Competition between the B and Q biotypes of Bemisia tabaci and its relevance to insecticide resistance

Key Words：Key words Bemisia tabaci， biotype， population competition

Abstract：     The insecticide resistance of specimens of a mixed population of the B and Q biotypes of Bemisia tabaci (Gennadius) collected in Hangzhou, Zhejiang Province, was monitored for several generations. When the population was reared on cotton without insecticides for 10 generations, the proportion of B-type to Q-type individuals in the F₀ population was similar, however the B-type completely replaced the Q-type in the F₁₀ population. Resistance to imidacloprid, abamectin and fipronil in the F₁₀ population was significantly reduced compared with the F₀ population, but resistance to α-cypermethrin was similar between the F0 and F₁₀ populations. These results indicate that the B-type is competitively superior to the Q-type in the absence of insecticide selection pressure under laboratory conditions. However, the Q-type is competitively superior in field conditions where neonicotinoids are widely used, presumably because it has greater potential to develop resistance to neonicotinoids than the B-type.