IDENTIFICATION, SYNTHESIS, AND BIOACTIVITY OF A MALE-PRODUCED AGGREGATION PHEROMONE IN ASSASSIN BUG, PRISTHESANCUS-PLAGIPENNIS (HEMIPTERA, REDUVIIDAE)

Pristhesancus plagipennis, a large Australian assassin bug, possesses three pairs of dorsal abdominal glands (DAGs). In the male, the anteri or and posterior glands are hypertrophied and secrete an attractant ph eromone. Gas chromatography-mass spectrometry (GC-MS) analyses of male DAG extracts and airborne volatiles emitted from calling males showed the pheromone signature to be dominated by a novel component. Subsequ ent chemical manipulations, GC-MS, and chiral-column analyses establis hed its identity as (Z)-3-hexenyl (R)-2-hydroxy-3-methylbutyrate. Mino r components included 3-methylbutanol, 2-phenylethanol, (Z)-3-hexenol, decanal, (E)-2-hexenoic acid, and three minor hexenyl esters. Bioacti vity studies using laboratory olfactometers and outdoor flight cages d emonstrated attraction by female P. plagipennis to calling males, hept ane extracts of male posterior DAGs and a synthetic formulation of the (Z)R enantiomer of the major ester, alone or in combination with othe r components of male anterior and posterior DAGs. Males were also attr acted to the major ester. The racemate and S enantiomer of the ester w ere not attractive. Contamination of the (Z)R enantiomer with 30-60% o f the E isomer also made the compound nonattractive. This is the first report of an aggregation pheromone in the Reduviidae. The prospects f or pheromonal manipulation of P. plagipennis populations to enhance th e value of this predator in horticultural ecosystems, are discussed.