SFB-TRR 212

Role of niche choice in rapid host adaptation of Colorado potato beetle

In a heterogeneous environment, individuals can have different responses and select different microenvironments (niche choice) that increase their fitness. While evolutionary theories predict that individual niche choice can facilitate rapid adaptation in a heterogeneous environment and maintain genetic diversity, direct empirical evidence is rare. This is mainly due to the difficulties in directly assessing multi-generational fitness consequences of niche choice in evolutionary processes. As genetic trade-offs, pleiotropy and microbiota can also confound and affect niche choice, it remains currently unclear to which extent individualised niche choice can contribute to rapid adaptation and the maintenance of genetic diversity. To address these questions, we will investigate how niche choice affects the evolutionary process of insecticide resistance and gut microbiota in Colorado potato beetles (Leptinotarsa decemlineata, CPB), using an integrative approach that involves experimental evolution, trait manipulation, metagenomics and individual-based modelling. For the niche choice behaviour, we will focus on oviposition choice, one of the most important traits of maternal care in phytophagous insects.

Specifically, we will evolve CPB populations that consist of six genotypes in a greenhouse for twelve generations under a full factorial design: presence/absence of host plant differences and presence/absence of oviposition choices. We will quantify the evolutionary changes in oviposition choice, host adaptation and population fitness. Then, we will determine the effects of oviposition choice on genomic features and microbiota using a high-throughput sequencing approach. Finally, we will use an individual-based modelling approach explore under which conditions oviposition choice affects host plant adaptation.

We hypothesise that

1. In the presence of insecticide-treated plants, oviposition choice to insecticide-treated plants will increase over generations
2. Oviposition choice facilitates rapid host plant adaptation when different host plants are present
3. The effects of oviposition choice on host plant adaptation are determined by: i) differences in heritable oviposition preferences within the population; ii) mechanisms of oviposition choice; iii) levels of niche differences; iv) genetic architecture of the oviposition choice and performance

The outcomes will shed light on how phytophagous insects rapidly adapt to different host plants in nature and may facilitate the development of sustainable crop management strategies, a pressing issue in the society.