|Chemical signaling investment in the gumleaf skeletonizer moth Uraba lugens Walker|
|Hieu Pham1,2, Kathryn McNamara1, Mark Elgar1. 1The University of Melbourne, Melbourne, VIC, Australia; 2Vietnam National University of Agriculture, Hanoi, , Vietnam
Variation in chemical signaling is predicted for sex-pheromones that convey more than the signaler’s location, but also provides information about the signaler and hence have a role in sexual selection. Using the gum leaf skeletonizer moth, Uraba lugens, we investigated experimentally how larval population density and adult age influence the calling behaviour of virgin females. Older, virgin females typically commence calling earlier in the evening than younger females, and the likelihood of a female calling during the night declined significantly four days after eclosion. Binary choice experiments, using a Y-maze olfactometer, revealed that virgin males prefer the odour from younger than older females, perhaps in response to pheromone concentration. Female calling is influenced by their larval experience: adult females from high density larval populations commenced calling earlier, and appear to call more ‘loudly’. Olfactometer assays revealed that males prefer females from high density than low density larval populations. Our experiments highlight the largely overlooked capacity of females to adjust their signaling of sex-pheromones in chemical communication systems.