FEMALE MATING SWARMS INCREASE PREDATION RISK IN A 'ROLE-REVERSED' DANCE FLY (DIPTERA: EMPIDIDAE: RHAMPHOMYIA LONGICAUDA LOEW)

Abstract

AbstractMate acquiring activities often expose males to increased risks of predation. In species where females are more competitive than males (i.e. a reversal in the conventional mating roles), the mate-acquiring biology of females is expected to increase their exposure to predators. Our observational study of a role-reversed dance fly, Rhamphomyia longicauda Loew (Empididae), supports this prediction. Within predominantly female swarms, R. longicauda display structures in flight that are assessed by males. Structural and behavioural components of the display should increase the risk of predation on females. We found more females than males captured in spider webs. This bias in predation was not due to a female-bias in population sex-ratios of the dance fly and the nature of web predation appears to rule out the hypothesis that spiders actively favour females as prey.