*INSECT PEST MANAGEMENT DEPARTMENT OF CROP PROTECTION UNIVERSITY OF NAIROBI

*GENERAL PRINCIPLESInsect management: essential component of crop productionTactics include: Get latest info on control, spray threshold n insecticide resistanceAvoid periods of high insect activity e.g early planting Agronomic practices that break insect cyclesRegular crop inspection for pests and natural enemiesKnow critical stage of the cropSpray if EIL detectedUse proper spray equipment

*Monitoring Regular scouting of the crop for insectsCritical to allow timely control of insectsQuality monitoringKnowledge of likely pests/beneficials n lifecyclesMonitoring frequency n pest focus crop stagesSampling technique size, parametersBalancing random sampling with areas of obvious damageRecord keeping indicates whether pest nos are increasing, decreasing or constantAccurate recording of results criticalRecord sheets shd have types n nos of insects, size of insects, crop stage.................

*Sampling methods for monitoring

Beat sheetEffective for sampling catepillars, bugs, aphids, mitesUse on pulse crops from budding onwards twice weekly n once weekly during vegetative stageDifficult to use when crops are wetVisual checkingSweep net samplingSuction samplingTraps pheromone, light.

*Pest management/ Integrated pest managementIPM/PM uses knowledge of pest biology n habitats to choose the best combination of common sense control methods that will keep pests under control.Definition A set of management activities that farmers implement to mantain the intensity of potential pests at levels below which they become pests without endangering productivity and profitability of the farming system, the health of th farm family n lifestock and th quality of the adjacent and downstream environments Wightman, 1998IPM is driven by economic concerns but ensures sustainability of the enterprise n minimizes environmental n health risks

*IPM foundation principles and concepts1st principle: Agro-ecosystem any management aaction must have this in perspective2nd principle: Pest economic levels Any pest can exist in some tolerable levels3rd : Maximize effectiveness of natural control factors

Features of agro-ecosystems that contibute to frequent pest outbreaks are:Experience frequent disturbancesDominated by domesticated plantsLow species diversityUniformity in planting n harvesting at same timeReceive nutrients fron external sources.

*Economic principlesIPM realized that eradication of pest is not necessary to ensure profitabilityAll crops can tolerate a certain amount of pest damage without affecting yields EIL lowest population density of a pest that will cause economic damage; the amount of pest injury that will justify the cost of controlCalculating EILs Gain threshold = intervention cost per area/ value per unit of cropEstimate the units damaged per pest per areaCalculate EIL = gain threshold/loss per pest

*Economic thresholdThe pest dennsity at which control measures should be implemented to prevent pest populations from reaching EIL. Estimated to be 80% of EILLimitations:Lack of mathematical definition of ETLack of valid EILsInability to make cost effective and accurate population estimatesInability to predict critical ET variables e.g market values n population trendsLack of simple means to inco-orporate externalities e.g environmental costs into EILsSubjective nature of EILs

*Agro-biological effects of chemical pesticidesHave a huge influence on how IPM is implementedPesticide resistance occurs due to natural genetic variation in a population's susceptibility to pesticidesDevelopment of resistance can be reduced by;Low kill strategy to allow some susceptible individuals to survive n breedSwitching life-stage target target the adult stage as juveniles develop resistance fasterLimited spray windowPesticide rejuvenation Add a compound to the pesticide which blocks resistance mechanism when th resistance mechanism is knownDiversification of control methods

*Pest resurgence and pest replacement Pest resurgence occurs when a pest population that has been suppressed rebounds to a higher population level than before control Pest replacement occurs when a minor or secondary pest becomes an important pest due to control measures used on target pest population Main causes of these are:Reduction in natural enemy populationsControl measure kills the natural enemySuppresses pest popln till natural enemy starveAffected pests consumed by natural enemies thus secondary toxin accumulation kills the natural enemyNatural enemy repelled and emigrate

*HormoligosisA phenomenon whereby pests show increased vigour when exposed to sub-lethal doses of pesticidesOccurs when control measure causes a change in the physiology of the pest I.e metabolismShift in environment I.e nutritional change in plantShift in pest behaviour I.e increased reproductionRemoval of competitorsIf two pest species compete for the same food source, selective removal of one species will benefit the other species, resulting in pest replacement.

*Tools, Methods and Tactics of IPMPreventionGood Agronomic Practices They encourage good crop health and bolster crop resistance to pestThey include:Spatial methods e.g Plant spacing, Intercropping, Strip cropping, Cropping patterns I.e avoiding planting alternate hosts near each otherSequence-related methods e.g crop rotation, multiple cropping, over seeding and under sowingPlanting materials and inputs e.g host-plant resistance, disease free planting material, crop genetic diversity, plant appropriate crops and cultivars, fertilization, irrigation without overdoing

*InterventionChemical interventionsSynthetic pesticides, botanicals, inorganic pesticides, semiochemicals, hormonesBiological interventionsPredators Catch and consume prey. Neuroptera, Hemiptera, Diptera, Coleoptera, Arachnida, snakes, birds, fish.... They are fairly generalistsParasitoids Lays eggs in the pest host and the resulting larvae consume and ultimately kill the host. Mostly of the order Hymenoptera and Tachinid family of Diptera. They are highly host specificPathogens Infect pest with fatal or debilitating disease. Fungi, bacteria, nematodes, viruses. They are very specific and are often referred to as biopesticides because way of application is similar

*Categories of biological interventionsNatural biocontrol Methods that seek to conserve or increase effectiveness of existing beneficialsAugmentation Releasing beneficials in order to help existing ones control a pest problemInundative release- Releasing large numbers of beneficilas to control pest problemSeasonal inoculative release- Releasing a small number of beneficials early in the season to give them head startClassical biological control Introduction of a non-native organismHerbivores To control weeds

*Cultural interventionsBorder crops, trap crops, mulching, pruning, altered harvesting and planting dates, efficient harvesting and storage, fertilization, irrigation, multiple cropping, weeding.........Considered to be labour intensiveMany are preventiveThey affect pest populations in three ways:Make agro-ecosystem unfavourable for the pestDisplace the crop in time and space making it unavailable to the pestMake agro-ecosystem dangerous by encouraging natural enemies

*Physical interventions

DirectTillageBarriersTemperatureWaterAir

PS: Detailed explanations in the manual

*Genetic interventionsHost-plant resistanceSterilizationGenetic displacementGenetic improvement of beneficials.

Detailed explanations of the above are in the manual

*RegulationQuarantineEradicationControl districtsCrop-free periodsPlanting time restrictionsEnforced growing of particular cultivarsCompulsory sanitation measuresRegional diversificationIsolation

PS: READ THE DETAILED EXPLANATIONS IN THE MANUAL

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