Postharvest Practices and Farmers Knowledge in Managing Maize Pests in Eastern Cape Province, South Africa

1. Introduction

Maize cultivation performs well in a vast range of regions, including the tropics, subtropics and temperate zones [1]. Albeit maize is predominantly grown in Latin America, Asia and sub-Saharan African countries like South Africa, where it plays a pivotal role in food security and agricultural economy [2]. The total amount of maize production worldwide is approximately 1.137 million metric tonnes [2]. In South Africa maize is the most important staple crop in terms of production and consumption [3]. Farmers normally rely on their storage techniques and knowledge to preserve maize during the long off-season period before the next harvest [4].

Maize storage practices in South Africa among commercial and smallholder farmers vary significantly and are influenced by economic resources and access technologies [5]. Commercial maize farmers predominantly use metal silos for grain storage, which is considered the most effective method in South Africa in protecting maize [6]. On the other hand, smallholder farmers mostly use inqolobane, metal containers and sack [7]. Nonetheless, these maize storage methods used by smallholder farmers are ineffective except for metal containers [8].

Maize plays a major role in the food security of small-scale farmers as food and cash crop for millions of rural farm families [9]. However, this beneficial food material has several challenges [10]. Studies in sub-Saharan Africa which includes South Africa, have shown that maize is susceptible to infestation by rodents, fungi, and insect pests during the storage period [11]. For example, farmers and workers postulated that, rodent infestation is influenced by the presence of waste and spilled grains near grain storage facilities [12]. Further, research findings have elucidated that, poor postharvest practices and storage facilities have extensively contributed on maize grain being contaminated by mycotoxin due to fungal infestation. Similarly, high temperatures and poor storage conditions favour insect pest infestations [13].

Some of the major primary insect pests of maize includes maize weevils, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), rice weevil, Sitophilus oryzae (Linnaeus) (Coleoptera: Curculionidae), maize grain moths, Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) and larger grain borer, Prostephanus truncates (Horn) (Coleoptera: Bostrichidae) that directly contribute significantly to postharvest losses through feeding and reproduction, impacting the quality and quantity of stored grain [14]. Indirectly, the presence and feeding of these insect pests can elevate grain temperature and moisture levels stimulating grain deterioration and enhancing fungal activity [15].

Consequently, primary insect pests attracts secondary insect pests of maize such as rust-red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Terebrionidae), flat grain beetle, Cryptolestes pusillus (Schohnerr) (Coleoptera: Cucuridae), saw toothed grain beetle, Oryzaephilus surinamensis (Linnaeus) (Coleoptera: Silvanidae) and grain mites, Acarus siro (Linnaeus) (Acarina: Acaridae), which cannot damage the whole grain but infest grains that are either mechanically damaged or previously infested by primary pests [16].

Various methods have been used in the management of these insect pests, including chemical control, biological control, cultural control, and others [17]. Nonetheless, the use of inorganic pesticides like aluminium phosphide, malathion, ethyl formate, etc., has been reported as the commonly preferred method in managing insect pests of maize [18]. However, the extensive usage of these pesticides results in resistance to targeted pests like maize weevils reducing their effectiveness [19]. Moreover, there are growing concerns on human health hazards and contamination of the environment at large due to excessive use of inorganic pesticides [20]. Thus, there is a need to develop integrated pest management approach that is safe and cost-effective for smallholder farmers [21].

Despite of these challenges caused by storage pests of maize, there is a paucity of information on farmers’ knowledge and practices in managing these pests in some parts of Eastern Cape province [22]. To establish effective pest management approaches for smallholder farmers, this study aims to delineate their knowledge and current control practices. Thus, the objectives of the current study were to: (1) document methods used by smallholder farmers to store maize; (2) evaluate farmers’ knowledge of storage pests of maize; (3) determine practices used by farmers in managing storage pests of maize.

2. Materials and Methods

2.1. Study Area

The study was conducted in King Sabata Dalindyebo local municipality (KSDM) (31° 38’ 15.8” S, 28° 30’ 30.1” E) under Oliver Reginald Tambo District Municipality (ORTDM) in the Province of Eastern Cape, South Africa. The specific study sites in KSDM were 16 villages (Baziya, Nyibeni, Ndibela, Ngcotyeni, Bityi, Gunjane, Mokolweni, Etafeni, Kukhambi, Kugutya, Manyosini, Chanti, Qunu, Krakra, Noncwenga and Mayenge). According to KSDM annual report [23], The KSDM is the largest from the five local municipalities within ORTDM in terms of surface area, which covers about 302 700 hectares with approximately 520 000 human population. The annual rainfall in the ORTDM varies, but on average, it’s about 900 millimetres per year [24]. Rainfall is usually higher during the summer months, between December and February, while winters are generally drier. Farming systems are diverse with subsistence farming being common among local communities. Additionally, maize, sorghum, beans, and vegetables are among the staple crops grown by smallholder farmers [25].

2.2. Data Collection

The questionnaire survey was conducted from November 2023 to March 2024 to determine farmers’ current knowledge and control practices for maize storage insect pests. Purposive sampling was conducted, where farmers who are willing to participate were selected from 16 villages. The list of the farmers came from Ukhanyo Farmer Development (UFD) and the Department of Rural Development and Agrarian Reform (DRDAR). A semi-structured questionnaire with both open and closed ended questions were administered to 77 smallholder farmers. Prior administering the questionnaire, the purpose of the study was explained to all farmers and written consent obtained. The questionnaire was piloted using 10 farmers to ensure its validity. Information sought includes, (i) farmers socio-demographic profile, (ii) farm characteristics, (iii) purpose of farming maize, and (iv) facilities used to store maize and their knowledge on stored maize pests, and v) control practices used for maize weevils.

2.3. Data Analysis

Questionnaire data were summarized, and descriptive data analysis conducted using frequencies and percentages Microsoft excel 365.

3. Results and Discussion

3.1. Socio-Demographic Characteristics of Farmers

A total of 77 farmers from 16 villages in ORTDM in Eastern Cape Province (ECP) participated in the current study. The results show the majority of the maize farmers were males (71.43%), while the remaining (28.57%) were females (Table 1). This result agrees with other research findings on gender differences in agriculture. For example, Agbugba et al. [26] reported that in Amathole District in ECP from a total of 109 farmers 66.1% were males. Similarly, Kibirige [27] indicated that in Chris Han District in ECP 66% of farmers were males. These findings can be attributed to the fact that most households are headed by men [24]. Additionally, agricultural land is normally allocated to males than females due to sociocultural norms and patriarchal constructs [28].

In terms of age, education and farming experience, the current study found that majority (62.34%) of farmers were elderly people above 56 years, over 90% of them had formal education and 76.62% had 10 years of farming experience (Table 1). Similar findings were reported by Afolayan et al. [29], who found that most farmers in OR Tambo District, Amathole District and Chris Han District in ECP were above 56 years and more than 90% farmers had formal education (primary, secondary and tertiary) with over 10 years of farming experience. These results may be true that farming is practiced by older age group of people in Eastern Cape Province because youth in rural areas are migrating to cities in search of better living and opportunities [30]. On the other hand, the education and farming experience plays a pivotal role for farmers in understanding and adoption of sustainable practices for effective farming performance [31].

3.2. Farm Characteristics

The result of the current study shows that most farmers (70.13%) had 1 hectare (Figure 1) and predominantly used their land for cultivating yellow maize (90.91%) than white maize (3.90%), and only 5.19% cultivated both yellow and white maize. Similar results were reported by Mdoda and Gidi [32], which demonstrates that majority (60%) of smallholder farmers from OR Tambo, Amathole and Chris Hani Districts in ECP, their farm size was ranging from 0.5 to 2.5 hectares and 50.6% of them are growing maize. Moreover, Sibanda et al. [33] reported that the majority (70.8%) of smallholder farmers preferred yellow maize than white maize. This can be attributed to the fact that yellow maize has multipurpose by feeding livestock, poultry and for human consumption, which then make it to have a better market value [33].

3.3. Purpose of Farming

Maize was mainly grown and stored for human consumption, income generating and for feeding livestock by most farmers (57%) (Figure 2). Whereas 3% of the farmers used their maize as livestock feed (Figure 4). These findings concur with the results reported by Nzeyimana and Odularu [34], which shows that 67.8% of farmers use maize for various purposes such as human consumption, livestock feed and generating income. This shows that maize has multifunctional role in agriculture and significantly contribute to household food security [35].

Figure 4. Percentage of farmers and how they use stored maize.

Figure 4. Percentage of farmers and how they use stored maize.

3.4. Facilities Used to Store Maize, Storage Forms of Maize, Farmers’ Knowledge of Storage Pests and Control Practices

A large proportion of farmers (81.82%) in the current study store their maize in metal tanks, followed by those who store maize in sacks in their houses (7.79%) (Table 2). Conversely, Thamaga-Chitja [8] reported about 20 years ago that 52% of farmers in KwaZulu Natal used inqolobane to store maize as opposed to metal tanks and sacks. The results shows that the farmers are progressively moving from the use of traditional storage techniques to modern ones [23]. The reason being the modern techniques for storing maize, such as hermetic bags and metal containers offer noteworthy advantages in reducing postharvest losses, particularly from insect pests [36]. However, they present challenges such as high initial cost and advance knowledge for implementation, as that can impede their adoption by smallholder farmers [37].

The current study found that most farmers (97.40%) stored their maize in shelled form, and the stored maize was mostly infested by maize weevils (89.61%) and maize grain moths (74.03%) (Table 2). These results are in consonance with many other studies. For example, Mendoza et al. [38], stated that 90% of farmers dry their maize and store them in a shelled form. The reason being shelled maize is less liable to spoilage and infestation by pests. The removal of the protective husk lowers the moistness and provides less conducive conditions for microbial growth [39]. In this region, farmers managed maize storage pests mostly through phosphine fumigation in the form of aluminium phosphide tablets (84.42%) (Table 2). Megerssa et al. [40], reported that in Ethiopia, about 58.7% of farmers had insects as their most common pest of stored maize, with maize weevils being the most important followed by maize grain moths. Furthermore, Megerssa et al. [40] observed most farmers (75.3%) use inorganic pesticides like aluminium phosphide compared to traditional practices (17%) like the use botanical biopesticides and cultural practices. Their findings support those reported in this study.

Despite the effective contribution of aluminium phosphide in pest management, its indiscriminate usage has led to acute and chronic harmful effects on humans and the development of resistance by the insect pests [41]. The side effects are likely to affect maize farmers in the Eastern Cape, South Africa. To safeguard aluminium phosphide poisoning, farmers should implement safety measures like participating in training programs and using personal protective equipment (PPE) when using this chemical [42,43]. We intend to start sensitizing maize farmers in this region and propose training workshops to address this danger.

3.6. Conclusion and Recommendations

Subsistence farmers mostly had formal education which helped those adopting recent storage innovations like using metal tanks than traditional silos for storing their maize. Most of them had a farm size of 1 hectare and predominantly cultivated yellow maize. Metal tanks tend to be the most preferred storage facility for storing maize. Even though this method is likely to favour pest infestation, especially the weevils. Several weevil species are known to infest stored maize. Nonetheless, only one weevil species was reported Sitophilus zeamais and a moth Sitotroga cerealella. There is a possibility that other stored maize pests occur in this region but were not detected during the current study. The study found that insect pest control tactics were dominated by chemical pesticides namely aluminium phosphide. Concern for human health-related issues emanating from the use of this pesticide in preserving maize, necessitates an effort to find alternative methods that are safe to supplement this current method.