GENETIC SELECTION FOR AND EVALUATION OF NONDIAPAUSE LINES OF PREDATORY MIDGE, APHIDOLETES APHIDIMYZA (RONDANI) (DIPTERA: CECIDOMYIIDAE)

Abstract

AbstractFour lines of Aphidoletes aphidimyza (Rond.) were selected for nondiapause (one for 50 generations) under L:D 8:16 and 21 ± 1°C. In three selected lines, diapause incidence dropped rapidly in the first four or five generations, with means of 3–11% thereafter. There was no clear response to selection in the fourth line. Neither morphology nor sex ratio was affected by nondiapause selection in any lines, nor was fecundity affected in the longest-reared line. Reciprocal crosses indicated that the diapause trait was dominant; the effect of relaxing selection pressure was a gradual increase in diapause incidence after eight generations. There was a correlation between increased diapause incidence and slower development in selected lines. Diapause larvae took longer to develop than nondiapause larvae from the same line. Selection for nondiapause under L:D 8:16 with fluctuating thermoperiods was unsuccessful.