Chemoecological studies on the reproductive behaviors of the darkwinged fungus gnat, Bradysia paupera (Diptera: Sciaridae)

摘要

From the chemoecological studies in this paper, the acquired knowledge related tothe reproductive behaviors of the darkwinged fungus gnat, Bradysia paupera, canbe summarized as follows:1. Rearing single pregnant females clarified that this species reproduces71unisexual offspring and has a preference for fungus as food.2. Mating behaviors of B. paupera consisted of a series of stereotyped malebehaviors including intermittent wing fanning (WF), walking with a zigzagapproach (ZA) while continuing WF, abdomen curling (AC) forward beneaththe thorax while using his claspers to grab the female abdomen, pivoting 180degrees around body axis and mating occurrence (MO).3. Female flies emit volatile sex pheromone from the body surface from thelater pupal stage until death. Female cuticular sex pheromone evokes aseries of copulating behavior and causes strong chemotaxis flight in malesirrelative of the dial periodicity.4. Male flies begin sexual responses 30 min after adult eclosion and responseincrease to a maximum at 2 hr after emergence.5. Low light intensity depresses male flight activity, but not other locomotoractivity, low illumination has no affect on close range mating behavior.6. Properly setting of antenna preparations and use of the correct saline allowsfor recording of electrophysiological responses from tiny antennae of male B.paupera based on ordinary amplifier facilities.7. n-Aldehydes of C6-C18, 2-ketones of C16-C21 and n-hydrocarbons ofC10-C26 were identified from female cuticular lipids. 2-ketone of C16-C21and n-aldehydes of C6-C9 are also common in male cuticular lipids.8. Male antenna responded with comparatively more sensitivity to n-aldehydesthan 2-ketones and n-hydrocarbons. In n-hydrocarbons males were moresensitive to carbon chains of C11-C12 than longer or shorter ones. Femaleantennae were more sensitive to food related compound s than extracts of amate.9. n-Aldehydes of C10-C13, n-hydrocarbons of C11-C13 and other chemicalswith structure similar to undecanal elicited typical sex pheromonalbehaviors in males. Among these substances undecanal was the most activecomponent.10. An n-undecanal and n-aldehyde mixture trapped significantly more malesthan females in preliminary field tests.11. Trace amounts of EAD active components important for sex pheromonalactivity remain to be identified.