Control of the larger grain borer prostephanus truncatus (horn) (Coleoptera: Bostrichidae) in different maize seed and grain storage methods

Abstract

Background and Objective: Maize (Zea mays L.) is the primary staple food in many African countries, including Mozambique with seasonal production but continuous consumption. Post-harvest losses have been attributed to storage pests with maize weevil [Sitophilus zeamais (Motschulsky)] causing 10-20% losses while the larger grain borer [ Prostephanus truncatus (Horn)] causes losses of between 30-90%. Seed security is the key to household food security among resource poor farmers in developing countries and seed storage methods play an important role in keeping seed viability and seedling vigour over time in susceptible maize cultivars. New storage methods and technologies have been developed to reduce these post-harvest losses. This study was carried out to evaluate the efficacy of different methods on controlling losses from larger grain borer (LGB) infestation. Materials and Methods: Five different maize seed storage methods which included metal silos; Super Grain bag™ inside polypropylene bags; polypropylene bag with pre-fumigated seed with Gastoxin™ (a phosphine fumigant); polypropylene bag with Actellic Super® and polypropylene bag alone were evaluated for preservation of seed quality and control of LGB using a complete randomized design replicated four times through 6 months storage sampling within 2 months. One way ANOVA using GenStat (12th edition) statistical software were applied for analysis using 5% level of significance and four specific orthogonal contrasts were used to separate different storage methods. Results: Metal silo had the highest efficacy over the 6 months of storage, showing the lowest seed weight loss of 3.9%, the lowest seed damage of 15.6%, a high seed germination of 77% and high vigour, with a low electric conductivity of less than 3.6 µS cm -1 g-1. The Super Grain bag™ inside polypropylene bag was second in efficacy. The polypropylene bag alone was the worst, showing high seed weight loss of 28.0%, high seed damage of 88.9%, the lowest germination of <5% and worst vigour and with the highest electric conductivity of more than 6 µS cm-1 g-1. Conclusion: The metal silos demonstrated the best efficacy over other storage methods. If adopted, could reduce the negative impact of larger grain borer and other storage pests that causes post-harvest losses among small-scale.