Pheromone—continued

The isolation, structural elucidation, and total synthesis of insect pheromones continue to be a very active area of natural product research (c/. Vol. 8, pp. 66, 102). A recent paper in this area describes the identification of ancistrodial (36) and ancistrofuran (37) as components of the defence secretion of termite soldiers Ancistrotermes cavithorax). 

The delivery of male courtship pheromones is widespread among plethodontid salamanders (Houck and Arnold 2003), and other courtship pheromones are being discovered for this group (Houck, Palmer, Watts, Arnold, Feldhoff and Feldhoff 2007). The mode by which these pheromones are transferred to the female apparently has been modified from delivery via diffusion into the circulatory system to delivery that directly stimulates vomeronasal receptors (Fig. 20.1 Houck and Sever 1994 Watts et al. 2004 Palmer et al. 2005 Palmer et al. 2007). The behavior patterns and morphologies associated with these two delivery modes often remain static for millions of years. In contrast, evolution at the level of pheromone signals is apparently an incessant process that continuously alters the protein sequence and composition of pheromones both within and among species (Watts et al. 2004 Palmer et al. 2005 Palmer et al. 2007). 

An alternative combination of an aggregation-alarm pheromone system is found in L. konoi. This species produces the aggregation pheromone lardolure (44) as a minor component, and the alarm pheromone neral (2) as a major component. If both pheromones are presented simultaneously, aggregation pheromone activity manifests only after the alarm pheromone has dissipated. Furthermore, it seems likely that the mites can regulate the production of each component independently, because the evidence suggests that each is produced at a different site. Therefore, lardolure may be produced essentially continuously, and its function as an attractant is temporarily overridden by the rapid release of the alarm pheromone under adverse circumstances. 

One particular example of controlled release is sustained release. In this form the desired material is continuously released over a period of time at a constant rate. Two timely publications (3)(4) cover the general area of controlled release, which can also include the controlled release of agricultural materials and biological materials, far example, pheromones. In using the term microencapsulation in this article, the author intends to refer to capsules in the size range of 1 micron to 1000 microns. Capsules below 1 micron in size are frequently referred to as nanocapsules and they are made by one or more very specialized methods (5). The term capsule refers to macro objects in the order of 1 millimeter or larger. This term of capsule is frequently used in the delivery of pharmaceuticals. 

As in most Lepidoptera, spruce budworm males locate conspecific females by flying upwind along a pheromone plume. The blends and release rates of these pheromone components form an important part of a specific communication system for the species. Once the communication system of an insect is understood, especially the pheromone chemistry as it relates to male behavior, it can be used in a variety of ways. For example, pheromones can be used to detect the presence of an insect in an area, to remove males from a population by trapping or poisoning and in air-permeation techniques in which the controlled and continuous release of pheromone components in the forest can disrupt mating. The latter use of pheromones appears to alter the normal male behavioral responses to the natural pheromone (16). 

Large scale use of pheromones cal dispenser system which must re continuously over the prescribed p same time, being able to withstand ment. 

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