Influence of diet, sex and viral infections on the gut microbiota composition of Spodoptera exigua caterpillars

Gut microbiota plays essential roles in very diverse processes in all organisms, including insects. Previous studies have shown that changes in gut bacterial composition of caterpillars affects to the insecticidal properties of entomopathogens, opening the possibility of improving the use of entomopathogens in pest control by manipulation of the host microbiota To do that, a better characterization of the host gut microbiota and its interaction with other microbial agents is required. Here we have analysed the gut microbiota of larvae from the major pest Spodoptera exigua under different conditions, and the results have revealed a high variability among individuals and a major influence of the environmental bacteria. These observations suggest the lack of a resident microbiota as it was already claimed for other species of caterpillars. In addition, insects naturally infected with viruses showed a different microbiota composition in comparison with virus-free insects and few taxa specifically associated to the infection have been identified.