An aphid circadian rhythm: Factors affecting the release of sex pheromone by oviparae of the greenbug, Schizaphis graminum

Abstract

Adult oviparae of Schizaphis graminum emit a sex pheromone from scent plaques on the metathoracic tibiae, as do oviparae of other aphid species. By allowing males to walk along a wire walkway, a turning response and an increased rate of antennation were observed when the aphids were within 1–2 cm of a pheromone source. Adult males responded but 4th instar larval males did not. The onset of the release of the pheromone by the oviparae is triggered by the initiation of the light phase in a LD-cycle, and is governed by a circadian rhythm with a free-running period of 25.6 hr under continuous illumination of 15 lx. Daily pheromone release peaks 4–7 hr after lights-on and reaches a maximum on days 6–8 of adulthood.