Study Of Mitochondria Membrane And CarE On Aphis Sp.of Resistance-bifenthrin

Aphis sp.is one of the major pests of medlar, and it has great impact on medlar quality. Chemical control is mainly used for controlling Aphis sp. in Mongolia nowadays, and pyrethroids is one of the most widely used pesticides and long-term application of pyrethroids has contributed to the resistance to Aphis sp.. To determine the resistant level, the bifenthrin was used for toxicity assays of Aphis sp. from different regions. Then the role of carboxylesterase in resistance to pyrethroids and suppression effect on carboxylesterase in Aphis sp. of different resistant level to other pesticides were studied profoundly. The mitochondrial membrane fluidity of Aphis sp. of different resistant level was studied as well. The results are shown as follows:1、To determine the resistant level, the bifenthrin was used for toxicity assays of Aphis sp. from different regions in Mongolia in residual film in glass tube. The results indicate that the Strain I was sensitive at present, LC50=0.057mg/L, The LC50 of Strain Ⅱ and Ⅲ were 0.230mg/L and 0.592mg/L, respectively. Strain Ⅱ and Ⅲ were of low resistant level and the resistant fold were 4 and 10, respectively, compared with Strain I. Strain IV was of medium resistant level and the LC50 is 1.696 mg/L, the resistant fold was 30. Strain VI was of very high resistant level and the LC50 was 48.419mg/L, the resistant fold was 850.2、We studied on the biochemical characteristics of different Aphis sp. strains carboxylesterase and effects of TPP. The results showed that with the increase of Aphis sp. resistance level, CarE specific activity gradually increased, the specific activity of high-level resistant strain was 2.508nmolmin-1mg-1, and it was 8.7 times as many as susceptible strains (its specific activity 0.287μmolmin-1mg-1). Compared Km and Vmax of susceptible strain with resistant strains furtherly, we found that Km was almost unchanged, but Vmax of high-level resistant strain was 2.08 times of the susceptible strain. TPP make resistant strains Aphis sp. characterized by significant inhibitory effect,the maximum inhibition rate of TPP is 93.72%,the one of sensitive strains at the same concentration is only 19.48%.3、Discussing the effect of organophosphates and carbamate on different anti-bifenthrin aphid sp. Strain. Organophosphates,such as chlopyrifos, triazophos, omethoate,inhibits CarE among different resistence level, which is the same result as carbamate like isoprocarb and methomyl.With the increasing level of resistence level, the median inhibition concentration(I50) is increasing. At the same time, choosing four representative pesticide in the highest resistance level strain for biological assay and CarE in vitro inhibition. The inhibition effect of organophosphates to CarE is prefer than carbamate. Methomyl possess the greatest inhibition effect, LC50 is 0.640mg/L.Meanwhile, omethoate possess the slightest inhibition effect, LC50 is 18.783mg/L. The I50 of triazophos and omethoate are 0.629×10-5mol/L and 0.151 ×10-3mol/L. The ISO of isoprocarb and methomyl are 0.229×10-3mol/L and 1.023×10-3mol/L. Four pesticide’s dynamic curve on Aphis sp. indicate that inhibition speed are from fast to slow and finally it becomes flat.4、The effects of Pyrethroids insecticides on the mitochondrial membrane fluidity of different drug-resistant strains were measured using DPH as fluorescent probes. The results show that the membrane fluidity increased and fluorescence polarization degree decreased as the increase of resistant level comparing with sensitive strain. The effects of different concentration of pyrethroid insecticides on the mitochondrial membrane fluidity of sensitive strain(P=0.326) and high-level resistant strain(P=0.235) were different. The effects of different pyrethroid insecticides on the mitochondrial membrane fluidity of all resistant strains of Aphis sp. differed at different temperatures (15-45℃).