Appendix 3.6: Statistics for the importance of maize in Katumba ward
4.4 Discussion
4.4.3 Predominant pests of maize in Katumba ward and their implications .1 Predominant insect pests .1 Predominant insect pests
Findings in Tables 3.2 revealed that the majority of the farm households in Katumba ward experience storage problems due to the infestation of maize by S. zeamais and S. cerealella. The high numbers of insects observed through laboratory tests in 93 % of samples of stored maize confirmed the above perceptions. Therefore, S. zeamais and S. cerealella were the most important insect pests that infested stored maize in Katumba ward. Weevils, especially S. zeamais (Mulungu et al., 2007), and beetles, mainly Tribolium species (Katinila, 1998) have been reported as the main insect pests that cause post-harvest maize loss in Tanzania. However, the farm households in Katumba ward perceived S. cerealella as next to S. zeamais in relation to its importance where infestation of maize by insect pests is concerned. The findings corroborate with the reports from other places such Western Africa (Tadasse, 1996) and Kenya (Oduor, 2000) where S. cerealella has been named among the major insect pests of stored maize.
There was no significant difference between the proportions of infested maize samples for the local varieties and the improved maize varieties. The independent samples T-test (α>0.05) further confirmed that there was no significant difference between the mean numbers of insect pests per 120 maize kernels for the maize samples of the indigenous and improved varieties alike. This implies that farm households in Katumba ward experienced infestations of insect pests, especially S. zeamais and S. cerealella species in stored maize regardless of the type of seeds that they grew. The fact that the insect infestation occurred on both the improved and local varieties of maize is an indication of the poor resistance to insect infestation of the maize varieties that the farm households grew. This corroborates with the concern that in Tanzania maize breeding is done mainly for the purpose of increasing yield rather than for improving resistance of the food crops to infestations (Kaliba et al., 1998). Thus, among other factors, maize seeds that are resistant to insect infestations both in the field and in storage in Katumba ward were also required by the farm households. Therefore, it is important that the maize breeding programmed in Tanzania be encouraged to produce maize seeds that are resistant to infestations.
The climatic conditions such as temperatures and relative humidity that characterize Katumba ward play a role in promoting growth of the insect pests. In general temperatures between 15 -40
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0C are known to promote insect activity in cereals (Semple et al., 1992). Thus, the 100C-250C that characterizes the temperatures in Katumba ward (Anon, 2008) are within the range in which insect activity in grains takes place. However, the temperatures in Katumba ward are cooler than other parts of Tanzania such as Dodoma, where temperatures are within the range of 18 - 31 0C (Government of the United Republic of Tanzania, 2003). Thus, the temperatures in Katumba ward may not be as much supportive of infestations as the temperatures in the warmer areas.
The presence of insect pests in the maize confirmed that the quality of the maize in Katumba ward was poor. The fact that 88 % of the maize samples that were tested for insect infestation were also found to be infected with moulds suggested that there was an interaction between the insect infestation and fungal infection. A chi square test (α<0.05) confirmed that there was an association between the infested and the infected maize samples (Appendix 4.2). Thus, the insects influenced the development of moulds. It has been noted that while feeding on the maize the insect pests make holes in the maize kernels, which in turn cause maize to be susceptible to fungal infections (Sallam, 1999) and other micro-organisms such as bacteria (Hill, 2008).
Insect activity in stored grain has also been associated with the increase in heat and moisture content in the storage facilities, which further leads to moisture content problems (Williams, 2004). Thus, the insect pests in the maize in Katumba ward possibly led to moisture content production and fungal growth in the maize. Apart from the insect pests causing the reduction of maize by weight through feeding on it (FAO, 1985), it has been noted that contamination of maize by waste products produced by the insect pests in stored maize are also inevitable where maize is infested by insect pests (Mejia, 2003). Thus, the presence of large numbers of insect pests in stored maize in Katumba ward implies that maize would possibly be contaminated, and that the health of the consumers and household food security of the farm households were being compromised.
4.4.3.2 The implication of the presence of high levels of insect pests in stored maize on the capacity of roof and sack storage methods to protect stored maize from insect infestation More than half of the farm households in Katumba ward experienced infestation of maize by the insect pests during storage, which implies that sack and roof storage methods did not offer
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adequate protection to stored maize against insect pests. The fact that 95 % of the maize samples from the sack storage facilities and 90 % of the maize samples from the roof storage facilities were infested by insect pests shows that the percentage of infested maize samples from the two storage systems was not significantly different. The independent samples T-test (α >0.05) further confirmed this. Thus, maize stored using roof and sack storage technologies in Katumba ward was equally susceptible to infestation by insect pests. Furthermore, the performance of both sack and roof storage technologies with respect to protecting stored maize from insects infestation in Katumba ward was equally poor.
The poor performance of the roof storage method in Katumba ward is contrary to the general view concerning roof and sack storage methods, whereby the former is regarded as capable of drying and protecting stored grain from insect infestation; while the latter is considered as capable of cooling the stored grain from the heat that comes as a result of the perspiration of the grain (UNIFEM, 1995). This can be explained in terms of the climatic conditions in Katumba ward, which are characterized by wetness and low temperatures (Anon, 2008) , which most likely made it impossible for maize in the roof storage facilities to become dry fast and therefore, created favourable conditions for insect infestation to occur. Insect activity takes place especially at 15 -40 0C (Yigezu et al., 2010). Thus, the increase in the intensity of the insect infestation in maize that was collected from the roof and sack storage facilities after five months of storage implies that the temperatures in the storage facilities was within the range of temperatures which are conducive to the growth of insect pests. The 2 - 14 months duration for which the farm households stored maize using the roof storage method would also have a negative impact on the extent of damage and loss by the insect pests.
One of the characteristics of a perfect storage method is that it shoud be suitable for use in the climatic conditions of the place where it is being used (Coulter and Schneider, 2004). The roof and sack storage methods in Katumba ward did not fulfill this requirement, thus, are not ideal for use in this ward.
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4.4.3.2 Types of rodents that infest stored maize in Katumba ward
Three types of rodents attacked stored maize in Katumba ward, namely: brown rats, black rats and house mice. Brown rats were the most predominant type followed by house mice. Like the insect pests named above, the rodents that infest maize in Katumba ward reduced not only the amounts of maize and nutrients that could have been available to the farm households, but also posed a health threat the farm households through consumption of maize which may be contaminated with diseases that the rodents transmit. The diseases that are transmitted by brown rats include the weil disease, cryptosporidiosis, viral hemorrhagic fever (VHF), Q fever and hantavirus pulmonary syndrome, while house mice transmit lyme disease, chloromeningitis, and aseptic meningitis (Public Health of Canada, 2008, Mills and Childs, 2001). Thus, maize which is infested by brown rats and house mice puts the consumers at risk of suffering from the indicated diseases.
The fact that rodents are hosts to many emerging viral diseases that are fatal to humans and animals in Africa has been acknowledged (Merck, 2011). Studies conducted on humans and rodents in several urban and per-urban areas in Tanzania in 2003 - 2006 associated the occurrence of the following deadly bacterial infections with rodents: plague caused by Yersinia pestis, and leptospirosis caused by Leptospira (University of Greenwich, 2006). The occurrence of taxoplasmosis a parasitic infection caused by Toxoplasma gondii was also associated with rodents (University of Greenwich, 2006). No research has been conducted in Rungwe district to investigate the occurrence of diseases transmitted by rodents, thus, people may be suffering from these unnoticed. Therefore, more research should be conducted in Katumba ward and Rungwe district in general, to investigate the occurrence of the diseases transmitted by rodents.
Furthermore, it is also possible that the rodents made holes in the storage containers, which would allow movement of moisture from outside into the containers. The infestation of stored maize by rodents also implies that the occurrence of rodents’ excretions in the maize would be inevitable. Consequently, this would contaminate the maize, create moisture problems in the stored maize as well as create conditions that are favorable for the growth of moulds and other micro- organisms such as bacteria (FAO, 1985; De Groote, 2004).
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4.4.3.4 Predominant fungi species in Katumba ward and the farm households’
understanding of moulds
The findings imply that for the majority of the farm households in Katumba ward stored maize was exposed to infection by moulds which cause Gibberella and Diplodia ear rots, namely, Gibberella zeae, synonym Fusarium graminearum and Diplodia maydis (Van Rensburg and Flett, 2010) synonym Stenocarpella maydis (Moremoholo and Shimelis, 2009), respectively. The findings also imply that for a significant number of farm households in Katumba ward stored maize was infested by Aspergillus and Penicillium species of fungi which caused Aspergillus and Penicillium ear rots, respectively (Moremoholo and Shimelis, 2009). Furthermore, the findings suggested that for a small percentage of farm households maize was infested by Fusarium species responsible for causing Fusarium ear rot of maize such as F. verticillioides (Parsons and Munkvold, 2010) and F. proliferatum (Robertson-Hoyt et al., 2007). These fungal infections could reduce the nutritive value of the infested maize and their metabolic activities in the infested maize could produce mycotoxins, chemical compounds that are harmful to the consumers.
At least half of the farm households that took part in this study were not aware of health problems that are associated with mouldy maize. This explains the majority of the farm households’ failure to acknowledge maize loss due to moulds regardless of the fact that the infection of maize by moulds was common to them. It also explains the farm households’ use of mouldy maize for human consumption or feed purposes. The use of mouldy maize for consumption purposes could subject the consumers, both human and animals to ill health due to the associated mycotoxins (Van Rensburg and Flett, 2010; Sweeney et al., 2000; Atkins and Norman, 1998). Thus, the importance of the extension officers in this ward to educate the farm households on these issues cannot be overemphasized.
The farm households’ ignorance regarding moulds is further revealed through the fact that at least 50 % of the farm households simply threw away mouldy maize if they felt that it was very badly damaged. The practice of simply throwing away mouldy maize would accelerate the problem as the moulds would continue to grow where conditions are favorable. Katumba ward is known to be characterized by wetness throughout the year and cool temperatures ranging from 10 - 25 0C (Anon, 2008), which naturally leads to high humidity. High humidity and temperatures ranging
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from 10 - 43 0C allow growth of fungi (FAO, 2003). Thus, the temperatures in Katumba ward are within the range of temperatures which in combination with high humidity favours the growth of moulds. Thus, the fungi in the mouldy maize that the farm households threw away in Katumba ward could easily multiply and intensify the problem of fungal infection of maize. The farm households’ ignorance in relation to moulds also explains the farm households’ reluctance to control moulds in stored maize. Thus, the role of the extension officers as educators is critical for ensuring that the farm households are informed concerning health problems associated with pathogenic moulds and for preventing the infection of stored maize by moulds.
4.4. 4 The relationship between maize loss and maize variety in Katumba ward
Both the farm households that grew the improved varieties of maize and the farm households who grew the local varieties of maize almost equally experienced maize loss due to rodents, insect pests and moulds. A Chi-Square test (α>0.05) confirmed that there was no significant association between specific maize variety and the farm households’ losing maize to insect pests, rodents or moulds.
4.4.5 The association between maize loss and drying prior to storage in Katumba ward The practice by the majority of the farm households of storing maize insufficiently dried maize in the roof storage facilities, together with the fact that it took more than two weeks for the maize to dry, impacted negatively on the safety of the stored maize. Moist grain perspires faster than dry grain leading to increase in temperature and an increase in moisture content of the grain through condensation (Williams, 2004), which creates favorable conditions for pests especially insect pests, moulds and other micro-organisms and subsequent contaminations. To prevent infestations and infections from occurring it is recommended that maize be adequately dried prior to storage (De Groote, 2004) rather than during storage. Weinberg et al., (2008) and Reed et al. (2007) recommend rapid drying of maize followed by cooling and treating with fungicides to prevent it from being infested by moulds. However, unless storage facilities are moisture proof, dry maize stored in climatic conditions which are characterized by high humidity can still take in some of the moisture from the storage area. The prolonged rainfall that characterizes the climatic conditions in Katumba ward (Anon, 2008) leads to high humidity, which can subject maize stored in sacks or in roofs of houses to moisture content problems. The farm households’
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complaint that maize was not dry enough at harvest, and the fact that for the majority of the farm households maize was infested by moulds during storage, are indications that the sources of heat that the farm households depended on for drying maize were inadequate. Consequently, it took a lot more than 48 hours to become dry enough for storage, which led to growth of moulds n the stored maize. Accumulation of the moulds in the roof storage facilities over time was also possible. Thus, an efficient alternative method for drying maize rapidly prior to storage is a basic need for the farm households in the ward, whereas the sack and roof storage methods need to be made moisture proof for better performance against the climatic conditions in the ward. The Vulnerability Assessment Committee and the agricultural extension staff in Katumba ward could assist with finding and implementing efficient methods of maize drying.
4.4.6 The implication of the inadequacy of the methods used by the farm households to