مریم فامیل

Resistance development to both insecticides and transgenic crops has been frequently reported in Helicoverpa armigera populations, necessitating efforts to find new control measures. This study was aimed to evaluate the efficiency of attract and kill method using Noctovi®, a synthetic plant volatiles-based attractant for controlling H. armigera. In addition, the attractiveness of the Noctovi® for adults of H. armigera was evaluated under field conditions using delta traps. One liter per hectare of Noctovi® mixed with Permethrin, 5 ml A.I. or Thiodicarb, 7 ml A.I. was sprayed on tomato plants of the middle row (100 m length) just before sun set every two weeks. As infestation criteria, means percentages of infested tomatoes in attract & kill, insecticidal treatment and control (without any treatment application) plots were statistically compared. The results revealed that the Noctovi® was attractive for gravid females and males of H. armigera. Means percentages of infested tomatoes in attract & kill, insecticidal treatment and control (respectively 2.91±0.18, 4.68±0.24 and 5.14±0.28) were significantly different and the infestation in attract & kill treatment was significantly less than those of insecticidal treatment and control ones. At the same time, the infestation in insecticidal treatment was significantly less than that in control.

Health and environmental side effects of chemical insecticides and development of resistant population of Helicoverpa armigera Hubner (Lepidoptera: Noctuidae) to pesticides have resulted in increasing demands for non-chemical control approaches against this pest. In this research, the efficacy of two biological control agents were studied under field condition. Treatments consisted of releasing Habrobracon hebetor (Say) (Hymenoptera: Braconidae), Trichogramma evanescence Westwood (Hymenoptera: Trichogrammatidae) and combination of H. hebetor + T. evanescence (HABROBRACON-TRICO). The results revealed significant differences in the number of infested tomato fruits among treatments and harvesting times. The infested fruits was the lowest (2.68 ± 0.14%) in plots treated by HABROBRACON-TRICO. Moreover, the highest (3.36 ± 0.50%) and the lowest (2.88 ± 0.22%) damaged fruits was recorded in the second and fourth harvesting times, respectively. There was significant interaction between harvesting times and treatments. Regarding the tomato yield in treatments, findings revealed significant difference among treatments in both main harvesting times. However, there was no significant differences in total yield in treatments. It could be concluded that biological control agents can be used as a promising alternative for synthetic insecticides in control of H. armigera in tomato farms without significant crop losses.

Longevity, host preference, length of life stages and the number of offspring of Habrobracon hebetor were evaluated on the host larvae of Ephestia kuehniella treated with lethal and sub-lethal doses of Bacillus thuringiensis Experiments were conducted in a completely randomized design under laboratory condition. The number of eggs decreased from 3.9 in control to 1.4 and 2.7 in lethal and sub-lethal doses, respectively. By reducing the number of parasitoid offspring from 3.7 in control to 0.6 and 1.2 in lethal and sub-lethal doses, also the adult parasitoid longevity decreased from 15.6 days in control to 12.3 and 13.7 days in lethal and sub-lethal doses, respectively. In the lethal dose of Bt treatment, duration of embryonic and larval stages of the wasp showed a significant increase compared to control, but pupal stage duration decreased in both lethal and sub-lethal doses of Bt treatment. Generally, by reducing the usage dose of Bt and avoiding its application during the critical stages of parasitoid life, the efficiency of their use in integrated pest management can be improved.