James R. Cate

Functional response of Catolaccus grandis (Burks) (Hymenoptera: Pteromalidae) in field cages

Abstract Cylindrical field cages enclosing a single cotton plant were used to study the functional response of Catolaccus grandis (Burks) to its host, the cotton boll weevil. Different densities of infested cotton squares (from 2 to 22 per plant) were exposed to an individual female parasitoid inside every cage. The data were fitted to a model modified from Hollings disk equation. The instantaneous searching rate ( a ′) in a 24-h period was 0.743. The handling time ( T h ) was 0.013 ( R 2 = 0.5631; F = 56.03; df = 2, 17; P T h = 0.0 and a ′ = 0.634 ( R 2 = 0.5656; F = 56.66; df = 2, 17; P a ′ = 0.1818, 0.9527, 0.9013, 0.9923, 0.9084, 0.6006, and 0.2803 and T h = 0.3314, 0.0009, 0.0066, 0.0082, 0.0471, 0.3692, and 0.0746 at age groups 1 through 7, respectively, in a period of 24 h. Multiple regression analysis of the same data showed significant effects of age, mean daily temperature, mean relative humidity, uninfested squares per plant, and flowers per plant on rates of parasitism. Interactions and quadratic effects were observed between the variables. The effect of environmental factors on rates of parasitism are discussed.