Control of grape berry moth (Lepidoptera: Tortricidae) in relation to oviposition phenology.

Abstract

We monitored the phenology of oviposition by grape berry moth, Paralobesia viteana (Clemens) (Lepidoptera: Tortricidae), in grape (Vitis spp.) vineyards, to determine the optimal timing for control of this pest. Egg deposition was monitored throughout the growing season by visually inspecting grape clusters twice weekly and counting the number of eggs. Male moths were captured on pheromone-baited traps during the same period. Two main periods of egg deposition were detected in all farms and years: the first period in June-July and the second period during August. These episodes of concentrated oviposition were separated by a brief period of low intensity but continuous oviposition. The proportion of eggs laid during the first peak ranged from 9 to 35% of all eggs laid throughout the monitoring period at each site, whereas eggs laid during the second peak ranged from 43 to 78% of all eggs laid. From 49 to 99% of male moths were captured before or during the first peak in oviposition. In field trials with varying application timing of methoxyfenozide targeting the postbloom oviposition, a single application of this selective insecticide at approximately 700 degree-days, or approximately 12% of cumulative season-long oviposition, provided significant control of grape berry moth comparable with two applications of methoxyfenozide or a three-spray program with broad-spectrum insecticides. Use of predicted oviposition phenology and selective insecticides with long residual activity can improve protection of grapes against infestation by P. viteana.