Research On Plant Insecticides And The Synergism Of Mixture Of These Compounds

The thesis takes the extensive plant resources - Melia azadarach -Tripterygium wilfordii, Sophora flavescens as study objects, the bioactivity of their extractions on the larvae of Abraxasmiranda and Sopodoptera litura were tested by bioassays. The synergictic action of extraction from the fruits of Melia azadarach with alcohol combined Artemisia argyi oil or Bamboo vinegar in different ratio against the experimental insects was also preliminarily discussed in this paper.The Laboratory experimental results indicated that the 3th instar Abraxasmiranda and the 4th instar Spodoptera ]jtura larvae' s food quantily is only 24.31% and 22.12% of the control after they are the leaves treated with 1000mg/l extraction cf the fruits of Melia azadararch in 48 hours, the larvae' s growth weight was only - 20. 36% and - 2L 27%;The 3th instar Abraxasmiranda larvae' s food quantily is only is only 37.83% and 42. 10% of the control after they ate the leaves treated with 800mg/l extraction of Tripterygium vilfordii with alcohol or ammonia water, the growth weight was only 37. 55% and 50. 74% than the control. The 3th instar Abraxasmiranda and the 4th Spodoptera litura larvae' s growth weight was only 22. 01% and 19. 46% of the control after they ate the leaves treated with 1600mg/l extraction of Sophora flavescens in 48 hours, it also had toxic ity on the 2th instar Abraxasmiranda and Spodoptera litura larvae, the mortality was 42.36% and 54.69% respectively in 24 hours.The AFC50 of extraction from the fruits of Melia azadarach with alcohol and Tripterygium wilfordii with alcohol or ammonia water against the 3th instar larvae of Abraxasmiranda in no-choice test were 248.53 mg/1,277. 33 mg/1 and 383. 97mg/l respectively in 48 hours. The LC50 of them were 199. 53mg/l, 116. 41mg/l and 314. 96mg/l respectively. Against the 4th instar larvae of Sopodoptera litura , the LC50 were 101.44 mg/1, 204. 80 mg/1 and 335.07 mg/1 respectively in 48 hours.Effect of the extractions from the fruits of Melia azadararch with alcohol on the feeding behavior of the fifth instar larvae of Sopodoptera litura eating treated-leaves was quavtitatively described through continual observation for lOh in the laboratory. The result showed that the temporal feeding patterns of the 5thinstar larvae which were treated with extractions from the fruits of Melia azadararch were different from those untreated. The meal length ,the net time spent eating inameal, the inter-feeding gap and the intra-feeding gap length, the boult numbers and the numbers of the types of gaps of the larvae treated with the extractions from the fruits of Melia azadararch were significantly different from those untreated. The results showed that essential oil from Artemisia argyi combined with the extraction from the fruits of Melia azadarach with alcohol in 1:9,3:7,5:5,7:3,9:1 had significant synergictic action on the 3th Abraxasmiranda instar larvaes, the cotoxicity coefficients were 125.87,171.09,227.64,114.11 respectively; They had been acted on the 4th Spodoptera litura instar larvaes , the cotoxicity coefficients were 101. 51, 239. 08, 374. 04, 325. 44, 149. 22 respectively . When the extraction from the fruits of Melia azadarach with alcohol combined with bamboo vinegar in 1:9, 3:7, 5:5, 7:3, 9:1, it had significant, synerrict.ic action on the 3th Abraxasmiranda and the 4th Spodoptera litura instar larvaes,the cotoxicity coefficients were 121.49, 182.82, 231.66, 366.51, 166.82: 112.82, 285.02, 356.18,313.40,105.57 respectively. It is suggested that these different kingds of plant insecticides combination was an usful method for controlling resistant Abraxas mirand and Sodoptera litura.The Laboratory experimental results indicated that the extraction from the fruits of Melia azadararch had obvious of contact poison, ant ifeedant and growth inhibited on the experimental insects. The extraction of Tripterygium wilfordiiw\t\\ alcohol or ammonia water also had properties bioactivity to the experimental insects. The extraction of Sophora flavescenshad no obvious antifeeding on the te...