Phototactic behaviour of Eucryptorrhynchus scrobiculatus and E. brandti (Coleoptera: Curculionidae) adults

Abstract

ABSTRACTEucryptorrhynchus scrobiculatus and E. brandti (Coleoptera: Curculionidae) are destructive weevils on Ailanthus altissima in China. This study examined phototactic behaviour of E. scrobiculatus and E. brandti in response to eight light-emitting diodes (LEDs) in the laboratory and field. Effects of gender, starvation, and light and dark experience on the phototactic behaviour of the insects were evaluated. The results demonstrated that, the two species of weevil were phototactic insects and most sensitive to violet light (400–405 nm), followed by blue–violet light (420–430 nm). They were less sensitive to red (655–660 nm), white (6000–6500 k), blue–green (470–480 nm), yellow (590–595 nm), blue (450–455 nm), and green (515–530 nm) light. In the light intensity range of 200–1000 lux, the light intensity had no significant effect on the phototatic behaviour of E. scrobiculatus and E. brandti. Phototactic behaviour of the insects was affected by gender. The phototaxis indices of the two species of weevil increased with starvation, reaching a plateau after 2 or 3 d of starvation. The phototaxis indices of E. scrobiculatus and E. brandti were significantly affected by various wavelengths of light following exposure to the light for 3 h or in different dark experience time. In the mark-release-recapture test, the number of E. scrobiculatus and E. brandti adults trapped by violet (400–405 nm) light traps is the largest. The information provided here provides a basis for survey and control of E. scrobiculatus and E. brandti.