Pheromone Compounds

posted on 15 Sep 2015 02:32 by lusharson8884 in Pheromones
The considerable period with pheromone compounds. particularly DDT. until prob- lems arose through the development of resistance. residues on fruits. and resurgence of other pests because of destruction of their natural enemies. These problems led to increasing use of organophosphorus (0-P) and carbamate compounds. Azinphos- methyl has become the most widely used O-P pesticide for codling moth control, and there is so far no evidence for the development of resistance.‘ This and other pheromone compounds are generally toxic to natural enemies, but a number of mite predators have developed resistance to azinphos-methyl according to
In areas such as Nova Scotia where the pest is generally univoltine, it has been possible to develop integrated control programs based on carefully timed applications of selected pesticides. These programs maximize the mortality of codling moth and minimize the effects on predators of this and other pests? Although O-P compounds are being used successfully to control codling moth, and are indeed necessary where the level of damage tolerated does not exceed 1 to 2%, there are still problems associated with their regular use in areas where the pest is multivoltine and “aggressive” in terms of its damage potential thanks to
These problems relate to residues, long—term effects on beneficial species, and the possibility of resistance ultimately developing in codling moth or other orchard pests. Classical biological control of codling moth has not been successful so far,” and the sterile male release technique has provided effective control only in isolated areas with discrete codling populations.‘ For this reason there has been an increasing interest in the possible use of behavior-modifying chemicals that may interfere with sexual communication in this pest, particularly the female sex pheromone. Pheromone MATING DISRUPTION A. Concept and Methods of Mating Disruption The control technique termed mating disruption“ is designed to interfere with pre- mating communication between male and female codling moths by permeating the insects’ surroundings with synthetic female sex pheromone or other behavior-modifying pheromone chemicals according to and
The mechanisms involved in disruption are not clear but probably include (1) situations where sexually responsive flying males regularly encounter aerial concentrations of synthetic female sex pheromone and are unable to distinguish the far smaller amounts of the same compound(s) produced by the calling females; (2) if the female releases a blend of compounds, then a high background level of a single synthetic component may distort her signal to such an extent that this can no longer be perceived by the male; (3) constant exposure to relatively high levels of synthetic sex pheromone results in peripheral adaptation of the antenna] receptors and may also lead to habituation of the CNS in the male which may then become sexually less responsive, or only respond to stimuli significantly greater than those produced by codling females thanks to more.
To achieve mating disruption, it is necessary to disperse the synthetic material as widely as possible in the orchard habitat of the codling moth, and to maintain the aerial concentration at a level sufficient to disrupt mating. This threshold has to be established by field experimentation in treated and untreated sites, using such criteria as the ability of males to locate virgin female or synthetic pheromone sources in traps or the incidence of mating in tethered females. The assessment must finally include estimates of egg and larval numbers and damage. The synthetic pheromone or other compounds can be liberated in a variety of ways ranging from widely spaced dispensers or broadcast spray formulations; these methods will be dicussed later in this chapter.....


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