Inhibition of Carpophilus freemani Dobson (Coleoptera:  Nitidulidae) Aggregation Pheromone Response by a Z-Double-Bond Pheromone Analog

Males of Carpophilus freemani Dobson (Coleoptera: Nitidulidae) produce an aggregation pheromone that attracts beetles of both sexes. The major component of the pheromone was previously identified as (2E,4E,6E)-5-ethyl-3-methyl-2,4,6-nonatriene. The response of C. freemani to this pheromone in a wind tunnel bioassay was inhibited 26−47% (P < 0.01) by a 10-fold excess of (2E,4E,6Z)-5-ethyl-3-methyl-2,4,6-nonatriene, a double-bond configurational isomer. This artifact of synthesis is not produced by C. freemani and does not attract C. freemani. In the presence of a synergist, significant inhibition was not observed with equivalent amounts of pheromone and pheromone analog. Although technical-grade pheromone used to monitor C. freemani in the field contains 8−30% of the pheromone analog, this amount of the analog is insufficient to cause significant inhibition in laboratory wind-tunnel bioassays. Keywords: Triene; hydrocarbon; Coleoptera; Nitidulidae; Carpophilus freemani; Freeman sap beetle