Variational Regulation Of Pesticide Resistances Of Myzus Persicae (Sulzer) In Fujian Province

The sensitive baselines of tobacco aphid Myzus persicae (Sulzer) to methomyl, phoxim, fenvalerate,λ-cyhalothrin, imidacloprid and acetamiprid were established in this paper. The resistant levels and the activities of detoxification enzymes activity and target enzyme of the aphids were determined in Nanping, Sanming and Longyan of Fujian province in 2009. Comparing with the monitoring results in 2008, the LC₅₀ of methomyl to the aphids increased 1.004, 1.046 and 1.051 times respectively in Nanping, Sanming and Longyan of Fujian province; the LC₅₀ of phoxim were 0.787, 0.922, 0.912 times smaller respectively; the LC₅₀ of fenvalerate increased 1.186, 1.328 and 0.56 times respectively; the LC₅₀ ofλ-cyhalothrin increased 1.367 and 1.139 times in Nanping and Longyan but was 0.897 times smaller in Sanming; the LC₅₀ of imidacloprid increased 1.345 and 1.244 times in Nanping and Longyan but was 0.965 times smaller in Sanming; the LC₅₀ of acetamiprid increased 1.498, 1.724 and 1.868 times respectively. Because methomyl, phoxim,λ-cyhalothrin and imidacloprid were not used in tobacco fields of Fujian in recent years, the resistances of aphids for these pesticides tended to weaker. There were not high-resistant populations in Fujian except the aphids of Nanping with high-resistant to acetamiprid. The activities of three enzymes showed significantly different in three main planting tobacco areas. Sanming population was highest, Nanping population was high and Longyan population was low. Comparing with the data tested in 2007, the CarE activity rate of aphids increased 3.249, 3.335 and 4.491 times respectively in Sanming, Nanping and Longyan; the Ache activity rate increased 1.336, 1.664 and 1.782 times; the GSTs activity rate increased 1.591, 1.811 and 2.447 times. The research of some pesticides applied alternately and a pesticide applied sustainedly showed that the resistant factors of tobacco aphids increased to 2.397, 3.608, 5.891 and 8.598 respectively after the methomyl was sprayed three, five, seven and nine times sustainedly; increased to 2.717, 3.114, 4.861 and 5.169 for imidacloprid, increased to 2.341, 3.577, 6.277 and 11.767 forλ-cyhalothrin. The resistant factors of tobacco aphids to methomyl were increased to 2.522, 2.661, 2.839 and 3.196 respectively after the three pesticides were applied alternately one time, two times, three times and four times; increased to 2.490, 2.603, 2.742 and 2.898 respectively toλ-cyhalothrin, increased to 2.716, 2.980, 3.259 and 3.519 respectively to imidacloprid. The impacts of tobacco varieties on resistant differences, detoxification enzymes activity and target enzyme activity of aphids were studied. The results showed that the resistant order of aphids on different tobacco varieties was CB-1, K326 and Yunyan87 from strong to week; the effects of different tobacco varieties activities on detoxification enzymes and target enzyme of aphids were significant, the activity order of CarE, AchE and GSTs of aphids on different tobacco varieties was CB-1, K326 and Yunyan87 from strong to week.