The objectives were to evaluate the efficiency of entomopathogenic fungi against Plutella xylostella (L.) and the compatibility of the most virulent isolates with some of the insecticides registered for use on cabbage crops. Pathogenicity tests used isolates of Beauveria bassiana, Metarhizium rileyi, Isaria fumosorosea, Isaria sinclairii, and Lecanicillium muscarium standardized at a concentration of 10⁷ conidia/ml. Cabbage leaf discs were immersed in these suspensions, and after evaporation of the excess water, were placed 10 second-instar larvae of P. xylostella, totaling 10 leaf discs per treatment. Mortality was assessed 7 d after treatment, and the isolates that caused mortality >80% were used to estimate LC₅₀ and LT₅₀. The compatibilities of the most virulent isolates and the insecticides were tested from the mixture of these into the culture medium, and after solidifying, the medium was inoculated with an aliquot of the isolated suspension. The following parameters were evaluated: growth of the colony, number and viability of conidia after 7 d. The isolated IBCB01, IBCB18, IBCB66, and IBCB87 of B. bassiana, LCMAP101 of M. rileyi, and ARSEF7973 of I. sinclairii caused mortality between 80 and 100%, with LC₅₀ and LT₅₀ between 2.504 to 6.775 × 10⁴ conidia/ml and 52.22 to 112.13 h, respectively. The active ingredients thiamethoxam and azadirachtin were compatible with the entomopathogenic fungi. The results suggest that the use of these isolates is an important alternative in the pesticidal management of P. xylostella, with the possible exception of the associated use of chemical controls using the active ingredients thiamethoxam or azadirachtin.

The fall armyworm (Spodoptera frugiperda) is one of the most important pests of maize, causing up to 20% production losses when defoliation occurs near to flowering, or even complete destruction of plants. Among the alternatives to control this pest, the use of Bacillus thuringiensis (Bt) has gained attention due to its efficiency and low impact on natural enemies. Strains Bt dendrolimus HD 37, Bt aizawai HD 68, Bt kurstaki HD 73, Bt darmstadiensis HD 146, and Bt thuringiensis 4412 were tested against second instar larvae in in vivo assays. Suspensions of Bt aizawai HD 68 and Bt thuringiensis 4412, containing 3 x 10(8) cells/ml, induced mortality of 100% and 80.4%, respectively. To test virulence, cell concentrations of 8 x 10(5) to 3 x 10(8) cells/ml of strains Bt aizawai HD 68 and Bt thuringiensis 4412 were applied on the second instar larvae: LC50 were 6.7 x 10(6) and 8.6 x 10(6) cells/ml, respectively.

We investigated the use of Bacillus thuringiensis isolated in the state of Amazonas, in Brazil, for the biological control of the dengue vector Aedes aegypti. From 25 soil samples collected in nine municipalities, 484 bacterial colonies were obtained, 57 (11.78%) of which were identified as B. thuringiensis. Six isolates, IBt-03, IBt-06, IBt-07, IBt-28, IBt-30, and BtAM-27 showed insecticidal activity, and only BtAM-27 presents the five genes investigated cry4Aa, cry4Ba, cry10Aa, cry11Aa, and cry11Ba. The IBt-07 and IBt- 28, with lower LC50 values, showed equal toxicity compared to the standards. The isolates of B. thuringiensis from Amazonas constitute potential new means of biological control for A. aegypti, because of their larvicidal activity and the possibility that they may also contain new combinations of toxins