Soil applications of two neonicotinoid insecticides to control mealybugs (Pseudococcidae) in vineyards

Abstract

Grapevine leafrollassociated Virus 3 debilitates grapevines reducing yields and juice quality and eventually makes vineyards uneconomic Mealybugs (Pseudococcus spp) are the key insect pests of grapes in New Zealand because they are the principal vectors of this virus Until recently all insecticides registered for their control depended on direct contact but mealybugs live in hardtotreat parts of vines This research tested the efficacy of two neonicotinoid insecticides imidacloprid and SCAL 5085 that have translaminar and systemic activity Two field trials were conducted on commercial vineyards with the insecticides applied as soil drenches In the first trial imidacloprid applied at 0525 g ai/vine reduced mealybug abundance by >99 compared with untreated vines and autumn and spring applications were equally effective Half this rate was less effective although drenching in autumn was better than in spring In the second trial treatments were applied in winter and SCAL 5085 at 0263 g ai/vine provided equivalent control to imidacloprid at 0525 g ai/vine