Population Genomics and Ecological Adaptation of a Phytophagous Insect Pest and Their Implication on Insect Management

In the current work, we are interested in studying population genomics of a phytophagous insect species Diatraea saccharalis, which is a hazardous pest for sugarcane and maize in Brazil. The species exhibits insecticide resistance and potentially presents host-associated interbreeding populations. We expect to access the consequences of geographical and host selection on the population genetic structure and to develop novel pest control strategies based on the ecological and evolutionary knowledge of D. saccharalis. A pilot study was conducted using sugarcane borers from corn and sugarcane (Pavinato et al, in press) and a set of microsatellite markers developed for the species (Pavinato et al 2013). Based on pairwise differentiation this study showed that borers from sugarcane and corn share little genetic similarity, suggesting limited interbreeding and gene flow between the subpopulations. Indeed, a clustering analysis indicated the presence of two populations largely dependent on the host, although was not completely. Two approaches of next generation sequencing (RADtag and GBS) were also tested in collaboration with MCIC/OARDC – The Ohio State University. We investigated the genome of six samples (three from sugarcane and three from corn) and generated over 100 million base pairs of DNA sequence. The data allowed genomic characterization and gene identification via comparative genomics. Preliminary analysis showed that genomic differentiation is related to the host plant that samples were collected. With this approach we will better estimate the amount of interbreeding among populations, and identify candidate genes that may be involved in local (insecticide resistance) and host adaptation.