| The methyl bromide and phosphine are widely applied fumigants which played a critical role in cereal fumigation, soil disinfection, quarantine treatment and vehicle sterilization. However, the methyl bromide has been listed in Montreal Protocol due to its property of ozone depleting. As an alternative of methyl bromide, phosphine, has caused severe resistance development of several insects because of irrational and long-term application. For coping the adverse effect to the phytosanitary industry by phasing out of methyl bromide, this study investigated the value of ethyl formate on fumigation application. Four pests (Tribolium castaneum, Callosobruchus maculates, Bursaphelenchus xylophilus and Bactrocera dorsalis) and corresponding hosts are choosen for fumigation experiments. The quality and residue of ethyl formate in flour and mung beans after fumigation were evaluated for the purpose of comprehensive evaluation of ethyl formate as a fumigant. Besides, the prelimary toxicology mechanism of ethyl formate was studied by detecting the difference of proteins expression after treatment on T. castaneum to provide evidence for further application of ethyl formate. The results are following:1. The fumigation effect of ethyl formate towards T. castaneum in flour and residue analysis.The purpose of this research is to evaluate the fumigation activity of ethyl formate against T. castaneum and residue in flour after fumigation. The results indicate that ethyl formate is effective in disinfecting all life stage of T. castaneum in flour, and the sensitivities of life stages of T. castaneum to ethyl formate, which arranged from strongest to weakest, were egg, low instar larva, adult, high instar larva and pupa. The LCt99 for disinfecting all life stages of T. castaneum in 6 h and 12 h at 23℃are 448.42 mg h L-1 and 599.34 mg h L-1, respectively. The ethyl formate residue could be detected 15 days after fumigation which desmonstrates ethyl formate degraded slowly in flour after fumigation.2. Toxicity, residue and impact on quality of ethyl formate fumigation towards C. maculatus and mung bean.The toxicity of ethyl formate to C. maculatus and its impacts to mung bean were evaluated. The results indicate C. maculatus were eradicated by ethyl formate fumigation within 24 h exposure and the sensitivities of life stages of C. maculatus to ethyl formate, which arranged from strongest to weakest, are adult, egg, low instar larva, high instar larva and pupa. The LCt99 for disinfecting all life stages of C. maculatus in 6 h, 12 h and 24 h at 23℃are 511.43 mg h L-1, 760.84 mg h L-1 and 822.98 mg h L-1 respectively. The residue of ethyl formate was declined to undetecable level within 3 d after exposure. And ethyl formate fumigation showed no influence on the appearance and germination percentage of mung bean.3. Nematicidal activity of ethyl formate towards B. xylophilusThe nematicidal activity of ethyl formate towards B. xylophilus was evaluated. Results of bio-assay indicated that B. xylophilus is sensitive to ethyl formate. The LC50 of B. xylophilus to ethyl formate in 3 h, 6 h. 12 h, 24 h and 48 h under 25℃are 2.63 mg L-1, 1.60 mg L-1, 0.99 mg L-1, 0.41 mg L-1 and 0.20 mg L-1, respectively. The B. xylophilus showed higher mortality under relative low temperature and lower mortality was observed under relatively higher temperature which indicates that the nematicidal activity of ethyl formate is significantly affected by temperature. The disinfection experiments of nematodes infected woods were carried out in plexiglass bins and the fumigant concentration was detected by portable GC during the exposure for computing the Ct product. The results show that B.xylophilus were eradicated from wood in 12 h treatment and the LCt99 of ethyl formate to B. xylophilus in 6 h and 12 h are 453.94 mg h L-1 and 424.14 mg h L-1, respectively.4. The study of fumigation toxicity of ethyl formate to B. dorsalis and phytotoxicity to fruits.The fumigation activity of ethyl formate to B. dorsalis and phytotoxicity was studied. The LC50 of high instar larva of B. dorsalis to ethyl formate at 3 h, 6 h. 12 h and 24 h are 54.68 mg L-1, 14.30 mg L-1, 12.54 mg L-1, 12.54 mg L-1. The lavae of B. dorsalis inside fruits showed fair mortality after ethyl formate fumigation. The The LCt99 of ethyl formate to B. dorsalis at 6 h, 12 h and 24 h are 880.90 mg h L-1, 553.63 mg h L-1, and 798.49 mg h L-1, respectively. The sensitivities of larva and egg stages of B. dorsalis to ethyl formate, which arranged from strongest to weakest, are egg, low instar larva and high instar. However, the fruits showed relatively severe phytotoxicity after exposure.5. The preliminary research of compared proteomics on toxicology mechanism of ethyl formate.The T. castaneum model of ethyl formate fumigation was established and the 2-D PAGE was used to separate the proteins differently expressed after fumigation. The 2-D result indicates a perfect 2-D image was achieved while the rude protein of T. castaneum was precipitated by acetone. And out of total 8 differently expressed proteins, 7 proteins were escalated after ethyl formate fumigation and 1 proteins was down-regulation which may be the executors or products of injury mechanism.
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