Could Aqueous Extract from Castor Plants be the Solution to Effectively Control the Pink Mealybug Nymphs?

Abstract

Objective: To evaluate under laboratory conditions the potential of the leaf extract of the species Ricinus communis L. regarding its insecticidal activity on nymphs of the pink mealybug and determine the Lethal Concentration 50 (LC50). Theoretical reference: Maconellicoccus hirsutus is one of the key pests of several crops and has been diagnosed in more than 350 plant species. The species was reported for the first time in Brazil in 2010 in the State of Roraima, and has since spread to other Brazilian states causing considerable economic losses to the affected areas. Method: The castor bean leaf extract was tested on M. hirsutus insects with varying concentrations. Application was done directly using an airbrush connected to a calibrated compressor. Evaluation occurred at 24, 48, and 72-hour intervals post-application. Results and discussion: As the dosage of the extract was increased, a significant increase in the mortality rate of mealybugs was observed. The lethal concentration for 50 % of the M. hirsutus population (LC50) was calculated at 6.14%, with a confidence interval between 5.40 % and 7.02 % (m/v). Implications of the research: The research proposes a sustainable approach to controlling pink mealybug nymphs, using an aqueous extract of R. communis leaves. Originality/value: This article stands out for its innovation in exploring a sustainable approach to pest control, presenting an effective alternative to reduce dependence on chemical pesticides. This proposal is especially relevant to promote the adoption of more sustainable agricultural practices aligned with the principles of sustainable agriculture and providing benefits for both agricultural production and the environment.