The Phosphine Fumigation On Coleoptera Laemophloeidae Insects With Effective Concentration And Time

In this work, to understand the development of pest resistance during the phosphine application, the resistance levels and mortality with phosphine fumigation of the rusty grain beetles from different areas were mainly studied, including the quick knockdown method of phosphine, the recommended methods for the detection and measurement of the pest resistance by the FAO, and observing the mortality of the insects in laboratory simulation chamber and in field fumigation.By the quick knockdown method of phosphine, the results include that: all pest strains were resistant strains, and the resistance levels of most insects were high. By the FAO method, the results were that: the resistance ratio of Shang Rao strains of rusty grain beetles was 590 time-fold, and the LC50 value was 6.4922 mg/L; the resistance ratio of Zhang Zhou strains of rusty grain beetles was 620 time-fold, and the LC50 value was 6.8188 mg/L; the resistance ratio of Chang Le strains of rusty grain beetles was 560 time-fold, and the LC50 value was 6.1588 mg/L; the resistance ratio of Shan Tou strains of rusty grain beetles was 596 time-fold, and the LC50 value was 6.5613 mg/L; the resistance ratio of Lv Liang strains of rusty grain beetles was 668 time-fold, and the LC50 value was 7.3427 mg/L. The resistance levels of these several rusty grain beetles strains were very high. The half knockdown time got by the quick knockdown method was obviously correlate with the resistance ratio got by the recommended method by FAO, and the resistance ratio was higher, the half knockdown time was longer.In the laboratory simulation chamber, the lethal time of different resistant strains of the rusty grain beetles had a positive correlation with the resistant level, namely the resistance ratio was higher, the lethal time was longer. It couldn’t have good effect on the high resistant rusty grain beetles exposed in 200ml/m3 phosphine concentration even 30 days. But the mortality could raise when prolonging the exposure time and improving the phosphine concentration.In the field fumigation, the rusty grain beetles of 500 time-fold resistance ratio, carbon dioxide and phosphine mixture fumigation, the concentration of phosphine in 15 days varying from 765 mL/m3 to 370 m L/m3 can be lethal to the rusty grain beetles in different resistance levels. It could obtain 100% mortality to the rusty grain beetles with lower tolerance to phosphine in 7 days. And in the field fumigation, the lethal time had no obvious correlation with the resistance ratio. To compared with the results in the laboratory simulation chamber, the lethal time was shorter and the effective value of concentration and time was smaller in the field fumigation.Rusty grain beetles of the 23 strains come from the five grain ecological zones, and the resistance levels were all at very high level. The development of resistance levels expressed on not only the increasing the scale of resistance insect, but also the raise the resistance ratio. In the field fumigation, the effective concentration of phosphine and maintaining for as long as possible exposure time can effectively kill the high resistance of rusty grain beetle.