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Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/30/2000 Publication Date: 1/1/2001 Citation: N/A Interpretive Summary: Biorational insect control by means of sex pheromones is dependent on both the amount of active ingredients emitted within the control area and how much it takes to disrupt vital male behaviors to mate. Heretofore, the relationship between the amount of active ingredients necessary to disrupt mating has been considered complex and theoretically required a large amount of active material. Now, work done at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Fla., demonstrates that the fervor of the male and his discovery of the female is simply related to the amount of pheromone that is detected. Consequently, there is a substantial narrowing of the difference between the amount of the ingredient which is theoretically needed and that which has been empirically determined to be effective. As a consequence, for at least some pest species, more emphasis can be placed on deploying lesser amounts of ingredients with concomitant less expensive technology costs which will serve to broaden sex pheromone use for field control. Technical Abstract: Sex pheromone signals are detected and coded quantitatively through ensembles of specialized antennal neurons usually located in sexually dimorphic sensilla. The detection event can be monitored either by recording from single receptor cells or by electroantennograms (EAG's) which are a bulk measure of many stimulated receptor cells. The signal is relayed to the brain which elicits the appropriate behaviors. Studies have demonstrated that there is a quantitative relationship between all of these measures, but none have demonstrated what this relationship is. The data in this report on the cabbage looper, Trichoplusia ni (Hubner), establishes a common abscissal axis for comparing the proportion of behavioral responses to electroantennograms and spiking activity of `receptor cells that are specialized to detect (Z)-7-dodecenyl acetate (Z7-12:Ac), the single most effective component of the sex pheromone. The average rate of spiking by antennal receptor cells was found to be linearly related to the average percentage of upwind flight response. By expressing the abscissa in Molar units, it was possible to compare among several assays of spiking activity and behavior. Emission rates of Z7-12:Ac previously have been reported from glass and rubber septum substrates. With some notable exceptions, there is agreement between all behavioral and electrophysiological measures from other laboratories when responses are plotted against the same abscissal scale. Emphasis was placed on behavior and spiking activity as the benchmark of a female's level of emission because it is unlikely that males would be exposed to higher levels in nature or be able to respond to improbable low ones. The benchmark is important to establish the relevancy of an experimental stimulus strength to that found in a natural context. |
