Atividade dos óleos essenciais Piper aduncum e Piper marginatum sobre a Cochonilha Planococcus citri (Risso, 1813) (Hemiptera: Pseudococcidae)

Abstract

The mealybug Planococcus citri (Risso, 1813) they are considered difficult to control because of the protection offered by their waxy layer. The most used form of P. citri control is through the use of systemic insecticides. Bioactivity of essential oils of the Piper genus have been investigated as promising alternatives to synthetic insecticides. Therefore, this study aimed to evaluate the activity of P. aduncum and P. marginatum essential oils on P. citri, through bioassays of topical toxicity in migratory nymphs; residual toxicity in migratory, second instar nymphs and adult females; repellency; and ovicide. The commercial botanical insecticide Azamax® was used for comparison. The CL's50 values estimated through the concentration-response curve for P. aduncum oil were 2.85 μl/mL for the topical test in migratory nymphs, and 1.83 and 1.50 μl/mL for the residual test in nymphs migratory and second instar, respectively. The estimated CL's50 for P. marginatum oil were 2.36 μl/mL for the topical test on migratory nymphs, and 2.28 and 3.81 μl/mL for the residual test on migratory and second instar nymphs, respectively. The CL's 30 and 50 of the oils estimated through tests with migratory nymphs caused mortality of 23% and 35%; and 25% and 36% of females for P. aduncum and P. marginatum, respectively. In the ovicidal test, CL's 30 and 50 reduced by 13.33% in both CL's of P. aduncum oil; and 11% and 20.56% with P. marginatum oil at the hatching of P. citri nymphs. In the repellency test, the CL10 of P. aduncum was more repellent than the CL10 of P. marginatum. The oils showed promise in P. citri nymphs, but more specific studies are needed for eggs and adults of this species.