REPRODUCTIVE, DEVELOPMENTAL AND NUTRITIONAL BIOLOGY OF THE TOMATO MOTH, LACANOBIA-OLERACEA (LEPIDOPTERA, NOCTUIDAE) REARED ON ARTIFICIAL DIET

Several aspects of the biology of the tomato moth, Lacanobia oleracea (Linnaeus) were investigated when these insects were fed an artificial diet and kept under laboratory conditions. The six larval stadia occu pied a total period of 35.6 days at 20 degrees C and 65% r.h. Larvae o f each stadium could be separated by their head capsule widths, but no t weight ranges, which overlapped. Feeding studies carried out on larv al L. oleracea revealed instar dependent changes in the indices of foo d consumption and utilization. Larvae increased in weight from the fou rth to sixth instar due to a combination of the increased efficiency w ith which ingested food was converted to body tissue, and increased fo od consumption by older larvae. Sixth (final) instar larvae exhibited three distinct behavioural phases; during one of these, the feeding ph ase, larvae consumed a greater amount of diet than either the fourth o r fifth instars. The mean pupal period of non-diapausing pupae was 25 days. Pupal diapause was induced when larvae were reared under short d ay conditions. The male to female sex ratio of adult moths was 1:1.3. Mating generally began during the first scotophase after adult eclosio n, and stopped soon after the start of the next photophase. Females us ually mated only once, but males were capable of mating at least seven times. Oviposition normally commenced on day 2 of adult life, and the mean total egg production was 1186 eggs/female. Sex pheromone compone nts were not present in solvent extracts of the pheromone glands of 20 -day-old female pupae, but low levels were detected in pharate adults. A further increase in pheromone levels in newly-emerged moths was det ected and, in isolated virgin moths, pheromone levels increased each d ay of adult life until day 9. Pheromone levels were significantly lowe r in two-day-old mated adult females, than in two-day-old virgins.