Self-defense against field and storage pests of maize landraces of San Juan Ixtenco, Mexico

Abstract

To explore the possibility that maize landraces possess self-defense traits against insect pests,
native varieties and a commercial hybrid were assessed experimentally for pest abundance
in the field and postharvest. The varieties used were from San Juan Ixtenco, Tlaxcala: white,
yellow, red, blue, black, cacahuazintle and the Dekalb hybrid DK2027®, which is also grown in
there. The null hypothesis that the abundance of phytophagous insects would be equal in all of
the maize varieties explored was contrasted, assuming that pest abundance is the result of the
expression of genetic traits present in the plants. The insect species quantified were Geraeus
senilis (Gyllenhal), Nicentrites testaceipes (Champion), Rhopalosiphum maidis (Fitch), Rhopalosiphum padi (Linneaeus) Spodoptera frugiperda (Smith), Sitotroga cerealella (Oliver), Sitophilus
zeamais (Motsch) and Diabrotica spp. The collected data produced evidence against the
null hypothesis for seven of the eight insect species, suggesting possible mechanisms of resistance
in the less permissive varieties. All of the varieties exhibited permissiveness (possible
susceptibility) for some pests but not for others (possible resistance). Permissiveness for only
one of the pest species occurred in the yellow, blue and red maize varieties. Cacahuazintle
and black permitted two pests, while white permitted three of the species. Only the hybrid was
permissive for four pest species. Blue white and the hybrid maize varieties exhibited non-permissiveness
for only one of the pests, while yellow, cacahuazintle and red showed non-permissiveness
for two species and black for four pests.