EFFECT OF TEMPERATURE AND DIET ON HIND WING COLORATION DEVELOPMENT AND ELYTRAL HARDNESS OF ADULT COLORADO POTATO BEETLE (COLEOPTERA, CHRYSOMELIDAE)

The effects of food and temperature on the development of colour pigme nt in the hind wings of adult Colorado potato beetle, Leptinorarsa dec emlineata (Say), were investigated. In a replicated study, adults were held at 18 degrees C, 28 degrees C and 18/28 degrees C on potato foli age (Solanum tuberosum L.), potato tubers, or without food in controll ed-environment chambers. Representative subsamples of wings were colle cted at two-day intervals, mounted on microscope slides, and photograp hed to document the progression of colour change. Observations were al so made on elytral hardening over time. Hind wing colour developed mor e quickly at 28 degrees C than at 18 degrees C, and after three weeks had attained a deeper red colour at the higher temperature. Colour dev elopment was also more rapid when adult beetles were fed on foliage co mpared with tubers. In foliage-fed beetles, elytra hardened more quick ly at 28 degrees C than 18 degrees C, and many tuber-fed beetles never developed hardened elytra, regardless of temperature treatment. Unfed beetles developed no hind wing colour pigment and their elytra remain ed soft for the duration of the experiment. Colour plates documenting wing colour development over time are presented; variation in colour d evelopment under the conditions tested suggests that the use of hind w ing colouration to estimate beetle age in the field may be problematic .