Rodents in agriculture and public health in Malawi: Farmers’ knowledge, attitudes, and practices

Given that rodents are responsible for nearly 280 million cases of undernutrition worldwide and that about 400 million people are affected by rodent-associated zoonoses annually, management of rodent populations that are agricultural pests and/or reservoirs of pathogens is a major food security and public health matter. In sub-Saharan Africa, the median crop loss due to rodents is about 16% in the field and around 8% during storage. The impact on public health is not well-established, albeit over 60 zoonotic diseases can be spread to humans via rodents. Therefore, focusing on rodent-related community knowledge, attitudes, and practices is crucial to establishing robust baseline information as a springboard for future targeted studies. The study was conducted in September 2020 in Lilongwe and Nkhata Bay districts in Central and Northern Malawi, respectively. A semi-structured questionnaire, focus group discussions, and interviews with key informants were used. Farmers reported rodents were a major problem for staple crops (maize, rice, and cassava) and the main species responsible were the Natal multimammate mouse (Mastomys natalensis), silver mole-rat (Heliophobius argenteocinereus), and house mouse (Mus musculus domesticus). Awareness of rodent-associated health risks is very low, as exemplified by reports of rodent–human bites, eating rodent-contaminated food, and processing and consumption of wild rodents in poor hygienic conditions, and these practices were flourishing when Malawi was a bubonic plague endemic country. Rodent management is less practiced, and when practiced, it is symptomatic. It is considered a matter of individual households and typically relies on the use of rodenticides and insecticides without proper dosage and user instructions. We recommend rigorous campaigns to create better awareness among the public regarding the impacts of rodents on agriculture and community health and the need for community engagement for effective rodent management. A paradigm shift is needed by adapting and adopting practices of ecologically-based rodent management and reducing dependence on synthetic chemical rodenticides

Bioactivity of common pesticidal plants on fall armyworm larvae (spodoptera frugiperda)

The fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) is a recent invasive pest species that has successfully established across sub‐Saharan Africa where it continues to disrupt agriculture, particularly smallholder cereal production. Management of FAW in its native range in the Americas has led to the development of resistance to many commercial pesticides before its arrival in Africa. Pesticide use may therefore be ineffective for FAW control in Africa, so new and more sustainable approaches to pest management are required that can help reduce the impact of this exotic pest. Pesticidal plants provide an effective and established approach to pest management in African smallholder farming and recent research has shown that their use can be cost‐beneficial and sustainable. In order to optimize the use of botanical extracts for FAW control, we initially screened ten commonly used plant species. In laboratory trials, contact toxicity and feeding bioassays showed differential effects. Some plant species had little to no effect when compared to untreated controls; thus, only the five most promising plant species were selected for more detailed study. In contact toxicity tests, the highest larval mortality was obtained from Nicotiana tabacum (66%) and Lippia javanica (66%). Similarly, in a feeding bioassay L. javanica (62%) and N. tabacum (60%) exhibited high larval mortality at the highest concentration evaluated (10% w/v). Feeding deterrence was evaluated using glass‐fibre discs treated with plant extracts, which showed that Cymbopogon citratus (36%) and Azadirachta indica (20%) were the most potent feeding deterrents among the pesticidal plants evaluated. In a screenhouse experiment where living maize plants infested with fall armyworm larvae were treated with plant extracts, N. tabacum and L. javanica were the most potent species at reducing foliar damage compared to the untreated control whilst the synthetic pesticide chlorpyrifos was the most effective in reducing fall armyworm foliar damage. Further field trial evaluation is recommended, particularly involving smallholder maize fields to assess effectiveness across a range of contexts

Agroecological management of fall armyworm using soil and botanical treatments reduces crop damage and increases maize yield

IntroductionFall armyworm continues to disrupt smallholder farming systems across sub-Saharan Africa, with sporadic outbreaks and chronic cereal crop losses. Smallholders have been adapting to the pest by increasing crop surveillance for targeted control measures and developing low-cost solutions. For example, some report placing soil or ash in maize whorls where the mechanism of pest control may be suffocation, abrasion leading to desiccation, or through the introduction of soil-borne entomopathogens.MethodsTo verify the efficacy of this approach we evaluated different soil types on maize infested with fall armyworm to assess their efficacy. We also evaluated the efficacy of pesticidal plant species, powdered and placed in leaf whorls to control fall armyworm. Results and discussionDifferent United States Department of Agriculture-characterised soil types (sand, loam, clay) and wood ash were effective in reducing the number of larvae and maize leaf damage by approximately 50%. Maize yield with the synthetic control (chlorpyriphos) was 13,700 kg/ha, which was 42% higher than the untreated control (7,900 kg/ha). Soil and ash treatments yields between 10,400 to 12,400 kg/ha were 24-36% higher than the untreated control. Dry soil applied after watering was most effective regardless of soil type. However, wet soil treatments applied before watering were also highly effective in reducing the number of fall armyworm larvae and reducing insect damage to maize leaves. Botanical powders from Azadirachta indica, Nicotiana tabacum, Cymbopogon citratus and Lippia javanica were also effective when applied to maize leaf whorls. Plant powder treatments and water extracts were significantly effective in reducing the number of larvae and leaf damage. The highest yield obtained with botanicals was observed with A. indica powder (5,600 kg/ha), C. citratus extract (5,800 kg/ha) and N. tabacum extract (5,800 kg/ha), where the synthetic treatment yield was 6,900 kg/ha and the untreated yield was 1,700 kg/ha. We conclude that smallholder farmer innovations in managing fall armyworm are effective low-cost options. Scientific validation of soil treatments and botanicals should help increase the confidence of policy makers and allow knowledge extension services to recommend their use to smallholder farmers, which in turn may reduce reliance on imported synthetic pesticides and improve farmer resilience, circular economies and human and environmental health

Sukkerrørproduksjon i Malawi : skadedyr, plantevernmidler og potensial for biologisk kontroll

Sugarcane is an importance source of energy and livelihoods worldwide. The production of sugarcane is significantly affected by several insects, weeds and pathogens commonly referred to as pests. In addition, climate scientists predict that climate change or variability will affect sugarcane production and its associated pests. Chemicals called pesticides, beneficial pathogens and insects called natural enemies or biological control agents are used to control these pests. Little is known about the diversity and richness of both pest and natural enemy species nor the properties of the pesticides used against them in Malawi Few studies indicate that insects such as stemborers and aphids, and weeds are the most common pests; and that their control is heavily dependence on pesticides in Malawi. However, most pesticides are harmful to the environment and improper use may lead to human poisoning. Knowing the main pests and using pesticides that are least harmful to the environment and natural enemies coupled with good crop management practices may contribute to solving this problem. To document pest composition and how they were controlled, a review of literature, questionnaire and farm surveys were conducted in the major sugarcane growing areas of Malawi. The questionnaire survey was administered to 55 farmers and 7 representatives of 1474 farmers. We collected 221 insect samples from 48 sugarcane fields and isolated beneficial fungi from 12 soil and 60 plant samples collected from 12 sugarcane fields in southern Malawi, respectively. The best way to inoculate sugarcane was determined) in a potted experiment conducted using a commercially available formulation of beneficial fungi (Beauveria bassiana strain GHA). We identified the fungi and insects samples to genus and/or species level largely using morphological characteristics. Molecular characterization based on partial sequencing of Bloc gene region in 50 fungal samples and cytochrome oxidase subunit I (COI) gene region in 65 insect samples, respectively, were conducted to support morphological identifications. Separate DNA polymorphism and phylogenetic analyses were performed for the insect and fungal samples. Environmental and human health risks associated with pesticides in use were determined using the environmental impact quotient (EIQ) and World Health Organization (WHO) Classification of Pesticides by hazard. We also explored the likely impact that climate change or variability will have on the type and amount of pesticides used in sugarcane production using Malawi as a case study. The results indicated that weeds and insects infest sugarcane in Malawi. The main insect pests were stemborers (Chilo partellus and Busseola fusca), soil-dwelling insects’ pests (Heteronychus licas and H. arator, Anomala spp.), sugarcane thrips (Fulmekiola serrata), red spider mites (Tetranychus urticae), aphids (Sipha flava) and the fall army worm (Spodoptera frugiperda sp. 1). DNA polymorphism analysis revealed low genetic differentiation among C. partellus and B. fusca populations in Malawi. A total of 16 pesticides were used to manage the pests. These are slightly to moderately hazardous to humans, 50 % are highly toxic to bees and 70% can contaminate the environment. Individuals who sprayed these pesticides had minimal protective wear. As a result, at least 65% had experience skin irritation, headache, coughing and running nose as a result of being exposed to these pesticides. The predicted rise in temperature will reduce the efficacy of less toxic pesticides especially cypermethrin. Leaching of sorbed pesticides through high rainfall intensity and increased frequency of floods. Beneficial fungi in three genera namely Beauveria, Metarhizium and Isaria were identified from soil and sugarcane samples collected from southern Malawi. More isolates (81.7%) were collected from soil than from plants (36.7%). The majority of these isolates (72%) were Beauveria species. Molecular identification and phylogenetic analysis identified the Beauveria isolates as B. bassiana were closely related to B. bassiana AFNEO_1 clade isolated from the coffee berry borer, Hypothenemus hampei in coffee fields of South America and in Africa. However, the Malawian B. bassiana clearly clustered in a separate clade. This is the first report of B. bassiana occurring as an endophytes of sugarcane; and B. bassiana, Metarhizium and Isaria species occurrence in agricultural fields in Malawi. Results from the sugarcane inoculation experiment showed that B. bassiana could be effectively inoculated in sugarcane using foliar and soil sprays, and stem injections. Stem injections were highly effective (75%) compared to foliar sprays (43%) and soil sprays (25%) plants inoculated, respectively. The inoculated B. bassiana was recovered in both old and new leaves and stem tissue, even though the recovery rate decreased with time. However, plants that had got stem injections were much shorter that plants that had foliar and soil inoculation, and control plants. The results especially those on natural occurrence of beneficial fungi particularly B. bassiana and Metarhizium spp. will be useful in the control of not only of pests in sugarcane but also in several crops mainly vegetables.Sukkerrør er en viktig kilde til energi og som levebrød over hele verden. Produksjonen av sukkerrør er betydelig påvirket av insekter, ugras og plantesykdommer ofte betegnet som skadegjørere. I tillegg forutsetter klimaforskere at klimaendringer eller variasjon i klima vil påvirke sukkerrørsproduksjonen og tilhørende skadegjørere. Kjemiske plantevernmidler og biologiske kontrollmetoder brukes til å kontrollere disse skadegjørerne. I Malawi kjenner vi lite til forekomst og diversitet av skade- og nytteorganismer i sukkerrørproduksjonen eller til egenskapene til plantevernmidlene som brukes. Tidligere studier tyder på at ulike sommerfugllarver, bladlus og ulike ugrasarter er blant de vanligste skadeorganismene og at kontroll er sterkt avhengighet av plantevernmidler. Plantevernmidler kan imidlertid være skadelige for helse og miljø. Å kjenne de viktigste skadegjørerne og bruke plantevernmidler som er minst mulig skadelige for miljøet og nytteorganismer kombinert med god agronomi, kan bidra til å løse dette problemet.Capacity Building for Climate Change Adaptation in Malawi (CABMACC) project number 1207026003. CABMACC is a collaborative project supported by the Norwegian Government and the Government of the Republic of Malawi implemented by International Environment and Development Studies (Noragric) of Norwegian University of Life Sciences (NMBU) and Lilongwe University of Agriculture and Natural Resources, (LUANAR), Malawi

Determination of Genetic Diversity in Chilo partellus, Busseola fusca, and Spodoptera frugiperda Infesting Sugarcane in Southern Malawi Using DNA Barcodes

publishedVersio

Natural Occurrence of Entomopathogenic Fungi as Endophytes of Sugarcane (Saccharum officinarum) and in Soil of Sugarcane Fields

Simple Summary Sugarcane, an important cash crop in Malawi, is susceptible to numerous insect pests, and many farmers rely heavily on chemical insecticides for their control. Biopesticides containing insect pathogens are used in several countries outside Malawi; however, the occurrence and use of insect pathogens is limited in Malawi. In this study, we evaluated the natural occurrence of insect pathogenic fungi in sugarcane (Saccharum officinarum) and in soil samples from sugarcane fields in Chikwawa District, southern Malawi. Insect pathogenic fungi from soil were isolated by baiting using larvae of the greater wax moth (Galleria mellonella). Insect pathogenic fungi were also isolated from surface-sterilized sugarcane leaves, stems, and roots. We found three types of insect pathogenic fungi: Beauveria bassiana, Metarhizium spp., and Isaria spp. Beauveria bassiana and Isaria spp. were found mostly from sugarcane leaves and stems, while Metarhizium spp. was mainly found in soils. To the best of our knowledge, this is the first report of B. bassiana and Isaria spp. occurring naturally as endophytes in sugarcane. Further, it is the first report of B. bassiana, Isaria spp. and Metarhizium spp. in the soil of sugarcane fields in Africa. Abstract The natural occurrence of entomopathogenic fungal endophytes in sugarcane (Saccharum officinarum) and in soil samples from sugarcane fields was evaluated in Chikwawa District, southern Malawi. Fungi from soil were isolated by baiting using Galleria mellonella larva. Fungal endophytes were isolated from surface-sterilized plant tissue sections. Forty-seven isolates resembled the genus Beauveria, 9 isolates were Metarhizium, and 20 isolates were Isaria. There was no significant difference in the number and type of fungal isolates collected from soil and from plant tissue. There was, however, a significant difference in the part of the plant where fungal species were isolated, which fungal species were isolated, and the number of fungal species isolated at each location. Phylogenetic analysis of 47 Beauveria isolates based on DNA sequencing of the Bloc intergenic region indicated that these isolates all belonged to B. bassiana and aligned with sequences of B. bassiana isolates of African and Neotropical origin. The Malawian B. bassiana isolates formed a distinct clade. No larvae died from infestation by multiple fungi. To the best of our knowledge, this is the first report of B. bassiana and Isaria spp. occurring naturally as endophytes in sugarcane. Further, it is the first report of B. bassiana, Isaria spp., and Metarhizium spp. in the soil of sugarcane fields in Africa

Rhachiella Aspöck & Aspöck & Johnson & Donga & Duelli 2020, gen. nov.

Genus Rhachiella gen. nov. Type species (by present designation): Rhachiella malawica spec. nov. Diagnosis. Head with flat vertex, slightly inflated genae, scape twice as long as broad. Pronotum approximately rectangular. Apices of wings rounded. Radius and Media free to wing base. Male with penisfilum; female with pseudohypocaudae having two apical processes. Description: With the characters of the type species. Systematics: Rhachiella gen. nov. is the sister-group of Mucroberotha with the long penisfilum of the males as a synapomorphy. Rhachiberotha + (Mucroberotha + Rhachiella gen. nov.) constitute the sister-group of Hoel- zeliella.Published as part of Aspöck, Ulrike, Aspöck, Horst, Johnson, James B., Donga, Trust Kasambala & Duelli, Peter, 2020, Rhachiella malawica gen. nov., spec. nov. from Malawi-another beauty of the Afrotropics (Neuroptera: Rhachiberothidae), pp. 131-140 in Zootaxa 4808 (1) on page 132, DOI: 10.11646/zootaxa.4808.1.7, http://zenodo.org/record/392799

Rhachiella malawica Aspöck & Aspöck & Johnson & Donga & Duelli 2020, spec. nov.

<i>Rhachiella malawica</i> spec. nov. <p> <b>Holotype:</b> male, Malawi, Southern Province, Lake Zomba, 1458m, -015°21’37” / +035°18’32”, 17-XI- 2018 JB Johnson, P. Duelli, T. Donga leg.</p> <p> <b>Type locality:</b> Malawi, Lake Zomba.</p> <p>General appearance (Figs 1, 2, 3) with the typical rhachiberothid look, hairiness, bright yellowish habitus, with only basal parts of antennae dark brown; pterostigma of male brownish, with a yellowish patch in the centre, however yellowish with a brownish patch in the centre in the female.</p> <p>Length of forewing of males 6.5–6.7 mm, of females 6.8–7.2 mm.</p> <p>Description of male (Figs 2–4): Head flat, yellow, with paired brown stripes on the vertex, laterally brownish; frons yellow with brown spot, base of clypeus dark brown, genae slightly inflated; scape twice as long as broad, scape, pedicellus and first segment of flagellum dark brown, rest of flagellum yellow. Mouthparts dark brown. Pronotum brownish, with two pairs of brownish tubercles. Meso- and metanotum with a yellow median fascia, and with a median brown line. Meso- and metanotum brown, mesonotum with yellowish patches laterally.</p> <p>Femora of raptorial forelegs with two rows of brown, comb-like thorns (Fig. 3).</p> <p>Forewing (Figs 2, 4): Radius and Media free to wing base. Pterostigma brownish, with a yellow patch. Wing membrane hyaline with light smoky shadows around cross veins and forkings. Venation: longitudinal veins yellowish, cross-veins brownish. Hindwing: Basal Media anterior sinuate. Pterostigma brownish, much smaller than in forewing.</p> <p>Abdomen: Tergites yellow, with median brown line, pleurae yellow with brownish zig-zag line, sternites whitish-yellowish.</p> <p>Genital segments of male (Figs 5–6): Tergite and sternite of segment 8 much shorter than the previous ones, with distinct spiraculum, tergite 9 ribbon-like with a small ridge. Sternite 9 inconspicuous, short, with deep incision. Ectoproct with distinct trichobothria rosette, apex broad finger-shaped, sculptured. Gonocoxites 9+11 extremely reduced to a tiny weakly sclerotized structure. Gonocoxites 10 paired basally, fused with the unpaired gonapophyses 10, terminating in a long penisfilum. Hypandrium internum of typical shape.</p> <p>Description of female (Figs 1, 7): Eidonomic characters similar to those of the male. Pterostigma yellowish with brownish patch in the centre, however less contrasting than in the male.</p> <p>Genital segments of female (Figs 8–10): Sternite 7 reduced to a small band-like sclerite. Pseudohypocaudae with two apical digitiform processes. Gonocoxites 9 with short apex (hypocaudae).</p> <p>Bursa copulatrix connected by a long ductus with receptaculum seminis, which comprises a complex system of ducts.</p> <p> <i>Rhachiella malawica</i> <b>spec. nov.</b> is differentiated from all known species of <i>Rhachiberotha</i> by the lack of tubercles on the head, by possession of a <i>penisfilum</i> in the male (lacking in <i>Rhachiberotha</i>), and by <i>pseudohypocaudae</i> with two processes (only a simple apex in <i>Rhachiberotha</i>).</p> <p> <i>Rhachiella malawica</i> <b>spec. nov.</b> is differentiated from all known species of <i>Mucroberotha</i> by a flat head (domed in <i>Mucroberotha)</i>, by Radius and Media of forewing free to wing base (fused in <i>Mucroberotha).</i></p> <p> <i>Rhachiella malawica</i> <b>spec. nov.</b> is differentiated from <i>Hoelzeliella</i> by the rounded apex of the forewing (slightly sinuate in <i>Hoelzeliella).</i></p> <p> <b>Etymology:</b> <i>Rhachiella</i> is derived from <i>Rhachiberotha</i>. It has feminine gender; <i>malawica</i> is an adjective derived from the country where the species has been discovered.</p> <p> <b>Material studied:</b> Holotype, male, and 4 males, and 4 females, paratypes: Malawi, Southern Region, Lake Zomba, 1458m, -015°21’37” / +035°18’32”, 17 Nov 2018, J.B. Johnson, P. Duelli, T. Donga leg. Holotype, and 1 female in MM, 1 male and 1 female in WFBEMI, 2 males and 1 female in NHMW, 1 male and 1 female in HUAC.</p> <p> The specimens were taken 30 m from the lake shore of the Zomba-dam, mainly on trees at the edge of natural vegetation, while most other trees along the shore were ornamentals. It was noteworthy that the times of the collections occurred between mid-afternoon and early evening, mostly 3-5 PM local time. Trees that had not yielded specimens of <i>R. malawica</i> earlier in the day did yield specimens when revisited during this time period.</p> <p>1 male paratype (MM): Malawi, Southern Region, Zomba, Forest path near Sunbird Hotel, 1521m, -015°21’55” / +035°18’5”, 16 Nov 2018, JB Johnson, P. Duelli, T. Donga leg., collected on a bush along a path on a steep slope. Rain forest, natural vegetation (Fig. 11).</p> <p> <i>Rhachiella malawica</i> <b>spec. nov.</b> is known from the region of Zomba in Malawi only and thus in the centre of the hitherto known distribution of Rhachiberothidae (Figs 12 –14).</p>Published as part of <i>Aspöck, Ulrike, Aspöck, Horst, Johnson, James B., Donga, Trust Kasambala & Duelli, Peter, 2020, Rhachiella malawica gen. nov., spec. nov. from Malawi-another beauty of the Afrotropics (Neuroptera: Rhachiberothidae), pp. 131-140 in Zootaxa 4808 (1)</i> on pages 132-136, DOI: 10.11646/zootaxa.4808.1.7, <a href="http://zenodo.org/record/3927992">http://zenodo.org/record/3927992</a&gt

Rhachiella malawica gen. nov., spec. nov. from Malawi-another beauty of the Afrotropics (Neuroptera: Rhachiberothidae)

Aspöck, Ulrike, Aspöck, Horst, Johnson, James B., Donga, Trust Kasambala, Duelli, Peter (2020): Rhachiella malawica gen. nov., spec. nov. from Malawi-another beauty of the Afrotropics (Neuroptera: Rhachiberothidae). Zootaxa 4808 (1): 131-140, DOI: 10.11646/zootaxa.4808.1.