FEMALE MATE CHOICE TACTICS IN A RESOURCE-BASED MATING SYSTEM - FIELD-TESTS OF ALTERNATIVE MODELS

In this study we test theoretical models of female mate choice tactics in natural populations of pine engrave;sl Ips pini (Say) (Coleoptera: Scolytidae], a species with a resource-based mating system and high s earch costs. We first develop distinguishing predictions for each of f our models of mate choice: random. comparison tactics, and fixed and a djustable thresholds, These predictions relate to commonly collected f ield data that include the visiting behavior of females and the qualit y of accepted and rejected mates. Using these types of data, we conclu de that pine engravers use an adjustable threshold mate choice tactic because females often accepted the first male encountered, rarely revi sited males, visited similar numbers of males in patches of different quality, accepted higher-quality males than those they rejected even o n their first encounter with a male in a patch, and had higher accepta nce thresholds In high-quality patches than in low-quality patches. Th is adjustable threshold tactic is consistent with a one-step decision rule and is predicted to occur in species such as pine engravers in wh ich search costs art high and females have information about patch qua lity before beginning a search in a patch.