SEX RECOGNITION IN DIGLYPHUS-ISAEA WALKER (HYMENOPTERA, EULOPHIDAE) -ROLE OF AN UNCOMMON FAMILY OF BEHAVIORALLY ACTIVE COMPOUNDS

The sexual behavior of the ectoparasitoid Diglyphus isaea is described . Recognition of the female by the male occurs at close range. Males i nitiate courtship behavior in the presence of a living female regardle ss of age, as well as in the presence of a female killed by freezing. Courtship behavior is not observed in the presence of a dead female wa shed with organic solvents but could be elicited using a lure covered with a female organic extract. These findings demonstrate that each se x develops a specific chemical signature that can be dissolved in hexa ne and transferred to a lure. Analysis of organic extracts by gas chro matography revealed chemical dimorphism between the two sexes. Gas chr omatography coupled with mass spectrometry showed that the main compon ents in females were eaters of medium-chain fatty acids and long-chain 11-alcohols. There were few hydrocarbons. Female esters, which were p resent in only small proportions in males, were recovered in the nonhy drocarbon fraction obtained after fractionation of the total extract o n a silica-filled microcolumn as a mixture containing 11-heneicosyl, 1 1-docosyl, 11-tricosyl, 11-tetracosyl, and 11-pentacosyl octanoate, an d 11-docosyl, 11-tricosyl, 11-tetracosyl, and 11-pentacosyl decanoate. These results demonstrate that there is a specific gender-related che mical signature.