THE EFFECT OF NOVEL ENVIRONMENT AND SEX ON THE ADDITIVE GENETIC-VARIATION AND COVARIATION IN AND BETWEEN EMERGENCE BODY-WEIGHT AND DEVELOPMENT PERIOD IN THE COWPEA WEEVIL, CALLOSOBRUCHUS-MACULATUS (COLEOPTERA,BRUCHIDAE)

Progeny from full-sib/half-sib families of a population of Callosobruc hus maculatus near genetic equilibrium were reared either in an ancest ral (30 degrees C, 70 per cent relative humidity) or in a novel (25 de grees C, 45 per cent relative humidity) environment. The life history traits, emergence body weight and development period were measured in both sexes. Insects developed faster and emerged heavier at a higher t emperature and humidity. For both sexes, in the ancestral environment additive genetic variation and 'narrow-sense' heritability estimates w ere higher for body weight, the morphological trait, than for developm ent period, the primary fitness trait. For both sexes, matrix analyses revealed significant differences between the estimated additive genet ic variance-covariance (G) matrices from each environment. In the nove l environment, the evolved genetic architecture appeared to break down , possibly as a result of novel gene expression; the trade-off between emergence body weight and development period was disrupted with an as sociated increase in additive genetic variation for both life history traits. In both environments, female insects developed more slowly and emerged heavier than male insects. Matrix analyses show significant d ifferences between the G-matrices of each sex, suggesting that differe nt constraints may operate in the two sexes.