ABSTRACT

The rate of convergent lady beetle, Hippodamia convergens Guerin-Meneville, predation on the cotton aphid, Aphis gossypii Glover, was measured by assigning a single predator randomly to one of five prey density treatments in a petridish in the laboratory at 26.6 oC. Prey density treatments included 25, 50, 100, 210, and 400 aphids per petridish arena. Predation response was recorded 1 h, 4 h, 8 h, 16 h, 24 h, and 48 h after assigning predators to their prey treatments. Rate of consumption increased through time, with all 25 aphids eaten during the first 4 hours of the experiment. At the highest density, lady beetles consumed 40 aphids in 1 h, 100 aphids in 4 h, 150 aphids in 8 h, 270 aphids in 24 h, and nearly all 400 aphids in 48 h. Predators showed a curvilinear response in the time they used to consume their prey in relation to total available time. These data demonstrate that convergent lady beetles have potential to suppress larger populations of cotton aphids through continuous feeding by changing their predation efficiency during feeding. The analysis of age-specific mortality without prey or water showed that lady beetle adults could survive for an extended period of time. The ability of a predator to survive without prey for an extended period of time delays or prevents the rebound of pest populations and is a significant factor in natural biological control.