OVIPOSITION RESPONSE OF LOBESIA-BOTRANA FEMALES TO LONG-CHAIN FREE FATTY-ACIDS AND ESTERS FROM ITS EGGS

Avoidance of occupied ovisposition sites supposes that females perceiv e information related to their own progeny. Fatty acids identified fro m egg extracts have been reevaluated using a different extraction meth od, and we have investigated the dose-dependent oviposition response o f European grape vine moths (Lobesia botrana) to myristic acid, palmit ic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, me thyl palmitate, methyl oleate, and ethyl palmitate; all except ethyl p almitate have been identified from eggs of L. botrana. A methylene dic hloride extract of eggs from L. botrana revealed the presence of satur ated free fatty acids (myristic, palmitic, and stearic) and unsaturate d acids (palmitoleic, oleic, linoleic, and linolenic) in amounts rangi ng from 3.9 ng/egg equivalent for myristic acid to 30 ng/egg equivalen t for palmitic and oleic acids. The extract also contained traces of m ethyl palmitate and methyl stearate. The greatest avoidance indexes we re observed in response to palmitic, palmitoleic, and oleic acids. All the other compounds tested caused weaker responses. A reduction in th e number of eggs laid was observed when moths were exposed to each of the esters applied at 0.3 mu g per application spot. Reduction in eggs laid was also observed at a 10-fold higher dose of oleic acid. The pr esent results confirm that general and simple molecules can be involve d in the regulation of oviposition site selection and that they may pa rticipate in chemical marking of the eggs.