Transcription
Integrated Pest Management manual forFall armyworm, stemborers and Strigain MaizeAuthors: Paul-Andre Calatayud, Subramanian Sevgan, Beritah Mutune,Rachel Owino, Vicky Koech, Belinda Weya, Henri Tonnang, Saliou NiassyISBN: 978-9966-063-50-2
Table of ContentsAbout SCLAMP-EA project3Purpose of manual4Objective of manual4Abbreviations5Introduction6Fall armyworm7Stemborers10Striga14Integrated pest management16Summary of Maize IPM technologies27References37Annexe 1: Farmers’ guide on how to establish a Push-pull plot41Annexe 2: Technology profile template for Maize IPM45Contacts of input providers472Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize
About SCLAMP-EA projectScaling-up Climate-Smart Pest Management Approaches for Enhanced Maize and TomatoSystems Productivity in Eastern Africa (SCLAMP-EA) is a project funded by GIZ (GermanCorporation for International Cooperation). It is a 3-year project, running from 2020 to 2022.The purpose of the project is to facilitate the large-scale adoption of proven and piloted ClimateSmart Pest Management (CSPM) technologies and practices by smallholder farmers to improvetheir food and nutrition security through mitigating yield losses due to key insect pests in maizeand tomato.The projects’ target areas are: Ethiopia (Southern/SNNPR in Dawuro, Angacha and Shebedino; Northern/Amhara in SouthWollo and Western Oromia Region in Sasiga and Diga); and Uganda (Central Uganda in Rakai and Kyotera; Eastern Uganda in Kamuli, Namutumba,Mbale and Kween; and Northern Uganda in Amuru, Nwoya, Adjumani and Pakwach/Southern West Nile).Map showing project areas in Ethiopia (L) and Uganda (R).Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize3
Purpose of manualTo present Integrated Pest Management (IPM) practices that are recommended to beimplemented by maize growers. These IPM practices will reduce damage caused by Fallarmyworm, maize stemborers and Striga, increase maize yield, protect the environment, andsafeguard human health – through reduced use of synthetic chemicals.This manual describes Fall armyworm, maize stemborers and Striga, symptoms of damage andavailable management options.Objective of manualTo strengthen the practice of IPM for Fall armyworm, maize stemborers and Striga in Ugandaand Ethiopia. The challenge currently being faced by farmers and extension officers is the lack ofadequate information on available IPM practices. Consequently, there is a low adoption rate of IPMpractices and over reliance on synthetic chemicals for pest and disease control.4Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize
AbbreviationsAEZAgro-ecological zoneCABICentre for Agriculture and Bioscience InternationalcmCentimetreCSPMClimate Smart Pest ManagementEILEconomic Injury LevelFAOFood and Agriculture OrganizationFAWFall armywormgGramGAPGood Agricultural PracticesGIZGerman Corporation for International CooperationicipeInternational Centre of Insect Physiology and EcologyIPMIntegrated Pest ManagementkgKilogramPPTPush-pull TechnologySCLAMP-EAScaling-up Climate-Smart Pest Management Approaches for Enhanced Maizeand Tomato Systems Productivity in Eastern AfricaToTTraining of TrainersUSDUnited States DollarIntegrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize5
IntroductionMaize is the main staple food crop grown in Africa, and it is estimated that approximately 208million people on the African continent depend on maize as a staple food. The average maizeyield in sub-Saharan Africa is very low, less than 1 ton per hectare, due to many abiotic and bioticconstraints. Among the biotic constraints, insect pests and weeds are the most important pestsof maize. Stemborers such as Busseola fusca (African maize stalkborer), Sesamia calamistis(African pink stemborer) and Chilo partellus (spotted stemborer) used to be considered the mostimportant pests of maize in Africa. The Fall Armyworm (FAW), Spodoptera frugiperda, whichinvaded Africa in 2016, is now considered as the leading insect pest of maize and a threat tofood security.Striga or ‘witchweed’ is a parasitic weed that affects cereal crops in most parts of Africa.Stemborers, FAW and Striga weed are the three most destructive pests of cereal crops and canreduce yields of maize and sorghum on smallholder farms. These pests can cause yield losses of30% to 100% if they are uncontrolled. Control of stemborers or FAW by insecticides and controlof Striga weeds by herbicides is expensive for resource-poor farmers and is also harmful to theenvironment.Integrated Pest Management (IPM) is an approach to crop production and protection thatcombines different management practices to grow healthy crops and minimize the use ofsynthetic pesticides. IPM emphasizes the growth of a healthy crop with the least possibledisruption to the ecosystems. The best way to control both pests and diseases is to keep plantshealthy (Table 1).Table 1: Good agricultural practicesBuild healthy soil that provides a home to friendly insects and provide crops with adequate nutrients.Ensure that soil moisture is adequate to prevent moisture stress.Use resistant varieties. Plant seeds which are resistant to common pests and diseases.Use recommended spacing for each crop. Planting crops too close together limits the sunshine and airthat reaches the leaves, and allows diseases to thrive. But planting crops farther apart leaves room forweeds, dries the soil and may reduce the harvest.Plant at the right times. Planting with the first rains can make crops benefit from nitrogen rush, and thecrops will be mature enough to resist pests or diseases that come at a certain time.Ensure crop diversity through intercropping, and practise agro-forestry. Large areas with only one kindof plant attract pests.6Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize
Fall armywormFall armyworm (Spodoptera frugiperda), FAW, is an insect pest of American origin. It is a heavyfeeder which derives its name from its feeding habit. Once an ‘army’ of FAW infests an area, theyeat almost everything in the area, before moving to the next available food source.FAW feeds on more than 80 varieties of crops, including maize, sorghum, rice, millet, wheat,sugarcane and vegetables, but primarily affects maize.Fall armyworm life cycleEGGPUPALAR VAADULTFigure 1: FAW life cycleFall armyworm is a fertile insect, laying up to 2,000 eggs in a lifetime. Adult females lay eggs in batchesof 100 to 200 on the underside of leaves. The female also deposits a layer of greyish scales betweeneggs and over egg mass, giving FAW eggs a hairy or mouldy appearance. Eggs hatch into larvae in 3 to5 days, and after hatching, larvae migrate to the whorl. The destructive larval stage takes 14 to 28 days,after which the pest falls to the soil for pupation. The pupation process takes place in 7 to 14 days. Anadult moth emerges from the pupa and begins to lay eggs after 3 to 4 days (Figure 1).Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize7
Distribution of FAWFAW has rapidly spread to andthroughout Africa since 2016(Figure 2).2016201720182019Figure 2: FAW distribution in AfricaMeans of dispersal for FAWFall armyworm neonates spin a silk thread that they use to balloon away from the egg mass tonearby host plants. Larvae crawl from one host plant to another. Adult moths can fly over 30 to200 kilometres a day, assisted by the wind.Damage by FAWThe young larvae feed where eggs were laid; the first two instars feed on young leaves, causinga characteristic skeletonizing or ‘windowing’ effect (Figure 3). Older larval instars feed near thefunnel and upper leaves, causing large holes, and leaving sawdust-like excreta (frass). Badlyinfested fields may look as if they have been hit by a severe hailstorm. In a young crop, FAWfeeding can kill the growing point, causing dead heart in maize, which prevents any cobsforming. Fall armyworm can also destroy silks and developing tassels, thereby limiting fertilizationof the ear. Maize plants may have the cobs attacked by larvae boring through the cob (Figure4). Damage to cobs may lead to fungal infection, aflatoxins and loss of grain quality. At highdensities, large larvae may act as armyworms and disperse in swarms, but they often remain inthe locality on wild grasses, if available.8Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize
Figure 3: Windowing on maize leavesFigure 4: FAW larva on maize cobDifference between stemborer damage and FAW damageWhen the stemborer larvae are growing, they start to feed inside the maize stems (A), causingdead-heart (B) if the maize plant is young, or visible holes (C) along the stem on older maizeplants, as shown in Figure 5.ABCFigure 5: Stemborer larva in stem (A), damage caused by stemborer, dead heart (B), and holes on the stem (C)Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize9
In contrast, FAW larvae feed only on leaves and not inside the maize stems, causing large ragged holes,as shown in Figure 6.Figure 6: FAW damage showing large ragged holes and sawdust-like frassStemborersThe stemborers’lifecycle (Figure7) consists ofdevelopment fromeggs to adults,through six larvalstages. At early larvalstages, the smalllarvae (or caterpillars)feed on leaves. Asthe larvae grow, theybore into the stemand feed inside theplant stems, up tothe pupal stage.Stemborers pupate inthe stem.Figure 7: General scheme of stemborer’s lifecycle10Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize
Busseola fusca (Figure 8) takes about 60 days to develop from egg to the adult stage, although thisduration varies greatly depending on climatic conditions, which include variations in humidity, temperatureand atmospheric pressure.ABCDEFigure 8: Developmental stages of Busseola fusca: (A) eggs laid between a leaf sheath and stem, (B) larvae, (C) pupa,and (D) male and (E) female adultsSesamia calamistis (Figure 9) completes its life cycle within 44 to 56 days.ABCDFigure 9: Developmental stages of Sesamia calamistis: (A) egg, (B) larva, (C) pupa, and (D) male (above)and female (below) adultsIntegrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize11
The complete life cycle of C. partellus (Figure 10) ranges between 38 and 55 days.ABCDFigure 10: Developmental stages of Chilo partellus: (A) eggs laid on leaf surface, (B) larva, (C) pupa, and (D) male (left)and female (right) adultsDistribution of Busseola fusca, Sesamia calamistis and Chilo partellusBusseola fusca is distributed widely throughout sub-Saharan Africa (Figure 11A). In thecontinent’s eastern and southern parts, B. fusca occurs mostly in mid- and high- altitude areas ( 600 m) where it is often the most serious pest of maize. However, B. fusca is also found in lowaltitude areas mostly feeding on maize as well as cultivated and wild sorghum.Sesamia calamistis is mainly found in sub-Saharan Africa and some of the Indian Ocean islandscommonly occurring in wetter localities at all altitudes (Figure 11B). Sesamia calamistis feeds ona wider range of crops than B. fusca: maize, sorghum, pearl millet, wheat, rice and sugarcane,and it is considered a critical and economically important maize pest in West Africa.Chilo partellus is native to Asia where it is a pest on maize and sorghum. It was first reported inMalawi in the 1930s and spread in the 1950s to most East Africa countries. Since then, it hasbecome widespread throughout Eastern and Southern Africa and several West African countries(Figure 11C). Chilo partellus is considered to be the most important stemborer species in mostlow- to medium-elevated areas of Eastern and Southern Africa.In addition to altitude, other factors play key roles in determining the distribution of stemborers,e.g. crop lifecycle and the presence of host plant.Maize is widely grown in Uganda, and presently, B. fusca, S. calamistis and C. partellus occurvirtually in all maize growing regions.12Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize
ABCFigure 11: Distribution map of Busseola fusca (A), Sesamia calamistis (B) and Chilo partellus (C) in Africa (Source:CAB international)Damage by stemborersYield losses caused by stemborers vary greatly among regions, depending on the agroecology,density of stemborer population, season, soil fertility status, crop type and phenology duringinfestation. Accordingly, yield reductions ranging between 15 and 50% have been estimated inEast Africa, while in South Africa, losses exceeding 50% have been reported, thus indicatingthe importance of stemborers as major yield-limiting factor for cereal crops in the region. It hasbeen estimated that stemborers cause yield loss of 15% to 50% in East Africa. Crop losses dueto stemborers in Ethiopia ranges from 10% to 50% while in Uganda, the crop losses range from10% to 30%.Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize13
StrigaStriga, commonly known as witchweed, is a parasitic plant that occurs naturally in parts ofAfrica, Asia, and Australia. In East Africa, there are two common species of the witchweed,Striga hermonthica (purple witchweed) and Striga asiatica (red witchweed). Striga hermonthicais common around the Lake Basin, while S. asiatica is mainly found in the coastal areas. Thecrops most affected are maize, sorghum, rice, finger millet, tef and sugarcane. The parasitic plantgrows by attaching itself onto the host plant.Striga lifecycleStriga is an annual plant, one Striga plant canproduce up to 20,000–50,000 seeds, whichlie dormant in the soil until a cereal crop isplanted. This dormancy can last for over 15years.Germination occurs within 24 hours ofexposure to a stimulant (usually a cerealplant). In the absence of a host, Striga rootswill grow to 4 or 5 mm before dying. AsStriga germinates, its roots grow towardsthe host crop. They develop an intrusiveorgan (haustorium) which penetrates hostroot cells. Striga draws nutrients from a hostplant, causing severe stunting and yieldloss. Striga develops underground, whereit may spend the next four to seven weeksbefore emergence when it rapidly flowers andproduces seeds (Figure 12).Figure 12: Striga lifecycle14Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize
Striga is distributed widely throughoutsub-Saharan Africa (Figure 13).Means of dispersalStriga seeds are small (0.2 mm long)and are spread by: wind run-off from heavy rains contaminated crop seeds animal manure farm machinery and toolsFigure 13: Distribution Map of Strigain Africa (Source: CAB international).Damage by Striga weedPlants affected by Striga exhibit stunting,wilting and chlorosis (Figure 14). If bothstemborers and Striga weed attack maizeplants, the yield loss is often 100%. Strigaweed causes most of the damage to themaize by the time it emerges.Figure 14: Maize plant choked byS. hermonthica.Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize15
Integrated pest managementIntegrated Pest Management (IPM) is an approach designed to manage pests and diseases withas little damage as possible to people and the environment. The focus is on long-term preventionor suppression of pest problems. Different techniques are used within IPM, including scoutingand monitoring, as well as preventive cultural, mechanical, and biological control in a compatiblemanner. Corrective chemical control measures are used as a last resort.The emphasis of IPM is on control, not eradication. Wiping out a whole pest population is oftenimpossible, expensive and environmentally unsafe. IPM programmes work to create acceptablepest levels.Economic Injury Level (EIL) is the point where a pest begins to cause enough damage to justify thetime and expense of control measures. Below the EIL, it is not cost-effective to control the pestpopulation because the cost of treatment exceeds the amount of damage. Above the EIL, thebenefit of treatment is greater than the cost of treatment. The EIL of stemborers is 1 larva per plant,and EIL of Striga is 1 weed. One larva can cause considerable yield loss, mainly on maize due tothe inability to compensate for stem damage by the formation of tillers.By allowing a pest population to survive, selection pressure is reduced, and this lowers the chanceof pests developing resistance to chemicals. By not killing all the pests, with chemicals, numbers ofpests unresistant to chemicals should remain, which will then dilute the prevalence of any chemicalresistant genes that might appear.Integrated pest management methods for FAW, stemborers and Striga weedIPM is as a knowledge-intensive system that has a continuous improvement cycle. With eachcycle (crop or season), more emphasis is placed on preventive strategies and gaining knowledgenot only about maize pests and their behaviour but also about what conditions are favourable orunfavourable to their development. This is illustrated in Figure 15.16Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize
EVALUATION ANDPLANNINGChanges tomanagementtechniques.PREVENTIONKnowledgeof pest, siteselection, culturalcontrol.MONITORINGCONTROLPest, crop,Mechanical,weather, soil,biological andrecord keeping, usechemicalof traps.control.DECISION MAKINGEconomic injurylevel.Figure 15: Five components of IPMScoutingScouting is a crucial tool in IPM. It entails field observation made during the crop production cyclefor pests, diseases, weeds and crop health (nutrition and water needs). Proper field observationsprovide information about the status of the crop and enable decision making on appropriateinterventions to be taken, for example fertilizer application, irrigation or pest and disease control.Scouting should be done regularly, at least once a week and more often after an infestation isdetected. Scouting is achieved by picking and inspecting plants at random from sampling sitesand recording the observations. Different sampling sites should be chosen each time the crop isinspected.Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize17
How to carry out scouting For effective control, start scouting every 3 to 4 days as soon as your maize has emerged,early in the morning or late in the evening.Upon arrival at the field, quickly do a visual assessment and scan for “hot spots” whilemoving through the field.Walk through your maize farm in a W pattern (Figure 16). Stop five times.At each stop, examine 10 to 20 plants. Focus on the newest two to three leaves emergingfrom the whorl, as this is where the FAW likes to feed and where FAW moths lay eggs.Observe the general health of the maize plants (leaf colour, soil moisture, and presence ofweeds, e.g. Striga).Look out for the physical signs of pest (egg masses, larvae, pupae and moths) or diseasesymptoms.Look out for signs of FAW, stemborer or Striga damage such as deadheart, windowing,frass, ragged and torn leaves, silk, tassel, ear damage, stunting and chlorosis.Record the number of seedlings that are infested and calculate the percentage (%)infestation for this scouting location.Now move to the next spot. Examine 10 to 20 plants. Record the data. Repeat the processa total of five times.After scouting the five locations in the field, calculate the total percentage (%) infestationacross the field.Figure 16: Scouting pattern18Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize
MonitoringRegional FAW and stemborer monitoring is intended to actively track the presence, population,and movement of pests within a specified geography. This is conducted by trained technicalpersonnel at sites throughout a country or region, but can also be conducted at the village andfield levels by both smallholder farmers and village-level progressive farmers. In both cases,monitoring relies on pheromone traps erected near fields to trap adult male moths. Trappedmoths are identified, counted, and recorded. The data collected is used to inform appropriateaction (reporting the data to appropriate authorities and conducting more intensive, targeted fieldscouting to inform crop management recommendations and decision making).The data collection tool app, called FAW Monitoring Early Warning System (FAMEWS), can beused to collect the scouting and pheromone trap data.Mechanical controlMechanical control is the management of pests by using physical means or hands-on methodssuch as: Post harvest tillage: Tillage reduces stemborer populations by burying them deeply into thesoil, or by breaking the stems and exposing the larvae to adverse weather conditions, aswell as birds, rodents, ants, spiders and other natural enemies. Crushing egg masses and hand-picking larvae: Farmers can mechanically kill FAW eggs andyoung larvae. This method should be done as soon as possible, beginning a week afterplanting. Eggs are laid in a mass, and can be easily found on maize leaves. They can beimmediately crushed. Young larvae can be picked off the leaves, before they penetrate deepinto the whorl. Handpicked larvae can be used as chicken feed. Crushing egg masses andhand-picking larvae is very effective in small areas, but is very labour intensive. Pour sand or ash into the leaf whorl: Sand and ash irritate the soft-skinned FAW larvae,forcing them out of the whorl or directly killing them through suffocation. Uproot Striga weed when they start to flower, but before they set seed, and burn them. Notethat Striga can still grow again from seeds already in the soil. Mass trapping using pheromone traps: Pheromones traps t can be used for both monitoringand control. If sufficient male moths can be captured, there will be a reduction in thenumber of fertilized eggs. One male can mate with several females, therefore a highproportion of males needs to be trapped for this approach to be effective.Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize19
Cultural controlCultural control is the modification of the crop environment in order (i) to avoid the meeting ofcrop susceptible stage with pest highest density, or (ii) to improve the crop growing condition, or(iii) to make the environment unfavorable for the pest. Cultural control methods include: 20Intercropping: Plant rows of other crops between the maize. Intercropping is effectivewhen non-host plants are used. Maize can be intercropped with legumes (e.g. pigeon pea,cow pea, velvet beans, lablab beans) or with other crops (e.g. cassava, sweet potatoes,pumpkins). Intercrops reduce pest damage by: (i) improving soil health and promotingvigorous plant growth through nitrogen fixation, (ii) inhibiting movement of larvae amongplants, (iii) preventing female moths from laying eggs, through visual or chemical disruption,and (iv) providing habitat for natural enemies. Crop rotation will reduce pest populations, butFAW can quickly build up.Habitat management using push-pull strategy: Plant Desmodium in between maize rows torepel stemborers from the maize. Plant Napier grass along the borders of the maize plot asa trap crop to pull stemborers away from the maize (Figure 17). Other benefits of push-pullare increased crop yields, increased fodder production, increased nitrogen fixation andreduced soil erosion.Field sanitation: Remove volunteer plants or alternative host plants. This helps in limitingthe initial establishment of stemborers that would infest the next crop. Weed regularly,starting two weeks after germination, and then weed again after six to eight weeks.Weeding reduces competition for nutrients by weeds, some of which are alternate hosts ofstemborers.Crop residue management: Slash maize stubble immediately after harvest and laying it out(horizontally) on the ground for 4-8 weeks. The sun’s heat will destroy stemborer larvae andpupae in the stem. Residue can also be used to feed cattle or to make compost.Mulching: Spreading of plant materials such as straw, leaves, crop residues, green manurecrops, or saw-dust on the soil surface. Mulching enhances soil biological activity, increasessoil organic carbon, and thus supports improved plant growth. Mulch also provides habitatfor natural enemies. To reduce the possibility of crop residues harbouring pests and disease,maize stubble should be slashed and laid out on the ground for 4-8 weeks.Fertilization: Use legume crops, well-composted organic manure and inorganic fertilizers toprovide adequate and balanced plant nutrition. Fertilization increases levels of soil organiccarbon, soil biological activities and increases pest resistance. Unbalanced plant nutritionthrough the use of inorganic fertilizers on poor soils can lead to increased pest damage. Forexample, the use of high levels of nitrogen fertilizer leads to increased leaf damage.Early planting: Plant maize after the first effective rains. This provides good growingconditions for maize and ensures that the crop will be established while pest population islow. Avoid late planting because stemborers and FAW populations build up later in the cropseason. Farmers can also plant early maturing maize varieties.Crop rotation: Plant non-host crops after maize. Rotate maize with cassava or with legumessuch as groundnuts, soybeans or cowpea for minimum 3 years. The roots of these legumeswill induce suicidal germination of Striga seeds residing in the soil and improve soil fertilityIntegrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize
through nitrogen fixation. Crop rotation increases the abundance of natural enemies andreduces pest and weed build up.Attract predators and parasitoids: Ants are important natural predators of FAW larvae. Theycrawl up the plants, into the whorls, and eat FAW larvae. Farmers have found that they canattract ants to their maize fields by putting fish soup in their maize fields. These substancesattract ants to their maize fields, and then they stay, and find and eat FAW larvae. Sprayingof maize leaves with 10-20% sugar solution attracts wasps that eat or parasitize FAW.In addition, farmers can prevent the spread Striga by the following actions: Avoid grazing animals in crops infested by Striga because the animals will spread Strigaseeds. Wash mud off farm machinery, tools, shoes or feet after working in infested fields. Avoid dropping cobs on the soil or threshing them in fields infested with Striga.“Push”Volatile chemicalsproduced by inter-croppedplants (Desmodium) repelmoths“Pull”Volatile chemicals fromborder trap plants (Napiergrass) attracts moths to layeggs away from the maizeNapier modiumNapier grassFigure 17: Push-pull technologyIntegrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize21
Control of Stemborers, Fall Armyworm and Striga weed using push-pull strategyThere are two options of the Push–pull strategy as outlined below:1. Conventional push–pull: a cropping strategy, where farmers use Napier grass as a border cropand Desmodium legume (silverleaf and greenleaf Desmodium) as an intercrop. Recommendedfor areas with reliable rainfall.2. Climate-smart push–pull: a cropping strategy, where farmers use Brachiaria spp. (a droughttolerant grass) as a border crop and Desmodium legume (drought-tolerant greenleafDesmodium) as an intercrop. Recommended for hot, dry conditions.Biological controlBiological control is the use of living organisms to suppress the population density, or impact ofa specific pest organism, making it less abundant or less damaging than it would otherwise be.These organisms are also known as “natural enemies”. Examples of biological control agents areparasitoids, predators, nematodes, fungi, bacteria, protozoa and viruses.Biological control is implemented through three methods:a) Classical biological control (importation of natural enemies), where the natural enemy isintroduced in a new environment to achieve control;b) Augmentative biological control (mass-production of natural enemies), in which a largepopulation of natural enemies already present is regularly released to increase their numberfor control;c) Conservation biological control (maintenance of natural enemies), in which measures aretaken to maintain natural enemies through adaptation of specific cultural practices.Biological control agentsNatural enemies of stemborers and FAW are parasitoids, and predators such as ants, beetles,predatory bugs, spiders and earwigs.Parasitoids are a group of insects that parasitize other insects or arthropods at any host stage.Insects that parasitize eggs are called eggs parasitoids, insects that parasitize larvae are calledlarval parasitoids, and insects that parasitize pupae are called pupal parasitoids. A parasitoid isonly parasitic in its immature stage. The free-living adult parasitoids lay their eggs inside the host or22Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize
attach them outside the host. The most abundant and widespread parasitoids of maize stemborersin the East African region are the egg parasitoids Telenomus spp. and Trichogramma spp., and thelarval parasitoid Cotesia sesamiae. Telenomus remus and Trichogramma are the main egg parasitoidwasps of FAW in North and South America. In Kenya, augmentative releases of T. remus and T.chilonis effectively controlled the damage caused by FAW.Predators, such as ants, spiders and earwigs can cause high mortality of eggs and young larvae.CotesiaThese are small wasps whose adults deposit multiple eggs in the body of stemborers or FAW.After about three days, the parasitoid larva emerges; it feeds inside the body tissue of stemborersor FAW. Soon after leaving the host, the parasitoid larvae will
2 Integrated Pest Management manual for Fall armyworm, stemborers and Striga in Maize Table of Contents About SCLAMP-EA project 3 Purpose of manual. 4 Objective of manual: 4 Abbreviations: 5 Introduction: 6 Fall armyworm: 7 Stemborers: 10 Striga: 14 Integrated pest management: 16 Summary of Maize IPM technologies: 27
