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.
Stable co-existence of similar species should be facilitated by mechanisms impairing, besides exploitative, interference competition. We investigated avoidance of intra- and interspecific conflicts in a four-species community of shrews [Sorex minutus Linnaeus, 1766,S. araneus Linnaeus, 1758,Neomys anomalus Cabrera, 1907, andN. fodiens (Pennant, 1771)], using the method of dyadic encounters in a neutral arena. We tested whether the use of passive (habituation, reduction of mobility, increase of inter-individual distance, and stillness) and active (‘to-and-fro’ and ‘keeping distance’ behaviours) forms of conflict avoidance depends on species, size or domination rank. The duration of conflicts was positively correlated with mobility and negatively with inter-individual distance, whereas it was unrelated to time of stillness and the active forms. The repertoire of conflict avoidance mechanisms was not species-specific and the display of these mechanisms depended rather on the size and domination rank of animals participating in a given interaction. In contrast to rodents, shrews did not avoid conflicts by the most passive forms: freeze and stillness reactions. All other forms were used with a higher or lower efficiency by all species. However, consistent with our predictions, large shrews (asN. fodiens) used mainly the passive mechanisms of conflicts avoidance (‘wait-and-see’ strategy), whereas small shrews (asS. minutus) invest proportionally more time in active forms (‘escape’ strategy).