Adapative responses of insects to anthropic pressures

The RADIANT project, selected as an emerging project in 2016, took place in 2017-2019.       Project leaders: Myriam Harry (EGCE) and Carmen Bessa-Gomes (ESE)

Partners

• in BASC: GQE Le Moulon
• non academic: Terre & Cité

In the context of the rapid rate of global changes, the anthropization constitutes a major selective force, which strongly impacts living organisms. The radiant project proposed to examine how insects adapt to rapid global changes. We have chosen to focus on insects because due to their short life cycle, insects develop rapid ecological and evolutionary responses to land use changes. Moreover, insects can have major impacts on socioecosytems, insects being associated with both ecosystem services and disservices. 

The impact of human disturbance on insect communities will be evaluated by focusing on two model systems: (1) pollinating insects and their interaction with plants, through the evaluation of the plant-pollinator network, by measuring insect species richness, species distribution and assemblage, and by analysing features of the plants involved in the interaction; (2) insect vectors and their human interaction by studying chemosensory genes involved in habitat or host attraction. 

Results 

Insects that significantly contribute to vital ecological services such as pollination, on which both humans and ecosystems depend, could be affected by human disturbances, with the decline of their populations and diversity. In this context of urbanization, domestic gardens may constitute a potential refuge for biodiversity. We examined the functional floral diversity used by pollinators in private domestic gardens in urban areas. According to our analysis, the functional diversity of floral traits within gardens was superior to that of spontaneous flora in the urban environment. Moreover, the contribution of a given genera to the floral functional diversity was negatively associated with its frequency, with rare genera contributing the most. This should have a high impact on pollinators and our analysis indicate that insects use a higher functional and specific diversity inside domestic gardens than outside of them, on both common and rare flowers. 

But adaptation to anthroposystems can result in the spread of disease vectors, entailing negative impacts on human health. Some species blood sucking bugs (Triatominae) have invading human dwellings and are vectors of Trypanosoma cruzi, the causative agent of Chagas disease in humans, endemic to Latin America. By sequencing the whole genome of nine species from wild and anthropic habitats, we annoted the chemosensory genes especially the gustative and olfactive receptors that allow the insects to interact with their environment. The study of the receptor evolution showed the occurrence of gene copies (duplications) in some species but without link with the habitat while positive selection was evidenced for some receptors according to. Further studies will be performed to characterize the receptor functions with an applied perspective of insect regulation in human dwellings. 

===> The researcher explains in VIDEO the RESULTS of this part of the project (LabEx Scientific Days, January 2021)

In the aftermath of the Radiant project, we have proposed three PhD projects, two concerning pollinating insects and their interaction with plants (2018-2021, ED SdV, SEVE) and one dealing with the evolution of chemosensory genes in Chagas disease vectors (2019-2022, Ed SDSV Univ Paris Saclay). We are also applying for ANR funding to pursue our research on the role of private gardens as biodiversity refuges.