Geographic and Temporal Variation in Moth Chemical Communication

Abstract

In moth pheromone communication signals, both quantitative and qualitative intraspecific differences have been found across geographic regions. Such variation has generally been hypothesized to be due to selection, but evidence of genetic control of these differences is largely lacking. To explore the patterns of variation in pheromone signals, we quantified variation in the female sex pheromone blend and male responses of two closely related noctuid moth species in five different geographic regions for 2-3 consecutive years. We found significant variation in the ratios of sex pheromone blend components as well as in male response, not only between geographic regions but also within a region between consecutive years. The temporal variation was of a similar magnitude as the geographic variation. As far as we know, this is the first study reporting such temporal variation in moth chemical communication systems. The geographic variation seems to at least partly be controlled by genetic factors, and to be correlated with the quality of the local chemical environment. However, the pattern of temporal variation within populations suggests that optimization of the pheromonal signal also may be driven by within-generation physiological adjustments by the moths in response to their experience of the local chemical environment. Kirkpatrick and Ravigne 2002). However, the evolution of behavioral isolation is poorly understood (Coyne and Orr 2004). To gain insight into the evolution of prezygotic behavioral isolation it is essential to quantify intraspecific variation in the premating signals, on which selection may operate, and biotic and abiotic factors that contribute to this variation.Premating signals are generally hypothesized to be under stabilizing selection

Within-population variability in a moth sex pheromone blend: genetic basis and behavioural consequences

“…Geographical variation has been found both in female signals [34][35][36][37] and male responses [22,23,38]. This suggests that moth sex pheromone signals and behavioural responses are affected by local environmental factors, although this variation may also be due to environmentally independent sexual selection.…”

Managing resistance to Bt crops in a genetically variable insect herbivore, Ostrinia nubilalis

“…However, as with IRM plans for O. nubilalis, differences in host utilization between possible races of cotton pests have not been carefully considered. Research indeed points to the possibility of pheromone races within Helicoverpa armigera, the Old World sister species of H. zea (Tamhankar et al 2003, Cho et al 2008, and to variation in pheromone composition and male response in Heliothis virescens (Groot et al 2009). Given the large differences we observed for unstructured refuge utilization between O. nubilalis pheromone races and the potential impacts on Bt-resistance evolution and IRM, more research into possible races of cotton pests appears warranted.…”

Identification and field evaluation of a new blend of the sex pheromone of Hypsipyla grandella

“…The compounds Z3-16:OAc and 16:OAc were not identified in gland extracts obtained from H. grandella females in the present study. These different blends identified in populations from Cuba and Brazil might indicate specific geographic sex pheromone blends originated by reproductive isolation of H. grandella, as it has been shown for other Lepidoptera, when geographical isolation conduced to variance of sex pheromone blends (Groot et al, 2009).…”

“…The higher efficiency of the four component blends could be explained because the major components are used by male moths at a long distance, and generate an initial attraction response in males, while minor components should play a role in approaches and courtship (Zhang et al, 2012). In the field experiment set in Garça, SP, Brazil, the traps containing the four compounds captured 10 H. grandella males, over 28 days, and the control traps captured only 1 male (c 2 = 15.25 df = 1, p < 0.001) (Linn Jr. et al, 1984;Groot et al, 2009). …”