GONADAL DEVELOPMENT AND EGG-LAYING RESPONSE OF FEMALE WHITE-PINE WEEVILS REARED ON ARTIFICIAL AND NATURAL DIETS

Reproductive processes in female Pissodes strobi (Peck) fed with a 5% ground bark artificial diet following summer emergence were studied. F emales exposed to different temperature and photoperiod regimes were d issected every other week and their reproductive organs were observed to evaluate the maturation time according to the treatments. After 12 weeks, half the females were transferred onto lateral branch sections of white pine and the other half onto artificial diet supplemented wit h 10% ground bark of white pine, and their realized fecundity was dete rmined. During the first 12 weeks, ovary development was detected but very few mature oocytes were found. No significant differences were ob served for the maturation times between the different abiotic conditio ns used, but significant differences were observed in female egg-layin g response on natural and artificial diets. Females that completed the ir sexual maturation at 24 degrees C and 16L:8D laid over a 3-week per iod 14.4 +/- 8.8 (mean +/- SE) and 2.6 +/- 2.6 eggs per female on whit e pine sections and artificial diet, respectively. Oviposition behavio ur was compared with results from an earlier experiment conducted with spring-emerging white pine weevils on natural and artificial substrat es. The egg-laying responses on white pine seedlings and on an artific ial diet with a concentration of 15% ground white pine bark were 0.892 +/- 0.124 and 0.171 +/- 0.394 eggs per female per day, respectively.