Influence of sulphur plant nutrition on oviposition and larval performance of the cabbage root fly

摘要

1 Oilseed rape plants (Brassica napus) (L.) (Brassicaceae) were grown under different levels of sulphur supply and tested for the oviposition preference and larval performance of cabbage root flies Delia radicum (L.) (Diptera: Anthomyiidae). 2 Adult females laid more than three-fold as many eggs on control S_n (normal field concentration) than on sulphur-free S_0 plants. By contrast, no significant difference was observed between control and double normal concentration (S_+) plants. 3 The larval performance was evaluated using three additional, intermediate sulphur levels between S_0 and S_n, and the plants were infected with equal numbers of eggs. The percentage pupation at the end of larval feeding ranged from 6% (S_0) to 32% (S_n or S_+) and theaverage number of pupae, or of emerging flies, was significantly correlated with sulphur application. 4 The weight of emerging males and females was correlated with plant sulphur supply. 5 The duration of development from eggs to adult emergence was approximately 2 days longer in females than in males. Females originating from plants with a normal or higher sulphur supply tended to emerge 1-2 days earlier.