The current food security crisis has led to vigorous debate on how best to feed the growing global population. It has been reported that the maize weevil contributes up to 40% of total production in food–grain losses during storage, mainly in developing countries. The Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) maize weevil is one of the most significant pests of stored grains and is mostly accountable for maize damage [1]. In 48 days, 18.3% of losses are predicted to result from an average of two insects per grain [2]. In addition, the significant grain damage may lead to the reduction in nutritional quality, weight, and germination rates of seeds, and it may also affect human health. Insects can also transmit pathogenic fungi, including Aspergillus flavus, which has a link to several types of bacteria. Larvae and adults are responsible for most of the damage to the grains, and 50% of the eggs can be laid within the first 5 weeks of an adult’s life [3]. The female drills the grain in order to create tiny, chewed chambers for oviposition, which are then sealed by a secretion, protecting the creature so that it can continue its life cycle there. Consequently, the majority of solutions emphasize adult control [2]. Ecological and occurrence data have shown that maize weevil thrives in regions of the world that are warm and tropical, particularly in those where maize is grown [4]. Moreover, the maize weevil is shipped in grain shipments to every country in the world, and it can infect food where grain moisture and temperature are favourable. There is also a growing concern regarding the development of resistance in numerous stored product insects, including the maize weevil, in grain stores and flour mills as well as in the food industry ^[5][6][5,6]. In South Africa, maize is used in livestock feed, and a significant portion of the country’s households depend on it. The United States is the biggest producer of maize in the world with 2000 million tons per annum, followed by China with 717 million tons per annum [7]. In Africa, South Africa is the biggest producer of maize with an annual production of approximately 10 million tons, although it can vary depending on the rainfall. Furthermore, maize is used industrially to manufacture an array of products, and it is traded both locally and internationally for financial gain and economic growth [8].

Severe food insecurity at the global level has been rising in recent years, mainly in Africa and Latin America [9]. However, as these grains are collected, stored, processed, and marketed to customers, 10–30% of these significant cereal crops, such as maize, are lost to insect pests after harvest. Although this process can be effectively controlled by synthetic chemical pesticides [10], the majority of farmers in Africa are resource poor and have neither the means nor the skills to obtain and handle pesticides appropriately [5]. The prohibitive costs of commercial synthetics, the increasing development of insect resistance to pesticides, toxicity concerns, and an often erratic supply of pesticides have given impetus to the search for alternative insect control measures [11]. About 80% of pesticides that are used lead to water contamination, thus affecting animals, farmers, and consumers of agricultural products, and putting them at risk of serious health problems. A body of evidence has shown that farmers exposed to inorganic pesticides by spraying crops on a regular basis have developed many health problems, some of which are fatal ^[12][13][12,13].

In view of the above, it is essential to develop more eco-friendly, greener, and sustainable alternative pest management strategies. Medicinal plants have been the focal point of eco-friendly and sustainable research investigations. Despite this, research on medicinal plants as a pest control substitute is in short supply, and so is knowledge about this possibility.

2. Host Plants and Feeding

Based on the knowledge ^[14][15][16][14,15,16], the maize weevil is well known to consume and infect a wide range of hosts including maize, wheat, rice, sorghum ^[17][18][17,18], oats, rye, cottonseed, buckwheat, peas, and barley [19]. Although it has been observed that maize weevils prefer whole grains, they also feed on pet food, pasta, other processed grains, and even fruits ^[20][21][20,21]. In view of this [22], it can be concluded that maize weevil pests infect biscuit crops and non-cereals crops, such as yam and cassava chips as well as other host plants. Both adults and larvae are capable of surviving on a variety of grain-based foods. Furthermore, it was reported in North America that maize weevils feed on stored grain and on fruits such as peach or apple, and that they inhabit forests or grasslands in southern Japan, where they feed on flowers in the spring [23]. In general, the maize weevil’s success depends on its capacity to find and recognize an appropriate host species, access s plant’s fitness, and efficiently use the resources of the plant [23]. Food materials that contain more than 10% water are more likely to favour Sitophilus species population dynamics [24]. By reducing their components, the maize weevil has an impact on processed food materials and the nutritional content of the food materials [25]. This makes sense, since the maize weevil is found in warm, humid regions all over the world, particularly where maize is grown [26]. Grain quantity has an impact on the biology of Sitophilus zeamais, including oviposition, distribution of eggs, adult emergence, body weight, and sex ratio. In general, the maize weevil can infest grains prior to harvest ^[27][28][27,28]. Crop damage occurs in various stages in the life cycle of the maize weevil. When the female weevil penetrates, a single egg is laid inside the grain’s kernel, resulting in damage to the grain [29]. The egg is then shielded by a waxy secretion that seals the hole and hardens. When the larva hatches, it eats the grain’s pulp. The embryonic stages grow inside the grain, protecting them from pesticide contact, hence the fact that chemical treatment of this pest is only effective against the adult weevil [30]. Meanwhile, the maize weevil is causing serious economic losses as well as crop weight loss, quality loss, and disease transmission through fungal growth. It can even destroy grains that have been stored in all types of storage facilities by increasing the amount of free fatty acids [31]. The establishment of secondary and mite pests and pathogens may be aided by the invasion of this primary colonizer. As an invader, the maize weevil enters packages through openings that have already been made due to subpar seals, openings made by other insects, or mechanical damage [32]. Maize is a global industrial raw material and is also utilized in various manufacturing products such as producing alcohol (breweries) ^[33][34][35][33,34,35]. The main tool in the battle against weevil infestation in maize is currently conventional synthetic pesticide [1]. In most cases, pesticides are applied to the grain when it is placed into silos or as a surface treatment after storage in order to control the problem [36]. However, a body of evidence has shown that the current pesticides are ineffective against resistant pests. In addition, there is a great concern regarding the negative impact to the environment with respect to hazards, and the science community is similarly unsettled about the severe side effects on non-target organisms as well as the extravagant price tag [37]. Several reports have shown that the maize weevil affected maize in Southern and Eastern Africa, Central America, and Mexico ^[17][38][17,38]. In addition, the maize weevil has been found in a variety of crops, such as wheat in India, Australia, most of Europe, Northern Asia, and Northern Africa [39], as well as rice in China [40]. The loss of sorghum and oats were reported, too, in South Asia and Sub-Saharan Africa [41] and in Central Europe, respectively [42]. Europe described having barley losses, as well, due to the maize weevil [43]. The maize weevil thus affects a broad spectrum of host crops across the world.