Fall armyworm (Spodoptera frugiperda), a highly destructive and fast spreading agricultural pest native to North and South America, poses a real threat to global food security In this paper, to explore the dynamics and implications of fall armyworm outbreak in a field of maize biomass, we propose a new dynamical system for maize biomass and fall armyworm interaction via Caputo fractional-order operator, which is not only a nonlocal operator but also contains all characteristics concerned with memory of the dynamical system We define the basic reproduction number, which represents the average number of newborns produced by one individual female moth during its life span We establish that the basic reproduction number is a threshold quantity, which determines persistence and extinction of the pest Finally, we simulate the Caputo system using the Adam–Bashforth–Moulton method to illustrate the main results

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A mathematical model for fall armyworm management on maize biomass

The rhizospheric transformation and bioavailability of mercury in pepper plants are influenced by selected Chinese soil types

Increasing outbreaks of virus species infecting pepper (Capsicum spp.) is a major problem for growers in Africa due to a combination of factors, including expansion of pepper cultivation, abundance of insect vectors and climate change. More than 45 viruses have been identified to infect pepper crops causing economic loss in terms of reduced quality and marketable yield, sometimes up to 100%. The Pepper veinal mottle virus (PVMV), Potato virus Y (PVY) and Cucumber mosaic virus (CMV) are endemic in many countries including Uganda, Mali, Cameroon, Morocco and Nigeria. Current management options for virus infection in Capsicum spp. is by the integration of several approaches. More importantly, eradication of infected plants, cultivation of disease resistant varieties, improved cultural practices and judicious use of insecticides especially when plants are young and easily colonized by vectors. In recent years, eco-friendly control measures are needful to reduce occurrence of virus diseases in Capsicum spp.

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Management of Viruses and Viral Diseases of Pepper ( Capsicum spp.) in Africa

The fall armyworm (FAW, Spodoptera frugiperda) is a major crop pest in southern Africa. It threatens the livelihoods and food security of smallholder farmers in the region by negatively impacting maize yield. Although scientific evidence suggests that natural enemy-mediated predation can potentially reduce FAW infestation, the effectiveness of natural enemies such as birds, bats, parasitoids, and generalist predators on FAW is poorly understood. This study reviews existing literature to assess how birds, bats, parasitoids, and generalist predators’ control FAW infestation, as well as the role of forest or tree cover in natural enemy mediated pest control of FAW in maize in southern Africa. We then present a case study to examine the role of forest proximity in reducing FAW infestation in maize in Zimbabwe. We conclude that birds, bats, parasitoids, and generalist predators are likely drivers of the reduced success of FAW near forests in southern Africa. While predators influence FAW survival and development, their role is largely undermined by parasitoids, which are more efficient in affecting FAW populations. Birds, bats, parasitoids, and generalist predators play an important role in controlling FAW on farms in heterogenous landscapes with diverse vegetation and near-forest proximity. The findings of our case study from Zimbabwe suggest that the distance to forest had a much higher impact on FAW incidence than maize variety, planting date, or the rate of nitrogen applied. Lack of enough case studies from maize in southern Africa makes it challenging to assess the mechanism and the effectiveness of bird predation on FAW. For this reason, further research is necessary to examine how predation by birds, bats and arthropods and parasitism impacts maize yield. We discuss research barriers, recommend appropriate methods for experimental studies, and suggest possible management options to control FAW in southern Africa.

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Forest Proximity Positively Affects Natural Enemy Mediated Control of Fall Armyworm in Southern Africa

Globally, maize is an important cereal food crop with the highest production and productivity. Among the biotic constraints that limit the productivity of maize, the recent invasion of fall armyworm (FAW) in India is a concern. The first line of strategy available for FAW management is to evaluate and exploit resistant genotypes for inclusion in an IPM schedule. Screening for resistant maize genotypes against FAW is in its infancy in India, considering its recent occurrence in the country. The present work attempts to optimize screening techniques suited to Indian conditions, which involve the description of leaf damage rating (LDR) by comparing injury levels among maize genotypes and to validate the result obtained from the optimized screening technique by identification of lines potentially resistant to FAW under artificial infestation. Exposure to 20 neonate FAW larvae at the V5 phenological stage coupled with the adoption of LDR on a 1–9 scale aided in preliminary characterize maize genotypes as potentially resistant, moderately resistant, and susceptible. The LDR varies with genotype, neonate counts, and days after infestation. The genotypes, viz., DMRE 63, DML-163-1, CML 71, CML 141, CML 337, CML 346, and wild ancestor Zea mays ssp. parviglumis recorded lower LDR ratings against FAW and can be exploited for resistance breeding in maize.

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Leaf Damage Based Phenotyping Technique and Its Validation Against Fall Armyworm, Spodoptera frugiperda (J. E. Smith), in Maize

Pepper (Capsicum spp.) is an important vegetable crop in the Eastern Africa region where it is grown mainly by small-scale farmers. However, productivity of the crop is limited by many abiotic and biotic constraints. The abiotic constraints include high cost of seeds and inputs, shortage of improved varieties, drought, low soil fertility and lack of technical knowhow among others, while biotic constraints are dominated by diseases and insect pests. Numerous diseases especially those that are caused by viruses pose serious threats in pepper production. Currently, over 68 viruses are known to affect pepper on a worldwide scale and have serious impact on the quantity and quality of pepper produced. Out of the 68 viruses, 12 belonging to seven genera namely Potyvirus, Cucumovirus, Tobamovirus, Polerovirus, Tospovirus, Alfamovirus and Potexvirus have been reported in Eastern Africa. Pepper veinal mottle virus, Potato virus Y and Cucumber mosaic virus are the most widespread and damaging viruses in the region. Yield losses ranging from 10 to 100% in pepper production have been reported for various viruses namely; Pepper veinal mottle virus, Potato virus Y, Chilli veinal mottle virus, Ethiopian pepper mottle virus, Cucumber mosaic virus, Pepper mild mottle virus, Tobacco mosaic virus, Pepper vein yellows virus, Tomato spotted wilt virus, Alfaalfa mosaic virus and Potato virus X. This article provides an overview of the important pepper viruses occurring in Eastern Africa with reference to their geographic distribution, yield-losses, symptoms, transimission, management methods and research gaps that need to be addressed. It can be concluded that viruses are a major constraint to pepper production in the target region.

Diversity and economic importance of viral diseases of pepper (Capsicum spp.) in Eastern Africa

Agriculture is the major economic activity of the people of Rwanda, providing employment to about 86% of total population and contributing up to 47% of domestic goods and exports. Actual threats include outbreak of a new invasive insect pest, the fall armyworm Spodoptera frugiperda. In this review we describe the fall armyworm outbreak in African countries, particularly in Rwanda. An overview is given on available control options, management of the fall armyworm outbreak, and its implications in Rwanda. The information gathered will assist in controlling fall armyworm in newly invaded regions.

Outbreak of Fall Armyworm ( Spodoptera frugiperda ) and Its Impact in Rwanda Agriculture Production

Effect of border crops and intercropping on aphid infestation and the associated viral diseases in hot pepper (Capsicum sp.)

Accurate diagnosis is a prerequisite to effective management of plant diseases especially those whose symptoms are not very specific. A survey was conducted from February to March 2018 to detect the presence and determine the distribution of six viruses infecting pepper in Rwanda. A total of 225 symptomatic samples were collected from high, mid and low-altitude zones, and analysed using serology assay with antibodies to cucumber mosaic virus (CMV), potato virus Y (PVY), pepper veinal mottle virus (PVMV), pepper mild mottle virus (PMMoV) and tobacco mosaic virus (TMV). Polymerase chain reaction was used to confirm the results from serology and to test for the presence of pepper vein yellows virus (PeVYV), which has no commercial antibodies. Amplified DNA fragments were sequenced and compared with other known pepper viruses available in the GenBank database. Seventy-three percent of the samples tested positive for at least one of the viruses. CMV, PVY, PVMV, TMV and PMMoV were detected in all zones but PeVYV was detected in the mid and low-altitude areas. CMV was the most widespread and was detected in 48% of the samples, followed by PVMV and PVY in 23.6% and 18.2%, respectively. There were both single (36%) and mixed (34.6%) infections of the viruses. Sequence and phylogenetic analysis confirmed the presence of CMV, PeVYV, PVMV and TMV in the country. This is the first report of TMV, PMMoV and PVY infecting pepper in Rwanda. Efforts towards the development of sustainable management for these viruses should be put in place to improve yields and quality of hot pepper.

Bancy Waithira Waweru

Papers

Diversity and economic importance of viral diseases of pepper (Capsicum spp.) in Eastern Africa

Outbreak of Fall Armyworm ( Spodoptera frugiperda ) and Its Impact in Rwanda Agriculture Production

Effect of border crops and intercropping on aphid infestation and the associated viral diseases in hot pepper (Capsicum sp.)

Detection and distribution of viruses infecting hot pepper (Capsicum spp.) in Rwanda

Farmers' knowledge and perceptions of virus diseases affecting hot pepper and their management in Rwanda