Integrating of Trichogramma spp. and gamma irradiation for control of angoumois grain moth, Sitotroga Cerealella (Lepidoptera: Gelechiidae) in stored wheat grains
摘要
The angoumois grain moth, Sitotroga cerealella (Olivier), is a major lepidopteran insect pest of stored grains. Therefore, this study assessed the effectiveness of Trichogramma evanscens and Trichogrammatoidea bactrae, individually and in integration with gamma irradiation against S. cerealella under large scale condition. A dose of 144.4073 Gy (LD90) for S. cerealella eggs irradiated within the 50–150 Gy range, was applied in the experiments. The infestation rate of S. cerealella on stored wheat grains and the associated weight losses were evaluated under the different treatments. All treatments decreased the internal infestation of all stages of S. cerealella and delayed its emergence as compared to control. Both T. evanscens and Tr. bactrae parasitoids significantly reduced S. cerealella adult emergence (84.21 and 79.71%), increased adult longevity (8.14 and 8.46 days), decreased egg laying (66.11% and 64.00%) and decreased hatchability rates (69.62% and 72.48%).When integrating parasitoids with gamma irradiation, both T. evanscens and Tr. bactrae were consistently more effective, resulting in reductions of egg laying (99.27 and 98.96%), and reduction in hatchability (45.63 and 40.11%). Release of T. evanscens or Tr. bactrae alone reduced infestation and grain weight loss to (37.52% and 13.86%, respectively) for T. evanscens and (53.19% and 19.50%, respectively) for Tr. bactrae, compared to 86.12% and 34.23% in the control group. Combining gamma radiation with T. evanscens or Tr. bactrae further reduced infestation (5.15% and 6.46%) and grain weight loss (1.10% and 13.76%), respectively. Moreover, integrating gamma irradiation with the egg parasitoid species provided more effective control compared to individual treatments.