Effect of a phloxine B-cucurbitacin bait on diabroticite beetles (Coleoptera : Chrysomelidae)

Cucurbitacin E glycoside, extracted from a bitter mutant of Hawkesbury wate rmelon [Citrullus lanatus (Thunb.) Matsum. & Nakai (Syn. Citrullus vulgaris Schrad)] is the active ingredient of a feeding stimulant for the corn root worm complex, It is the primary component of a water-soluble bait that can be combined with toxins for adult diabroticite control, Studies were conduc ted using phloxine B (D&C Red 28), a xanthene dye, as the toxin. This dye w as efficacious against Diabrotica undecimpunctata howardi Barber, spotted c ucumber beetle, and Acalymma vittatum (F.), striped cucumber beetle, in cuc umber plots and could be recovered from cucumber leaves for 8 d after treat ment. The average amount of dye recovered per dead spotted cucumber beetle at 8 d after treatment was 0.173 mug. Concentrated and sugar-free fermented forms of the watermelon extract were developed and compared with the fresh juice in field applications on cucumber plants. There was no significant d ifference in mortality of beetles from phloxine B-bait prepared with fresh, fermented, or concentrated extract, although in laboratory studies, fermen ted juice had higher feeding stimulant activity.