Evidence for the existence of a male-produced aggregation pheromone secreted from the prothoracic femoral setiferous sex patch ofTribolium castaneum is reported. Both sexes were attracted toca. 60 ng of crude secretion. Males and females perceive the pheromone on the day of emergence while perception differs between the sexes: male response reaches a maximum on day 1 posteclosion, when tested at <1, 1, and 30 days; females show a maximum response at 30 days posteclosion. Behavioral responses to pheromone odors and a complex Chromatographic profile are reported.

A dual-choice pitfall bioassay was used to demonstrate the existence of a male-produced aggregation pheromone in the maize weevil. Both males and females showed a highly significant preference for extracts of disks exposed to wheat-feeding males over extracts of disks exposed to wheat kernels only. Neither sex responded significantly to extracts from females. Mating did not reduce pheromone release by males. Response by virgin females to pheromone was significantly higher than response by mated females, but males of either mating status responded equally well. There was no apparent daily periodicity in the responsiveness to pheromone. Rice and maize weevils showed a strong interspecific cross-attraction. Granary weevils of both sexes responded well to maize weevil extracts, but only females showed a significant response to rice weevil extracts. Neither maize nor rice weevils responded significantly to granary weevil extracts.

A scanning electron microscopy study was made of the male setiferous sex patches and analogous structures in 11 families of Coleoptera (Anthribidae, Bruchidae, Ciidae, Cleridae, Coccinellidae, Dermestidae, Leiodidae, Ptinidae, Staphylinidae, Tenebrionidae, and Ostomatidae). These secondary sexual characters appear to have several features in common including relatively long, often ridged, setae, cuticular ducts (frequently cribriform pore plates), and the production of a secretion. It is suggested that these structures may all be concerned with the production, release, and dissemination of pheromones.

No abstract

Evidence for a male-produced aggregation pheromone inSitophilus granarius is reported. Hexane extracts of Tenax®-trapped volatiles from males held on wheat were attractive to both sexes in a multiple-choice olfactometer and pitfall bioassay chamber. A quantitative relationship existed between days of insect exposure on disks and degree of responsiveness. The maximum response was to 35 insect-day-equivalents. Diel-related activity showed both sexes responsive during photophase and nonresponsive during scotophase.