Evaluation of pests affecting maize imported across Malawi borders

Abstract

Cross-border trade is one of the major factors that puts maize at risk as it creates pathways for spread of different maize pests in Malawi. This study was carried out to identify pests associated with imported maize in order to improve phytosanitary measures and reduce the introduction of pests. Random sampling technique was used to collect imported maize at selected borders and commercial cities with the aim of identifying pests present during importation. There were no significant differences (p>0.05) in the population of insect pests before and after incubation in all the surveyed districts. Significant differences were observed after incubation for larger grain borer (LGB) and common maize weevil. The highest percentage infestation (32%) of living LGB was recorded in Karonga and the least in Mzuzu (p<0.05). On the other hand, for maize weevil, the highest percentage infestation (20%) was recorded in Nkhatabay while the least was observed in Lilongwe district (p<0.05). Common fungal pathogen species isolated included Fusarium (70%), Aspergillus (29%) and Penicillium (1%). The highest percentage of kernel infection with Fusarium sp. was recorded in Dedza and Lilongwe while for Aspergillus sp. were in Mzuzu. The Aspergillus sp. isolated were A. niger (29%), A. flavus (22%) and A. parasiticus (5%) while Fusarium sp. isolated was Fusarium verticilloides. The study provided the status and causes of storage losses by various pests on maize. It is recommended that the phytosanitary system present at various Malawi borders where maize is imported should be strengthened. This can be achieved through human and infrastructure capacity building, strict compliance with importation regulations and improved funding of organizations mandated to ensure phytosanitary compliance.

Key words: Aspergillus sp., consignment, food security, grain storage, random sampling, sanitary and phytosanitary measures.