Samurai Wasps Used to Solve Stink Bug Problem


via Wikipedia

Ever since shipping containers were sent to America, the brown marmorated stink bug has become one of the fastest-breeding pests. Despite its harmless and possibly cute looks, this small speckled insect has become a smelly nuisance to homeowners and a costly issue for orchard growers.

Since the arrival of this stink bug was introduced to the U.S. in the 1990s has tried to survive in a new environment. Unfortunately, due to it being a hardy species and a very capable flyer, this bug has exploded in population in its new home as there are no natural predators to prevent. Ever since the species arrival, the brown marmorated stink bug is responsible for the destruction of millions of dollars worth of crops as it feeds on fruits and vegetables by piercing the skin and sucking out the juices which leave the produce unsalable. Another problem occurs during the winter where stink bugs find shelter in homes and business in huge numbers and smell similar to old socks when squished.

Pesticides have been used as a solution to eliminate the stink bugs, but the chemicals also target native bees and other pollinators. After years of trying to control the stink bug populations, scientists discovered a solution came with the recent emergence of a known predator of stink bugs– samurai wasps.

The samurai wasp is a miniature parasitoid wasp that is known to be a predator of the brown marmorated stink bug. As adults, samurai wasps search for eggs laid by brown marmorated stink bugs. The eggs laid by the stink bug are usually arranged in clusters of 28 eggs. Unlike most parasitoids which only use a couple of eggs, the samurai wasp lays its eggs into most of the eggs in the group. As the wasp’s larvae develop, it eats the stink bug egg and kills the would-be stink bug. Once fully developed, these wasps emerge from the infected stink bug egg to continue the cycle.

However, USDA regulations prevent the release of invasive species in the field even if they may be beneficial unless they’re already present. Past mistakes have been made before in releasing invasive species such as the mongoose to Hawaii, stoats to New Zealand, and cane toads to Australia. It’s almost impossible to know what a predator will go after in a new environment as there may be more appealing options available then the intended prey.

But samurai wasps are already in the States from arriving accidentally sometime before 2014. This is good news for orchard growers as last year, apple and peach growers lost $35 million due to the brown marmorated stink bug. Unlike the native parasitoids which favor laying their eggs in multiple native species, the samurai wasp only targets brown marmorated stink bugs. This is because the two species have evolved alongside each other in Asia.

Just because a few wasps were found doesn’t mean the stink bug issue is resolved. However, researchers know that samurai wasps populations exist in 10 states in the U.S. Now, it’s being determined how effective these wasps are at restraining the stink bug population. In Asia, 60-90% of brown marmorated stink bug eggs are parasitized, and scientists are eager to find out if the same results will occur in a different climate. The samurai wasp seems to be a practical solution to beat back the stink bug onslaught, one egg at a time.