新型农药纳米分散剂型的表征和防效的比较研究

为明确高效氯氟氰菊酯固体纳米分散体的理化性状及其对鳞翅目害虫的田间药效，采用市售乳油和微囊悬浮剂作为对照剂型，通过形貌特征、分散性能、接触角和滞留量测定，对其分散特性及界面性质进行了表征和分析，并开展了田间药效试验，研究了其速效性和持效性。结果显示：该制剂的平均粒径和多分散指数（20.63 nm和0.36）均小于乳油（460.60 nm和0.455）和微囊悬浮剂（1 077.00 nm和0.505），水稻叶面接触角比乳油小9°(左)和6°(右)，甘蓝叶面接触角比微囊悬浮剂小46°(左)和41°(右)，且甘蓝叶面上固体纳米分散体的滞留量比微囊悬浮剂大4.83 mg/cm2。纳米化减小了颗粒粒径，改善了兑水分散特性，减小了接触角，增大了滞留量。田间药效结果证明固体纳米分散体使用剂量为乳油推荐剂量（18.75 g a.i./hm2）的432%时，对水稻二化螟的白穗防效和保苗效果分别为85.64%和90.18%，防效显著优于乳油，表现出优异的速效性。使用剂量与微囊悬浮剂的推荐剂量（11.25 g a.i./hm2）相当时，对甘蓝菜青虫的药后1 d、3 d、7 d和14 d防效分别为83.55%、90.00%、93.48%和88.00%，显示出较好的持效性。上述结果表明高效氯氟氰菊酯固体纳米分散体因其小尺寸效应和表面效应，分散性能、靶标展布附着和渗透力显著增强，速效性好，持效期长，可有效提高农药生物活性，降低使用剂量和施用频次，是一种高效安全环保的新型农药制剂。

Comparative Study on Characterization and Field Efficacy Evaluation of New Pesticide Nanodispersion

In order to clarify the physicochemical properties and field efficacy of lambda-cyhalothrin solid nanodispersions against Lepidoptera pests, commercial pesticide formulation semulsifiable concentrates and micro-capsule suspending agents were used as the control formulations, the morphology, dispersibility, contact angles and retention volumes were measured, the dispersion and interfacial properties were characterized and analyzed, and field efficacy test was also carried out to study its quick effect and persistent effect. The results showed that the mean particle size and polydispersion index (20.63 nm and 0.36) were all lower than those of emulsifiable concentrates (460.60 nm and 0.455) and micro-capsule suspensions (1 077.00 nm and 0.505), the rice contact angle was 9° (left) and 6° (right) smaller than emulsifiable concentrates. The contact angle of cabbage leaf was 46° (left) and 41° (right) smaller than micro-capsule suspending agents, and the retention amount of solid nano-dispersion on cabbage leaf was larger than that of micro-capsule suspending agent as 4.83 mg/cm2. Nanocrystallization reduced the particle size, improved dispersion characteristics, reduced contact angle and increased retention volume. The results of field efficacy showed that the solid nanodispersion of lambda-cyhalothrin had good rapid and persistent effects. When the dosage of solid nano-dispersion was 43.2% of the recommended dosage of emulsifiable concentrate (18.75 g a.i./hm2), the control effect of white head and protection effect upon seedling of the rice stem borer were 85.64% and 90.18%, respectively. The control effect was significantly better than that of emulsifiable concentrate, showing excellent quick effect. When the dosage of the solid nano-dispersion was equal to the recommended dosage (11.25 g a.i./hm2) of the commercial microcapsule suspension, the control effect to the cabbage caterpillar after applying pesticide 1 d, 3 d, 7 d and 14 d were 83.55%, 90.00%, 93.48% and 88.00%, respectively, which showed a good persistence. The results indicated that the solid nano-dispersion of lambda-cyhalothrin could effectively enhance the bioactivity of pesticide, because of its small size effect, surface effect, dispersive property, target spreading attachment and penetration force, quick effect and long persistence. It could also reduce the dosage and frequency of application. Therefore, it is a new type of safe and environment friendly pesticide formulation.