Studies On The Ethyl Formate Fumigation Against Booklice

Booklice are minute insects with world-wide distribution and are commonly found in stored products and households. It damages stored products and leads to great loss when the population occurs in abundance. Because of long-term unreasonable use of chemical pesticide resistance of booklice to insecticides and C A increasingly serious which pose an alarming threat to stored stored product. People urgently need to look for a kind of new fumigants to control stored grain insect pests. Ethyl formate is a potential fumigant with properties of rapid insect control and being friendly to environment. In this paper, the fumigation activities of ethyl formate against adults of L. bostrychophila, resistant strains (RDDVP), L. entomophila and different geographical population booklices. In addition,the effects of ethyl formate on AChE on the resistant and susceptible strains of L . bostrychophila were also studied. These experiments aimed to provide date impormation to for EtF application to control booklice.1 The fumigation activities of EtF against booklice1.1 Fumigation lethal effect of ethyl formate on adults of Liposcelis bostrychophilaLethal effects of ethyl formate (EtF) on adults of L . bostrychophila were studied by the sealed jar fumigation method under different conditions. Results showed that treatment time and temperatures significantly affected fumigation effects of EtF on Liposcelis bostrychophila adults. There was a fairly higher fumigation activity of EtF within 24 h, and the fumigation efficacy of 16℃treatment was better than that under 31℃.The LC₅₀s of L .bostrychophila adults fumigated by ethyl formate under the exposure times of 12 h, 24 h, 36 h, 48 h, and 60 h were 15.882, 15.676, 14.011, 13.154 and 10.495μL/L.Under the conditions of 20, 25, 30℃and 24h fumigation, the LC₅₀s were 11.372, 13.283 and 15.676μL/L, respectively, whereas after 48h fumigation, the corresponding LC₅₀s were 10.857, 12.891 and 13.154μL/L. 1.2 Fumigation lethal effect of ethyl formate on adults of Liposcelis entomophilaThe lethal effects of ethyl formate (EtF) on adults of L. entomophila were systematically studied by the sealed jar fumigation method under different EtF dosages, treatment times and temperatures. The results indicated that fumigation efficacy of EtF to L. entomophila was good. There was a fairly higher fumigation activity of EtF within the short time period, which showed that ethyl formate possessed a rapid control effect on L. entomophila. At 20℃, 25℃and 30℃after 24 h fumigation, the LC₅₀ of were 7.769,8.964 and 9.900μL/L, respectively.1.3 The fumigation activities of ethyl formate against the resistant strains of Liposcelis bostrychophilaFumigation activities of ethyl formate (EtF) on DDVP-R and PH₃-R strains of L .bostrychophila were studied by the sealed jar fumigation method under different conditions. Results showed that treatment time and concentration significantly affected fumigation effects of EtF against L .bostrychophila adults at 30℃. The LC₅₀s of EtF against two resistant strains L. bostrychophila increased as the temperature increased from 20℃to 30℃. Under the conditions of 27℃±0.5℃and 24 h fumigation, the LC₅₀s were siginificantly lower for DDVP-R and PH₃-R strains than that of the susceptible strains and the LC₅₀S of DDVP-R strains were siginificantly lower than that of PH₃-R strains.1.4 The fumigation activities of ethyl formate against several species of booklice from different locationsFumigant activity of ethyl formate (EtF) against L. bostrychophila from Xi'an of Shanxi province, Fuzhou of Fujian province and Zhenzhou of Henan province, L. paeta from Nanyang of Henan province, L. decolo from Pingyao of Shanxi province, L. mendax from Yancheng of Jiangsu province were studied by the sealed jar fumigation method. Results showed that fumigant activity of EtF on Liposcelis bostrychophila from Fuzhou of Fujian province was the best, on the contrary was L. bostrychophila. from Xi'an of Shanxi province. Comparing different specises booklice, fumigant effect of EtFon L. mendax Pearman from Yancheng of Jiangsu province was the best, next was L. paeta from Nanyang of Henan province, L. decolo from Xi'an of Shanxi province was the poorest. In a word, the susceptibility of several booklice to EtF appeared in the order of L. mendax Pearma from Yancheng of Jiangsu province > Liposcelis bostrychophila from Fuzhou of Fujian province >L. paeat from Nanyang of Henan province > L. bostrychophila from Zhenzhou of Henan province > L. bostrychophila from Xi'an of Shanxi province > L. decolor from Pingyao of Shanxi province. 1.5 The fumigation activities of EtF on five kinds of booklice in simulative storehousesThe fumigation activities of ethyl formate (EtF) against the adults of L . bostrychophila from Zhengzhou of Henan province , L. entomophila from C Tongliang of Chongqing municipality, L. paeta from Nanyang of Henan province, L. mendax from Yancheng of Jiangsu province and L. decolor from Pingyao of Shanxi province were studied in simulative storehouses with wheat and maize. The results showed that fumigation efficacies of EtF against booklice vary with foodstuffs in the simulative storehouses and the fumigation efficacy of EtF against different species of booklicee also vary in the simulative storehouses. Five kinds of booklouse can survive in the middle and lower layers of wheat storehouse and maize storehouse with a dose of 20 g/m³ after 24 h treatment under 30℃. the corrected mortalities of L. entomophila from Tongliang of Chongqing municipality and L. decolor from Pingyao of Shanxi province were 90%, the other three booklouse were 100% in upper layers of simulative wheat storehouse. The corrected mortalities of four booklouse in upper layers of simulative maize storehouse were 100% and some living adults of L. bostrychophila from Zhengzhou of Henan province when the EtF dose was 30 g/m³, but the corrected mortalities of all species booklice were 100% in simulative wheat storehouse. The fumigation efficacy in wheat storehouse was better than that in the maize storehouse at the same EtF concentration.2 The acetylcholinesterase effects of EtF on resitant and susceptible strains of Liposcelis bostrychophila BadonnelWith the sublethal EtF dose to fumigate L. bostrychophila adults, the effects of ethyl formate on acetylcholinesterase (AChE) in the resitant and susceptible strains of Liposcelis bostrychophila were studied. The results showed that there was a significant decline on AChE specific activity from susceptible strains and resitant strains of L. bostrychophila, the specific activity of AChE in RDDVP and RPH3 strains were obviously reduced as compared with their susceptible counterparts (P<0.05). The specific activity of AChE decreased from 29.74 nmoles/mg pro./min to 20.93 nmoles/mg pro./min under the condition of 32 hour fumigation with the dose of 10μL/L at 30℃. As for RDDVP, the specific activity of AChE decreased from26.24 nmoles/mg pro./min to 18.97 nmoles/mg pro./min. In vitro the effects of EtF on two strains of L. bostrychophila were little.