Date of Award
Master of Science
Agricultural and Biosystems Engineering
Biorenewable Resources and Technology
Thomas J. Brumm
Maize, being an important agricultural crop and among the three most widely grown in the world, plays an important role in the livelihood of smallholder farmers contributing 34-36% daily calorific intake in East Africa and 10% in West Africa. In developing countries, population growth is expected to occur with increasing food demand. Conversely, maize experiences post-harvest losses (PHLS) especially from the maize weevil (Sitophilus zeamais), which if minimized, could help to reduce the number of hungry people in the world that is about 870 million people and majority (850 million people) being in developing countries. For the economies of smallholder farmers, better storage leads to fewer losses, more income, more grain available to seed, greater family stability, lower risks of family/country conflicts, improvement in political stability and quality of life. The different approaches which were studied to control the maize weevils included: evaluation of hermetic maize storage for smallholder farmers, effect of blending maize kernels with amaranth during storage on maize weevil mortality, and effect of storage containers physical disturbance on maize weevil mortality.
The first study found 100% maize weevil mortality for hermetically sealed containers and the oxygen levels inside them declined from 21% to between 3 and 10%. From the maize, maize-amaranth experiment, it was concluded that blending maize with amaranth during storage reduced maize weevil population growth by 46% compared to storing maize alone. From the last experiment, we found out that physical disturbance resulted in 81% weevil mortality. The overall conclusion is that there are effective low-cost ways to control maize weevils by hermetic storage, physical disturbance and blending maize with amaranth during storage. Hermetic storage is the best among the researched methods to effectively control the maize weevils, followed by physical disturbance and then maize-amaranth mixture.
Possible future research can be to:
* Investigate the possible causes and how to eliminate and/or minimize maize spoilage on barrel walls. This experiment will seek to minimize and/or eliminate molds that were observed and the aflatoxin detected from samples picked from barrel walls.
* Hermetic storage should be investigated without letting the weevils to first go first through lifecycles to increase in population. This experiment will investigate if kernel spoilage occurs on barrel walls if hermetic sealing in done from the first day of storage.
* Investigate how long it takes for a female maize weevil to bore through a kernel. This test will establish how frequently it is necessary to disturb the weevils.
* Setting up the same maize-amaranth experiment (50:50 by volume) but having an extra layer of amaranth on top to investigate if this can help completely control the maize weevil. This extra layer will reduce and/or eliminate the maize kernels that were available during our experiment.
* Due to observation of no spoilt kernels for maize blended with grain amaranth on barrel walls, more research should be done to quantify the observations. This experiment may lead to hermetic and maize-amaranth mixture methods being used together by smallholder farmers to eliminate and/or mimimize weevils while experiencing no mold maize in metallic storage containers.
* Investigate the effect of physical disturbance using larger storage containers. Since farmers use larger storage containers compared to what we investigated in laboratory setting, it is necessary to find out what will happen in real life.
* Implement and test the researched methods in a developing country. These tests will help determine if the proposed methods are feasible.
Bbosa, Denis, "Pesticide free methods of maize weevil control in stored maize for developing countries" (2014). Graduate Theses and Dissertations. 14083.