Insecticidal and inhibitory effects of Meliaceae and Asteraceae extracts to silverleaf whitefly

Resumo

Bemisia tabaci (Gennadius) is a polyphagous insect that causes direct and indirect damage on tomato. Spraying with synthetic insecticides is one of the main control tools for the whitefly; however, the abusive use of this tool can impact the environment and human beings. This study evaluated the bioactivity of extracts from plant species from Asteraceae and Meliaceae families. A preliminary bioassay was accessed the effects of the extracts at 2% (w/v) on infestation and oviposition of the whitefly. Then, the nymphicidal and ovicidal effects of the chloroformic extract of Trichilia pallida (Sw.) – TP-Cl at six concentrations were evaluated. Finally, the TP-Cl LC₅₀ was estimated. All extracts were repellent to the whitefly, except that ones from T. pallida (Sw.) (ethanolic) and Melia azedarach L. (hexanic), considered neutral at 24h. All the extracts caused deterrence of oviposition. All concentrations of TP-Cl revealed nymphicidal activity and the highest ones provided the lowest egg viability averages. The estimated LC₅₀ was 0.0955%. These results provide evidence for the potential of the extracts to be used as alternative control agents of B. tabaci biotype B in tomatoes.