Submitted to: International Society of Chemical Ecology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 31, 2006
Publication Date: July 15, 2006
Citation: Lapointe, S.L. 2006. Plant-herbivore interactions of a generalist tropical herbivore, Diaprepes abbreviatus (Coleoptera: curculionidae). International Society of Chemical Ecology Meeting. p. 207. Technical Abstract: The tropical weevil Diaprepes abbreviatus was introduced into Florida from the Caribbean in the 1960s. It has since become a major pest of citrus and ornamental plants in that state, and has expanded its range into California and Texas. This weevil threatens a number of important crops because of its high degree of polyphagy and lack of effective natural enemies. We have sought to advance the understanding of the chemical ecology of D. abbreviatus by studying its interactions with host and non-host plants. Genetic control of resistance was demonstrated in crosses between Citrus and Poncirus trifoliata (L.). However, production of resistant varieties is constrained by the relatively low level of reistance in sexually compatible citrus and the long generation time required for breeding citrus trees. While D. abbreviatus has become a pest of citrus, laboratory studies showed that other plants, native and introduced into its native range, are as good or better hosts than citrus. Attempts to show specific attraction to species of citrus and other plants or their odors have been unsuccessful. A tropical legume, Tephrosia candida DC was shown to be toxic to larvae and repellent to adults of D. abbreviatus in greenhouse and laboratory assays. Bioassay-driven chemical fractionation and a new bioassay method have contributed to the discovery of at least one compound(s) responsible for these effects. To date, no semiochemical has been identified for D. abbreviatus. Electroantennogram studies demonstrated antennal response to common plant volatiles such as linalool, geraniol, and citral. However, no behavioral attraction to these compounds was demonstrated. We have identified at least two compounds produced by D. abbreviatus that evoke a consistent antennal response in GC/EAG studies. These are being investigated as potential sex or aggregations pheromones.