Abstract :
[en] Maize (Zea mays L) is one of main nutrients sources for humans and animals worldwide.
In Africa, storage of maize ensures food resources availability throughout the year.
However, it often suffers losses exceeding 20% due to insects such as the larger grain
borer, Prostephanus truncatus (Horn) (Coleoptera; Bostrichidae), major pest of stored
maize in the tropical countries. This study aims to select resistant varieties to reduce
maize storage losses and explain the physicochemical parameters role in grains susceptibility. In the first study, maize grains were artificially infested under no-choice
method with insects. Susceptibility parameters such as weight loss, grain damage, number of emerged insects, median development time and susceptibility index varied significantly through maize varieties. Dobie susceptibility index (SI) was assessed as a major
indicator of resistance. The most resistant varieties were Early-Thaï, DMR-ES and
Tzee-Yellow. Conversely, Synth-9243, Obatampa and Synth-C varieties were susceptible. SWAN, Across-Pool and Tzee-White were classified as moderately resistant varieties. The insect reproductive potential was significantly different in the nine maize
varieties and Early-Thaï, DMR-ES and Tzee-Yellow varieties were the least favourable
host. To assess the relationship between grains physicochemical characteristics and
varietal susceptibility, moisture, total phenolics, palmitic acid, proteins, amylose, density and grain hardness were evaluated according to standardized methods. Palmitic
acid, SI, insects emerged and grain damage were significantly and positively correlated
with each other, and negatively correlated with grains hardness, phenolics and amylose
contents. Maize susceptibility index was significantly and negatively correlated to amylose, and phenolics contents and positively correlated to palmitic acid content. This
study identified three resistant maize varieties to P. tuncatus and revealed that the
major factors involved in this resistance were hardness, phenolic and amylose contents
of grains.
Title :
Varietal susceptibility of maize to larger grain borer, Prostephanus truncatus (Horn) (Coleoptera; Bostrichidae), based on grain physicochemical parameters
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