Boll Weevil Sex Attractant

Chemical studies on the sex attractant of the boll weevil led to the isolation (454) and identification (38) of four terpenoid compounds. Tumlinson et al. (455) suggested a hypothetical biosynthetic scheme in which all four compounds could be derived from a geraniol-like compound. Hardee (45 showed that male boll weevils required feeding for the synthesis of the attractant substances. Cotton squares proved to be the best diet, but pheromone production was demonstrated on a variety of diets. Mitlin and Hedin (457), using C tracers, obtained evidence 

Approximately 0.02% of the label was incorporated into the volatile fraction. While all four components accounted for only 39% of the volatile fraction they contained 57—80% of the radioactivity. It is assumed therefore that in spite of the boll weevil being an obligate insect of cotton, it does not seem to require any specific component in the cotton for the synthesis of the four terpenoid sex attractants. 

Hedin 458) has recently summarized factors that influence the biosynthesis of the boll weevil pheromone complex. Total synthesis was at a maximum during the summer and a minimum during the winter. In this study Hedin 458) did two types of experiments. The first series exposed 10-day-old adult weevils to a saturated atmosphere of a number of terpene hydrocarbons. It was found that only myrcene and limonene produced detectable amounts of oxygenated substances and that males produced more than females. No compounds isolated suggested that the weevils are capable of cyclizing alicyclic terpenes or their pyrophosphates. 

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The boll weevil sex attractant is a mixture of four compounds, two alcohols and two aldehydes. 

Di(dicyclopropylmethyl) ether has been made from dicyclopropylmethanol using polystyrene-supported aluminium trichloride. a-Cyclopropyl 1,2-di-ketones,a-cyclopropyl and a-cyclobutyl thioketones, (629X and the male boll-weevil sex attractant (630) are compounds which have been made by modification of groups bonded to cyclopropane and cyclobutane rings. The kinetics of the Cannizzaro reaction of cyclopropanecarboxaldehyde have been investigated. ... 

Thus, the structure of the following terpene alcohol, one of the components of the boll weevil sex attractant, was provided in part by microozonolysis when it yielded 3,3-dimethylcyclohexanone. 

Babler, J. H., and T. R. Mortell Facile route to 3 of 4 terpenoid components of the boll weevil sex attractant. Tetrahedron Lett. 1972,669—672. 

Cyclobutane.—One of the most interesting novelties recently discovered is a monoterpene representative of the cyclobutanes (apart from the bicyclic systems containing cyclobutanes). The sex attractant of the male boll weevil (Anthonomus grandis, Boheman) was identified as the cis-substituted cyclobutane (73), a stereospecific synthesis of which (Scheme 4) was reported shortly afterwards. ... 

Insects communicate by releasing pheromones—chemical substances that other insects of the same species detect with their anteimae. There are sex, alarm, and trail pheromones, and many of these are alkenes. Interfering with an insect s ability to send or receive chemical signals is an environmentally safe way to control insect populations. For example, traps with synthetic sex attractants have been used to capture such crop-destroying insects as the gypsy moth and the boll weevil. Many of the flavors and fragrances produced by certain plants also belong to the alkene family. 

Boar taint is a flavour found in the meat of boars but not of sows.) It is produced by boars and is released in a fine aerosol when the boar salivates and champs his jaws. When the sow detects the pheromone in air, she immediately adopts what is known as the mating stance in readiness for the boar. Grandisol is a sex attractant for the male boll weevil, a serious pest for cotton growers. 

The aggregation pheromone grandlure of the male Boll weevil (Anthonomus grandis) (Fig. 8.85) consists of four components. In field trials, the attractive effect of grandlure on both sexes was recognised. [209]... 

Chrysanthemic acid is a monocyclic terpene containing a three-membered ring. Its esters are found in the flower heads of pyrethrum (Chrysanthemum cinerariaefolium) and are naturally occurring insecticides. A cyclobutane is present in grandisol, the sex-attracting chemical nsed by the male boll weevil (Anthonomus grandis). 

Grandisol (6), the sex attractant of the boll weevil, has been synthesized by four different methods utilizing the photoadducts (7)—(10) as respective starting materials. 

The males of the cotton boll weevil Anthonomus grandis, Coleoptera, Plate 6), a serious pest of cotton, produce a sex pheromone to attract females. The pheromone, known as grandlure, consists of a mixture of at least four monoterpenes (Figure 6.7). The males make these compounds from geraniol and nerol (the cw-isomer of geraniol), present in the cotton buds on which they feed. 

One aspect of the current work on chemical control of insects centers on the use of sex pheromones as lures. Recently, chemists at the U.S. Department of Agriculture s Boll Weevil Research Laboratory isolated and synthesized components of the sex attractant of the male boll weevil, a pest responsible for a prodigious loss of cotton crop in the United States. A stereoselective synthesis of the active pheromone was later carried out at the Zoecon Corporation, and is outlined below. A key feature of this synthesis is the photochemical cycloaddition of ethylene to 3-methylcyclohex-2-enone, followed by oxidative disconnection of the resulting c/s-fused bicycio[4.2.0] octane (A) thereby generating the cis disposed side-chains. 

Traas, P. C., H. Boelens, and H. J. Takken Two step synthesis of a sex attractant of male boll weevil from isophorone. Rec. Trav. Chim. 95, 308—311 (1976). 

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. 

Monoterpenes contain 2 isoprene units, 10 carbon atoms. Examples include the essential oils citral (lemon grass oil) and menthol (peppermint oil) and grandisol, the sex attractant of the cotton boll weevil (Figure 11.29). 

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