EVALUATION OF A WATER-SOLUBLE BAIT FOR CORN-ROOTWORM (COLEOPTERA, CHRYSOMELIDAE) CONTROL

Laboratory and field-cage experiments evaluated the efficacy of a wate r-soluble bait for control of adult diabroticites. The bait was compos ed of a water-soluble feeding stimulant derived from a bitter mutant o f Hawkesbury watermelon (Citrullus vulgaris Schrad), a dye toxin (phlo xine B: D & C Red Dye No. 28), and a modified food starch (Mira Sperse 626). In the laboratory, southern corn rootworm, Diabrotica undecimpu nctata howardi Barber adults, were exposed to separate bait components and combinations thereof. Eighty percent of adults exposed to the com plete bait formulation died within 24 h. Adult mortality increased wit h higher concentrations of dye and increasing light intensity. Incorpo ration of the feeding stimulant with the dye reduced the lethal time. The complete bait was most active in sunlight, killing 90% adults in 1 h. Under fluorescent lights, the LT90 for the adults was 48 h. In fie ld cages, using corn plants treated with the bait formulation, numbers of live western corn rootworm, D. virgifera virgifera LeConte, adults were reduced by 80% compared with the untreated control. This new wat er soluble toxic bait appears suitable for testing on a larger scale i n the field as a component of an IPM program for corn rootworm pests.