Biological control of Pseudococcus viburni on apples and pears

Mealybug fecundity was relatively low compared to other mealybug species ranged between 23 and 49 crawlers per female during the three seasons.  This biological limitation was negated in old and woolly apple aphid infested orchards where an abundance of refuge sites were found on the trees.  Of all the orchards, old Packhams pears were the most susceptible to mealybug attack due to the presence of bark on the main stem as well as suitably sized fruit calyxes through most of the season.  Pesticide applications were numerous in all the orchards and hampered the presence of bio-control agents.  In the unsprayed orchards, around 12% parasitism was found.  These levels of parasitism is however not adequate and does not indicate that there is a density-dependent relationship between the parasitoids and its prey.  For these reasons we currently do not believe that biological control of mealybugs is a viable option, even when no pesticide sprays are done and believe that action should be targeted towards monitoring.  We believe that export decisions should be made based on seasonal pheromone trap counts as well as physical fruit sampling during the latter part of December and believe that monitoring using these methods will help to prevent rejections due to mealybug infestation.