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

Abstract

AbstractReproductive processes in female Pissodes strobi (Peck) fed with a 5% ground bark artificial diet following summer emergence were studied. Females exposed to different temperature and photoperiod regimes were dissected 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 with 10% ground bark of white pine, and their realized fecundity was determined. During the first 12 weeks, ovary development was detected but very few mature oocytes were found. No significant differences were observed for the maturation times between the different abiotic conditions used, but significant differences were observed in female egg-laying response on natural and artificial diets. Females that completed their sexual maturation at 24 °C and 16L: 8D laid over a 3-week period 14.4 ± 8.8 (mean ± SE) and 2.6 ± 2.6 eggs per female on white pine sections and artificial diet, respectively. Oviposition behaviour was compared with results from an earlier experiment conducted with spring-emerging white pine weevils on natural and artificial substrates. The egg-laying responses on white pine seedlings and on an artificial 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.