
Wee Wasps Vanquish Big Bad BeetlesBy Linda
McGraw October 27, 1999Good things really do come in small
packages. Just ask Agricultural Research
Service entomologists in Manhattan, Kan., who found that tiny, normally
harmless wasps about a quarter-inch long can control insect pests in stored
grains. Biological control is an important part of integrated pest management for
stored commodities such as wheat, corn, or grain sorghum, according to Paul W.
Flinn and David W. Hagstrumof ARS Grain Marketing and
Production Research Center. Damage caused by larvae of the lesser grain
borer, rice weevil and maize weevil costs the U.S. wheat industry millions of
dollars annually. The tiny wasps, Theocolax elegans, dont feed on grain but on
lesser grain borer larvae that typically attack commodities stored in bins and
elevators. For their study, the researchers used six 1,000-bushel bins filled with
wheat. They released the parasitic wasps into three of the bins. Next, they
released lesser grain borers into all six bins. After 131 days of storage, the
beetles were reduced by 91 percent in the treated bins compared to the bins
without wasps. The Manhattan researchers then milled the wheat flour and sent it to the
Federal Grain
Inspection Service in Kansas City, Mo. FGIS analyzed it for insect
fragments. Flour from the wheat exposed to wasps had 89 percent fewer insect
fragments than flour from the control bins. Thats because the harmless
adult wasps stay outside the grain kernels, so they are easily removed when
grain is cleaned in flour mills. Scientific contact: Paul
W. Flinn, ARS Grain Marketing and Production Research Center, 1515 College
Avenue, Manhattan, KS 66502, phone (785) 776-2707, fax (785) 537-5594,
[email protected]. U.S. Department of Agriculture | |