Moisture content, insect pests and mycotoxin levels of maize at harvest and post-harvest in the Middle Belt of Ghana

Authors: DANSO, JAMES - Kwame Nkrumah University Of Science And Technology; OSEKRE, ENOCH - Kwame Nkrumah University Of Science And Technology; MANU, NAOMI - Kwame Nkrumah University Of Science And Technology; OPIT, GEORGE - Oklahoma State University; Armstrong, Paul; Arthur, Franklin; Campbell, James - Jim; MBATA, GEORGE - Fort Valley State University

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2017
Publication Date: 12/1/2017
Citation: Danso, J., Osekre, E., Manu, N., Opit, G., Armstrong, P.R., Arthur, F.H., Campbell, J.F., Mbata, G. 2017. Moisture content, insect pests and mycotoxin levels of maize at harvest and post-harvest in the Middle Belt of Ghana. Journal of Stored Products Research. 74:46-55. https://doi.org/10.1016/j.jspr.2017.08.007.
DOI: https://doi.org/10.1016/j.jspr.2017.08.007

Interpretive Summary: Insect pests and fungal contaminates cause extensive damage in sub-Saharan Africa and affect food safety and security. As part of a USAID research project, a survey was conducted in Ghana to determine the insect pest species and fungal contaminants present during the major and minor crop-producing seasons of summer and late-autumn in the primary corn producing region, the middle belt of the country. More insect pests were generally present during the minor season, which was the dry season, and more were found on-farm after the corn was harvested and piled while waiting to dry. Fungal contamination was also greater in the major season, the wet season, compared to the dry minor season. Results can be used to show the risk levels of the various post-harvest stages of corn in Ghana, and in particular improving methodologies to reduce the time harvested heaped corn is kept in fields before drying.

Technical Abstract: Moisture content, insect pest infestation and mycotoxin contamination of maize are challenges to food safety and security, especially in the tropics where maize is a staple grain. However, very little documentation is available on the impact of these factors on maize in Ghana. This study focused on post-harvest losses of maize and assessed grain moisture content, insect pests and mycotoxin (aflatoxin and fumonisin) levels on-farm at three stages (i.e., in the field before harvest, after heaping of cobs (ears) into piles post-harvest, and post-drying); data for the major and minor cropping seasons in the Middle Belt of Ghana were collected. Data showed that grain moisture content decreased significantly from the field stage (17.2–19.0%) to the post-drying stage (12.4-14.2%). The mean grain moisture content was significantly greater in the major season (20.4%) than in the minor season (12.5%). Maize weevil, Sitophilus zeamais Motschulsky, Angoumois grain moth, Sitotroga cerealella Olivier, and corn sap beetle, Carpophilus dimidiatus Fabricius were the dominant insect species that attacked maize on-farm. Mean numbers of each species were generally significantly greater in the minor season than in the major season (6.3 per 500 g), but in both seasons, greater numbers were detected at the heaped stage compared to field and post-drying stages. Percentage insect damaged kernels and weight loss were significantly lower at the field stage than at both the heaped and post-drying stages; statistically similar levels were observed in the latter two stages. Mean aflatoxin (ppb) and fumonisin (ppm) levels were significantly higher in the major season (29.1 ppb, 1.6 ppm) than in the minor season (3.5 ppb, 1.0 ppm). Results also showed some variation between locations sampled, but in general more insect damage and quality deterioration occurred during the major season compared to the minor season. Data can be used to help design more efficient management strategies to prevent on-farm losses of maize in Ghana.