Evaluation of a Water-Soluble Bait for Corn Rootworm (Coleoptera: Chrysomelidae) Control²

Laboratory and field-cage experiments evaluated the efficacy of a water-soluble bait for control of adult diabroticites. The bait was composed of a water-soluble feeding stimulant derived from a bitter mutant of Hawkesbury watermelon (Citrullus vulgaris Schrad), a dye toxin (phloxine B: D & C Red Dye No. 28), and a modified food starch (Mira Sperse 626). In the laboratory, southern corn rootworm, Diabrotica undecimpunctata howardi Barber adults, were exposed to separate bait components and combinations thereof. Eighty percent of adults exposed to the complete bait formulation died within 24 h. Adult mortality increased with higher concentrations of dye and increasing light intensity. Incorporation 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 field 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 water soluble toxic bait appears suitable for testing on a larger scale in the field as a component of an IPM program for corn rootworm pests.