Post-harvest insect infestation and mycotoxin levels in maize markets 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; MCNEIL, SAMUEL - University Of Kentucky

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2018
Publication Date: 3/1/2018
Citation: Danso, J.K., Osekre, E.A., Manu, N., Opit, G.P., Armstrong, P.R., Arthur, F.H., Campbell, J.F., Mbata, G., McNeil, S.G. 2018. Post-harvest insect infestation and mycotoxin levels in maize markets in the Middle Belt of Ghana. Journal of Stored Products Research. 77:9-15. https://doi.org/10.1016/j.jspr.2018.02.004.
DOI: https://doi.org/10.1016/j.jspr.2018.02.004

Interpretive Summary: Insect pests and fungal contaminates cause considerable damage and lead to product loss and devaluation in sub-Saharan Africa, including the country of Ghana. As part of a USAID research project, a survey was conducted in several markets where corn (maize) is stored in bags and ultimately sold, to assess the presence of insects and fungal contaminants. Stored product insects were present throughout the September to December, when the crop from the major season is stored and sold, and throughout January to April, when the minor season crop is stored and sold. Infestations were not correlated with temperature or moisture content, but did increase during the storage seasons, indicating insect infestations were present at the time of storage. More insects were generally found in the markets when the major season crop was stored compared to the minor season, and also more fungal contaminants were found as well. Results show that improved management of corn prior to bagging and storage should be emphasized to limit insect infestations and fungal contamination, along with increased awareness of the capacity for infestations to increase while bags are stored in the commercial markets. Monitoring and intervention techniques should be emphasized as well.

Technical Abstract: This study focused on assessing maize post-harvest losses in three maize markets in the Middle Belt of Ghana during the storage periods after the harvest of major and minor cropping seasons, September– to December and January– to April, respectively. The major and minor cropping seasons in the Middle Belt occur during the periods April–August and September–December, respectively. Storage temperature of bagged maize, grain moisture content (MC), and relative humidity (r.h.) were monitored monthly, along with insect infestations, percentage weight loss of kernels (% WL), the percentage of insect damaged kernels (% IDK), and percentage of discolored grains (% DG). Aflatoxin and fumonisin levels were assessed at the beginning and end of the major and minor crop storage seasons. Cryptolestes ferrugineus Stephens, Cathartus quadricollis Guerin-Meneville, Carpophilus dimidiatus (Fabricius), Sitotroga cerealella Olivier, Tribolium castaneum Herbst, and Sitophilus zeamais (Motschulsky) were found in all markets. Mean insect infestation levels varied throughout the sampling period and were generally similar in the three markets, but were not correlated with temperature, MC, or r.h. (P = 0.05) Mean % WL, % IDK, and % DG peaked in November and December and were usually correlated with total insect populations (P < 0.05). Aflatoxin levels of 2.9 to3.4 ppb were found in all markets in the minor season maize samples, but levels ranging from 38.2 to 64.0 ppb were found in the major season samples. Fumonisin levels for all markets ranged between 0.7–2.3 ppm. Environmental conditions favor insect pest population development throughout the year in maize stored in markets in Ghana, thus the maize must be monitored regularly and appropriate interventions implemented to avoid product loss.