Submitted to: Biocontrol
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2004
Publication Date: 10/3/2005
Citation: Lewis, L.C., Gunnarson, R.D., Robbins, J.C. 2005. Trichogramma brassicae and SLAM(R), an integrated approach to managing European corn borer and corn rootworms. Biocontrol. 50:729-737. Interpretive Summary: The European corn borer (ECB) and the corn rootworm (CRW) are the most serious pests of corn causing in excess of 1 billion dollars in crop losses per year. Management of the corn rootworm using prophylactic applications of a soil insecticide is one of the greatest uses of an insecticide. An areawide program that uses lesser amounts of insecticide was initiated to manage the corn rootworm. Using Slam, an attracticide/adulticide, adult rootworm are attracted to a point source and killed using a formulation of cucurbitacin, an attractant, and a small amount of insecticide. Slam is applied just prior to the time of egg laying by the rootworm. Simultaneously, in many fields there are infestations of the European corn borer. We wish to also manage the ECB without the use of a chemical insecticide. In this study we used an egg parasitoid, a tiny wasp that lays its eggs in the ECB eggs, killing them. There is a possibility that the Slam would be detrimental to the wasp, rendering it ineffective. Thus studies were conducted to determine if Slam and the wasp could be employed simultaneously. Scientists conducted laboratory research in which they exposed the wasp to ECB eggs to which Slam had been applied either before or after exposure or not at all. In all situations Slam did not interfere with parasitism. Slam and an egg parasitoid can be used simultaneously to manage the CRW and the ECB, respectively. This research benefits insect pest managers by providing information on the possible use of two environmentally friendly options to manage insect pests of corn.
Technical Abstract: Diabrotica virgifera virgifera, the western corn rootworm (CRW), and Ostrinia nubilalis, the European corn borer (ECB) are the most serious pests of corn in the U.S. corn belt causing an estimated $50 - $220 of crop loss per hectare per year. An attracticide/adulticide (Slam) that employees a behavior modifying chemical (cucurbitacin) and a small amount of insecticide (carbaryl) is used in an areawide program to manage the CRW. This program may coincide with the second flight of the ECB. Thus there is a possibility that an application of Slam would be detrimental to biologicals used to manage the ECB. One such biological is Trichogramma brassicae (Tb), an egg parasitoid. Laboratory research was conducted to determine if Tb and Slam are compatible. Research was conducted under the following treatments: ECB eggs, no Slam, Tb; Slam prior to ECB egg laying, Tb; ECB eggs followed by Slam, Tb; ECB eggs parasitized by Tb, Slam applied; and all corresponding control treatments. Slam was allowed to air dry prior to any exposure. Percentage parasitism and emergence of adults were measured. There were no significant differences in parasitism, range 87 to 91, or in adult emergence, range 72 to 81. Emerged adults were then exposed to fresh ECB eggs to determine efficacy of the subsequent generation. Again no differences were recorded; percentage parasitism ranged from 81 to 92 and percentage adult emergence ranged from 72 to 84. The possible use of Slam and T. brassicae are discussed.