Median lethal concentration (LC₅₀) of four insecticides used to control Bemisia tabaci Biotype B for the predator Macrolophus basicornis

The predator Macrolophus basicornis (Stal) (Hemiptera: Miridae) has great potential in the biological control of the whitefly Bemisia tabaci Biotype B (Gennadius) (Hemiptera: Aleyrodidae) by preying on eggs and nymphs. However, the management of B. tabaci in tomato fields has been largely accomplished by spraying insecticides that can limit the action of this predator. In this sense, the objective of this study was to determine the median lethal concentration (LC₅₀) of the main Brazilian commercial insecticides recommended for the control of B. tabaci on adults of M. basicornis. The insecticides evaluated were etophenproxy + acetamiprid, acetamiprid, pyriproxifen + acetamiprid and bifenthrin. The obtained LC_50s were 22.6 ppm (18 - 27.2) for etophenproxy + acetamiprid, 4 ppm (3.4 - 4.6) for acetamiprid, 35.8 ppm (29.6 - 42) for pyriproxifen + acetamiprid and 73.6 ppm (54 - 92) for bifenthrin. All insecticides have shown high toxicity to this natural enemy. The neonicotinoid acetamiprid showed greater toxicity in relation to the other treatments, corresponding to 19 times the LC₅₀ value of bifenthrin. These insecticides should be used in a judicious way, especially at the beginning of tomato cultivation, in order to prevent biological imbalance and elimination of the predator. The values obtained from the LC₅₀ are important to estimate the potential residual effect of insecticides on the predator's mortality after application, seeking compatibility with the application times and releases of this biological control agent. These results will contribute to future selectivity studies for M. basicornis.