Pheromones oviposition deterrent

Figure 9.18 The oviposition deterrent pheromone of the cherry fruit fly. It consists of a dihydroxystearic acid with a glucose molecule attached as an ether and an amide of the amino-acid sarcosine...

Additional compounds found in the pheromone gland of female cigarette beetles are (2S,3R,l R)-2,3-dihyro-2-ethyl-3,5-dimethyl-6-(r-methyl-2 -oxo-butyl)-4ff-pyran-4-one 121 (P-serricorone), its (rs)-epimer (a-serricorone), and its reduction product, serricorole, 122 which shows (l/S,2/S)-configuration [245-247]. These compounds showed only weak attractivity [245], however, they obviously act as oviposition deterrents [248,249]. 

The use of single semiochemicals in the field is not usually sufficient for pest control, but by combining semi-ocheinicals, substantial protection can be achieved using an integrated approach called the push-pull system. The push is located in the crop and may comprise antifeedants, nonhost semiochemicals, attraction of predators or parasitoids, oviposition deterrents, or epideictic pheromones. The pull component comprises lures or trap areas away from the crop containing the sex pheromone, host odors, oviposition... 

The residual properties of oviposition-deterring pheromones are of particular importance to the host discrimination process. In cases where deterrent components from occupied resources may be emitted until completion of larval development, such as pheromonal release by larvae of Ephestia, Plodia and Heliothis, host discrimination mediated by pheromone may remain at a high level. However, in cases where deterrent components have only moderate residual activity under dry conditions or are water-soluble, both of which characterize tephritid pheromones, host discrimination mediated by pheromone may break down well before the completion of larval development. Here, one might suspect selection would favor female detection of larvae, or their effects. This does in fact seem to be the case in R. complete (Cirio, 1972) and R. pomonella (Averill and Prokopy, unpublished data), but further research is needed to explore this aspect more fully. 

A very remarkable example of a pheromone is the oviposition deterrent of the cherry fruit fly Rhagoletis cerasi. This substance is placed on the cherry fruit by the female fly after she has laid her egg in it (Ernst and Wagner, Helvetica Chimica Acta, 1989, 72, 165). Its purpose is to stop other females of that species from laying eggs in the same fruit. The pheromone must be stable and non-volatile and remain intact in sun and rain. It consists of sugar, fatty acid and amino-acid portions, which together ensure a non-volatile, UV transparent and insoluble substance (Figure 9.18). 

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