During a two-year-period, a study was made in the field in order to know the ocurrence of aphids in the broccoli crop. It was possible to know that the total aphid population is higher in winter plantings where more than 240 aphids/plant were found Spring and fall plantings, in comparison, less than 20 aphids/plant were encountered. The species more common were the cabbage aphid (Brevicoryne brassicae L.), the most prevalent species in the crop, getting more than 80% of the population, and the green peach aphid (Myzus persicae Sulzer) with a little bit more than 17% of the total. The natural parasitism in all plantings was around 17%. By species, parasitism in B. brassicae was higher in springs (70% of the total) and fall plantings where the parasitic wasp Diaretiella rapa e (MacIntosh) was probably more active. The sane pattern was obtained for M. persicae, in which the parasitism was again higher in spring and fall plantings (20% of the total) and very low during the winter. Regarding leaf preference, a very defined pattern was found in the M. persicae than for B. brassicae.
POPULATION DYNAMICS OF APHIDS ON BROCCOLI IN THE MEXICAN BAJIO VALLEY.
