Mealybugs and their parasitoids in Nelson pipfruit orchards

Abstract

Three species of mealybug are major pests on a wide range of horticultural crops in New Zealand Pseudococcus longispinus P calceolariae and P viburni They can be found throughout New Zealand although they rarely become pests south of Marlborough Because colonies often establish in the calyx and stem of developing fruit they can cause rejection of export fruit During the 2008 Nelson apple harvest an increase in mealybug numbers was recorded for some commercial orchards A sample of 58 mealybuginfested apples was kept in a climate chamber at 20C to determine if any parasitoids were present From these 16 Tectracnemoidea sydneyensis (Hym Encyrtidae) and two Coccophagus gurneyi (Hym Aphelinidae) parasitoids were reared The following season 5400 fruit were examined from an infested block to determine mealybug species and the level of fruit infestation 188 of the fruit were infested 155 by P longispinus and 1 by P calceolariae Another 89 infested fruit were kept in individual containers at 20C From this sample 308 mealybugs were counted of which 305 were P longispinus and three were P calceolariae Fifteen percent of the P longispinus were parasitised by T sydneyensis Results from this study confirmed that P longispinus was the predominant mealybug species and that T sydneyensis was the most common parasitoid