Insects rely critically on their olfactory system for finding mates and host plants. Odor cues are detected through binding of chemical signals to odorant receptors (ORs) expressed in olfactory neurons. OR gene families follow a birth-and-death evolutionary process by which insects can adapt to detect new odors through gene duplication events. In mammals, gene duplications in specific OR families correlate with the evolution of herbivory, suggesting adaptation to species’ ecological niche. Insects use a diversity of host plants, but little is known about how OR gene family evolution is affected by a species’ diet breadth. To investigate this, we conducted RNAseq on western (WCR), northern (NCR), and southern corn rootworm (SCR) neonates and adult antennae, given their natural variation in host plant breadth. We hypothesize that expanding diet breadth would correlate to OR gene family expansions. This approach allowed us to determine how many OR genes are possessed by each rootworm species, and to compare OR gene expression levels between the life stages of each species. These results provide insight into the evolution of this gene family in the context of host diet breadth in this genus of important agricultural pests.
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