Journal of Chemical Ecology (1996) 22, 2233-2249

Thomas W. Phillips, Joel K. Phillips, Francis X. Webster, Rong Tang and Wendell E. Burkholder (1996)
Identification of sex pheromones from cowpea weevil, Callosobruchus maculatus, and related studies with C. analis (Coleoptera: Bruchidae)
Journal of Chemical Ecology 22 (12), 2233-2249
Abstract: Female cowpea weevils, Callosobruchus maculatus, produce a sex pheromone that elicits orientation and sexual behavior in males. Bioassay-directed isolation of the sex pheromone was conducted and compounds in the active fraction were identified and synthesized. Volatiles were collected from individual virgin females by adsorption on filter paper dises and hexane extraction. A bioassay was used in which the locomotory response of single males in glass vials was recorded upon exposure to treatments or controls. Crude extracts were subjected to silica gel column chromatography with solvents of increasing polarity; all activity eluted with methanol. Activity in the highly polar methanol fraction suggested a carboxylic acid or a compound with multiple polar functionality. Acid-base partitioning of the crude extract isolated all activity in the acid fraction, confirming that the pheromone was a carboxylic acid. The acid fraction was further fractionated by preparative GC with a Carbowax column. The most active GC fraction contained the following five 8-carbon acids identified by GC-MS and comparison with synthetic candidates: 3-methyleneheptanoic acid, (Z)-3-methyl-3-heptenoic acid, (E)-3-methyl-3-heptenoic acid, (Z)-3-methyl-2-heptenoic acid, and (E)-3-methyl-2-heptenoic acid. Each of the synthetic acids was active individually for males, and combinations of two or more of the acid pheromones had an additive effect. Upwind flight responses to natural and synthetic pheromones were observed in a flight tunnel. (Z)-3-Methyl-2-heptenoic acid was previously identified as the sex pheromone for the related C. analis, but this and the other four acid pheromones from C. maculatus were inactive for male C. analis. There was no cross-attraction between C. maculatus and C. analis in reciprocal studies using extracted volatiles from females of both species, GC-MS analysis of C. analis female volatiles failed to detect any of the C. maculatus compounds but did find an unidentified C-8 acid with a GC retention time different from any of the C. maculatus pheromones.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Thomas W. Phillips

Research topic(s) for pests/diseases/weeds:
pheromones/attractants/traps

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Callosobruchus maculatus
	Callosobruchus analis