Variation in developmental synchrony of the nantucket pine tip moth (Lepidoptera: Tortricidae) with implications for chemical control

Regional variation in developmental phenology of the Nantucket pine tip moth, Rhyacionia frustrana (Comstock), was studied at four locations in southeastern Virginia and northeastern North Carolina. A companion study assessed the effects of developmental asynchronony on insecticide spray timing efficacy. Substantial variation in developmental synchrony was found within a relatively small area, with more synchronous development at Greensville and Isle of Wight Co., VA sites, and high levels of asynchrony at Sussex Co., VA, and Hertford Co., NC, sites. The Greensville Co. site showed a typical three generation developmental phenology, while the Isle of Wight Co. site had a more atypical two generation phenology. The Sussex and Hertford Co. sites appeared to have phenologies that were a combination of the other two sites. Spray timing evaluations with permethrin at the Sussex Co. site suggested that mid-April to early May and early to mid-July periods offer opportunities for effective chemical control of tip moths. These dates corresponded to the presence of high proportions of eggs and early-instar larvae in the field. Later season sprays were largely ineffective due to high developmental asynchrony, which resulted in the presence of high proportions of late-stage tip moths on virtually all collection and spray dates. Results suggest that multiple late-season treatments likely would be more effective. Overall, optimal spray dates at the Greensville Co. site, which had a typical three-generation tip moth developmental pattern, agreed most closely with published optimal spray period predictions which are based on historical temperature data.