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Title: CUTICULAR HYDROCARBONS ON ELYTRA OF THE DIAPREPES ROOT WEEVIL DIAPREPES ABBREVIATUS (L.) (COLEOPTERA: CURCULIONIDAE)

Author
item Lapointe, Stephen
item Hunter, Wayne
item Alessandro, Rocco

Submitted to: Agricultural and Forest Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2004
Publication Date: 8/2/2004
Citation: Lapointe, S.L., Hunter, W.B., Alessandro, R.T. 2004. Cuticular hydrocarbons on elytra of the diaprepes root weevil diaprepes abbreviatus (l.) (coleoptera: curculionidae). Agricultural and Forest Entomology.

Interpretive Summary: The Diaprepes root weevil (DRW) is perceived by many growers and scientists as the greatest threat to sustainability of Florida's citrus crop. Various aspects of DRW's biology have not been adequately studied. Efforts to identify sex pheromones of this species have been unsuccessful. Pheromones are important tools for detection and monitoring many species of agricultural pests. We initiated a survey of the external morphology of DRW with an eye towards discovery of structures that secrete substances that affect the behavior of the adult insect. We report discovery of external ducts and describe the waxy filamentous secretions that coat the elytra (front wings) of DRW. These substances may be contact pheromones or act as carriers for volatile compounds involved in DRW communication.

Technical Abstract: Glands and associated structures on the elytra of teneral and mature Diaprepes root weevil, Diaprepes abbreviatus (L.), were elucidated by scanning electron microscopy (SEM). There were clear differences between teneral, callow adults and fully mature, emergent adults. In the field, teneral adults remain in the pupal soil until sclerotization of the cuticle is complete or nearly so. Phenotypic variation of the elytra in this species consists of varying patterns and coloration of scaled intervals between a variable number of raised ridges devoid of scales. In addition to being thinner and lighter in color than fully mature adults, the elytra of teneral adults were devoid of waxy hydrocarbon secretions. External gland openings were observed on teneral elytra and mature elytra washed with methylene chloride at the base of each scale. SEM evidence to document the production of waxy hydrocarbons by these glands and partial characterization of these by gas chromatography and mass spectrometry are presented.