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Several species of herbivores feed on maize in field and storage setups, making the development of multiple insect resistance a critical breeding target. In this study, an association mapping panel of 341 tropical maize lines was evaluated in three field environments for resistance to fall armyworm (FAW), whilst bulked grains were subjected to a maize weevil (MW) bioassay and genotyped with Diversity Array Technology's single nucleotide polymorphisms (SNPs) markers. A multi-locus genome-wide association study (GWAS) revealed 62 quantitative trait nucleotides (QTNs) associated with FAW and MW resistance traits on all 10 maize chromosomes, of which, 47 and 31 were discovered at stringent Bonferroni genome-wide significance levels of 0.05 and 0.01, respectively, and located within or close to multiple insect resistance genomic regions (MIRGRs) concerning FAW, SB, and MW. Sixteen QTNs influenced multiple traits, of which, six were associated with resistance to both FAW and MW, suggesting a pleiotropic genetic control. Functional prioritization of candidate genes (CGs) located within 10–30 kb of the QTNs revealed 64 putative GWAS-based CGs (GbCGs) showing evidence of involvement in plant defense mechanisms. Only one GbCG was associated with each of the five of the six combined resistance QTNs, thus reinforcing the pleiotropy hypothesis. In addition, through in silico co-functional network inferences, an additional 107 network-based CGs (NbCGs), biologically connected to the 64 GbCGs, and differentially expressed under biotic or abiotic stress, were revealed within MIRGRs. The provided multiple insect resistance physical map should contribute to the development of combined insect resistance in maize. [ABSTRACT FROM AUTHOR]

Abstract: Field studies were conducted during 2003 and 2004 for three consecutive growing seasons. The treatments were (1) market crop wastes (MCW) compost incorporated in the soil, (2) un-composted MCW incorporated in the soil, (3) un-composted MCW applied as a surface mulch, (4) a conventional chemical fertilizer (NPK) incorporated in the soil, and (5) the untreated control. Response variables recorded included plant height and width, leaf area, tissue nitrogen content, nodulation; occurrence of Aphis fabae, Maruca vitrata and the associated natural enemies; and grain yield. Results indicated that significant differences in plant attributes and yield were only detected in the second and subsequent season of the crop or when weather conditions were stressful. For the insect pests, it was only A. fabae infestation that varied among treatments with MCW amended plants sustaining higher infestations than NPK and the untreated control, a trend that held for all the seasons. Natural enemy occurrence followed the trend of A. fabae infestation. After the first and subsequent harvests, more P, K, Ca, and Mg were extracted from the soil from MCW plots than NPK plots. The study indicated that yields accruing from MCW amended plots were comparable and sometimes even higher than those from NPK despite the higher A. fabae infestation of the former. [Copyright &y& Elsevier]