HISTOCHEMICAL AND ULTRASTRUCTURAL STUDY OF THE MIDDLE INTESTINE OF A Bt-CROPS-RESISTANT POPULATION OF Diatraea saccharalis

SÁNCHEZ MATÍAS MARIANA DEL HUERTO; TERÁN, PAULA MARÍA; GARCÍA-DEGANO, FLORENCIA; GASTAMINZA, GERARDO; AJMAT, MARÍA TERESA

Tucumán

Jornada; XXXV Jornadas Científicas Asociación de Biología de Tucumán; 2018

Asociación de Biología de Tucumán

Development of transgenic crops through Bacillus thuringiensis (Bt) technology has been a significant advance in the substitution of agrochemicals and represents one of the solutions most respectful to the environment. Bt-derived Cry toxins are insecticidal proteins and their target is the insect middle intestine (MI) epithelium. The evolution of resistance to this technology is alarming; such is the case of unexpected damages by D. saccharalis in Bt maize detected in San Luis province (Argentina) in the 2012/2013 campaign. The objective of this work was to study histochemically and ultrastructurally the morphological characteristics of the intestinal epithelium of Bt-resistant larvae and to compare them with those of susceptible larvae, as a basis to explain the resistance mechanism. A toxicity bioassay was carried out feeding neonate larvae of both populations on Bt maize during 48 hs. Larvae were fix at 0, 6, 12, 24 and 48 hours for optical and electronic microscopy. PAS, Alcian Blue pH2.5 and Toluidine Blue stains were use. The progressive cellular damage of the MI epithelium of the susceptible larvae was descript. In contrast, the resistant larvae preserved the integrity of the intestinal epithelium and an increase in goblet cells was observe accompanied by the secretion of a thick peritrophic membrane of a glycoprotein nature.These morphological findings allow us to postulate that the production of the thick layer may interfere in the interaction between the toxin and the plasma membrane of the epithelial cells of the MI of resistant larvae.