Stink bugs, those flying pecan orchard pests, are finicky eaters. And while they prefer to munch on the pecan variety Desirable more than Stuart, they will feed on many kinds of pecans. But no matter which nut this bug favors, farmers prefer to keep them grounded.
Entomologist Michael T. Smith, working closely with both the Jenkins and Horton orchards, has developed a strategy for keeping stink bugs out of the air. Formerly in ARS' Southern Insect Management Research Unit at Stoneville, Mississippi, Smith says pecan growers may control stink bugs entering pecan orchards--and even reduce their feeding damage to trees adjoining crops such as soybeans--by planting and spraying within a trap crop.
The bait: a strip planted along orchard borders of a favorite bug-munchie such as speckled purple hull pea, an edible delight to stink bugs. This pea variety produces pods continuously over the season.
"It's like building a moat around a castle," says Smith, who is now with ARS' Beneficial Insects Introduction Research Laboratory in Newark, Delaware. "The bugs stop at the trap crop to dine and don't make it to the farmer's money-making crop."
Stink bugs, the most damaging pests in Mississippi pecan orchards, take flight into the orchards before and during soybean harvest. But they continue to enter orchards from August through pecan harvest, which may extend into November and December.
Stink bug feeding causes two types of pecan damage: black pit and kernel spot.
When the bug pierces the nut with its needlelike nose before shell hardening, it spews a chemical on the kernel, causing it to turn black and cease development, resulting in black pit. If the pest feeds after shell hardening, the result is kernel spot. Here, stink bugs drill through the hardened shell, "spit" on the kernel to make it soft, and suck the meat out, leaving a black spot on the kernel.
Trap cropping could greatly reduce this pecan damage. It concentrates the bugs in an area outside the orchard, so farmers can control them economically with insecticides. This reduces broad insecticide spraying and increases grower profits.
Reduced pesticide spraying also means less impact on the environment and beneficial insects. Most insecticides used to control stink bugs also kill the beneficial insects that control crop-damaging aphids.
In a recent field study, Smith found feeding damage within the trap-crop-protected area was about 50 percent lower than in the unprotected area.--By Tara Weaver, Agricultural Research Service Information Staff. ARS.
Michael T. Smith is at the USDA-ARS Beneficial Insects Introduction Research Laboratory, 501 South Chapel St., Newark, DE 19713; phone (302) 731-7330, ext. 41, fax (302) 737-6780.
"Baiting and Trapping Orchard Pests" was published in the January 1999 issue of Agricultural Research magazine.