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Title: CUTICULAR HYDROCARBONS AND WAX ESTERS OF THE ECTOPARASITOID HABROBRACON HEBETOR: ONTOGENETIC, REPRODUCTIVE AND NUTRITIONAL EFFECTS

Author
item Howard, Ralph
item Baker, James

Submitted to: Archives of Insect Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2002
Publication Date: 5/5/2003
Citation: HOWARD,R.W., BAKER,J.E., CUTICULAR HYDROCARBONS AND WAX ESTERS OF THE ECTOPARASITOID HABROBRACON HEBETOR: ONTOGENETIC, REPRODUCTIVE AND NUTRITIONAL EFFECTS, ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 53:1-18. 2003.

Interpretive Summary: The surface chemicals of a parasitic wasp that is used to control stored product moth pests have been identified. Two major kinds of chemicals were found: hydrocarbons and wax esters. In addition to identifying the chemicals, they were studied to see if they changed with age, with whether the wasp was mated or not, with whether the wasp was male or female and whether the food that the wasps had been reared on made any difference. All of these factors, except whether the wasp had been mated or not, affected the composition of their surface chemicals. Suggestions were made as to the possible biological roles of these chemicals, and the information obtained will be used to plan further experiments to allow these wasps to be used as better biological control agents.

Technical Abstract: Hydrocarbon and wax ester components of the cuticular lipids of the braconid parasitoid Habrobracon hebetor Say reared at 25°C on larvae of a pyralid moth have been identified by GC-MS and analyzed with respect to adult age, mating status, and diet. The hydrocarbons range in carbon number from C21 to C45 and consist of homologous series of n-alkanes, 11-, 13-, and 15-methyl alkanes, 13,17-dimethyl alkanes, and Z-5, Z-7 and Z-9-alkenes. The wax esters found in the cuticular lipid fraction are a series of homologous compounds with the acid portion being short chain, unbranched, even carbon number acids from C8 to C20 (predominately C8 to C16). The alcohol portion of the esters are secondary alcohols with carbon number from C22 to C25 (predominately C23 and C25) with the hydroxyl function located at C6, C7, C8 and C9. Gender, age, and nutritional states were significant factors for variation in several of the individual esters, but mating status did not affect wax ester composition. Ontogenetic examinations indicated that prepupal, and early pupal cuticular lipids contain only hydrocarbons. Low levels of wax esters are detectable in late stage pupae, and somewhat greater quantities of wax esters are present on newly eclosed adults. When pharate adults emerge from the cocoon, however, their cuticular lipids consists of ca. equal amounts of hydrocarbons and wax esters, and 6d post emergence from the cocoon, wax esters are the predominant lipid component.