The effect of different flowering plants on the fitness of Trichogramma brassicae (Hymenoptera: Trichogrammatidae)

عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
Many adult parasitoids require non-host food resources, such as nectar and pollen to optimize their viability. These food resources serve as energy source and may improve biological control efficacy of parasitoids. The present study was undertaken to assess the potential effects of five different flowering plants including: buckwheat (Fagopyrum esculentum), coriander (Coriandrum sativum), alyssum (Lobularia maritima), white mustard (Sinapis alba) and red clover (Trifolium pratense) to choose the best cover crop which cause more fecundity and longevity of adult parasitoids. In addition, 10% honey-water and no feeding were also considered as positive and negative control, respectively. The experiment was performed under laboratory conditions (25±1°C, 60±10% R.H. and 16L:8D) and T. brassicae wasps were reared on Ephestia kuehniella eggs. For this purpose, two floral clusters, including an open inflorescence and a cluster containing flower buds were used to ensure that sufficient nectar was present during the test. The inflorescence stems were placed within a penicillin vial, containing moist cotton and a little water to preserve plant vitality. The penicillin vial was bonded to the wall of a cylindrical container with dimensions of 5.7×18 centimetre. Then, approximately 100 newly emerged males and females (less than 24 hours old) were released. After 24 hours, 30 females were separated and transferred to the test tube with an egg card containing 50 flour moth eggs. The longevity of T. brassicae which fed on floral resources of white mustard (5.55±0.76 days), buckwheat (5.35±1.04 days) and alyssum (5.3±0.98 days) was increased significantly compared with wasps provided other treatments. T. brassicae which were exposed to red clover had the shortest longevity (3.95±1.54 days). Total fecundity varies significantly among different treatments after 24 hours of parasitoids exposure to the food sources immediately after adult emergence. Buckwheat flowers (42.1±8.34 eggs) and coriander flowers (37.7±9.69 eggs) significantly caused higher fecundity in T. brassicae compare with 10% honey-water and no feeding. Unlike the previous reports, T. brassicae provided with red clover lived fewer than control treatments, and there was not significant different in their fecundity compare with hungry wasps. This confirms that the presence of flowering plants can increase efficiency of parasitoids, and the certain flowers have a greater effect on their fitness than others, as in this study buckwheat and coriander had the most efficacy on biological characteristics of T. brassicae.
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