Control Efficiency Of Combination With Three Kinds Of Protectants And Phosphine On The Of Six Kinds Of Stored Grain Pests

It is of great significance to research stored grain protectant and phosphine for controlling stored grain insects for controlling phosphine resistant stored grain insects.Insecticide activity of pirimiphos-methyl,malathion,phosphine and deltamethri·pirimiphos-methyl against 6 kinds of stored grain pests on adults of Liposcelis entomophila（Enderlein）,Liposcelis bostrychophila（Badonnel）,Cryptolestes ferrugineus（Stephens）,Tribolium castaneum（Herbst）,Sitophilus oryzae（Linn-aeus）and Rhyzopertha dominica（Fabricius）were investigated in this paper.Insecticide activity of pirimiphos-methyl,malathion,or deltamethri·pirimiphos-methyl and phosphine combination against 6 kinds of stored grain pests on adults were investigated.The combinations of pirimiphos-methyl and phosphine,malathion and deltamethri·pirimiphos-methyl were investigated in practical application effect in granaries.The results were followed:1.The LD₅₀ of L.entomophila,L.bostrychophila,C.ferrugineus,T.castaneum,S.oryzae and R.dominica were 12.57,1.24,1.57,0.14,0.86 and 21μg/cm² for pirimiphos-methyl respectively.The LD₅₀ of L.entomophila,L.bostrychophila,C.ferrugineus,T.castaneum,S.oryzae and R.dominica were 8.88,2.21,1.96,0.39,0.26 and 3.40μg/cm² for malathion respectively.The LC₅₀ of L.entomophila,L.bostrychophila,C.ferrugineus,T.castaneum,S.oryzae and R.dominica were 0.89,0.23,0.81,0.14,0.31 and 1.42 mg/L for phosphine respectively.The upper part of grain of 1/8 wheat were mixed with deltamethri·pirimiphos-methyl to 4 mg/kg dose,the mortality of L.entomophila,L.bostrychophila,C.ferrugineus,T.castaneum,S.oryzae and R.dominica was 67.5%,60%,85.53%,83.13%,85.54%,73.68%after 14 days respectively.The mortality of 6 kinds of stored grain pests were increased with the increase of the depth of grain what mixed with deltamethri·pirimiphos-methyl.2.The synergistic toxicity index of the combination of LD₂₅5 of pirimiphos-methyl and LC₂₅5 of phosphine to L.entomophila,L.bostrychophila,T.castaneum and R.dominica were78.18,80.68,42.65,65.28 and 69.69,all of which were exhibited significant synergistic;The synergistic toxicity index for C.ferrugineus was 16.65,which was additive effect.The synergistic toxicity index of the combination of malathion and phosphine to L.entomophila,L.bostrychophila and R.dominica were 65.84,46.13 and 49.11,all of which were exhibited significant synergistic.The synergistic toxicity index for C.ferrugineus,T.castaneum and S.oryzae were 17.09,16.26 and 7.93,all of which were additive effect.When the grain surface upper of 1/8 wheat with deltamethri·pirimiphos-methyl to 4 mg/kg dose mixed,the mortality of L.entomophila,L.bostrychophila,C.ferrugineus,T.castaneum,S.oryzae and R.dominica was 87.8%,97.8%,90.0%,100%,92.2%and 78.9%after 14 days,and when the grain surface upper of 1/4 and 1/2 wheat with deltamethri·pirimiphos-methyl the mortality rate of 6 kinds of stored grain pests can reach 100%.3.Pest infestation wasn’t observed in rice what treated with pirimiphos-methyl or malathion before fumigated with phosphine until 7 months later in rice,the desity of C.ferrugineus,R.dominica and Liposcelis spp were decrease significantly compared with fumigated with phosphine individually in Nanping depot.The results revealed that the grain treated with pirimiphos-methyl or deltamethri·pirimiphos-methyl before fumigated with phosphine,the resistant against Liposcelis spp.and C.ferrugineus were increased significanly.And there is no need to fumigate in next year.Pest infestation population desity wasn’t observed in grain what treated with pirimiphos-methyl or deltamethri·pirimiphos-methyl until6 months,7 months and 3 months later,while C.ferrugineus,R.dominica and Liposcelis spp.were found in grain fumigated with phosphine individually in Liuzhou,Shucheng and Zhanjiang.These results revealed that the grain treated with pirimiphos-methyl or deltamethri·pirimiphos-methyl before fumigated with phosphine have higher resistance against Liposcelis spp.and C.ferrugineus.the grain depot which treated with pirimiphos-methyl or deltamethri·pirimiphos-methyl before fumigated with phosphine and another depot which fumigated with phosphine individually were both found the C.ferrugineus in result of the grain’s higher temperature.It shows that the control of stored grain pests is affected by grain temperature.The combinations of pirimiphos-methyl and phosphine,malathion and phosphine or deltamethri·pirimiphos-methyl and phosphine exhibited synergistic effects on adults of 6 kinds of stored grain pests were investigated in this paper.It can provide an effective method for the prevention and control of strong phosphine-resistant grain pests.