Post-harvest insect infestation and mycotoxin levels in maize markets in the Middle Belt of Ghana

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 to August and September to 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 (F.), 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 2.9–3.4 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 and 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.