Studies On Fumigation Activities Of Armoracia Rusticana Oil Against The Main Stored-grain Insects

Different AITC formulations which mixed Armoracia rusticana oil with ethyl formate or ethyl acetate were tested for their insecticidal activities against adults of the major stored-grain insects:Tribolium castaneum (H.),Rhizopertha dominica (F.) and Sitophilus zeamais (M.) by the method of triangle bottle obturation fumigation and selected the best AITC formulation. Evaluted the fumigate activities of AITC formulations under possible condications of outside. Also, the influence of fumigation on the quality of several commodities was assessed. The main results were as follow:1. Test the insecticidal activities of AITC formulations against adults of the major stored-grain insecs:Tribolium castaneum (H.), Rhizopertha dominica (F.) and Sitophilus zeamais (M.) by the method of triangle bottle obturation fumigation. Good insecticidal activity was achieved, the susceptibility of the major stored-grain insects: Rhizopertha dominica (F.)> Sitophilus zeamais (M.)> Tribolium castaneum (H.). Responses varied with exposure time, temperature, dose and formulation. The values of LC50 of AITC against the major stored-grain insects presented downtrend along with the increasing of exposure time or temperature. A longer exposure time or a higher temperature could enhance the insecticidal effects of AITC formulation. The LC50, CTC of AITC formulations which mixed Armoracia rusticana oil with ethyl formate or ethyl acetate in nine volume rate (1:9,2:8,3:7,4:6,5:5,6:4,7:3,8:2,9:1) was tested, respectively. Results showed that the best AITC formulation was Armoracia rusticana oil and ethyl acetate mixed in volume rate(6:4), its LC50, CTC was 1.33μL/L,174.172, respectively.2. Results in the fumigation simulation showed that AITC formulation presented effective against the major stored-grain insects, but less toxic than the fumigation in laboratory because of some adverse factors such as unstable temperature, inferior gas tightness and absorption of commodities. The susceptibility of the major stored-grain insects:Rhizopertha dominica (F.)> Sitophilus zeamais (M.)> Tribolium castaneum (H.), it's the same as the result in the laboratory. There are some positive impacts in the fumigation simulation such as higher temperature, longer exposure time, sultable formulation which could enhance the toxicity of AITC formulation, and low temperature is an adverse factor. Mortality of insects in different layers of the fumigation simulation was inhomogeneity:upper layer>middle layer>underlayer, it could improved by extending the exposure time or raising the temperature. In addition absorption of commodities is different in fumigation simulation. 3. The influence of fumigation on the quality of several commodities was assessed. After fumigation, there was no obvious influence on the germination rate of rape, bok choy, aubergine, cabbage and radish; marginal effect on the germination rate of Creeping Dichondra Herb; obvious influence on the germination rate of white clover. In addition, even using low dose AITC could reduce the germination rate of rice seeds. Results showed no obvious influence of fumigation on the woodwork, Chinese chestnut and mushroom, but serious influence on the oranges.