Quantitative Phosphorus-32 Labeling Method for Analysis of Predators of the Cotton Fleahopper (Hemiptera: Miridae)

Abstract

A method for the identification and quantitative evaluation of predators of the cotton flea hopper, Pseudatomoscelis seriatus (Reuter), is described. The method may be useful with other phytophagous Hemiptera, most notably Lygus spp. and Cicadellidae (S. O. Homoptera). Cotton flea hoppers are mass labeled by exposing the insects to 100-500 Micro Curie (µCi) phosphorus-32 (as H3PO4) for 1-3 h. After determining the mean CPM (counts, or disintegrations, per minute), a cohort of flea hoppers can be released on host plants in the field. After 24 and 48 h, the host and adjacent plants are sampled for labeled predators. The CPM of the radioactive predators is measured by liquid scintillation counting; an algorithm is provided to determine the number of individual prey items consumed by field captured predators. The algorithm requires species-specific assimilation indexes for the prey and the predator involved in the analysis. An example is furnished of a release of radioactive flea hoppers on cotton in 1987.