Fall Armyworm (FAW) (Spodoptera frugiperda) is a polyphagous and highly destructive pest of many crops. It was recently introduced into Africa and now represents a serious threat to food security, particularly because of yield losses in maize, which is the staple food for the majority of small-scale farmers in Africa. The pest has also led to increased production costs, and threatens trade because of quarantines imposed on produce from the affected countries. There is limited specific knowledge on its management among smallholders since it is such a new pest in Africa. Some synthetic insecticides have been shown to be effective in controlling FAW, but in addition to the economic, health and environmental challenges of pesticide use insecticide resistance is highly prevalent owing to years of FAW management in the Americas. Therefore, there is a need for the development and use of alternatives for the management of FAW. These include plant-derived pesticides. Here we review the efficacy and potential of 69 plant species, which have been evaluated against FAW, and identify opportunities for use among small-scale maize farmers with a focus on how pesticidal plants might be adopted in Africa for management of FAW. The biological activities were diverse and included insecticidal, insectistatic (causing increased larval duration), larvicidal, reduced growth and acute toxicity (resulting in adverse effects within a short time after exposure). While most of these studies have been conducted on American plant taxa many South American plants are now cosmopolitan weeds so these studies are relevant to the African context.

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Ageratum conyzoides L. (Asteraceae) is an aromatic, annual herb and cosmopolitan weed commonly known as billygoat weed or goat weed and is typically found in cultivated fields and other disturbed ecosystems. The species has been studied widely owing to its biological properties and its potential application in medicine and agriculture. Due to its importance and use in the treatment of burns and wounds, arthrosis, malaria, asthma, leprosy and dermatitis, its medicinal properties have been reviewed. A. conyzoides, however, also has insecticidal activity against a range of major pests of field crops and stored products including Callosobruchus chinensis L. (Coleoptera: Chrysomelidae), Chilo partellus Swinhoe (Lepidoptera: Crambidae), Sitophilus oryzae L. (Coleoptera: Curculionidae), Panonychus citri McGregor (Tetranychidae, Panonychus), Sitophilus zeamais Motchulsky (Coleoptera: Curculionidae), Plutella xylostella L. (Lepidoptera: Plutellidae) and Brevicoryne brassicae L. (Hemiptera: Aphididae). Evidence suggests that its efficacy is comparable to synthetic pesticides and that it is economically viable too while its impact on beneficial insects including ladybirds, hoverflies and spiders is much reduced compared to synthetics. Anti-microbial activity against important agricultural disease agents is also reviewed here including against Fusarium oxysporum Schltdl., (Hypochreales: Nectriaceae), Phytophthora citrophthora (R.E. Sm. & E.H. Sm.) Leonian, (Phythiales: Phythiaceae), Pythium aphanidermatum (Edson) Fitzp., (Peronosporales: Pythium), Fusarium solani Mart (Sacc.) (Hypochreales: Nectriaceae) and Gibberella zeae (Schwein.) Petch (Fusarium graminearum (Schwabe) (Hypochreales: Nectriaceae). These activities suggest a compelling multipurpose plant that has merit as a potential commercial species. Since earlier reviews have focused on medicinal properties of A. conyzoides and less on its potential value in agriculture, this review seeks to bridge this gaps by reviewing research on the various properties of this species that are relevant to food production. The review presents updated information on the use of this species as an agricultural resource and emphasizes its potential as an industrial crop.

Swiss chard (Beta vulgaris L. var. cicla) is a popular vegetable because it is nutritious, robust, easy to grow. It requires regular applications of nitrogen, which causes accumulation of oxalates and nitrates within the plant. Oxalates and nitrates are known health hazards but the use of organic fertilizers have been shown to reduce their accumulation and to promote accumulation of beneficial phytochemicals. We therefore determined the effect vermicompost (VC), Tithonia diversifolia green manure (Tithonia) and urea on the quality of Swiss chard. The experiment was laid out in a Randomised Complete Block Design (RCBD) replicated three times with thirteen treatments. Leaf nutrient elements, TSS, polyohenols, Vitamin C and antioxidants were determined using standard procedures. Treatment effects were significant only for aluminum, phosphorus and calcium. The values were highest on VC 50 kg N ha-1 and Urea 50 kg N ha-1, Tithonia 50 kg N ha-1 + Urea 50 kg N ha-1, and VC 50 kg N ha-1, and VC 100 kg N ha-1 for aluminum, phosphorus and calcium, respectively. Lowest response was reported on Tithonia 50 kg N ha-1, control and Tithonia 50 kg N ha-1 + Urea 50 kg N ha-1 for aluminum, phosphorus and calcium, respectively. The treatments significantly influenced the percentage of polyphenols, vitamin C and the antioxidant capacity while no significance was reported for total soluble solutes. The polyphenols and vitamin C content were highest on Tithonia 100 kg N ha-1 and control, respectively. Low polyphenol and vitamin C contents were recorded on VC 50 kg N ha-1 and VC 100 kg N ha-1, respectively. A similar trend was observed for antioxidant activity since a positive correlation was observed between the polyphenols and vitamin C and the antioxidant activity. Tithonia green manure improves Swiss chard quality.

AbstractFall armyworm (Spodoptera frugiperda, J.E. Smith) is a pest with devasting effects on maize. A laboratory biassay was conducted to analyse the phytochemicals and determine the efficacy of M. spicata and R. officinalis extracts on FAW. Treatments were laid out in a Completely Randomized Design (CRD) with 3 replications. The factors included solvent [Methanol (Me), dichloromethane (DCM), distilled water (Di)] and the plant species (M. spicata and R. officinalis). Coragen SC 200 (Co) and Distilled water (Di) were the positive and negative controls, respectively. FAW rearing, plant extract preparation and phytochemical screening were done using standard procedure. Data collection and analysis was done using standard procedures. The extract yield was highest for R. officinalis regardless of the solvent used. Me-R. officinalis and Di-M. spicata extracts yielded the highest. Saponins, glycosides, alkaloid, flavonoids and tannins. Flavonoid contents were 7.9036 mg/mL and 6.0073 ± 0.6117 mg/mL in methanolic extract of M. spicata and R. officinalis, respectively. M. spicatha and R. officinalis extracts caused 100% mortality to 3rd instar larvae. Based on the findings, both M. spicata and R. officinalis have several secondary metabolites that confer insecticidal activity of the plants against FAW, hence should be evaluated under field conditions.

The effects of Allium sativum and Allium cepa extracts on the Fall Armyworm and growth of Babycorn (Variety SG 18) under greenhouse conditions were evaluated. Treatments were laid out in a Randomized Complete Block Design (RCBD) with 3 replications. The factors included solvents used: Dichroloromethane (DCM), Methanol (Me), Distilled water (Di) and type of plant used: Allium sativum and Allium cepa. The positive and negative controls were Coragen SC 200 (Co) and distilled water (Di), respectively. Data collection and analysis was done using appropriate procedures. The extraction yield was highest with Methanol for A cepa and distilled water for A sativum, while DCM yielded the least for both plants. Saponins, glycosides, alkaloid and tannins were present in all the plant species, but their presence was influenced by the solvent type. Flavoniods were only present in DCM-A sativum extract whose content was 5.2378 ± 0.1094 mg/mL. DCM and Methanolic extracts of A cepa and A sativum were as effective as Coragen SC 200 against FAW larvae as opposed to distilled water extract. No significant differences were noted for plant height and leaf numbers. Further evaluation should be done towards making commercially available and effective insecticide for integrated FAW management.