Kavallieratos Nickolas G, Athanassiou Christos G, Saitanis Constantin J, Kontodimas Demetrius C, Roussos Alexander N, Tsoutsa Maria S, Anastassopoulou Urania A
Laboratory of Agricultural Entomology, Department of Entomology and Agricultural Zoology, Benaki Phytopathological Institute, 8 Stefanou Delta str., Kifissia, Attica, Greece.
J Food Prot. 2007 Jul;70(7):1627-32. doi: 10.4315/0362-028x-70.7.1627.
The insecticidal effect of two azadirachtin-based insecticides, NeemAzal-T/S and Oikos 32 EC, was examined against adults of the grain beetles Sitophilus oryzae and Tribolium confusum on wheat and maize under different temperature and humidity regimes. The insecticides were applied at three dosages, equivalent to 50, 100, and 200 mg of active ingredient per kg of grain. Adults of the above species were exposed to the treated grains at 20, 25, and 30 degrees C and two relative humidity levels (55 and 75%), and mortality was assessed after 14 days of exposure. All adults were then removed, and the treated substrate remained under the same conditions for 45 more days. After this period, the grains were checked for progeny production. In both species and both commodities, mortality increased with insecticide dosage. For many dosage-formulation combinations, mortality increased with temperature at 55% relative humidity but the reverse was observed at 75% relative humidity. Comparing the two formulations, NeemAzal-T/S was more effective than Oikos 32 EC at all the combinations tested. NeemAzal-T/S was more effective at high relative humidity, but the efficacy of Oikos 32 EC was not much affected by the relative humidity. Survival was high, even at the higher dosages, in some of the temperature-humidity combinations. Progeny production of S. oryzae in the treated grains was considerably higher than that of T. confusum. The results of the present study indicate that further dosage increases and longer exposure times are needed to obtain a complete (100%) adult mortality in all combinations tested. However, the feasibility of using higher azadirachtin dosages (>200 mg/kg grain) is questionable for cost reasons. Consequently, the use of these substances is not comparable to the use of traditional grain protectants, which are usually used at dosages of <5 mg/kg grain. Although azadirachtin-based insecticides can be used with success for protection of stored grain, our study demonstrated that under certain circumstances such an application may not be effective. Abiotic factors (formulation, temperature, and relative humidity) had a more serious impact on the efficacy of these insecticides than did biotic factors (target species and commodity).
研究了两种基于印楝素的杀虫剂NeemAzal-T/S和Oikos 32 EC在不同温度和湿度条件下，对小麦和玉米上的谷蠹Sitophilus oryzae和杂拟谷盗Tribolium confusum成虫的杀虫效果。杀虫剂以三种剂量施用，相当于每千克谷物50、100和200毫克活性成分。将上述物种的成虫置于20、25和30摄氏度以及两个相对湿度水平（55%和75%）下接触处理过的谷物，接触14天后评估死亡率。然后将所有成虫移除，处理过的基质在相同条件下再放置45天。在此期间后，检查谷物的后代产生情况。在两个物种和两种商品中，死亡率均随杀虫剂剂量增加而升高。对于许多剂型-剂量组合，在相对湿度55%时死亡率随温度升高而增加，但在相对湿度75%时观察到相反情况。比较两种制剂，在所有测试组合中NeemAzal-T/S比Oikos 32 EC更有效。NeemAzal-T/S在高相对湿度下更有效，但Oikos 32 EC的效力受相对湿度影响不大。在某些温度-湿度组合中，即使在较高剂量下存活率也很高。处理过的谷物中谷蠹的后代产生量明显高于杂拟谷盗。本研究结果表明，需要进一步增加剂量和延长接触时间，才能在所有测试组合中实现完全（100%）的成虫死亡率。然而，由于成本原因，使用更高印楝素剂量（>200毫克/千克谷物）的可行性值得怀疑。因此，这些物质的使用与传统谷物保护剂的使用不可比，传统谷物保护剂通常以<5毫克/千克谷物的剂量使用。尽管基于印楝素的杀虫剂可成功用于保护储存谷物，但我们的研究表明，在某些情况下这种应用可能无效。非生物因素（剂型、温度和相对湿度）对这些杀虫剂效力的影响比生物因素（目标物种和商品）更严重。
