Effect of pre-harvest exposures to adult Halyomorpha halys (Hemiptera: Pentatomidae) on feeding injury to apple cultivars at harvest and during post-harvest cold storage

The effect of exposing apples to brown marmorated stink bug, Halyomorpha halys, for discrete intervals before harvest and of post-harvest cold storage on feeding injury expression was evaluated in 2011 and 2012. Individual apples from four cultivars in experimental orchards in Virginia and West Virginia, USA were caged soon after fruit set to protect them from insect injury. During each of the four weeks preceding harvest of each cultivar, five adult H. halys were placed in a subset of cages for 7-days, then removed. Control fruit were not exposed. The proportion of injured fruit and the number of external injuries was evaluated at harvest, after which the fruit were held in cold storage for about 5 weeks, followed by assessments of the proportion of fruit injured and the number of external and internal injuries. Most exposure timings resulted in external injury at harvest, but fruit exposed closer to harvest tended to show less injury than those exposed earlier. Fruit from all cultivars showed external injury at harvest, with variation in the proportion of injured fruit among them. The proportion of injured fruit and the number of external injuries tended to increase during post-harvest cold storage in some, but not all cultivars. The number of external injuries at harvest and after cold storage underrepresented the number of internal injuries. Results are discussed in the relation to the length of pre-harvest protection required to mitigate fruit injury from H. halys.