Are variations in kernel-related morphometric and chemical parameters correlated with differences in Sitophilus oryzae attack in maize?

Maize (Zea mays L.) is one of the major crops worldwide, during grain seed storage it is susceptible to insect infestation that affects the productivity and greatly impacts on the quality of the products in quality and sanitary terms. In this context, Sitophilus oryzae (L.), which is present in various climates, is one of the primary pests for seeds of this crop. In this study, microscopy and biochemical analyses were performed on mature kernels of a set of eight inbred lines of economic and historical importance for both maize breeding and research activities. Experiments were carried out in order to verify if morphological and/or biochemical parameters under study were correlated to S. oryzae susceptibility. To this aim, S. oryzae was reared in laboratory-controlled conditions and the susceptibility index (SI, range :0-11), which depends on both number of emerging adults and their median developmental period, was measured. In particular, maize kernels of each of the eight maize lines were put in contact into glass jars with males and females of S. oryzae, less than 3 days old, for 13 days. Infested kernels were daily checked for new adult emergence. Four maize lines resulted susceptible to S. oryzae attack, since showing SI ranging from 7.5 to 9.7, while the others appeared to be moderately resistant (SI: 4.6-6.9). Our results confirmed the occurrence of variability for insect susceptibility among different maize genotypes, however, variations in the kernel traits analysed do not allow us to make predictions about the response to insect attack.