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Using two natural enemies in biological control of tomato leaf miner can prevent crop quantity and quality losses

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عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
Among tomato pests, the Tomato Leaf Miner (TLM), Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the most destructive pests that considerably affect the yield of tomato worldwide. The zoophytophagus bug, Nesidiocoris tenuis (Reuter) (Heteroptera: Miridae) is an omnivorous predator widely used in integrated pest management programs in both greenhouse and outdoor tomato crops. Release of this voracious predator in seedling (pre-planting release) can shorts the establishment period and improve the distribution of this beneficial predator, especially when weather conditions are less favorable. Trichogrammatid egg parasitoids especially Trichogramma brassicae Bezdenko are the most promising biological control agents which have been used successfully as inundative application against some agricultural pests especially lepidopteran insects. Simultaneous using the above-mentioned two natural enemies against TLM and its effect on quantity and quality of tomato fruits are not well studied. In this regards, using predator in the appropriate time and releasing optimum number of the parasitoid can be very important. The assay was carried out in an environmentally controlled plastic greenhouse (25 ± 5 °C, 50 ± 10% RH) in gauze-covered metallic cages (1 × 1 × 1.5 m, 0.5 mm2 mesh size) which were mounted on the ground. Four tomato seedlings were transferred into soil under each cage and were grown to a height of 35-40 cm before starting the experiment. The predatory bug and parasitoid wasp were used in two times (10 days before and after pest establishment) and two densities (10 and 30 female parasitoids per week), respectively. Based on the results, the highest value of some quantitative parameters such as total number of fruits (783.50 ± 50.56), percentage of undamaged fruits (87.41 ± 0.81), total yield (3116.93 ± 176.47 g) and undamaged yield (2729.07 ± 134.25 g) were obtained in “predator-in-first + 30 parasitoid per week” treatment. Weight of each fruit (ranging from 3.35 ± 0.16 to 4.16 ± 0.18 g) was not significantly different among treatments. Furthermore, in quality assessment, the highest percentage of water (89.32 ± 0.13), the greatest amount of carbohydrates (365.79 ± 53.44 mg/g FW), lycopene (131.29 ± 3.78 µg/g FW), beta-carotene (225.11 ± 5.54 µg/g FW), flavonoid (151.28 ± 14.43 mg/g FW) and total chlorophyll (237.14 ± 5.58 µg/g FW × 10-6) were significantly observed in the above-mentioned treatment. These results strongly showed the high performance of predator-in-first + parasitoid application in biological control of TLM.
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