SPATIAL MODELING OF PREFERRED WIREWORM (COLEOPTERA, ELATERIDAE) HABITAT

Potential damage to crops after the Conservation Reserve Program is wi despread One probable result is the increased occurrence of soil-insec t pests, primarily wireworms (Coleoptera: Elateridae). The likelihood of wireworm problems in the Iowa Conservation Reserve Program was comp ounded by the large amount of land enrolled in the program and the eco nomic importance of corn, Zea malls I,., the crop most often damaged b y wireworms in the state. As a result, farmers need to consider pest m anagement options that should include pest scouting. Wireworm presence /absence data from 1995 and 1996, and estimates of soil moisture from 89 Conservation Reserve Program fields were used to estimate variables useful for identifying where wireworms are more likely to occur. The most useful variables were a soil-moisture threshold of 17% and a mois ture analysis that included meteorological data from only 1 yr before sampling occurred. These variables were coupled with a hydrologic mode l and embedded in a geographic information systems (GIS) framework Thi s computerized habitat model was run on the study area Story County, I owa, and generated a map indicating areas where wireworms were more li kely to occur and where scouting should begin. Results of the model ru n indicate that most of Story County is suitable wireworm habitat and that there were areas considered highly favorable. The map generated b y this computer model can be used as a guide for directing scouting wi thin a field but does not identify areas where management tactics are necessary. The methodology used in this study is relatively simple, ye t it performs the difficult task of combining time, space, and climato logical variables to evaluate wireworm habitat over a landscape, Moreo ver, it demonstrates one application of GIS technology in a discipline where the subject has characteristics that are inherently spatial.