Mats SVENSSON
Department of Ecology, University of Lund, S-223 62 LUND, Sweden
Several studies of insect mating systems have identified male traits, such as age and body size, that influence mating success in the field. In moths is pheromone response of major importance. Here I show that male moths differ in their matefinding capabilities and it is related to both pheromone response and morphological correlates. Male turnip moths Agrotis segetum (Dennis & Schiff.) were caught alive in pheromone traps in the field and tested the consecutive night in a wind tunnel. Males caught with a three-component high release rate baits in the field were responding significantly less in a wind tunnel to a low release rate bait, compared to males caught with a low release rate bait. There were no difference between males caught with a pheromone bait with a distorted ratio and males caught with a high release rate bait. The response time, i.e. time to an invoked behavioural response, also differed, but not the flight time, i.e time to reach pheromone source from take-off. The molphological measurements revealed no differences in, wing span, wing area o. wing symmetry, but the weight differed between males typed low release-responding and males typed high release-responding. The last group was significantly heavier. Underlying reasons of the male response dimorphism are discussed.