Locomotory responses to temperature in the grain weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae)
The speed or orthokinesis and turning rates or klinokinesis of individual adults of the grain weevil, Sitophilus granarius (L.), were affected by both the rearing temperature and the testing temperature. In general, orthokinesis decreased with a decrease in temperature, but weevils reared at a low temperature showed a smaller decrease than those reared at a high temperature. Klinokinesis was greater when differences between rearing and test temperatures were large and least when the differences were small or absent. Effects of differences between rearing and test temperatures were less if weevils were kept at the test temperature for 24 hours before testing and absent if beetles were at the test temperature for 2 weeks. Orthokinesis was shown to be an unsatisfactory orientation mechanism at low temperatures although it may operate with some efficiency at moderately high temperatures. Klinokinesis was much more effective at extreme temperatures and is probably the chief locomotory mechanism of orientation to temperature in this species.