When it comes to household pests, the cockroach and bedbug rival each other for the top of the “least wanted” list. German cockroaches, one of the most common household pests, are typically associated with unsanitary or cluttered conditions and can spread germs and host allergens. But not all cockroach species are considered equal, according to the 2008 findings from USDA scientists in Texas. An exotic cockroach from Asia is actually helping Texas cotton farmers fight the cotton bollworm.
The Asian cockroach (Blattella asahinai) was discovered in the U.S. in 1986, when a pest control professional in Lakeland, Florida collected what he thought was a new strain of German cockroach. Although the cockroaches looked almost identical to German cockroaches, their behavior was very different. Upon further inspection, specialists discovered the insect was actually a cockroach that originated in Okinawa Island, Japan.
Female Asian (left) and German (right) cockroaches
German and Asian cockroaches are nearly identical, with a few small differences. Asian cockroaches have larger and narrower wings, smaller eggs and nymphs and distinctive variations in the larvae formation. Their behavior differentiates them further. Although both are considered household pests, German cockroaches prefer a warm house, while Asian cockroaches like to burrow in mulch or composting outside. German cockroaches feed on human refuse, while Asian cockroaches eat Lepidopteran eggs. Both species are active primarily at night.
Asian cockroaches have settled in several southeastern states, from North Carolina to Florida. In 2006, Texas cotton farmers discovered the insects in their cotton fields. However, unlike most crop pests, the cockroaches were not eating the plants; they were eating the cotton bollworm eggs.
Entomologist Bob Pfannenstiel from the USDA Agricultural Research Service (ARS) began examining the cockroaches soon after they were discovered. After determining that they were indeed Asian cockroaches, and not German cockroaches, he and his technician observed the insects every three hours over four days. During the night hours, Pfannenstiel observed the cockroaches feeding on cotton bollworm (Helicoverpa zea) and beet armyworm (Spodoptera exigua). Helicoverpa zea is a voracious and versatile pest, feeding on cotton (as cotton bollworm), corn (as corn earworm) and tomato (as tomato fruitworm).
The cockroach’s predation on a serious agricultural pest brings up an interesting conundrum. Should the insect be collected, reared and distributed to growers to battle their Lepidopteran pests? Will homeowners have to tolerate stray roaches from populations on nearby farms? Or does the stigma of a cockroach infestation outweigh agricultural needs for pest management tools?
Until researchers learn more about the Asian cockroach, they are reluctant to tout it as a new biocontrol option for farmers. Asian cockroaches can fly over great distances, making nearby residential neighborhoods possible landing spots for new Asian cockroach communities. Scientists plan to study the cockroach further for its value as a predator of agricultural pests. But for now, they plan to leave the Asian cockroach where it is, as a natural predator, to be treated as any other beneficial insect.
Filed under: Insects, Urban IPM Tagged: | Asian cockroach, cockroaches, German cockroach, roaches
