rio Itatinga, na cidade de Mogi das Cruzes, na divisa com Bertioga (SP).

Serapilheira é uma camada que mistura fragmentos de folhas, galhos e outros materiais orgânicos em decomposição, que fica sobre o solo das matas, formando húmus. O material abriga um rico ecossistema, composto por uma grande variedade de artrópodes, fungos e bactérias. Muitas espécies de formigas que constroem ninhos no solo visitam a região da serapilheira para coletar alimentos.

Ao contrário de formigas generalistas – como é o caso da maioria encontrada em ambientes urbanos –, as que vivem na serapilheira são em geral mais especialistas. Na serapilheira de florestas sem a interferência do homem, ocorrem diversas interações ecológicas que possibilitam a existência de outros pequenos animais que servem de alimento para as formigas.

No caso do estudo “Estrutura das comunidades de formigas de serapilheira em cultivo extensivo da Eucalyptus grandis dunnil Maiden, em áreas de Mata Atlântica”, coordenado por Maria Santina de Castro Morini, da UMC, as formigas de serapilheira foram usadas como um marcador biológico para verificar a capacidade de recuperação de áreas uma vez cobertas por Mata Atlântica nativa.

Na região escolhida para a análise foram pesquisados três tipos de ambientes: áreas em que a Mata Atlântica foi retirada para a plantação de eucaliptos, ainda em atividade; áreas em que o plantio foi desativado entre 28 e 30 anos atrás por pressões conservacionistas ou dificuldade de manejo; e unidades de conservação (UC) com mata nativa.

Nas áreas nunca desmatadas, foi possível encontrar, por metro quadrado, cerca de 25 espécies de formigas de serapilheira – do total de mais de 200 existentes. Nas florestas de eucaliptos, por outro lado, o número não passou de cinco por metro quadrado. “Essa diferença se dá por vários fatores, mas principalmente porque as folhas de eucalipto se decompõem mais lentamente e têm altos teores de tanino, que é tóxico para muitos organismos que servem de alimento para as formigas”, disse Morini, professora do curso de Ciências Biológicas da UMC.

Já em regiões onde a plantação foi desativada há cerca de 30 anos e a Mata Atlântica voltou a ocupar espaço, a média encontrada foi de 18 espécies por metro quadrado – sinal de que a mata foi capaz de se recuperar, assim como a fauna da região. A pesquisadora escolheu estudar regiões em que a plantação estava desativada havia cerca de 30 anos - ehavia várias delas -, permitindo a obtenção de dados mais seguros (por serem coletados em mais de uma área).

Para fazer a contagem, Morini trabalhou de julho de 2010 a julho de 2013 especialmente na região da Bacia Hidrográfica do Alto Tietê. Seu grupo de pesquisadores demarcava áreas de um metro quadrado de serapilheira – fosse em área de plantação de eucalipto, mata nativa ou plantação abandonada – e levava o material para o laboratório, onde as formigas eram contadas. Para cada área estudada foram retiradas seis amostras, totalizando 120 amostras de serapilheira.

Morini trabalhou em sintonia com um grupo de pesquisadores do Museu de Zoologia da Universidade de São Paulo (USP) durante a realização dos projetos “Riqueza e diversidade de Hymenoptera e Isoptera ao longo de um gradiente latitudinal de Mata Atlântica – a floresta pluvial do leste do Brasil” e “Biodiversity of Isoptera and Hymenoptera”, sob a coordenação dos professores Carlos Roberto Ferreira Brandão e Eliana Cancello. “Toda a metodologia que usei foi discutida para que os resultados pudessem ser comparados. Eu participava das reuniões para aprender o desenho amostral e as técnicas de coleta que seriam usadas no projeto deles e assim fazer no meu”, contou Morini.

Estudo sobre a microbiota

Em outro trabalho, intitulado “Diversidade de bactérias e de invertebrados e sua influência sobre a estrutura das comunidades de formigas de serapilheira em áreas de Mata Atlântica”, realizado também entre 2010 e 2013, a pesquisadora avaliou a diversidade de bactérias e de invertebrados e sua influência sobre a estrutura das comunidades de formigas.

A Mata Atlântica na região do Alto Tietê é protegida em áreas de barragens, unidades de conservação (UCs) e propriedades particulares. A pesquisa foi feita em fragmentos dessas áreas buscando avaliar o número de fungos e bactérias das amostras.

As áreas de floresta protegidas pelos órgãos públicos responsáveis pelas barragens e em propriedades particulares que valorizam o conservacionismo têm diversidade similar às UCs – indicando, segundo a pesquisadora, a importância dos fragmentos das barragens e das propriedades particulares para a proteção da biodiversidade da Mata Atlântica. “Minha pesquisa mostra que não apenas as UCs são importantes para o Alto Tietê, mas também as demais áreas; é preciso criar incentivos para que elas não sejam desflorestadas”, diz Morini.

A microbiota, por meio da decomposição do material orgânico, possibilita a existência de outros invertebrados (acarinas e colêmbolos, por exemplo) que servem de alimento para as formigas. É de se esperar que onde há mais microrganismos também existam mais espécies de formigas. A comprovação da hipótese, no entanto, ainda precisa ser feita.

“Ainda não podemos afirmar nada sobre a associação da microbiota e a riqueza de formigas. Esperamos fechar em breve o modelo que foi proposto no projeto”, disse Morini à Agência FAPESP.

Os resultados das duas pesquisas coordenadas por Morini devem ser publicados até o fim deste ano. “Por enquanto, estamos preparando um manuscrito para a Biological Conservation”, disse Morini.

Resultados parciais já renderam publicações como: Undecomposed twigs in the leaf litter as nest-building resources for ants (Hymenoptera: Formicidae) in areas of the Atlantic Forest in the southeastern region of Brazil, de Morini e outros, que pode ser lido na Psyche; Characterization of ant communities (Hymenoptera: Formicidae) in twigs in the leaf litter of the Atlantic Rainforest and eucalyptus trees in the southeast region of Brazil, de Morini e outros, que também está disponível na Psyche; e Occurrence and natural history of Myrmelachista Roger (Formicidae: Formicinae) in the Atlantic Forest of southeastern Brazil, de Morini e outros, publicado na Revista Chilena de Historia Natural.

Imagens

Durante suas pesquisas, Morini fotografou em laboratório e catalogou 235 espécies de formigas que vivem no Alto Tietê, no âmbito do projeto “Coleção biológica da fauna de formigas do Alto Tietê: organização de um acervo fotográfico”.

O resultado poderá ser visto em um catálogo com previsão de publicação para abril de 2014. Além das fotos, haverá textos contextualizando o ambiente em que essas formigas vivem, escritos por vários colaboradores, como Ramon Luciano de Melo, da Universidade Federal do Mato Grosso (UFMT), e Jacques Delabie, da Comissão Executiva do Plano da Lavoura Cacaueira (Ceplac).

A publicação abordará as coleções biológicas e a conservação da biodiversidade. O catálogo está sendo organizado por Morini; Silvia Sayuri Suguituru, também da UMC; Rodrigo Feitosa, da Universidade Federal do Paraná (UFPR); e Rogério Rosa Silva, pesquisador do Museu Paraense Emílio Goeldi. “Quero mostrar para todos, não apenas para os estudiosos, que a formiga é bonita morfologicamente. Ela não é uma praga e ajuda a área de mata. Com essa conscientização, espero que a sociedade ajude a protegê-las também”, diz Morini.

Morini estuda as formigas de serapilheira há mais de uma década e parte das conclusões a que chegou por meio de outros projetos também está no livro Serra do Itapeti: aspectos históricos, sociais e naturalísticos (Canal 6 Editora), organizado por ela e por Vitor Fernandes Oliveira de Miranda, e lançado em 2012.

Os 1.500 exemplares da obra foram distribuídos gratuitamente a instituições de ensino do Alto Tietê e ONGs. Está disponível para download em www.canal6.com.br/site/download. O livro ajuda a fomentar novas discussões sobre o assunto. De acordo com a pesquisadora, os dados sobre biodiversidade que a obra traz estão sendo usados para a criação da Área de Proteção Ambiental (APA) da Serra do Itapeti, na região de Mogi das Cruzes.

Insetos são considerados biomarcadores da saúde de um ecossistema; análise em áreas anteriormente ocupadas por eucaliptos foi realizada por pesquisadores da UMC (foto: Silvia Sayuri Suguituru)

Link:

http://agencia.fapesp.br/18753

Em alagamentos, formigas se unem para formar ‘balsa’ e proteger rainha

21/02/2014

Estudo mostra que filhotes formam base da estrutura.

Estratégia salva integridade da colônia em casos de chuva.

Em situações de alagamento, as formigas procedem a uma ação orquestrada que protege a maior parte da colônia. Elas se juntam, enroscando patas com patas, ou patas com mandíbulas, formando uma pequena “balsa”.

As larvas e as pupas sempre ficam embaixo, formando a base da embarcação. As operárias se distribuem ao longo da estrutura. Já a rainha ocupa o centro, exatamente no ponto mais protegido. A lógica dessa estrutura coletiva foi desvendada por pesquisadores da Universidade de Lausanne e da Universidade de Neuchâtel, ambas na Suíça. A pesquisa foi publicada nesta quarta-feira (19) no periódico científico “PLoS ONE”.

À primeira vista, pode parecer que as larvas e pupas que formam a base da balsa são sacrificadas em benefício da comunidade. Porém, investigações mais aprofundadas mostraram que esses filhotes, na verdade, tem grandes chances de sobrevivência, pois conseguem boiar com mais facilidade do que os outros membros da colônia.

Os pesquisadores observaram que, na presença da água, as operárias começam a coletar larvas e pupas. Segurando-as com as mandíbulas, os filhotes servem de base para a estrutura. Outras operárias se empilham sobre o grupo e, quando o nível da água se eleva, as rainhas se movem para ocupar o centro da pilha. Quando a estrutura toda começa a flutuar, ela geralmente é formada por três a quatro camadas de operárias. O estudo foi feito em laboratório com a espécie Formica selysi.

A pesquisadora Jessica Purcell, da Universidade de Lausanne, explicou que se esperava que os indivíduos que formavam a base da balsa fossem os que mais sofressem mais com a estratégia. “Ficamos surpresos de ver que as formigas sistematicamente colocam os membros mais jovens da colônia nessas posições”, diz Jessica. “Mas experimentos adicionais revelaram que os filhotes são os membros que têm a maior capacidade de boiar da sociedade, e que a estratégia não diminui sua sobrevivência; portanto, a configuração beneficia o grupo a um custo mínimo”, diz. [G1]

Link:

http://www.revistaecologica.com/em-alagamentos-formigas-se-unem-para-formar-balsa-e-proteger-rainha/

Harlequin Ladybugs Escape Enemies While Native Species Succumb

Dec. 4, 2013 — The astonishing success of the alien invasive harlequin ladybird in Britain has given a team of scientists a unique opportunity to investigate a key ecological theory -- the Enemy Release Hypothesis.

7-spot and Pine Ladybird parasitised by Dinocampus coccillanae. (Credit: Richard Comont)

The Enemy Release Hypothesis predicts that when a new alien species arrives into a country or region it is unlikely that the resident natural enemies will attack it.

Writing in the latest issue of the scientific journal Insect Conservation and Diversity the scientists conclude that, in the first ten years of the harlequin ladybird invasion -- the Harlequin arrived in the UK in 2004 -- it was much less likely to succumb to natural enemies (such as predators, parasites and pathogens) than the UK's native ladybird species such as the iconic 7-spot. Such natural enemies have evolved alongside native species and the research showed that they are less able to attack the new arrival.

The result may partly explain why the harlequin ladybird is such a successful invasive alien species -- supporting the notion that the harlequin is the "most invasive alien ladybird on Earth."

Ladybirds are generally not attacked by predators but there are a number of parasites -- species that live in or on another species, so called hosts, deriving nutrients and usually resulting in death of the host -- that exploit them. Ladybird parasites include wasps and flies (such as scuttles flies).

One of the most numerous ladybird parasites is a tiny wasp called Dinocampus coccinellae. It lays an egg inside a ladybird and subsequently hatches into a grub-like larva that devours the inside of the ladybird before emerging to pupate under the adult ladybird. It uses the adult ladybird as a bodyguard which twitches defensively above the small parasitic cocoon. The parasitic wasp emerges and the ladybird host dies.

The researchers monitored Harlequin ladybirds (Harmonia axyridis) and the native 7-spot ladybird (Coccinella septempunctata) for natural enemies over four years, from populations across southern England in areas first invaded by the harlequin ladybird between 2004 and 2009.

The study showed that about one in ten 7-spot ladybirds were parasitized by Dinocampus coccinellae whereas less than one in 100 harlequin ladybirds were parasitized The other common parasites that the team examined also favoured the native species of ladybird over the alien harlequin. The team found no evidence that the close proximity of harlequin ladybirds detracted the parasites from attacking the native species.

Paper lead author Richard Comont who carried out the research as a PhD student at the Centre for Ecology & Hydrology and is now Data Monitoring Officer at the BumbleBee Conservation Trust, said, "It's really exciting to find that native parasitoid species are attacking the harlequin, but they're only doing so in really small numbers -- the native 7-spot ladybird is almost 11 times more likely to be eaten than the harlequin. That really shows in part why the harlequin is increasing so quickly -- there's nothing holding it back."

Co-author Dr Helen Roy from the Centre for Ecology & Hydrology said, "The presence of the harlequin ladybird in Britain has given us the opportunity to test the enemy release hypothesis, a key ecological theory. Our work clearly demonstrates how some alien invasive species such as the harlequin ladybird can escape predators and parasites allowing them to successfully and rapidly spread across a country such as the UK."

Dr Roy added, "We need people to keep sending in records to the UK Ladybird Survey and we would be delighted to hear about any sightings of parasitized ladybirds. Every observation helps us to unravel the story of this alien invader and more broadly to our understanding of invasion biology."

Journal Reference:

Richard F. Comont, Bethan V. Purse, William Phillips, William E. Kunin, Matthew Hanson, Owen T. Lewis, Richard Harrington, Christopher R. Shortall, Gabriele Rondoni, Helen E. Roy. Escape from parasitism by the invasive alien ladybird, Harmonia axyridis. Insect Conservation and Diversity, 2013; DOI: 10.1111/icad.12060

Link:

http://www.sciencedaily.com/releases/2013/12/131204091136.htm

Climate Change May Disrupt Butterfly Flight Seasons

Nov. 21, 2013 — The flight season timing of a wide variety of butterflies is responsive to temperature and could be altered by climate change, according to a UBC study that leverages more than a century's worth of museum and weather records.

Butterfly specimens. (Credit: UBC)

Researchers from UBC, the Université de Sherbrooke and the University of Ottawa combed through Canadian museum collections of more than 200 species of butterflies and matched them with weather station data going back 130 years. They found butterflies possess a widespread temperature sensitivity, with flight season occurring on average 2.4 days earlier per degree Celsius of temperature increase.

"With warmer temperatures butterflies emerge earlier in the year, and their active flight season occurs earlier," says Heather Kharouba, lead author of the paper published this week in Global Change Biology. "This could have several implications for butterflies. If they emerge too early, they could encounter frost and die. Or they might emerge before the food plants they rely on appear and starve."

"Butterflies are also a bell-weather, and provide an early warning signal for how other wildlife may respond to climate change," adds Kharouba, who conducted the research while completing her PhD at UBC, and is now a post-doctoral researcher with the University of California, Davis.

The researchers utilized the day of collection found in records to estimate the timing of flight season for each species, and compared it with the historical weather data.

The study was possible thanks to the massive amount of data housed in museum collections and records. Much of the butterfly data in Canada has been centralized via the Canadian National Collection of Butterflies -- records in British Columbia being the exception. To gather data for this province, Kharouba relied on private collections. Only a small portion of the butterfly specimens found in UBC's Beaty Biodiversity Museum-Vancouver natural history museum are databased.

"Museum collection records are an under-exploited resource of ecological data and can provide a window into the past, and potentially the future," says Kharouba. "We should invest in efforts to properly database and centralize more of these records."

Journal Reference:

Heather M. Kharouba, Sebastien R. Paquette, Jeremy T. Kerr, Mark Vellend. Predicting the sensitivity of butterfly phenology to temperature over the past century. Global Change Biology, 2013; DOI: 10.1111/gcb.12429

Link:

http://www.sciencedaily.com/releases/2013/11/131121135623.htm

Butterflies Show Origin of Species as an Evolutionary Process, Not a Single Event

Oct. 31, 2013 — The evolution of new species might not be as hard as it seems, even when diverging populations remain in contact and continue to produce offspring. That's the conclusion of studies, reported in the Cell Press journal Cell Reports on October 31st, that examine the full genome sequences of 32 Heliconius butterflies from the Central American rain forest, representing five different species.

The evolution of new species might not be as hard as it seems, even when diverging populations remain in contact and continue to produce offspring. That's the conclusion of studies, reported in the Cell Press journal Cell Reports on Oct. 31, that examine the full genome sequences of 32 Heliconius butterflies from the Central American rain forest, representing five different species. (Credit: Marcus Kronforst)

"The butterflies have performed a beautiful natural experiment for us that lets us address important questions about evolution," said Marcus Kronforst of the University of Chicago. "Even as biologists, we often think of the origin of new species as a moment in time when a new species splits from an old one, and this type of thinking is reflected in the evolutionary 'trees,' or phylogenies, that we draw. In reality, evolution is a long-term process that plays out in stages, and speciation is no different."

Kronforst and his colleagues found that the initial divergence between butterfly populations is restricted to a small fraction of the genome. In the case of the butterflies, the key genes are those involved in wing patterning. The butterfly species under study all have very different wing patterns, which are important in the butterflies' mating behavior and predator avoidance.

Comparison of those closely related, interbreeding species to a slightly more distant third species showed that hundreds of genomic changes had arisen rather quickly in evolutionary time sometime after those early differences took hold.

"We find that only a small fraction of the genome is markedly different between closely related species, but then much more of the genome -- more than you'd expect -- shows similar differences between more distantly related species," Kronforst explained. "That indicates that the genetic changes that are important for causing speciation are tightly clustered early in speciation, but not so later on in the process; the overall pattern of genome divergence starts slow and then skyrockets."

The researchers view the process as a kind of tug-of-war between natural selection and gene flow. The result in the case of the butterflies has been a rapid divergence of species, driven by a combination of new mutations and borrowed genes. The butterfly genomes also show that the same spots in the genome have been important in multiple speciation events.

"Beyond butterflies, it is possible that this type of speciation, in which natural selection for ecology causes the origin of new species, has been important in the evolution of other organisms," Kronforst said.

Journal Reference:

Marcus R. Kronforst, Matthew E.B. Hansen, Nicholas G. Crawford, Jason R. Gallant, Wei Zhang, Rob J. Kulathinal, Durrell D. Kapan, Sean P. Mullen. Hybridization reveals the evolving genomic architecture of speciation. Cell Reports, 2013 DOI: 10.1016/j.celrep.2013.09.042

Link:

http://www.sciencedaily.com/releases/2013/10/131031124914.htm

Americans Would Pay to Help Monarch Butterflies

Oct. 28, 2013 — Americans place high value on butterfly royalty. A recent study suggests they are willing to support monarch butterfly conservation at high levels, up to about 6 ½ billion dollars if extrapolated to all U.S. households.

Monarch Butterfly (Danaus plexippus). (Credit: © manuelteles / Fotolia)

If even a small percentage of the population acted upon this reported willingness, the cumulative effort would likely translate into a large, untapped potential for conservation of the iconic butterfly.

Monarch butterfly populations have been declining across Mexico, California and other areas of the United States since 1999. A 2012 survey at the wintering grounds of monarchs in Mexico showed the lowest colony size ever recorded.

"The multigenerational migration of the monarch butterfly is considered one of the world's most spectacular natural events," said Jay Diffendorfer, a USGS scientist and the study's lead author. "However, managing migratory species is difficult because they can cross international borders and depend on many geographic areas for survival."

Much of the decline in monarch numbers has been blamed on the loss of milkweed, the native plants on which monarch caterpillars feed.

"While many factors may be affecting monarch numbers, breeding, migrating, and overwintering habitat loss are probably the main culprits," said Karen Oberhauser, a monarch biologist at the University of Minnesota and a co-author of the study. "In the U.S., the growing use of genetically-modified, herbicide-tolerant crops, such as corn and soybeans, has resulted in severe milkweed declines and thus loss of breeding habitat."

The authors suggest that the universal popularity of monarchs could encourage a market for monarch-friendly plants.

"This is the first nation-wide, published, economic valuation survey of the general public for an insect. The study indicates that economic values of monarch butterflies are potentially large enough to mobilize people for conservation planting and funding habitat conservation," said John Loomis, the lead economist on the study from Colorado State University.

"The life cycle of monarchs creates opportunities for untapped market-based conservation approaches," Diffendorfer continued. "Ordinary households, conservation organizations, and natural resource agencies can all plant milkweed and flowering plants to offset ongoing losses in the species' breeding habitat."

According to the annual survey of the National Gardening Association, households that identify as "do-it-yourself lawn and gardeners" spent $29.1 billion in related retail sales in 2012.

"By reallocating some of those purchases to monarch-friendly plants, people would be able to contribute to the conservation of the species as well as maintain a flower garden," said Oberhauser. "Helping restore the monarch's natural habitat, and potentially the species' abundance, is something that people can do at home by planting milkweed and other nectar plants."

Unfortunately, many plants purchased by gardeners have been treated with systemic insecticides that can kill both pollinators that consume the nectar, and caterpillars, like monarchs, that eat the leaves.

"This study shows that not only might consumers pay more for monarch-friendly milkweeds grown without systemic insecticides in the potting soil, but also that consumers might be more interested overall in buying nectar-producing plants or milkweeds if they knew a small percentage of sales will be donated to habitat conservation," said Diffendorfer.

Journal Reference:

Jay E. Diffendorfer, John B. Loomis, Leslie Ries, Karen Oberhauser, Laura Lopez-Hoffman, Darius Semmens, Brice Semmens, Bruce Butterfield, Ken Bagstad, Josh Goldstein, Ruscena Wiederholt, Brady Mattsson, Wayne E. Thogmartin.National valuation of monarch butterflies indicates an untapped potential for incentive-based conservation.Conservation Letters, 2013; DOI: 10.1111/conl.12065

Link:

http://www.sciencedaily.com/releases/2013/10/131028162959.htm