| Stomphastis thraustica Meyrick is one of the most important pests of Jatropha curcas L. The larva of leaf miner live in and eat the mesophyll, the infested areas by the larva form insect spots which show the growth record of the larva on the leaves. As the larva grows, the spots become wider and left their excrements in the insect spots, which would affects the transportation of water and nutrition, then retard the growth of the trees.Stomphastis thraustica Meyrick have rapid reproduction and occurred many generations annually in field, the generations were seriously overlapped, which caused difficulties in pest control activities. The purposes of this study were to select some insecticides with different mechanisms which were effective to control Stomphastis thraustica Meyrick, and raw insecticides can be formulated to micro-emulsion(ME). Comparing with other formulations, the advantages of ME as follow:ultra-fine-grain emulsion, strong permeability, adopting water in place of a plurality of organic solvents which fit the need of water solution pesticide agent producing. Utilizing these advantages, ME avoid shortcomings of traditional dosage form and enhance its efficiency. The major procedures and results of this experiment are as below:1.Insecticides screening:In this experiment, five kinds of insecticides with different mechanisms(triazophos, cypermethrin, monosultap, diflubenzuron and emamectin benzoate) are screened. The susceptibility of the egg, early larvae and 2nd-instar larvae of Stomphastis thraustica Meyrick to different insecticides was conducted with the immersion method and leaf dipping method. The results showed that emamectin benzoate exhibited highest efficacy against 2nd-instar larvae of Stomphastis thraustica Meyrick with LC5o=1.67mg/L after 48h. Triazophos exhibited lower efficacy than emamectin benzoate, but it exhibited strongly inhibitory to eggs, resulting in a 48.98% hatching rate. In view of this, emamectin benzoate and triazophos were chose to screen compound proportion. Several ratios were evaluated by applying the co-toxicity coefficient method and mathematical model. The result of screening is that the proportion of emamectin benzoate and triazophos is 1:26.4, and this co-toxicity coefficient(CTC) reached the highest which was 278.58, showing a synergistic effect and this ratio was used in mixture product development.2.The preparation of ME:based on structure theories of ME, after solvent, emulsifiers as well as their ratio screening and product quality test, the optimal prescription of 13.7% Emamectin benzoate and Triazophos ME was reported as follows:emamectin benzoate(0.5%), triazophos(13.2%), solvent(5～8%), the proportion of the mixture of surfactant,500:600:E-1310=1:2:3,which totally occupied 24% weight of the formulation, n-butanol(12%), the other component is water.3. The quality inspection of ME:the general indicators including heat-storage stability, cold-storage stability, emulsion stability, pH value and so on were examined referring to related domestic standard. The test results conformed to the standard4. The field experiments of ME:the experiment results indicated that the efficacy of 13.7% Emamectin benzoate and Triazophos ME was much better than that of emulsifiable concentrate. The control efficacy of 13.7% Emamectin benzoate and Triazophos ME diluted 1000,1500 and 2000 times were 96.41%,94.55% and 87.05.% respectively. |
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