Effect of Insect Growth Regulators, Temperature and Overwintering on Larvae of Pistachio Leaf White Borer (Ocneria terebinthina)
Pistachio leaf white borer, Ocneria terebinthina (Lepidoptera: Lymantriidae), is a minor pest of pistachio trees. In this study, effects of two insect growth regulators (pyriproxyfen & chlorfluazuron), temperature and overwintering were investigated on physiology and morphology of the larvae. In chlorfluazuron and pyriproxyfen treatments, longevity of the last larval instars with 20 and 30 days, respectively was significantly longer than the control with 9 days. Most of treated larvae molted to malformed prepupae and supernumerary larvae, respectively. No significant differences in total sugar and lipid were observed between pyriproxyfen, chlorfluazuron and control treatments, but glycogen content in chlorfluazuron treatment (5.78±0.66 mg/g fresh weight) was significantly lower than pyriproxyfen and control treatments (10.62±0.66 & 10.66±0.66 mg/g fresh weight, respectively). Protein content in pyriproxyfen treatment (8.75±0.24 mg/g fresh weight) was significantly higher than chlorfluazuron and control treatments (7.01±0.26 & 7.16±0.24 mg/g fresh weight, respectively). No significant differences in total sugar and lipid of the larvae reared at 25°C and 35°C were observed, but glycogen and protein contents in the larvae reared at 25°C (12.21±0.81 & 8.8±0.48 mg/g fresh weight, respectively) was significantly different from the larvae reared at 35oC (15.89±0.89 & 6.41±0.48 mg/g fresh weight, respectively). No significant difference in total body sugar and protein of non-overwintering and overwintering larvae were observed, but glycogen content in non-overwintering larvae (12.22±0.95 mg/g fresh weight) was significantly lower than overwintering larvae (38.62±1.02 mg/g fresh weight). In non-overwintering larvae, total body lipid (11.13±0.93 mg/g fresh weight) was significantly lower than overwintering larvae (15.06±1.14 mg/g fresh weight). The data suggest that pyriproxyfen, chlorfluazuron, temperature and overwintering significantly affected some physiological aspects of Ocneria terebinthina larvae.