Efficacy of Biocontrol Agents Beauveria bassiana and Plant Extracts on Dactylopius opuntiae Cockerell (Hemiptera: Dactylopiidae)

Opuntia ficus-indica is a cactus used as fodder for animals in arid areas worldwide. However, the palm is parasitized by the carmine cochineal scale insect (Dactylopius opuntiae) causing great damage to cactus plantations in the semi-arid region of Brazil. Leaf extracts aqueous and hydro-ethanolic of neem and citronella at concentrations of 50, 100 and 200 mg/mL, and strains suspensions of Beauveria bassiana (1 × 108 conidia/mL); were applied on cladodes infested by D. opuntiae, in the laboratory. After 10 days of treatment, the percentages of mortality were obtained on the adult females. Then, the most efficient extracts were selected in the laboratory tests for control tests in palm plantation, where 100 mL of the extracts were applied in the 100 mg/mL concentration on cladodes of palms. The results show that B. bassiana strains were not pathogenic to D. opuntiae. Only the aqueous and hydro-ethanolic neem extracts were effective in controlling the cochineal. We conclude that neem extracts are effective against D. opuntiae and can be used to control carmine scale in Opuntia ficus-indica in the field.