No. 3 Article 2/April 11, 2008

Baiting Recommendations and Toxicity Evaluations of Thianicotinoid Insecticides (Poncho and Cruiser) for Wireworms

The recommended scouting approach for wireworms is to establish bait stations a few weeks prior to planting. It is common knowledge that this pest management recommendation is rarely implemented in most commercial corn fields. However, in many areas of Illinois, planting this season will be delayed compared with previous years, so why not grab a shovel, get rid of some nervous energy, and give this approach a chance this year? According to the Entomological Society of America's Handbook of Corn Insects, the following procedures should be used in setting up bait stations:

Figure 1. Wireworm larvae.

Figure 2. Establishing wireworm bait stations.

Because of the escalating use of Bt hybrids, little regard is paid to potential wireworm infestations, the underlying assumption being that the thianicotinoid seed treatments (Poncho or Cruiser) will effectively control these secondary soil insects. But relatively few peer-reviewed articles have been published on the efficacy of these products against wireworm species. This is not surprising given the difficulty in establishing field plots with economic infestations. In the most recent issue of the Journal of Economic Entomology (Volume 101, issue 2), two papers were published by scientists who evaluated the lethal and sublethal effects of several insecticides, including Poncho (clothianidin) and Cruiser (thiamethoxam), against several economically important species of wireworms:

Vernon, R.S., W. Van Herk, J. Tolman, H. Ortiz Saavedra, M. Clodius, and B. Gage. 2008. Transitional sublethal and lethal effects of insecticides after dermal exposures to five economic species of wireworms (Coleoptera: Elateridae) [pp. 365-374].

Van Herk, W.G., R.S. Vernon, J.H. Tolman, and H. Ortiz Saavedra. 2008. Mortality of a wireworm, Agriotes obscurus (Coleoptera: Elateridae), after topical application of various insecticides [pp. 375-383].

I include here key points from each paper that shed new light on the performance of various insecticides used for wireworm control.

To learn more about the efficacy of these novel insecticides against wireworms, I encourage you to read the articles. Abstracts are available on-line.--Mike Gray

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