Studies Of Physical Dynamic Influence Of Sevaral Effective Adjuvents To Avermectin On Cabbage

Avermectins are 16-membered pentacyclic lactone compounds produced by strephomyces avermitilis, which have extensive and high effect on many kinds of pest and mite. But they are also photodegrated easily under the sunlight. So their pesisiting efficacy is very short. The synergism action of oil adjuvants, penetrative agents and cationic surfactants to avermectin was investigated in laboratory. And the influence of ultraviolet absorbents to avermectin was also studied. The physical dynamic influence of sevaral effective adjuvents to avermectin on cabbage cuticle was tested.The toxicity of the mixture of effective adjuvants and avermectin to 3rd-instar larva of Plutella xylostella was determined by bioactivity method. The result showed that the synergism increased after mixing oil A, rapeseed oil and sunflower oil to avevmectin. The synergism ratio of contact toxicity was 2.36, 1.80 and 1.73 respectively, while stomach toxicity was 1.81, 2.26 and 1.66. The synergism ratio of contact toxicity was 2.37, 1.43 and 1.33 respectively, while stomach toxicity was 1.69, 1.99, and 1.24 mixed with OPC-3 at the dose of 0.01%, 0.02% and 0.04% in avermectin emulsion; the contact synergism ratio of penertrative Agent T was 2.18, 1.78 and 1.92, the stomach synergism ratio was 2.13, 1.57 and 1.42; the contact synergism ratio of GFD-9 was 1.77, 1.98 and 1.48, the stomach synergism ratio is 1.54, 2.03 and 1.41. The synergism ratio of contact toxicity was 3.60, 2.74 and 2.67 respectively mixed with song xiang acid acetone, MW-1 and FL-1 at the dose of 0.01% in avermectin emulsion, while stomach toxicity was 1.67, 2.27 and 1.62. The change of surface tension, contact angle, deposition, drying times and penetrative quantity of avermectin 1EC emulsion with different effective adjuvavts were also tested. The result showed that the surface tension and contact angle reduced little, while the drying time prolonged and the deposition and penentrative quantity increased when added effective oil adjuvants into avermectin emulsion. By adding effective penetrating agents, the surface tension contact angle and drying time reduced greatly, the penentrative quantity increased, but the deposition rate changed little. And when adding with effective cationic surfactants, the surface tension contact angle and drying time reduced greatly, while the deposition and penetrative quantity changed little.Under the ultraviolet intensity, the influence on decomposition of avermectin after plus ultraviolet absorbent was studied by HPLC. The result indicated that the photostability increased greatly after plusIing MML-834 and MML-2 to avermectin. The decomposition was cut down 76.74% and 77.46% respectlivey after 4 and 8 hours later under the ultraviolet light. The decomposion rate decreased to 37.92% and 47.09%. After treated 16 hours, the decomposion rate decreased to 33.55% and 48.55%; the decomposition rate decreased to 23.57% and 42.09% respectlivey after 24 hours under the ultraviolet.