SEMIOCHEMICALS FROM LOBESIA-BOTRANA (LEPIDOPTERA, TORTRICIDAE) EGGS DETER OVIPOSITION BY THE CODLING MOTH CYDIA-POMONELLA (LEPIDOPTERA, TORTRICIDAE)

The intention of this study was to falsify a hypothesis of interspecif ic avoidance of semiochemicals from egges by ovipositing tortricid fem ales. The oviposition responses of Cydia pomonella (L.) females to app les baited with blends of semiochemicals identified in another tortric id species, Lobesia botrana (Den. et Schiff.) were investigated. Exper iments were conducted in binary choice tests using natural oviposition substrates (apples). In each experimental arena, 4 mated females were offered 16 apples (8 treated and 8 untreated) and the number of egges was compared. Females avoid ovipositing on apples treated with a blen d of nine components characteristic of methanolic extracts of L. botra na eggs (fatty acids and esters) (complete blend), as well as a binary blend of palmitic acid and methyl palmitate (binary blend). Ovipositi on avoidance was already observed with these two blends at a dose of 7 2 eggs equivalent of L. botrana per apple and this effect increased wi th the dose. The blend of three major esters from complete blend (tern ary blend) did not provoke significant avoidance. In the control, only 8.3% of apples bore no egges, this percentage was increased with comp lete blend and binary blend (720 Lobesia eggs) respectively up to 37.5 % and 26.4%, but only to 18.1% of apples with ternary blend. Complete blend and binary blend used at high dose strongly reduced the mean num ber of eggs/apple on treated fruits (1.6 +/- 1.8; 9 compounds) +/- 2.2 ; 2 compounds) against 4.6 +/- 4.0 in the control. This reduction was not observed with the blend of 3 esters. It is concluded that, from th e present results, apples treated with compounds associated with L. bo trana eggs are avoided by C. pomonella ovipositing females. Esters alo ne cannot explain such an avoidance, and palmitic acid may partly caus e the avoidance response.