Phyllonorycter strigulatella (Lien. and Z.) ir Ph. sorbi (Frr.) (Lepidoptera, Gracillariidae) patelių feromono skleidimo elgesys temperatūrai kintant paros metu

Abstract

The pheromone release postures of virgin Phyllonorycter strigulatella and Ph. sorbi females were very similar to those of other species of the same genus with antennae held close to the wings, which were slightly spread and lowered, the abdominal tip dorsally curved and the distal segments extended. In both species with equal sex ratios, one peak of signalling activity was registered 0.5 h after the light had been put on and when 84% of Ph. strigulatella and 90% of Ph. sorbi individuals were active. The high pheromone release behaviour with 50% active females lasted for two hours. The calling activity of the group of females was about 6 h/day for both species. The total period of calling activity of an individual female lasted for 131 ± 62 min (mean ± SD) and 145 ± 73 min a day for Ph. strigulatella and Ph. sorbi respectively. The occurrence of one signalling peak per day in the species with equal sex ratios as found in Ph. strigulatella and Ph. sorbi, supported the hypothesis that pheromone release activity with a clear presence of two activity peaks during a photophase could be adaptive for species with a sex ratio strongly shifted towards females, as in Ph. junoniella