A QUANTITATIVE GENETIC ANALYSIS OF OVIPOSITION PREFERENCE AND LARVAL PERFORMANCE ON TWO HOSTS IN THE BRUCHID BEETLE, CALLOSOBRUCHUS MACULATUS.

Abstract

The presence of positive genetic correlations between oviposition or feeding preference for hosts, and performance on those hosts, is of fundamental importance to models of host race formation, sympatric speciation, and the maintenance of genetic variation within phytophagous insect populations. In this paper, I estimate the amount of genetic variation in oviposition preference and larval performance present in two California populations of a cosmopolitan pest of stored legumes, Callosobruchus maculatus (Bruchidae: Coleoptera), and examine whether positive genetic correlations exist between preference and performance. High levels of genetic variation in both preference and performance were detected in one population (Bay Area population, h2 = 0.73 for oviposition preference), but not in another population (Davis population). A second estimate of the amount of genetic variation for oviposition preference in the Bay Area population, after three generations of laboratory rearing, supports the hypothesis that the absence of significantly nonzero heritabilities in the Davis population is probably due to the three generations of laboratory rearing prior to the start of the experiment. No positive genetic correlations were detected between preference and any performance character measured. Data are also presented on the genetic correlations between performance on azuki (Vigna angularis) and cowpea (Vigna unguiculata). Genetic correlations were found to be positive for all characters in both populations of C. maculatus (range 0.132 to 0.542).