Crop storage practices and occurrence of fungi with public health importance from rodents’ trapped inside and outside the storage facilities in Mbeya, Tanzania

MSc Dissertation

Animals play an important role in the dispersal of seeds and fungal spores. Several species that consume fruiting bodies of fungi play a primary role in dispersal networks. Through the rodent-mycorrhizal dispersal relationship, the study was conducted in selected wards of urban and peri-urban areas of Mbeya-Tanzania to discover whether rodents could act as the network for the dispersal of other fungi related to public health. As well as assessment of knowledge, awareness, and practices based on storage conditions, that may influence rodent infestation: implication to fungal contamination in storage facilities. A total of 210 rodents were trapped in and outside the storage facilities in selected wards in Mbeya city of which Rattus rattus (51.0%) was a dominant species, Praomys 40(19.0%), Lophuromys 29(13.8%), Mastomys natalensis 19(9.0%), Mus musculus 9(4.2%), and Lemnicomys spp 4(1.9%). Fresh fecal samples from the rectum were collected. The second form of samples were 77 pellets collected from the ground making a total number of 288 fecal pellets. Both samples were preserved at -20 0C at Mbeya National Research Institute (NIMR) for further laboratory analysis. Colony morphology obtained through Microbiological analysis and identification in selective media. A total number of 6 different fungal isolates were observed and Aspergillus fumigatus was the dominant fungal species from the cultured samples, with a prevalence of 26% (76/288) showing the potential for aspergillosis in humans followed by Aspergillus niger and Fusarium species with a prevalence of 9% (27/288), Aspergillus flavus 3% (10/288) and Aspergillus ochraceus 1% (4/288). Nested PCR confirmed the presence of aflR gene from suspected isolates of Aspergillus flavus, bands observed at 800kb for the first round and 400kb for the second round. Indirect Competitive ELISA performed on 10 maize samples that infected with A. flavus isolates, 10 maize samples free from isolates contamination, and 4 pure isolates of A. flavus. The aim was to check whether the isolates were capable of producing toxins and their respective concentrations (ug/ul) were calculated. To confirm the findings a cross-sectional survey was conducted and a total number of 50 facility storage owners were questioned based on grains storage practices, factors for rodent infestation, facility- building conditions, type of material used for storage of grains, Storage facilities owners’ knowledge based on the effects of rodent infestation and ways to reduce the effects. Poor storage practices, types of storage sacks, facility maintenance and longevity of the facility, and poor knowledge of controlling pests and losses due to rodents and moulds were the major findings. The 74% of respondents indicated that they stored only maize, while 26% stored maize along with other grains such as rice and beans. Among the respondents, 28% agreed that storing maize with other products facilitated rodent infestation, 22% disagreed with this opinion, and the remaining participants were unsure. The 58% of the participants expressed confidence in their understanding of the factors that influence rodent infestation, while 42% did not. Regarding major maintenance of their storage facilities, 38% of the storage keepers performed it annually, while 20% did it whenever they deemed it necessary. In terms of rodenticide application within the storage premises, 54% of the respondents indicated its use.

The African Centre of Excellence for Innovative Rodent Pest Management and Biosensor Technology Development (ACE IRPM and BTD)