| The KT50 value was measured for the selected strains under the phosphine concentration of 2 mg·L-1. With FAO recommended method, we measured phosphine resistance levels of several kinds of powder feeding pests collected from different regions in 2014, and found the development trends and regional differences of pests resistance to phosphine, and analyzed the relevance of its KT50 and the corresponding LC50 value, and studied the completely death time of different resistant levels strains of different stages which was exposed in 100, 200, 300, 400, 500 mL/m3 respectively under the condition of 25℃, which will provide a scientific basis for monitoring resistance to phosphine and real storehouse fumigation.The main results were as follows:The range of KT50 value of 11 stains of Tribolium castaneum(Herbst) was 5.50~1160.00 min, the range of KT50 value of 6 stains of Oryzaephilus surinamensis(Linnaeus) was 3.52~72.21 min, the KT50 value of 1 strain of Tribolium confusum Jacquelin du Val was 6.57 min. Adopting the FAO recommended methods, the range of LC50 values of 11 stains of T. castaneum was 0.0093~2.4617 mg?L-1,the range of their Rf was 1.0~273.5; the range of LC50 values of 6 stains of O. surinamensis was 0.0101~0.0548mg·L-1, the range of their Rf was 0.8~4.6;and the LC50 value of 1 strain of T. confusum was 0.0115 mg?L-1, the Rf was 1.0. The LC50 and the corresponding KT50 value of 18 strains in three kinds of insect pests corresponding relationship is as follows: lg(LC50) = 1.0236 lg(KT50)- 2.7341, the correlation coefficient is 0.9761.Different kinds of adults with different resistance showed a certain differentiations of completely death time under different concentrations of phosphine. Under 100 m L/m3 lethal concentration, respectively the completely lethal time for adult of ZJXSTc strain of T. castaneum(Rf=1.0),BJXNTc strain of T. castaneum(Rf=5.9),HNHKTc strain of T. castaneum(Rf=130.9),GDGZTc strain of T. castaneum(Rf=273.5),SDHZTc-1 strain of T. confusum(Rf=1.0), HNZZOs strain of O. surinamensis(Rf=0.8), ZJHZOs strain of O. surinamensis(Rf=0.9), ZJTXOs strain of O. surinamensis(Rf=4.6) were 9, 27, 312, 456, 7, 7, 5, 27h;Under 200 m L/m3 lethal concentration, respectively the completely lethal time for adult of ZJXSTc,BJXNTc,HNHKTc, GDGZTc, SDHZTc-1, HNZZOs, ZJHZOs, ZJTXOs were 7, 21, 240, 312, 7, 5, 3, 21h;Under 300 m L/m3 and above lethal concentration, respectively the completely lethal time for adult of ZJXSTc, BJXNTc, HNHKTc, GDGZTc, SDHZTc-1, HNZZOs, ZJHZOs, ZJTXOs were within 5, 15, 168, 240, 3, 3, 3, 15 h. As for larva, its completely lethal time under different concentrations of phosphine was similar to the corresponding adult;egg and pupa presented a stronger phosphine tolerance under the same lethal concentration, and the corresponding lethal time lasted longer. For example, under 100 m L/m3 lethal concentration, respectively the completely lethal time for adult of BJXNTc strain of T. castaneum, SDHZTc-1 strain of T. confusum, ZJHZOs strain of O. surinamensis was 27, 7, 5h, and lethal time of corresponding larva was 21, 7, 5h, but the egg was 39, 9, 9h and pupa was 39, 9, 9h.The research results showed that the resistance in the powder feeding insect pests collected from different areas were different, and 6 strains of O. surinamensis and 1 strain of T. confusum had no phosphine tolerance. Knock-down method with high concentrations of phosphine can try rapid determination of insect resistance, it can be applied in practice. We used four stages of Tribolium in fumigation experiment, pupa showed the strongest phosphine tolerance, the second was the egg, instar larva and adult showed the weakest phosphine tolerance; in used four stages of O. surinamensis, egg showed the strongest phosphine tolerance, followed by was the pupa, instar larva and adult also showed the weakest phosphine tolerance. After fumigating 19 d at 25℃ and 300 mL/m3 phosphine concentration, it can only be completely lethal all life stages of GDGZTc strain(Rf=273.5) of high resistance to phosphine. |
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