SEX PHEROMONES OF NOCTUID MOTHS .14. FEASIBILITY OF BEHAVIORAL CONTROL BY DISRUPTING PHEROMONE COMMUNICATION IN CABBAGE LOOPERS

Experiments were conducted with Trichoplusia ni (Httbner), the cabbage looper, to evaluate the male inhibition technique for behavioral control. The technique is based on the permeation of the atmosphere with synthetic female sex pheromone. Assuming male adaptation to the omnipresent pheromone, and the fact that the additional increment of pheromone contributed by females in nature may be imperceptible to the males, the males would theoretically be incapable of orienting to and inseminating the females. The lower threshold for male behavioral responses to the cabbage looper female sex pheromone was established in the laboratory at about 2x10-14 g/liter of air about 60 molecules/mm3). In the laboratory, responsiveness to a high concentration of sex pheromone (2x10-9 g/liter) was completely inhibited when they had been conditioned for 25 minutes in air containing lower pheromone concentrations. A much higher concentration (5x10-5 g/liter) was required to prevent males from orienting to and mating with females in the confines of a 2-liter container. In the field, a concentration of roughly 1x 10-10 g/uter was sufficient to completely prevent orientation of males to pheromone-emitting females. For large-area cabbage looper mating control by sex pheromones, it was calculated that less than 0.5 g/ha (0.2 g/acre) must be expended per night.