| The meilingmycin in pesticidal invention was found by china, which was a new insecticidal antibiotic. This dissertation studies on meilingmycin and the other three insecticidal antibiotic avermectin, spinosad, liuyangmycin. Laboratory measurement of toxicity to different instar larva of taian's pullutella xylostella (L.) population of these four insecticides was carried out by insect-dip method. At the same time, the insecticidal activity to other insects and acarids of meilingmycin were studied .The meilingmycin's mode of activity was evaluated by using different measuring methods to toxicity.The ovicidal action to pullutella xylostella and Tetranychus urticae Koch of meilingmycin and its residual efficacy duration in entironment were investigated.The synergism of five synergists was tested, and the mechanism of meilingmycin was discussed by biochemical bioassay. The results could be summarized as follows:1. The meilingmycin's toxicity to every instar larva of pullutella xylostella was further higher than the four compared insecticidal antibiotics's. The meilingmycin's LC50 is 2478～50589 folds to the liuyangmycin's and its toxicity would decline with the development of instar larva.2. The insecticidal range of meilingmycin is very large, it has very high toxicity to insects and acarids, such as pullutella xylostella L., Tetranychus urticae Koch, Panonychus citri McGregor, Phyllocoptrota oleivora Ashamead, Panonychus ulmi Koch, Tetranychus urticae Koh, Aphis gossypii Glover, Lipaphis erysimi Kaltenbach, and its toxicity was equal or higher to the compared insecticide's, so it is an excellent acaricidal and insecticidal antibiotics. But meilingmycin is not susceptive to Pieris rapae Linne, its LD50 to 5 instar larva is only 0.0009 fold to Avermectin's.3. Meilingmycin's contact action is primary, at the same time it has nicer stomachic action and definite osmosis action. It is tested by dip method that meilingmycin's LD50 to pullutella xylostella (L.) is 3.8 folds to Avermectin's, its contact toxicity is the highest. The stomachic toxicity to pullutella xylostella (L.) was testified by leaf-dip method, it showed that meilingmycin's stomachic toxicity is inferior to Avermectin's, but markedly higher than Spinosad's; the osmosis action of meilingmycin is also lower than Avermectin's; Meilingmycin has neither systemic action nor fumigantion effect.4. The ovicidal action of meilingmycin is outstanding, it could observably restrain the egg hatching of pullutella xylostella (L.) and Tetranychus urticae Koch, the restraining effect is markedly higher than all the other compared insecticide. What's more, it did cause substantial mortality of newly-hatched larva of pullutella xylostella (L.).5. The efficacy duration in entironment of meilingmycin is around 7 days, when it was used by spray. Be used three days later, meilingmycin's reviseing death rate was 92%; five days later, meilingmycin's toxicity markedly dropped; seven days later, the reviseing death rate was 73.7%, fourteen days later, the toxicity of meilinmycin almost disappeared. The result also show that: the decompound velocity of meilingmycin in entironment is quicker than Avermectin's.6. Fourth instar larva of pullutella xylostella (L.) was treated by insect-dip method using meilingmycin and Avermectin , its dosage is equal to the LC50 to fourth instar larva of pullutella xylostella (L.), then measured the activity of CarE ,AChE and GST in one hour, two hour, four hour , and eight hour, the result showed that: meilingmycin and Avermectin could evidently restrain the activity of CarE ,AChE and GST , and with time increasing , the inhibiting effect could rise ; the inhibiting action of meilingmycin to CarE and AChE is much higher than Avermectin's. Steeped 4th larva of pullutella xylostella by meilingmycin and Avermectin , the maximal reaction velocityand the affinity to substrate of CarE was markedly lower than control group's, both of these could testify that the change of quality of CarE happened after steeped. But...
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