| Effect of Fumigant and its Combination with CO2 on Tetranychus cinnabarinus and Fresh Cut FlowersMaster candidate: Wang XinxiangAssoc. Prof. Liu huai Advisor:Assoc. Prof. Deng xinping(College of Plant protection, Southwest Agicultural University, Chongqing 400716, P. R. China)SummaryFumigation effects on mite pests and cut flowers were studied. The aim was to decrease the dosage of methyl bromide or discard it completely. The main results were as follows.1.Fumigation on adult of T. cinnabarinus1.1 Fumigation effect of methyl bromide, phosphine and essential oils at various dosage and different fumigation time on T. cinnabarinusT. cinnabarinus was sensitive to methyl bromide, the mortality of T. cinnabarinus increased with the dosage of methyl bromide. After 2h-exposure at 25℃, the mortality of 30g/m3, 35g/m3, 40 g/m3 methyl bromide were 86.46%, 91.37%, 97.73%, respectively. After In-, 1.5h-, 2h-exposure, the LD50 values were 27.8828±1.1833 g/m3, 21.4533 + 1.5520 g/m3, 18.8758±1.3084 g/m3, respectively.Phosphine showed perfect results to kill T. cinnabarinus. The mortality increased with phosphine concentration, when the fumigation time was fixed. The mortality increased with fumigating time under a definite phosphine concentration. After 1h-, 1.5h-, 2h-exposure to 0.15ml/L phosphine at 25℃, the mortality of 12h was 8.28%, 23.21%, 48.09%, respectively, while the mortality increasing to 68.22%, 96.84%, 100% respectively, after 48h. T. cinnabarinus show narcosis to phosphine, and this phenomena become more obvious with the dosage increase of phosphine.Essential oils showed certain fumigating effect on T. cinnabarinus, but toxicity increased with fumigation time. The mortality of T. cinnabarinus was near to 0 with 3.75ul/L Cymbopogom winterianus for 1.5h, while the mortality was 68%, and 90% for 12h exposure.1.2 Fumigating effect on adult mite with the mixture of methyl bromide and CO2Methyl bromide mixed with COj to adult mite with various concentrations and time. The results showed that the fumigation effect of methyl bromide on adult mite was quite obvious at 25℃. Under the condition of 1.5h exposure and the combination of 25% CO2 with methyl bromide of 30 g/m3, 35g/m\ 40g/m3, the mortality of mite was 89.67%; 97.73%, 100% respectively. While the mortality was 61.67%, 73.23%, 82.28% respectively, when 40%CO2 mixed with methyl bromide of 30 g/m3, 35g/m3, 40g/m3 under 2h exposure.1.3 Fumigation efficacy of mixture of Methyl bromide, Phosphine and tea tree oil on adult miteThe results showed that mortality of adult mite fumigated by the mixture of three kinds of fumigants for 1h, 1.5h, 2h were 89.61%, 97.25%, 100% respectively, with 20g/m3 methyl bromide and 0.05ml/L, 0.1 ml/L, 0.15 ml/L. When the concentration was up to 25 g/m3, the adult mite mortality reached up to 100% under same condition; The combination of methyl bromide and essential oil could increase its toxicity. Under bromine methane of 15g/m3 mixed with tea tree oil of 3.75 ul/L and oil of fruit of a cubeb litsea tree, 2h fumigation, the mortality of spider mites reached up to 100%. Phosphine mixed with tea tree could obtained good fumigation efficacy. Under the fumigation condition of phosphine concentration of 0.15ml/L, tea tree oil concentrations of 1.25ul/L 2.5 ul/L 3.75 ul/L, mortalities of mite were 76.83%, 89.75% and 97.97% respectively after the 2h fumigation. The results proved the efficacy was enhanced obviously.2.Effects of fumigants on egg of T. cinnabarinus2.1 Fumigating effect of single fumigants on eggA lot of researches show that it was more difficult to kill eggs of pests. Three fumigants selected for test originally restrained hatch to some extent. Fumigation with fixed time, the hatching rate of the mite egg was all reduced with fumigant concentration increase. When concentrations of the fumigants fixed, the hatching rate of the mite egg was all reduced with the extension of fumigation time. Under the 2h exposure of 15g/m3, 35g/m3 of methyl bromide, the hatching rate was...
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