Potencial repelente do extrato das folhas do nim (Azadirachta indica) no controle da cochonilha branca (Planococcus citri) na cultura do tomate

Abstract

Neem (Azadirachta indica) is a plant that has insecticidal properties and has been used as an alternative to control many pest arthropods. Among the pests that attack the crop, we can mention the white mealybug (Planococcus citri) that affects the cultivation of tomatoes. With that, this work was developed with the objective of evaluating the lethal effect of the aqueous extract of the powder of the neem leaves, on white cochoni in tomato plants. To carry out the study, five seeds of standard size (21 cm high and 20 cm wide) were planted with tomato seeds. After 25 days, the tomato plants were infested with 20 scale insects that were in the adult stage of development. After pupal development, the insects were treated using bioassays via spraying of tomatoes. The bioassay was composed of five treatments (four concentrations of aqueous neem leaf extract: 0.1g; 0.5g; 0.10g; and 0.15g and the control treatment: distilled water only). The applications were made during five days, with five repetitions, in the interval of 24 hours for each application. Two evaluations were carried out: in the first, the number of adult mealybugs killed per plant was counted, while in the second, pupal mortality was recorded. Abbott's method was used to calculate the efficiency of Neem. The mor tality of mealybugs was evaluated five days after spraying, showing that all treatments based on Neem showed a significant difference in relation to the control. The extracts in all concentrations evaluated had an effective insecticidal action in the control of Pla nococcus citri, controlling insects mainly in adulthood. The concentrations used did not provoke signs of phytotoxicity during the experiment, showing that the aqueous leaf extract has a natural defensive potential and is therefore a viable alternative in relation to chemical pesticides, and favorable for the rural producer due to its efficiency and low cost, and for causing less environmental impact.