On the physiological and behavioral mechanisms of pheromone-based mating disruption

Over the past several years my colleagues and I have been exploring ways of achieving moth mating disruption exceeding 95% efficacy even under high densities with limited insecticide inputs. The foundation for this work has been a series of studies examining the mechanisms underlying pheromone-based mating disruption in moth pests of pome fruit, stone fruit, walnuts, and citrus. Collectively, the results support competitive attraction or false-plume-following as an essential component of communicational disruption of moths in the family Tortricidae. Habituation of central nervous system (CNS) response appears to be an important supplementary mechanism for moths having oriented along plumes of high-dosage dispensers. Four main lines of evidence have led to these conclusions. Pheromone-based disruption of moths is density-dependent. Under high population densities, disruption increases as a function of increasing density of pheromone release sites. Effective mating disruption using high-dosage dispensers occurs in the field despite overall atmospheric concentrations not reaching levels high enough to desensitize moths by adaptation or habituation without close range (within cm) exposure to high dosage dispensers. Males are attracted to high-dosage dispensers in the field and such encounters desensitize the CNS but do not affect sensitivity of the peripheral nervous system. If competitive attraction followed by CNS habituation are the combined mechanisms achieving mating disruption, the following practical implications should be considered for developing high performance approaches and formulations: 1) distribution of dispensers should be uniform rather than clumped, 2) dispenser density should be high, and 3) release rate from synthetic dispensers should be within a physiologically attractive range but also sufficiently high to habituate male moth response following orientation.