Insects: neglected victims of climate change

Why?

'Animals such as dolphins, tigers and polar bears play an important role, mainly because they represent the relationship between humans and the natural world,' Hellmann said. 'But if you talk about ecological functions, then insects are the most important animals.'

Why are insects so important in terms of ecology? 'They carry disease, pollinate and have an economic impact on crops and logging,' said Hellmann, a biologist at the University of Notre Dame. In fact, nearly 80% of crops in the world need pollination, and the value of insect pollination is estimated at US $ 20 billion per year in the United States alone. In addition, an interesting fact is that insects are the most numerous species of all species on Earth.

Photo of larvae of Anise Swallowtail butterfly (Papilio zelicaon), one of the organisms that can be influenced by climate change. (Photo: Jason Dzurisin, University of Notre Dame)

They are also particularly sensitive to climate change - like other invertebrates, they are unable to regulate their own body temperature - so they are likened to "tiny thermometers". of nature, ' Hellmann explains.

Research steps

So how do these thermometers react when climate change makes their places too hot or too dry?

Research conducted by Hellmann and Shannon Pelini shows that global warming can affect an insect in different ways and levels at different stages of its life, simultaneously, variable Climate change affects every insect in its own way.

Most importantly, when climate change gets deeper, some insects will get stuck - like fish pushed out of water - in the environment they are used to. Therefore they can become extinct or lose important gene fragments in their populations. While other species can reach cooler climates by moving themselves north.

Anise Swallowtail Butterflies (Papilio zelicaon) mature are sun-dried. (Photo: Jason Dzurisin, University of Notre Dame)

Will these migratory species be able to survive in the unfamiliar environment they have just moved to? In response to this question, Pelini conducted laboratory tests involving the introduction of larvae (worms) of the two climate-exposed butterflies and plants in their territories. , and then adjust the survival and growth rates of these groups.

Coming here in the Proceedings of the National Academy of Sciences (PNAS), she will announce how the above-mentioned butterfly populations live on the fringes of the territory because of climate change, and various factors. may reduce or limit the expansion of northern territory to butterflies.

Hellmann is currently following Pelini's research with examining thousands of genes in the two butterfly species to determine which genes are active and which have been turned off by climate change. These studies are designed to clarify the genetic basis of some insects being able to withstand climate change, while others cannot.

Controversial strategy

The ability of some insects, plants and animals to exist outside their habitats poses a question: whether species are threatened with habitat abused by climate change. Can it be better to move manually to a new place? Hellmann warns that this idea, often referred to as 'artificial migration', or 'human-assisted migration' is still controversial.

'In some cases, artificial movement can be successful on a large scale and save a species from extinction,' Hellmann. 'But in other cases, the migratory species can grow too strongly in new habitats, cause extinction for native species, or even clog water pipes like the mussels that once caused out in the former Great Lakes lake area. ' Such risks have led some scientists not to support the artificial movement of animals.

'Ten years ago, we used to say,' There is no way. Artificial movement is a stupid idea. ' And the best strategy is to find ways to reduce greenhouse gas emissions. But in fact, we cannot afford to reduce greenhouse gases as required.

Biologist Jessica Hellman of Notre Dame University is leading Shannon Pelini, a doctoral student. Hellmann is studying the impact of climate change on pests and many other organisms. (Photo: Matt Cashore / University of Notre Dame)

That is why the research team led by Hellmann, funded in part by the National Science Foundation, has developed a new analytical tool to help policy makers determine whether or not to , when and how to move certain species of plants, animals or insects based on multifaceted benefit calculations.

These calculations include the potential for success of migration, the potential for ecological harm, related adjustments and the cultural importance of impacted species.

David Richardson of Stellenbosch University in South Africa says the tool is a new way to balance the risks of taking action (moving) and not acting ', helping species to overcome the impact of the variable. climate change. Details are published in a recent PNAS paper.

It is necessary to distinguish between conducting artificial migration and bringing pests to a new ecosystem. 'If we assume that a species is capable of being invasive, in other words it could become a threat to species in new habitats, then we will not consider it a candidate for artificial movement, ' Hellmann said.

Species that are most likely to become invasive include: high-growth species, weeds, and predators, such as brown snakes, for example. Species that are less likely to become invasive include species that are threatened, or very specific, or species that humans can control in some way.

'As long as we know for sure that the species moved will not become a harmful invader. That is the core of all the controversy surrounding artificial mobility, ' Hellmann concludes.