Natural Biological Controls for Stinkbugs

The invasive Brown Marmorated Stink Bug (Halyomorpha halys) was first discovered in the US in Pennsylvania in 2001. The insect rapidly proliferated here, in the absence of natural controls that help keep it in check in its native habitat in Asia. It has been causing significant crop damage to fruits and vegetables in the 41 states where the brown Marmorated stink bug is now found. For several years, the US Department of Agriculture (USDA) Agricultural Research Service (ARS) has conducted research using the tiny 1 to 2 millimeter long beneficial wasp (Trissolcus japonicus) found in Asia that uses the stink bug eggs to lay its own eggs. The developing wasp larvae consume the stink bug eggs as they develop into mature wasps.

Photo courtesy of the National Pest Management Association

Related tiny wasps of the same family, native to the US, help contain native species of stinkbugs. The USDA uses a quarantine ARS laboratory in Maryland for its research using Asian wasp to assure that this non-native species is not released into the wild in the US until its potential impacts are fully understood. However, USDA researchers have found Brown Marmorated Stink Bug egg masses collected in the Beltsville area had been pariticized by the Asian wasp, and other egg masses were being decimated by the related native wasp species. This research showed a significant number of Brown Marmorated Stink egg masses are being used as hosts by tiny parasitic wasps, with about a third of the parasitic wasps being of the Asian variety. While finding the Asian beneficial wasp actively attacking stink bug egg masses in the outside environment was unexpected, the fact that a larger proportion of the invasive stink bug egg masses are being destroyed by native beneficial wasps is increasing natural control.

Several ideas about the developing natural control of these insects by tiny beneficial wasps are being tossed around. Firstly, native tiny beneficial wasps, of which there are several species, are adapting to the new stink bug invader, and finding that its egg masses can be used as hosts. Further, the Asian beneficial wasp is confirmed to have found its way into the US, apparently from importation of products from Asia, just as the invasive Brown Marmorated Stink bug came to the US. So far, the tiny Asian wasp doesn’t hold any surprises in the way of adverse effects on the environment, as it behaves similarly to the related native species, using the stink bug egg masses as part of its life-cycle.

In addition, birds, amphibians and other animals have been observed to find easy meals eating adult Brown Marmorated Stink Bugs. The overall effect of these growing environmental controls is that there are less stink bugs around than there were in past years. In the spring, the stink bugs become more visible around homes as they emerge from overwintering. We are looking forward to again seeing fewer Brown Marmorated Stink Bugs this year.

Article by FCFCDB member

Nature note for 4/28/2019