Louisiana soybean producers are facing a new type of stink bug pest more difficult to control than the green and brown stink bugs they are accustomed to fighting, said LSU AgCenter entomologist Jack Baldwin.

The insect is about 2/3 the size of the southern green stink bug, and its scientific name is Piezodorus guildinii, Baldwin said.

“Piezodorus guildinii is a more established pest of soybeans in South America, especially in Brazil,” Baldwin said. “And research indicates it is equally, if not more, damaging than the southern green stink bug.”

This stink bug was first observed in light numbers in South Louisiana at the LSU AgCenter’s St. Gabriel Research Station in 2000. In 2002 and 2003, populations of the pest became high enough for insecticide testing, Baldwin said. Though not alarming, the results indicated the insect was more difficult to control than the southern green stink bug.

“Heavy populations were first reported this year from southern and southeastern Louisiana – where early-maturing soybean fields required multiple applications for, at best, mediocre control,” Baldwin said. “Populations of Piezodorus guildinii have since spread into the southwestern soybean parishes and into the Lower Delta parishes of northeastern Louisiana.”

Baldwin said environmental conditions and the insect’s tolerance to most insecticide treatments are probably the causes for this stink bug becoming a major pest in 2004.

“LSU AgCenter research in 2004 indicates that acephate is the most effective insecticide for control of Piezodorus guildini,” Baldwin said. “Because of the large acreage of late-planted soybeans in some areas of the state, a crisis exemption was recently declared for the use of acephate.
Writer: Tom Merrill

(This article appeared in the "What's New?" section in the fall 2004 issue of Louisiana Agriculture.)