Development of the bait principle for boll-weevil control: II. Field-cage tests with a feeding stimulant and the protozoan Mattesia grandis

Abstract

A formulation containing spores of the protozoan Mattesia grandis and a feeding stimulant made from cottonseed oil and a water extract of contton squares plus carrier materials and a marking dye was tested against a population of the boll weevil, Anthonomus grandis, on cotton in 1 16 - acre field cages. Effectiveness of the formulation was judged by the percentage of marked weevils and the incidence of disease among adults collected at the end of the test. Twenty to 30% of the treated population was marked during the main fruiting period, which is also the period of rapid development of the boll-weevil population, and 50% to 60% during the latter part of the test when the plants were maturing and fewer weevils were developing because of cooler temperatures. At the end of the test, 55% of the weevils were diseased. The diseased population producd about half as many adults as the check population. The treated adult population remained stabilized; the check had sharply defined, eruptive increases in number of adults as each generation emerged from squares or bolls. A feeding stimulant with spores or other effective agents might be effective in reducing populations in large open fields.