Effect of cotton genotypes on numbers of adult lady beetles (Coleoptera: Coccinellidae)

Abstract

Predatory arthropods can play an important role in the natural control of cotton pests, including bollworms (Heliothis zea Boddie and H. virescens F.). Smith & Fontenot (1942) reported that widespread use of calcium arsenate in cotton fields reduced the number of coccinellids, which resulted in increased damage by pests. Ewing & Ivy (1943) confined several predacious insects collected from cotton (individually in jelly glasses fitted with slightly moistened blotting paper) and supplied them daily with eggs deposited by insectary-reared bollworm moths. The maximum number of eggs destroyed in a day by a single adult of the convergent lady beetle (Hippodama convergent Guerin-Meneville) was 275. Adults of another species of lady beetle (Coleomegilla fuscilabris Muls.) frequently consumed all the eggs given them, an adult on average consuming 22 eggs per day. All the 12 species of predacious insects found in cotton fields survived on bollworm eggs. Whitcomb & Bell (1964) showed that the three most common lady beetles in cotton fields in Arkansas were: (1) spotted lady beetles (Coleomegilla maculata De Geer), (2) convergent lady beetles, and (3) ninespotted lady beetles (Ciccinella novemnotata Herbst). They recorded 24 species of lady beetles, all feeding on lepidopterous eggs including those of bollworms. Many of these predators were captured while feeding on small bollworm larvae. Van den Bosch & Kagen (1966) proposed guidelines for the mass releases of convergent lady beetle adults as a pest control measure in cotton. Lingren, Ridgway & Jones (1968) reported from small-container experiments that adult females of convergent lady beetles consumed an average of 129·9 bollworm eggs per day.