Insects are the most speciose terrestrial animal group and have evolved communication strategies to prevent interactions amongst related species. Chemical communication is abundantly evident amongst the Lepidoptera (in particular moths) where females often produce a
pheromone that is highly attractive only to conspecific males. Our understanding of the genetic control and evolution of male olfactory and behavioral traits remains somewhat limited. Two closely-related species of moth in the genus Heliothis have proven advantageous for examining
genetic regulation of olfaction/behavior because of their ability to interbreed and produce viable hybrid offspring. Importantly, the pheromonal blends produced by female Heliothis virescens (Hv) and Heliothis subflexa (Hs) differ in their 20 components. The female emissions of each species are well correlated with conspecific male behavioral preferences and the specificities of olfactory projection interneurons (PNs) in the sexually-dimorphic glomeruli that comprise the
macroglomerular complex (MGC) of the male antennal lobe. The number and spatial configuration of MGC glomeruli in the two parental species are essentially identical despite
differences in the pheromonal blends of the two species. Behavioral bioassays conducted in a wind tunnel have revealed that Hs-Hv hybrid males possess novel olfactory characteristics. The observed behavioral differences correspond to changes in the specificities of antennal lobe PNs with no obvious modification of MGC organization. These results suggest that heritable physiological and glomerular-association characteristics of MGC PNs play a pivotal role in governing the behavioral ability of hybrid males to discriminate between specific odor blends.
Supported by the National Science Foundation, IBN-9905683.
Species 1: Lepidoptera Noctuidae Heliothis virescens (tobacco budworm)
Species 2: Lepidoptera Nocuidae Heliothis subflexa
Keywords: neurophysiology, olfaction
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA