Dispersal of Rubidium-Marked Pink Bollworm 1

Abstract

Local dispersal of native pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), was studied from 1975 through 1977 in southern Calif. using rubidium (Rb) as a marker. When Rb was applied to cotton fields as an aqueous foliar spray, there was a significant increase in Rb content of adult pink bollworm with no apparent adverse effects on behavior. Dispersal of pink bollworm was assessed by using pheromone and light traps to capture males and females within the treated fields and at various distances outside the fields. The marked status of individual moths was determined by atomic absorption spectrophotometry. Marked adult males were found to be highly mobile within the cotton field throughout the growing season. Adult males also exhibited a late season dispersion outside of the fields. However, dispersal was not strictly density-dependent and may have been triggered by a change in the physiological state of the cotton plant. Males dispersed to a greater degree than females and the onset of dispersion differed for each sex. Overwintering adult males were highly dispersive early in the spring. Dispersal was suppressed in mid- to late spring, possibly due to the production of squares or nectar by the young cotton plants.