Pheromone for insect control

Peter Witzgall. Pheromones for Insect Control in Orchards and Vineyards, lOBC wprs. Bulletin 2001, VoL 24(2), pp. 114-122. 

Look up the use of pheromones for insect control. To what general class of biological materials do pheromones belong Are pheromones regarded as toxic to insects In what sense is their use to control insects a green technology ... 

Siddall s chapter in the ARI Proceedings is entitled Commercial Production of Insect Pheromones Problems and Prospects . This paper argues that industry in the USA is deterred from developing pheromones for insect control mainly because of the unrealistic and uncertain requirements of EPA — the very agency charged with the development of alternatives to hard pesticides. The participants in the ARI meeting resolved to request EPA to establish firm, realistic guidelines within one year. Siddall s chapter contains a number of recommendations that could form the basis for reasonable policy decisions. 

Hedin, P. a., R. C. Gueldner, and A. C. Thompson Utilization of the boll weevil pheromone for insect control. In M. Beroza, Ed., Pest Management with Insect Sex Attractants and other behavior-controlling chemicals. ACS Symposium Series N. 23. American Chemical Society, Washington, D. C. 1976. 

This is the first example of a reaction for which the presence of a chelating ligand was observed to facilitate rather than retard metal-catalysed epoxidation (Gao et al., 1987). It was found that the use of molecular sieves greatly improves this process by removing minute amounts of water present in the reaction medium. Water was found to deactivate the catalyst. All these developments led to an improved catalytic version that allows a five-fold increased substrate concentration relative to the stoichiometric method. Sensitive water-soluble, optically active glycidols can be prepared in an efficient manner by an in situ derivatisation. This epoxidation method appears to be competitive with enzyme-catalysed processes and was applied in 1981 for the commercial production of the gypsy moth pheromone, (-1-) disparlure, used for insect control (Eqn. (25)). 

Esterases of the Juvenile Hormone of Insects Many works have been dedicated to the inhibition of esterases of the juvenile hormone of insects. The purpose of these works is to control insect populations by ehminating their metamorphosis. Among the numerous trifluoromethyl ketones that have been synthesized, thioalkyl derivatives of trifluoroacetone have been shown to be the most active ones. Curiously, the corresponding alcohols are also excellent inhibitors. Trifluoromethyl ketones can also inhibit other insect esterases antenna esterases and esterases that are involved in the release of pheromones (Figure 7.33). The inhibition of these latter ones can also be interesting for insect control purposes. 

The apple fruit moth, Argyresthia conjugella, is an invasive pest that bores into immature apples and eats them from within. One of its sex pheromones is (Z)-11-hexadecenyl acetate, which is used commercially to attract and trap the adult insects. Insect attractants are important chemicals for use in "organic" farming, because sticky insect traps baited with pheromones are allowed for insect control underthe "organic" farming rules. 

Much less research has been done on food attractants than on sex pheromones. More emphasis on the understanding of such allomones and their potential use for insect control is needed. 

TABLE 11.9 Pheromones Used for Insect Control (Examples)... 

Product stereochemistry is a critical factor determining the applicability of metathesis pheromones to insect control [23]. The steric course of the metathesis reaction normally results in a (thermodynamic) cis/trans mixture, whereas the physiologically active pheromones are either isomerically pure compounds or specific cis/trans mixtures. When it is necessary to obtain a single stereoisomer, the separation step required is tedious and expensive. The synthesis of pure cis isomers via the metathesis reaction, therefore, forms a challenge for catalyst development. 

Successful use of pheromones in insect control depends upon successfully controlling insect behavior through the emission of synthetic pheromone blends. The behaviors that have turned out to be most amenable to and important for... 

A different strategy for controlled release is based on polymer permeability other than degradation. The active reagent may be encapsulated within a polymeric membrane or in a strip, as shown in Figure 5.53. Ideally the reagent is contained in the reservoir as a saturated solution with excess in suspension. This allows diffusion through the membrane at constant rate without loss of activity. Alternatively, the reagent may be dispersed in a polymer matrix and released to the environment by diffusion or extraction. A variety of membrane and matrix devices are commercially available [99]. Pheromone release strips for insect control and household fly and cockroach strips for release of insecticide are also in commercial use. 

Despite their environmentally desirable qualities, pheromones account for less than 1% of the 6 billion worldwide market for insect control products (5). The two major factors that relegate pheromones to only a few minor market niches are, perversely, their high target specificity, which makes them relatively unattractive in crop systems requiring the control of multiple pest species, and their high cost of synthesis compared to insecticides. The latter factor represents a significant market barrier even in the best of circumstances where only a single pest species predominates. 

Why are pheromones interesting compounds for insect control How are they used ... 

Silverstein, R. M. Pheromones Background and Potential Use for Insect Control. Science 1981,213 (Sept 18), 1326. 

Controlled release is important in agriculture, especially for insect control. One common example involves the pheromones, sex attractants released by insects. If you mix this attractant with an insecticide, you can wipe out all of one sex of a particular insect pest. A device for releasing one pheromone is shown schematically below. This pheromone does not subline instantaneously, but at a rate of... 

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