Effect of different canola genotypes on some biological parameters of the parasitoid wasp Diaeretiella rapae (Hymenoptera: Braconidae)

The cabbage aphid, Brevicoryne brassicae, is one of the major worldwide pests of canola and the parasitoid, Diaeretiella rapae, is the most important natural enemy of the aphid. In this research, duration of different life stages, percentage of adult emergence and sex ratio of the parasitoid wasp were investigated on three canola genotypes including the Okapi, Licord and Hyola401 (25±1°C, 60±5% RH and a photoperiod of 16L:8D). The experiment was conducted by using petri dishes with leaf discs on 7% water-agar. The results showed that the duration from oviposition until mummification on the Okapi (3.96±0.05) significantly differed from the Licord (4.57±0.01) and Hyola401 (4.72±0.04). The duration from oviposition up to emergence of the adult decreased on the Okapi in both male (7.91±0.11) and female (8.02±0.10). Also, the highest percentage of mummies was significantly observed on the Okapi (89.60±6.81) rather than the Licord (66.20±5.21) and Hyola401 (59.10±3.64). However, there was no significant difference in the percentage of emerged female among the genotypes. The shortest development time of the parasitoid were also occurred on the Okapi. The Okapi could increase the efficiency of the wasp for controlling the aphid rather than the two other genotypes. It is suggested to apply the augmentation biological control method by using the parasitoid wasp, D. rapae for the fields under the Okapi cultivation and also for the mass production of the parasitoid by using this genotype in integrated pest management programs.