ON COMMUNICATION IN THE AFRICAN SUGARCANE BORER, ELDANA-SACCHARINA WALKER (LEPIDOPTERA, PYRALIDAE)

The African sugarcane borer, Eldana saccharina Walker, has a complex communication system between the sexes that is little understood. As in some other members of the Gallerinae, ultrasound is emitted from tymbals on the tegulae of the male moth, which in E. saccharina are buckled by the wing couplers and reset during a characteristic, low-amplitude, type of wing-fluttering. The frequency of the sound extended from 20 to 120 kHz, with peaks between 30 and 80 kHz, in trains of 4-6 highly damped pulses each pulse lasting 100-mu-s. The ultrasound seems to induce wing fanning in the female, and is used for aggression toward other males. It may also act as an attractant of both sexes although in neither laboratory tests nor field trapping was ultrasound used. Scents are released from fore-wing glands of the male during a different, full-amplitude, type of wing fanning, as well as from eversible abdominal hair-pencils. Although the compounds in these presumed pheromones have been indentified in the literature, and functions assigned to them, their, role is not clear. Extracts from neither gland system were attractive on their own in traps but in olfactometer tests, hair-pencil extracts seemed the more attractive to females. During field trapping with live males as bait, many more males were caught than females; therefore part of the message emitted attracts other males to form groups. Bait males with one gland system or the other rendered inactive were less attractive to other males than intact males; but one gland system was as attractive as the other. The numbers of females caught were too few for statistical differences but the hair pencils seemed the more attractive.