Combining Paecilomyces fumosoroseus and imidaclropid as an integrated approach to control Bemisia tabaci was evaluated using life table parameters. In the laboratory, the index of population trend (I) of B. tabaci was 9.0216 in the untreated control after one generation. After applications of P. fumosoreosus at a concentration of 1×１０６ conidia/ml alone and in combinations with 0.3 and 0.1% of imidacloprid, the Is of B. tabaci decreased to 3.3769, 1.1986, and 1.8512, respectively. The results show that combinations of P. fumosoreosus with imidacloprid exhibit strong synergistic effects against B. tabaci, and the interference index of population control (IIPC) of B. tabaci with the same treatments were 0.3743, 0.1329, and 0.2052, respectively.
Under greenhouse conditions, the I and IＩＰＣ of B. tabaci in the first generation were evaluated with five treatments: one application of P. fumosoroseus (1×１０^６ conidia/ml) alone and in combination with 0.3 and 0.1% of imidacloprid, and 10% of imidacloprid alone, and two applications of P. fumosoroseus (1×１０^６ conidia/ml) alone. The Is for the five treatments were 8.4348, 6.3458, 7.9336, 3.6191, and 5.746, respectively, and the corresponding IIPC values were 0.7278, 0.5476, 0.6836, 0.3123 and 0.4959, respectively. The I values were reduced by 27.2, 45.2, 31.6, 68.8, and 50.4%, respectively, as compared with that in the untreated control. We found that the combinations of P. fumosoroseus and imidacloprid caused high mortality of young B. tabaci nymphs, whereas P. fumosoroseus alone caused high mortality of old B. tabaci nymphs. We also found that one application of the combinations of P. fumosoroseus with imidacloprid were more effective against B. tabaci than one application of P. fumosoroseus alone, but were not as effective as two applications of P. fumosoroseus used alone.
After applications of P. fumosoroseus with combinations of 0.3 and 0.1% of imidacloprid, and 10% of imidacloprid alone, the Is of B. tabaci in the second generation were 1.2443, 1.2915 and 7.8124, and the IIPC values were 0.1566, 0.1625 and 0.9830, respectively. When P. fumosoroseus was used alone once and twice, the Is were 2.0125 and 1.0718, and IIPC values were 0.2532 and 0.1349, respectively. Compared with the untreated control, the corresponding Is values in the above treatments were reduced by 84.3, 83.8, 1.7, 74.7, and 86.5%, respectively. P. fumosoroseus (1×１０^６ conidia/ml) applied twice provided the best control of B. tabaci, whereas 10% of imidacloprid alone was the least effective. Based on the life table parameters of B. tabaci for two generations, P. fumosoroseus combined with imidacloprid provided better control than each of the two used alone, and continuous applications of these two materials for controlling B. tabaci for two generations provided better control than for one generation. Practically, early application of P. fumosoroseus (1×106 conidia/ml) blended with 0.3% of imidacloprid would provide the best control of second instar B. tabaci.