TEMPORAL PATTERNS OF PARASITOID FLY (ORMIA-OCHRACEA) ATTRACTION TO FIELD CRICKET SONG (GRYLLUS-INTEGER)

Female flies, Ormia ochracea (Diptera, Tachinidae), orient to the call ing song of the field cricket Gryllus integer (Orthoptera, Gryllidae) and deposit larvae that burrow into and consume the cricket host. Sele ction pressure from O. ochracea has probably been important in the evo lution of male cricket songs and mating behaviour in G. integer and ot her cricket species. Tape-recorded G. integer calling song was broadca st to study the temporal rate of attraction of O. ochracea. Flies beca me phonotactic to cricket song approximately at sunset, and the highes t level of attraction was observed in the following hours of the eveni ng. Fly phonotaxis decreased in the hours immediately preceding sunris e and no flies were attracted during daylight hours. More male G. inte ger call at sunrise and in the preceding hours than earlier in the eve ning, perhaps in response to the lower probability of attracting O. oc hracea.