Field surveys of egg mortality and indigenous egg parasitoids of the brown marmorated stink bug, Halyomorpha halys, in ornamental nurseries in the mid-Atlantic region of the USA

The brown marmorated stink bug, Halyomorpha halys (Stål), is an invasive species native to regions of China, Japan, Korea, and Taiwan. In its native and introduced range, H. halys is considered a pest of tree fruits, vegetables, legumes, and ornamental trees. The highly polyphagous nature of this insect as well as its vast dispersal capabilities, require an integrated approach to management. Here we focus on the potential impact of indigenous natural enemies on H. halys in woody ornamental nurseries in Maryland, USA. We sampled naturally field laid H. halys egg masses for mortality and parasitism rates in 2012 and 2013. Overall, egg mortality averaged 54% for both years, and increased within season and between years. The largest source of mortality was from egg parasitoids with mean parasitism rates of 30.73 and 39.63% in 2012 and 2013, respectively. Mortality from predation was much lower and averaged 4.61% by chewing and 2.53% by sucking predators. We found seven species of Hymenopteran egg parasitoids attacking H. halys eggs, with Anastatus reduvii being the dominant species comprising 61.17 and 79.12% of all parasitoids in 2012 and 2013, respectively. The observed increase in parasitism over time and female biased sex ratio of parasitoids suggests that native parasitoids may be responding to the novel host, H. halys. Consequently, the use of these native eupelmid egg parasitoids in augmentative or conservation biological control may be a viable H. halys management strategy in ornamental nurseries. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10340-017-0890-8) contains supplementary material, which is available to authorized users.