Laboratory Insecticide Screening Against Wireworms, Yakima, Washington, 1980

The soil was Ritzville silt loam (Calciorthidlc Haploxerolls) with an organic matter content of less than 0.5/6. The larvae were field-collected and of medium size. The bioassays were conducted as follows: Insecticides were mixed with air-dry soil in a Twin shell blender for 10 min, distilled water was added (6.8 parts:100 parts soil by weight) and mixed for another 10 mln, and the treated soil was placed in 0.5 pt glass fruit jars. Dosage rates simulated broadcast treatments, and the incorporation of materials 6 inches deep in soil. One boiled wheat grain was pushed down ca 1 inch into the soil of each jar. One wireworm was then placed on the soil of each jar; only those that burrowed into the soil within 2 min were used in the test. The jars were covered with plastic lids and were held In a laboratory maintained at ca 20-25°C. Each treatment consisted of 10 jars (replicates), and Dyfonate was included in each test as a standard. Once a week, each jar was checked to determine mortality, the soil and larva were returned to the jar, new boiled wheat grain was added, and moisture, if required, was added to the soil as required. Percent mortality for any given week was based on the weekly cumulative total of dead larvae and moribund larvae that died the following week.