Annual and regional variability in adult <i>Dasineura mali</i> (apple leafcurling midge) emergence in New Zealand
Apple leafcurling midge is an important quarantine pest for New Zealand apple exports. Season-long pheromone trapping was conducted in Hawkeâ€™s Bay and Nelson from 2004â€“2017, and from 2012â€“2017 in Central Otago. Four generations occurred annually in Hawkeâ€™s Bay and Nelson and 3â€“4 in Central Otago. In Hawkeâ€™s Bay and Nelson, the timing of each peak varied by about 3â€“4 weeks between years, while the difference was ~2â€“3 weeks in Central Otago during fewer years of monitoring. Hawkeâ€™s Bay was up to a month earlier than Central Otago for the same peak within individual years. The major factor behind this variability was the accumulated number of growing degree-days. Insecticide sprays target midge larvae, but are timed against the second and third peaks of adult emergence. Variations in the timing of these peaks annually and across the main pipfruit growing regions, mean that specific insecticide timing recommendations are necessary each year for each region.