EMERGENCE AND CALLING RHYTHMS, AND MATING BEHAVIOUR OF THE ORANGE WHEAT BLOSSOM MIDGE, SITODIPLOSIS MOSELLANA (GÉHIN) (DIPTERA: CECIDOMYIIDAE)

In laboratory and field observations, male and female orange wheat blossom midge, Sitodiplosis mosellana (Géhin), emerged in late afternoon and early evening, with males emerging 1–2 h before females on average within a given day. Under laboratory conditions, males also emerged on average 0–3 days before females in three different experiments. Within 1 h of emergence, virgin females began to extend their ovipositors much of the time. This behaviour ceased upon mating, and was presumed to be calling behaviour: behaviour associated with pheromone release. Calling behaviour exhibited a daily rhythm both under controlled and field conditions. Females gradually increased the time spent calling in the last few hours of the photophase and called more than two-thirds of the time during the scotophase. Mating was preceded by wing vibration in the male prior to and during a walking approach. Receptive females spread their wings which facilitated mating. Mean duration of mating was 171 ± 15 s (±SE).