Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/1998
Publication Date: N/A
Interpretive Summary: Damage from insects that are pests of crops can be reduced through the use of sex pheromones that disrupt mating. Disruption of mating by the cabbage looper and other noctuid pests in the field commonly is thought to require a complete mixture of all of the sex pheromone components emitted by females. ARS Scientists at the Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL, discovered that although the female cabbage looper emits at least six compounds in its pheromone blend, only (Z)-7-dodecenyl acetate, the major component, is required to elicit all of the behaviors commonly associated with attraction of males and mating. Two additional pheromone components, (Z)-7-tetradecenyl acetate and (Z)-9-tetradecenyl acetate, for which there are specialized receptors in the antennae of male moths, play only a minor role in sex attraction and mating by cabbage loopers. These results suggest that for the cabbage looper, and possibly other noctuid pests with multiple component pheromone systems, the so-called minor pheromone components probably are not necessary to achieve suppression of mating when broadcast in high doses in cropping environments. Using only one pheromone component for control of mating would greatly simplify the formulation process and reduce the cost of mating disruption as a control strategy for cabbage looper and other crop pests.
Technical Abstract: Laboratory and field assays establish a function for (Z)-7-tetradecenyl acetate and/or (Z)-9-tetradecenyl acetate in perception and discrimination of sex pheromone by the cabbage looper moth, Trichoplusia ni (Hubner). While laboratory assays failed to establish unequivocally a role in discrimination of these two compounds at airborne concentrations that normally are found downwind of a female, field trap assays successfully did so. Even when wind tunnel airborne concentrations of either of these components alone or together exceeded that of a female by 1000X, no clearly defined functionality of these two compounds in male flight behavior was observed. Unpaired field traps baited with (Z)-7-dodecenyl acetate (Z7-12:Ac) alone captured more males than any mixture, demonstrating that either or both of the two 14-carbon acetates are discriminated. When paired, a plume of Z7-12:Ac was discriminated from a plume containing a six component mixture, however, the result was a reduction in the number of moths trapped by Z7-12:Ac, not an enhancement of the number captured by the mixture, a result previously observed. The data are consistent with a notion that one or both of the 14-carbon acetates affect some as yet unobserved close-in behavior(s) following contact with the female. There is no evidence that they enhance the active space of the pheromone plume as would be evident by captures exceeding that of Z7-12:Ac alone.