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Side effects of the natural pesticide Spinosad (GF-120 Formulation) on Eretmocerus paulistus (Hymenoptera: Aphelinidae), a parasitoid of the whitefly Aleurothrixus floccosus (Hemiptera: Aleyrodidae), under laboratory conditions

Víctor Tello, Luis Díaz, Matías Sánchez

Abstract


The side effects of the insecticide GF-120 NF 0.02 Naturalyte CB® were evaluated on adults of Eretmocerus paulistus Hempel, a parasitoid of Aleurothrixus floccosus (Maskell) in citrus orchards of northern Chile. LC50 and LC90 were determined by applying the insecticide using a Potter tower in decreasing doses from 0.96 to 0.1 mg a.i. L-1 (corresponding to 1% to 0.1% of the recommended dose, respectively). After 24 h of exposure, the results were fitted to a probit model, and the LC50 and LC90 were estimated at 0.21 and 0.79 mg a.i. L-1, respectively. In feeding tests and evaluation of the toxic effect of dry residues of GF-120, it was determined that a high percentage of mortality (100%) was obtained using a combination of 24.0 mg a.i. L-1 x residues at 1 hour drying time. Residues at 96 h (4 days) drying time with concentrations of 38.4 or 24.0 mg a.i. L-1 caused mortalities over 60%. According to the classification of the IOBC (International Organization for Biological and Integrated Control of Noxious Animals and Plants) the manufacturer’s recommended concentration of 96 mg a.i. L-1 was level 4, which is harmful (> 99%), as GF-120 concentrations can range from 0.77 to 72 mg a.i. L-1. The GF-120 residues applied on inert surfaces were harmful to E. paulistus with a high mortality rate under laboratory conditions. Field studies are needed to validate these results by evaluating parasitoid populations in insecticide-treated and untreated areas.

 

 

Se evaluó el efecto colateral del insecticida GF-120 NF Naturalyte 0.02 CB® sobre adultos de Eretmocerus paulistus, parasitoide de Aleurothrixus floccosus en cítricos en el norte de Chile. Se determinó la CL50 y CL90, aplicando el insecticida mediante torre Potter, en dosis decreciente desde 0,96 hasta 0,1 mg a.i. L-1 (correspondientes al 1% y al 0,1% de la dosis recomendada, respectivamente). Los resultados correspondientes a las 24 h se ajustaron a un modelo Probit y se estimaron en 0,21 y 0,79 mg i.a. L-1 (CL50 y CL90, respectivamente). En ensayos de alimentación y evaluación del efecto tóxico de residuos secos de GF-120, se determinó que la mayor mortalidad (100%) se obtuvo con una combinación de 24,0 mg i.a. L-1 x residuos de 1 hora. Residuos de 96 h (4 días), con concentraciones de 38,4 ó 24,0 mg i.a. L-1, produjeron mortalidades superiores al 60%. De acuerdo a la clasificación de la IOBC (International Organization for Biological and Integrated Control of Noxious Animals and Plants), la concentración recomendada por fabricante de 96 mg i.a. L-1 fue de nivel 4 (perjudicial, >99%), lo mismo ocurrió con concentraciones de GF-120 que variaron entre 0,77 a 72 mg i.a. L-1. Los residuos de GF-120, aplicados sobre superficies inertes fueron dañino para E. paulistus, con altas tasa de mortalidad bajo condiciones de laboratorio. Se requieren estudios de campo para validar estos resultados evaluando poblaciones del parasitoide en áreas tratadas y no tratadas con este insecticida.


Keywords


Bioassays, insect parasitoids, natural pesticide, residual effect, side effects, toxicity, bioensayos, efectos colaterales, efecto residual, insectos parasitoides, pesticida natural, toxicidad

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DOI: http://dx.doi.org/10.7764/rcia.v40i2.1108