Meeting Abstract
The Pea Aphid, Acyrthosiphon pisum, exhibits a remarkable adaptive response to seasonal changes in photoperiod. In spring and summer, aphids reproduce asexually, yielding large numbers of genetically identical female offspring. The longer nights accompanying the fall induce these asexual aphids to produce sexual males and females, which mate to lay frost-resistant eggs. These eggs diapause through the cold winter months, hatch into asexually reproducing females in the spring, and the cycle continues. Pea aphid populations have been shown to exhibit latitudinal variation in this photoperiod response, presumably reflecting local adaptation to variation in the timing of the first frost (e.g., Smith and MacKay, 1990). Populations from the southern United States have been reported to exhibit attenuated photoperiod responses or to have lost the ability to produce sexuals altogether. Here we describe a previously detected difference in the photoperiod response between strains from New York and Arizona. With an eye toward understanding what underlies this difference, we also describe differences in how these strains respond to Juvenile Hormone, which has been implicated in the induction of asexual fate (e.g., Corbit and Hardie, 1985; Ishikawa et al., 2012). Additionally, our attempt to inhibit JH using Methyl Linderone failed to induce sexuals as predicted, but still holds potential for furthering our understanding of the mechanism and evolution of this polyphenism. Smith and MacKay 1990. Latitudinal variation in the photoperiodic responses of populations of pea aphid (Homoptera: Aphididae). Environmental Entomology 19: 618-624. Corbit and Hardie 1985. Entomologia Experimentalis et Applicata 38: 131-135. Ishikawa et al. 2012. Insect Mol Biol 21: 49-60
