GENETIC AND DEVELOPMENTAL MECHANISMS UNDERLYING INSECT OVIPOSITOR VARIATION

The plant-penetrating ovipositor is arguably the most economically important animal organ. To reproduce successfully, a female insect must be able to lay her eggs into a suitable substrate using her ovipositor. Modifications to one or more ovipositor traits can alter ovipositor form and function, permitting colonization of new environments. As such, an understanding of the genetics underlying ovipositor traits could give insight into how insect pests colonize and spread to new plant hosts. While a handful of studies have investigated candidate genes and pathways underpinning ovipositor variation, these studies are still too limited to draw general conclusions about the genetics of the insect ovipositor. To help fill this knowledge gap, the overarching goals of this project are to: 1) identify candidate genes involved in ovipositor development; and 2) infer how changes to the function of these genes produce variation in form and function. Fulfilling these research goals will increase our knowledge of the proximate mechanisms that produce ovipositors and ovipositor variation. This knowledge can be used to formulate novel pest monitoring and management strategies and will provide opportunities to train undergraduates in skills pertinent to careers in STEM. To achieve these goals, the project uses a pair of economically important pine sawfly species (Neodiprion lecontei and Neodiprion pinetum) to:1. Describe the genetic architecture of insect ovipositor traits that differ between two pine sawfly species that are adapted to different pines; and2. Investigate the genes and pathways responsible for forming the insect ovipositor and identify candidate genes for adaptive differences in ovipositor morphology.To fulfill Objective 1, ovipositor traits will be measured in a set of recombinant hybrid females and quantitative trait locus mapping will be used to describe the number, location, and effect size of loci that contribute to variation in these traits. To fulfill Objective 2, RNA sequencing will be used to profile gene expression across key stages of ovipositor development in both species and look for genes that differ in expression across species and development.