The intention of this study was to falsify a hypothesis of interspecific avoidance of semiochemicals from egges by ovipositing tortricid females. The oviposition responses of Cydia pomonella (L.) females to apples baited with blends of semiochemicals identified in another tortricid species, Lobesia botrana (Den. et Schiff.) were investigated. Experiments 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 blend of nine components characteristic of methanolic extracts of L. botrana eggs (fatty acids and esters) (complete blend), as well as a binary blend of palmitic acid and methyl palmitate (binary blend). Oviposition avoidance was already observed with these two blends at a dose of 72 eggs equivalent of L. botrana per apple and this effect increased with the dose. The blend of three major esters from complete blend (ternary blend) did not provoke significant avoidance. In the control, only 8.3% of apples bore no egges, this percentage was increased with complete 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 number of eggs/apple on treated fruits (1.6 ± 1.8; 9 compounds) (1.8 ± 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 the present results, apples treated with compounds associated with L. botrana eggs are avoided by C. pomonella ovipositing females. Esters alone cannot explain such an avoidance, and palmitic acid may partly cause the avoidance response.

Clonal samples of aphids were used as the groups in canonical variate (CV) analysis, in order to compare the temperature responses of single genotypes, and thus to distinguish genotypic and environmental contributions to the phenotypic response pattern. The analysis was based on a large data set obtained by measuring 19 linear variables on adult apterae reared at four temperatures (10, 15, 20 and 26.5°C). The species used were Myzus persicae (Sulzer) and its close relative, M. antirrhinii (Macchiati). Two vectors - the scores on the first two CV's - were invariably needed to describe the temperature response. In each of three M. persicae clones, the first CV had a close linear correlation with temperature, partly corresponding to the decrease in body size at higher temperature, whereas the temperature relationship of the second CV fitted a quadratic function, being less at both high and low temperatures, and reflecting a change of ''shape'', partly comprising a relative decrease in lengths of appendages at low temperature. In M. antirrhinii the temperature relations of these two CV's was reversed, that of CV1 being quadratic and that of CV2 linear. When different genotypes of a species were combined in the same analysis, the first and second CV's still described the ''two-way'' response to temperature as for clones analysed separately, but the third and fourth CV's were totally independent of rearing temperature and separated samples according to their genotype. The consistency with which temperature effects are allocated to the first two variates seems to indicate the presence of two different aspects of the phenotypic response to temperature, perhaps reflecting different metabolic pathways by which temperature affects the pattern of growth.