磷化氢对小麦中玉米象致死效果的研究

玉米象Sitophilus zeamais(Motschulsky)的卵、幼虫以及蛹在粮食籽粒内部生活与发育,粮粒结构会影响熏蒸气体的渗透以及对隐蔽虫态的杀虫效果,了解粮粒内卵、幼虫、蛹以及成虫对磷化氢耐受能力的差异,有助于科学有效杀虫。本文测定了3个玉米象品系对磷化氢的抗药性,及在100、200、300、400和500mL/m3的磷化氢浓度下玉米象成虫及其隐蔽虫态卵、幼虫和蛹在不同熏蒸时间的死亡率。主要结果为:3个品系的玉米象对磷化氢均未产生抗性。在各磷化氢浓度下,经6h熏蒸后100mL/m3浓度下成虫的死亡率近59%,而500mL/m3浓度下死亡率在91%以上;经12h熏蒸后各品系成虫的死亡率均达100%,而其卵、幼虫和蛹死亡率均小于100%;经24h熏蒸后,各品系的卵、幼虫和蛹死亡率达100%的磷化氢浓度需要在400mL/m3及以上;经36h熏蒸后,100mL/m3浓度可完全致死玉米象BJXNSz品系的卵、幼虫和蛹,但对另外两个品系的卵、幼虫和蛹的致死率小于100%;磷化氢熏蒸48h以上的各浓度均可完全致死受试害虫。结果表明,100mL/m3以上的磷化氢浓度均可在不同时间致死玉米象各虫态,但完全致死玉米象各虫态的时间在100mL/m3浓度下需要48h,在500mL/m3浓度下需要24h,浓度升高完全致死害虫的时间缩短。玉米象卵、幼虫和蛹对磷化氢耐受力相接近且远大于成虫。

Mortality of Sitophilus zeamais Motschulsky in the wheat kernel to phosphine

In order to explore the application technology of S-metolachlor in wheat fields, the safety of S-metolachlor to wheat was evaluated and its safeners were examined indoors, and then the mechanism of efficient safener was studied. The results indicated that the wheat-seedling growth inhibition from S-metolachlor would be aggravated as the soil moisture increased and the temperature decreased. Meanwhile, four safeners were tested by seed treatment. At 0.5, 5 g/kg, benoxacor could significantly reduce the phytotoxicity from S-metolachlor. Fenclorim, dichlormid and AD-67 also showed moderate antidotal effect at 0.5 g/kg, but vanished at 5 g/kg. Further research showed that benoxacor was an excellent safener of S-metolachlor on wheat. When seeds treated at 0.5-4 g/kg, wheat-seedling growth inhibition rate caused by 150-600 g/hm2 S-metolachlor decreased by about 20%. As the best treatment, 1 g/kg benoxacor enhanced wheat-seedling resistance to S-metolachlor by more than 4 times. The physiological results showed wheat-seedling (4-6 d after sowing) GSTs activity significantly increased under seed treatment with 1 g/kg benoxacor, but no significant difference in GSH content, revealing that benoxacor might reduce wheat-seedling injury from S-metolachlor by improving GSTs activity rather than GSH content in wheat.