MORPHOLOGICAL ANALYSIS OF MIDGUT IN Diatraea saccharalis POPULATIONS SUSCEPTIBLE AND TOLERANT TO Bt-CROPS

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

Tucumán

Jornada; XXXIV Jornadas Científicas de la Asociación de Biología de Tucumán; 2017

Asociación de Biología de Tucumán

Diatraea saccharalis (Lepidoptera: Crambidae) is the pest with the greatest economic impact that affects sugarcane in the ArgentinianNorthwest and, to a lower extent, corn in the pampas. One strategy to control it is to develop transgenic crops which exhibit toxins withpesticidal properties produced by Bacillus thuringiensis (Bt crops). These toxins enter through the midgut?s peritrophic membrane andinteract with epithelial cells causing cell lysis. Evolution for resistance to this technology has been observed. In the province of San Luisunexpected damage by D.saccharalis on Bt hybrid corn was found. The aim of this paper was to comparatively analyse the microscopiccharacteristics of the midgut in susceptible (LS) and tolerant (LT) to Bt toxins (San Luis case) D.saccharalis populations. Assays werecarried out feeding larvae of both populations with Bt corn leaves for 7 days and then processing them through histological techniques foroptical and electron microscopy. In LS, the midgut showed total destruction of epithelium with partial conservation of the peritrophicmembrane and general melanization reaction. In LT the midgut showed three different regions, with features identical to the control larvae.The epithelium is cylindrical pseudostratified with granular, goblet and basal cells. Electron microscopy confirmed the integrity of theplasma membrane of the epithelial cells. The microscopy findings provide useful preliminary information to explain the underlyingmechanisms of the resistance phenomenon.