Bemisia tabaci MEAM1 gut-associated bacteria profiles during host-plant adaptation process

Polyphagous insects require an ability to overcome different sets of host plant defense compounds. In general, during host-plant switching, there is a quick response of the insect, which shows a reduced performance that only rebounds few generations later. Natural selection (a slow process) seems not be the main force driving this relatively short-term adaptation. Indeed, phenotypic plasticity and host-gut bacteria interactions are fast processes that could be involved in the host switching process. Gut-associated bacteria can help the host by processing the food and/or degrading the plant's defense compounds.The whitefly Bemisia tabaci, a tiny phloem-feeder, is considered an important polyphagous pest species. Reported microbiomes of B. tabaci are dominated by bacterial endosymbionts. However, because insects' gut microbiota can play a major role in host-plant adaptation and are mainly acquired from the diet/environment, we hypothesized that B. tabaci might acquire environmental bacteria that can provide different benefits/costs related to host adaptation. Accordingly, our goal was to explore the putative role of gut bacteria in the plant-adaptation process of B. tabaci under field conditions.We conducted a field-like assay by following the adaptation process of a B. tabaci population switching from watermelon (suitable host) to pepper (unsuitable) along four generations. Each generation, we collected samples for gut dissections (cDNA 16S rRNA amplicons) and performance assays (offspring survival). Amplicons were generated using a blocking strategy to decrease endosymbionts' load and analyzed with USEARH and phyloseq. Our results shown that B. tabaci adaptation to pepper took 2-3 generations but also some microbiome differences between watermelon/pepper populations. Genera significantly associated with watermelon or pepper diets and with generational time were identified. These data suggest that gut bacteria might help B. tabaci to adapt to new host plants.