PHEROMONE DEPOSITION ON LEAF TERRITORIES BY MALE CARIBBEAN FRUIT-FLIES, ANASTREPHA-SUSPENSA (LOEW) (DIPTERA, TEPHRITIDAE)

Male Caribbean fruitflies apply everted anal membranes associated with pheromone glands to the substrate while on leaf territories. There is a peak in abdominal dipping at the onset of the photoperiod, followed by a decline and then a more extensive period of activity in the seco nd half of the photoperiod. During peak signaling periods, most males had a distinct set of lateral abdominal pheromone glands protruded for most of the time. However, the frequency of anal pheromone gland dipp ing varied considerably over time. Episodes of wing fanning (which may disperse pheromones) and abdomen dipping coincide during a male's ten ure on a host leaf Host-plant leaves were contained for 48 h with sign aling males or immature females or kept without insects. Several, thou gh not all, of the constituents of the pheromone were found on leaves within 1 h of removing signaling males. None of these compounds occurr ed on either type of control leaf. Mature virgin female flies were mor e likely to be found in contact with host leaves that had been previou sly exposed for 48 h to the activities of sexually mature males than w ith unexposed control leaves. There was no difference in the reaction of mature virgin female Pies to unexposed control leaves or leaves pre viously exposed to the activities of other sexually immature female or male flies for 48 h. Presumably, the deposition of pheromones by matu re males accounts for the difference in reactions.