Pesticide Resistance Monitoring And Management Strategy Of Myzus Persicae (Sulzer) In Fujian Province

The sensitive baselines of methomyl, phoxim, fenvalerate,λ-cyhalothrin, imidacloprid and acetamiprid and their LC50 were established based on the sensitive strain of tobacco aphids Myzus persicae (Sulzer). The resistant levels of the aphids of Nanping, Longyan and Sanming in Fujian province were tested. The results showed that the tobacco aphids in these areas did not present high resistance to six pesticides so far. The medium resistant levels of aphids were found in Nanping populations to methomyl and acetamiprid (resistant factor 11.68 and 35.03), Samming population to fenvalerate andλ-cyhalothrin (resistant factor 15.21 and 14.87). The low resistant levels of aphids were found in Longyan populations to imidacloprid and acetamiprid (resistant factor 5.89 and 9.26), Samming population to phoxim (resistant factor 6.04). The test results indicated that tobacco aphids could display cross-resistance for phoxim and fenvalerate after the resistant development to methomyl, for fenvalerate andλ-cyhalothrin after the resistant development to phoxim, for fenvalerate after the resistant development toλ-cyhalothrin. The resistant factors of tobacco aphids increased to 1.19, 2.79, 4.48 and 6.89 respectively after the methomyl was sprayed two , four, six and eight times sustainedly, increased to 1.13, 2.42, 6.97 and 12.68 for phoxim, increased to 1.88, 2.05, 6.62 and 4.88 for imidacloprid, increased to 1.19, 2.37, 4.62 and 8.86 for fenvalerate, increased to 1.68, 2.64, 4.75 and 9.22 forλ-cyhalothrin, increased to 1.54, 3.30, 4.11 and 6.55 for acetamiprid. The order of pesticides applied alternately was methomyl,λ-cyhalothrin and imidacloprid. The resistant factors of tobacco aphids to methomyl were increased to 1.65, 1.84 and 2.01 respectively after the three pesticides were applied alternately one time, two times and three times; increased to 1.04, 1.18 and 1.67 respectively toλ-cyhalothrin, increased to 1.63, 1.75 and 5.05 respectively to imidacloprid. Therefore, the resistance of tobacco aphids should increase quickly if one pesticide was applied alone and sustainedly, and resistant development should be delayed if several pesticides were applied alternately.