To facilitate studies on the natural and chemical control of Hylemya (Erioischia) brassicae (Bch.) in Holland, the bionomics and abundance of the Anthomyiid were investigated in 1959-9 in fields in which cauliflower was grown. The numbers of eggs and larvae were estimated by scrutiny of soil samples and emergence of adults was observed with soil traps. In 1955, the numbers of eggs laid by each of the three succeeding generations increased, but in the 1956-59 they decreased; in 1955, 1957 and 1959, larvae and pupae of the first generation were more abundant than those of the second, but in the intervening years the reverse occurred.The numbers of adults emerging decreased towards the end of each season, through increase in the proportion of pupae that entered diapause or were parasitized. Mortality was high in larvae, and less than 10 % of the eggs gave rise to pupae. Aleochara bilineata Gylh. and Trybliographa (Cothonaspis) rapae (Westw.) caused 5.5-38 % mortality and miscellaneous insect predators 17 %; mortality in newly hatched larvae was 78-79.5 %, mainly through failure to become established on mature plants. Damage to the plant was determined both by density of larvae, and by the state of the crop; it was greatest in cool weather, which increased the fecundity of the flies and reduced plant growth. Reduction in the numbers of larvae by treatment of the plant base with insecticides, particularly aldrin and chlordane, was associated with a decrease in those of A. bilineata and miscellaneous predators, but it was not established whether this was due directly to insecticides or to the scarcity of H. brassicae.
|Qualification||Doctor of Philosophy|
|Award date||5 Feb 1960|
|Place of Publication||Wageningen|
|Publication status||Published - 1960|
- plant pests
- plant protection