Summary of commercially available pheromones of common stored-product beetles

Abstract

Introduction Since the explosion of pheromone identification and synthetic production of the 1960's, pheromone utilization has become a valuable technique for monitoring and control of insect infestations (Cork, 2004) Pheromones are collectively grouped into one family of specific chemical signals designated as semiochemicals. Specific pheromones in this category are synthetically created, placed in traps that are in turn used for population tracking, stages of development and mating disruption of common stored- product pest beetles. These insects have the dexterity to infest processed foods, whole grains such as barley, rye, corn, oat and rice. Trapping and monitoring through pheromone usage can assist in reducing the amount of insecticide used by pest-control managers, only spraying when insects surpass certain levels or when they enter a vulnerable stage. Many stored-product pest beetles produce pheromones that can be classified as long-chain carbon compounds, predominately consisting of acids, aldehydes, acetates and esters. Many of these pheromones are unsaturated and consist of one or more double bonds that can be oriented into an E or Z conformation creating one or more isomers. Pheromones produced by stored-product beetles are generally more complex when compared with pheromones produced by stored-product moths. As a result of this complexity, stored-product beetle pheromones contain a degree of chirality creating additional isomers. The chemistry used for producing these compounds is more involved but can be easily reproduced and contains highly stable intermediates leading to the commercial availability of these particular pheromones. 2. Commercially available pheomones for stored-product The majority of pheromones range anywhere from 7-18 carbons in length producing carbon-chained compounds. Pheromones vary by functional group (i.e., acid, aldehyde, acetate, ester), double bond position and the configuration of the double bond (E or Z). Some of these pheromones are also branched containing methyl groups at various positions on the compound. These methyl groups create chirality in the compound depending upon how they are oriented on the molecule (R or S configuration). These factors are attractant determining for a variety of different beetles. Small changes in double bond placement and orientation of double bond or methyl group substituents may prevent attraction. The same holds true for alterations of functional groups. Through the use of organic syntheses, coupling of smaller organic compounds and the manipulation of long chain carbon compounds, these particular beetle pheromones can be made commercially available.