The effect of (2R)-6-hidroxitremetone on walnut tree-infesting insects

BARRERA ILLANES, ALBERTO NICOLAS; NERI, ANABELLA; BENAVENTE, ALBA; POPICH, SUSANA BEATRIZ; AJMAT, MARÍA TERESA

Tucumán

Jornada; XXXI ANNUAL SCIENTIFIC MEETING; 2014

Asociación de Biología de Tucumán

THE EFFECT OF (2R)-6-HYDROXY-TREMETONE ON WALNUT TREE-INFESTING INSECTS.Barrera Illanes A; Neri A; Benavente A; Popich S and Ajmat MT. Departamento de Ciencias Básicas y Tecnológicas ? Universidad Nacional de Chilecito (UNdeC).Ruta Los Peregrinos s/n. Los Sarmientos. Chilecito. La Rioja.E-mail: majmat@undec.edu.ar The culture of walnut tree is a major source of income for the small and medium-sized companies of La Rioja and Catamarca. Crop yields depend, among other factors, on the phytosanitary condition of plots. The use of synthetic pesticides lowers the quality of marketable products (in-shell and husked walnut) and produces serious environmental imbalance. Current research tends to seek natural bioactive products, of microbial or plant origin. Plodia interpunctella (Lep.) larvae constitute a major pest for stored nuts. Previous studies revealed that (2R)-6-hydroxy-tremetone, an isolated secondary metabolite of the Asteraceae family, is able to control various species of mites affecting olive trees. The aim of this paper was to study the lethal and sub-lethal effect of low-dose (2R)-6-hydroxy-tremetone on P. interpunctella larvae fed on crushed nuts. Toxicity bioassay on P. interpunctella larvae were carried out, with low-dose tremetone-imbued diet (50, 100 and 200 mg/L). Morphological and quantitative death rate and weight observations were analyzed statistically according to Infostat v. 2013. As regards larvae weight, significant differences emerged between those treated with (2R)-6-hydroxy-tremetone 200 mg/L (17.08 ± 3.81) and the control group (14.65±7.68), according to the Shapiro-Wilks and Friedman tests. Death rate with 50 and 100 mg/L doses was 9% and 11% respectively. In both treatments abdomen and prolegs malformations were observed and color changes that resulted in death of insects at pupal stage. These preliminary results show that (2R)-6-hydroxy-tremetone in low doses has sub-lethal effects on P. interpunctella larvae. Future histological studies will allow us to identify the target tissues and organs of this compound.