The influence of some cabbage cultivars on green peach aphid Myzus persicae Sulz. and the distribution of the parasitoid Diaeretiella rapae (Mcintosh) (Hymenoptera: Aphidiidae)


Laboratory and field studies were undertaken to evaluate the influence of four cabbage cultivars, Kandura, Royal, Dabana and Red, on some biological aspects of green peach aphid Myzus persicae Sulz. (Homoptera: Aphididae) and on the distribution of the parasitoid Diaeretiella rapae Mcintosh. (Hymenoptera: Aphidiidae). Results indicated that production of young nymphs per female varied depending on the cultivar. The highest progeny production was 23.7 nymph/ female recorded on the cultivar Kandura and the lowest number was 7.3 nymphs/ female on Red cabbage. Females produced an average of 4.8 and 1.3 nymph when fed on the two cultivars respectively. The parasitoid D. rapae was found associated with the aphid and varied according to the host cabbage cultivar. The highest percentages of parasitism was 28% on Kandura cultivar and the lowest was 7% recoded on aphid fed on Red cabbage. Field studies showed that there were 8 generations for green peach aphid during the course of this study which lasted from the beginning of December to the end of March. the length of generation decreased with the increasing of temperature and varied according to cabbage cultivar. The activity of the parasitoid also varied with cultivar and temperature. The highest percentage of parasitism was 28% recorded on Kandura in the beginning of January. The red cabbage was the least preferred host plant for the D. rapae being the highest percentage of parasitism 7% observed late in February .Results also indicated that the parasitism increased with the increasing density of aphid. Therefore any control practice should take in consideration all possible means that would lead to conserve and assist this parasitoid in the field.