Mating behavior and its regulatory factors in the black fungus gnat, Bradysia paupera (Diptera: Sciaridae)

Abstract

In order to develop a new strategy for control of B. paupera, a serious pest insect in production of mushroom, Agaricus bisporus the mating behavior and related regulatory factors were elucidated in laboratory experiments. Mating behavior was analyzed by observation of 75 pairs of cultured flies. The typical mating sequence was: 1) beginning of male intermittent wing fanning (WF), 2) walking in a zigzag approach (ZA) while continuing WF, 3) abdominal curling (AC) forward beneath the thorax while opening claspers to grab female abdomen when near the female, 4) pivoting 180 degrees around body axis (P 180), 5) mating occurrence (MO). This sequence was very stereotypical whereas the females exhibited no characteristic synchronous actions. Mated females refused copulation with subsequent male copulation attempts by kicking the male off with the hind legs or escaping the males mating attempts. Bioassay results demonstrated that a female produced volatile sex pheromone evokes typical male copulating behavior. The threshold activity of the crude female extract eliciting WF and ZA in males was shown to be 2×10-3 female equivalents (FE) in the tube assay. Attractive activity of female extract was corroborated in wind tunnel assays. Male flies showed WF, ZA, and AC responses to all parts of the female body. Effects of female age on male responsiveness to pheromones seemed non-critical, because males demonstrated all responses (WF, ZA, AC) whenever exposed to females from the teneral period to 3 days after emergence. Males responded to melanized pupae with WF and ZA. In male flies, sexual responses began 30 min after adult eclosion, and increased to a maximum 2 h after emergence.