TOXICITY OF Argemone mexicana (L.) EXTRACTS AND IMIDACLOPRID ON Chrysoperla carnea (Stephens)

Abstract

In sorghum (Sorghum bicolor L. Moench) cultivation, the main pest is the sugarcane aphid (Melanaphis sacchari Zehntner (Hemiptera: Aphididae)). The insecticide imidacloprid is frequently used to control this insect, and in some cases, it is complemented with the release of lacewings of the species Chrysoperla carnea Stephens (Neuroptera: Chrysopidae). The insecticide has been shown to be harmful to non-target insects, such as the natural enemies of this aphid, so it is necessary to find other less harmful products. The objective of this study was to evaluate the toxicity of aqueous and oily extracts of chicalote (Argemone mexicana L.) on C. carnea and to contrast it with that of imidacloprid, with the hypothesis that extracts of A. mexicana applied to the developmental stages of C. carnea generate less mortality on the predator than imidacloprid. The aqueous and oily extracts had a concentration of 30 g L^-1. For imidacloprid, the recommended dose for sugarcane aphid control (0.35 g L^-1) was used. Mortality and the treatments effect were evaluated by exposure methods: T1) topical on larvae, T2) egg immersion, T3) treated Sitotroga cerealella eggs, and T4) liquid ingestion in adults. Mortality, hatching and emergence variables were analyzed with a one-way ANOVA, followed by Tukey’s comparison of means (p ≤ 0.05). Treatments were classified according to the toxicity levels proposed by the International Organization for Biological Control. The aqueous and oily extracts were in toxicity class 1 for C. carnea, except in eggs treated with the oily extract (class 4). Imidacloprid was classified in class 4 when applied topically and by ingestion in adults and in class 2 in ingestion of treated S. cerealella eggs. In general, extracts of A. mexicana could be used as selective insecticides, while imidacloprid can be considered incompatible with releases of this predator.