| Taking the original drug of emamectin-benzoate (hereinafter short for emamectin-benzoate) as research object, 0.5% emamectin-benzoate ME was researched by a systematic formulation experiment in this paper, actions of drops of emamectin-benzoate ME with different surface tension on cabbage and rice leaf were analyzed, and the insecticidal effects against (Plutella xylostella (L.), Chilo supperssalis (Walker) and Cnaphalocrocis medinalis Guenee) were definite. The main results were showed as followed.1. 29 kinds of different formulations of 0.5% emamectin-benzoate ME were prepared with inverse phase method, the kinds and dosages of cosolvents, surfactants, cosurfactants, excipients and antioxidants which were suitable for preparing the ME were screened out successfully after (54±2)℃thermal storage and (0±2)℃cold storage, the optimum formulation was determined. The specification of 0.5% emamectin-benzoate ME is as following: emamectin-benzoate: 0.5% (mass fraction, same as follows.); cosolvent: 6%; mixed-surfactants: 10%; cosurfactants: 2% n-pentanol; excipients: 2.5% PVA1788; antioxidants: 1% TBHQ; antifreeze: 2% ethylene glycol; tap water: add to 100%.2. Contents of emamectin-benzoate in 0.5% emamectin-benzoate ME were measured by HPLC which taking acetonitrile+water as mobile phase. According to FAO standard, the storage stability test of 0.5% emamectin-benzoate ME was carried on at 0℃, then it was shook lightly after 7 days, there were no obvious separation granule and oily things; fast heat storage was also carried on at (54±2)℃, the relative decomposition rate was 1.94% and all other index were eligible after 14 days.3. Surface tension and spreading characteristics of emamectin-benzoate ME drops on cabbage and rice leaf were studied at concentration of 0.78~12.50mg/L. Results showed that the surface tension of emamectin-benzoate ME at 1.56mg/L,3.12mg/L, 6.25mg/L and 12.50mg/L were smaller than the critical surface tension of cabbage and rice leaf; The contact angles of the drops of these solution were different when the drops were dropped onto cabbage and rice leaf, as time went on, the contact angle became smaller, and the higher the concentration was, the faster the contact angle became small,finally, the drops of that the surfactant reached the CMC (critical micelle concentration) in these solution at 3.12mg/L, 6.25mg/L and 12.50mg/L spread completely, while the drops of that the surfactant did not reach the CMC in these solution at 1.56mg/L could not spread completely. The surface tension of emamectin-benzoate ME were smaller than critical surface tension of cabbage and rice leaf at 1.56~100mg/L while the surface tension of emamectin-benzoate EC were greater than critical surface tension of cabbage and rice leaf, and the dynamic retention of the former on cabbage and rice leaf was obviously more than the latter's at the same concentration.4. Toxicity of 0.5% emamectin-benzoate ME was measured to Plutella xylostella (L.), Spodoptera exigua (Hübner), Prodenia litura (Fabricius) and Helicoverpa armigera (Hübner) by using FAO and domestic standard determination methods, results showed the toxicity of 0.5% emamectin-benzoate ME was slightly higher than that of 1% emamectin-benzoate EC. Pot efficacy tests of 0.5% emamectin-benzoate ME to control Plutella xylostella (L.) and Chilo supperssalis (Walker) showed that the seedling protecting effect of 0.5% emamectin-benzoate ME were better than 1% emamectin-benzoate EC's at the same concentration with a significant difference; the insecticidal effect of controlling Plutella xylostella (L.) reached 97.88% at 5.0mg/L of emamectin-benzoate ME at 10d after treatment, the seedling protecting effect reached 86.47% at 12.0mg/L of emamectin-benzoate ME at 15d after treatment, which were all higher than other treatments'efficacy.5. According to guidelines for field efficacy trials of pesticides made by Ministry of Agriculture, P.R. China, the field efficacy trials of 0.5% emamectin-benzoate ME to control Cnaphalocrocis medinalis Guenee were completed, results showed that the insecticidal effect and seedling protecting effect of 0.5% emamectin-benzoate ME were better than 1% emamectin-benzoate EC's at the same concentration; the insecticidal effect and seedling protecting effect of 0.5% emamectin-benzoate ME with mist sprayer were better than 0.5% emamectin-benzoate ME and 1% emamectin-benzoate EC both with manual spray at the same concentration with a significant difference; the seedling protecting effect reached 92.12%, the insecticidal effect reached 92.67% after 10d's treatment, while the manual spray did not reach such these effects.
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