EAG AND BEHAVIORAL-RESPONSES OF THE LARGER GRAIN BORER, PROSTEPHANUS-TRUNCATUS, AND ITS PREDATOR, TERETRIOSOMA-NIGRESCENS, TO THE BORER-PRODUCED AGGREGATION PHEROMONE

Electroantennogram (EAG) and behavioural studies were conducted with P rostephanus truncatus (Horn) (Col.: Bostrichidae) and the predatory be etle, Teretriosoma nigrescens Lewis (Col: Histeridae) in regard to the ir responses to the components of the prey-produced aggregation pherom one. There were hardly any differences between species or sexes regard ing perception thresholds. In field and olfactometer experiments, fema le P. truncatus were more responsive to the pheromone than males, and both sexes reacted more strongly to the minor pheromone component, T2, than to T1. Sex ratios among trap catches of I: nigrescens were sligh tly male-biased. .The predator did not differentiate behaviourally bet ween the pheromone components.