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

Abstract

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 materialThe online version of this article (doi:10.1007/s10340-017-0890-8) contains supplementary material, which is available to authorized users.

Surveying native egg parasitoids and predators of the invasive Halyomorpha halys in Northern Italy

“…In contrast, in Maryland (US), egg parasitism by native parasitoids contributed most to egg mortality, occasionally exceeding 35% (Jones et al, 2017). The differences between the two studies may be partially explained by the fact that parasitoids in Europe and North America were different species with likely different parasitism success.…”

“…Similar to studies conducted in Switzerland (Haye, Fischer, et al, ), overall, the parasitization (1.3%) and predation (2.9%) of eggs were low over all the years. In contrast, in Maryland (US), egg parasitism by native parasitoids contributed most to egg mortality, occasionally exceeding 35% (Jones et al, ). The differences between the two studies may be partially explained by the fact that parasitoids in Europe and North America were different species with likely different parasitism success.…”

“…Therefore, it was not possible to determine levels of egg abortion induced by parasitoids (Abram et al, ) or the mortality due to unemerged parasitoids, which likely led to an underestimation of actual parasitism. Furthermore, the study by Jones () was performed in woody ornamental nurseries, with a high plant biodiversity, whereas the present survey was conducted on untreated fruit trees and wild native plants in a region of intensive farming. Agricultural practices, such as the heavy use of insecticides and herbicides, tillage, and soil amending may have decreased the overall biodiversity and thus, the impact of natural enemies in this region, not only in the cultivated areas but also in the uncultivated boundaries (Philpott, ).…”

“…Similarly, surveys performed in invaded areas in the United States showed that Anastatus spp. were the most efficient endemic parasitoids attacking sentinel H. halys egg masses (Cornelius et al, ; Dieckhoff et al, ; Haye, Fischer, et al, ; Jones et al, ). In addition, Anastatus sp.…”

“…and Encyrtidae (Ooencyrtus spp. ) have been found successfully developing on H. halys eggs (Abram, Brodeur, Burte, & Boivin, 2016;Abram, Gariepy, Boivin, & Brodeur, 2014;Dieckhoff, Tatman, & Hoelmer, 2017;Haye, Fischer, Zhang, & Gariepy, 2015;Jones, Jennings, Hooks, & Shrewsbury, 2017;Roversi et al, 2016). Parasitism caused by indigenous egg parasitoids is generally low.…”