HISTOLOGICAL STUDY OF THE MIDGUT OF Diatraea saccharalis (LEPIDOPTERA: CRAMBIDAE) LARVAE TREATED WITH PIRROLIZIDINE ALKALOIDS OF Senecio rudbeckiaefolious

TERÁN, PAULA MARÍA; SÁNCHEZ MATÍAS MARIANA DEL HUERTO; MEREP, PAOLA; GASTAMINZA, GERARDO; AJMAT, MARÍA TERESA

Tucumán

Jornada; XXXVI Jornadas Científicas Asociación de Biología de Tucumán; 2019

Asociación de Biología de Tucumán

Senecio genus species contain a large variety of secondary metabolites whose demonstrated toxicity against herbivorous insects and vertebrate is attributed to the production of pyrrolizidine alkaloids (PA). In previous work, we checked the lethal and sublethal effects of the alkaloidal fraction of a methanolic extract of Senecio rudbeckiaefolious on Diatraea saccharalis larvae, the main pest that affects the cultivation of sugarcane in Tucumán. In Lepidoptera, the midgut epithelial lining has been postulated as a likely target for the action of insecticides. The aim of this work was to histologically analyze the midgut of D. saccharalis larvae fed on an artificial diet added with PA of S. rudbeckiaefolious. To this purpose, force-feeding bioassays were performed with aqueous solutions of the PA fraction at 100 and 200 mg/L concentrations. Larvae were fixed in Bouin‟s fluid at 7-, 10- and 14-days post-inoculation and processed by histological technique for arthropods. Although it was found that the PA affect neither the integrity of the midgut epithelium nor the peritrophic membrane that covers it, the secretion of a thick extracellular matrix was observed in the anterior region of the midgut and a significant reduction of the fatty bodies. The inhibition of larval development observed in the surviving larvae suggests that the PA exert their action on the insect neuroendocrine system, interfering with the molting process.