Postharvest Entomology and Insect Pest Control in Horticultural Produce

Postharvest Entomology and Insect Pest Control in Horticultural Produce

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  Unit 8. PostharvestEntomology and Control of insect pests in harvested produce: Protective measures in the field to control insect pests, Cold treatment, Fumigations and Irradiation of harvested produce for the control of different insect pests Prepared by Umesh Timilsina Assistant Professor CNRM, Bardibas Agriculture and Forestry University
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  Post-harvest Entomology • Post-harvestentomology is the branch of entomology that deals with the study of insect pests that infest horticultural produce after harvest during handling, storage, transportation, and marketing. • These insect pests cause quantitative and qualitative losses by feeding on fruits, vegetables, flowers, bulbs, tubers, and stored produce. • Effective post-harvest pest management is essential to maintain product quality, reduce economic losses, and satisfy domestic and international quarantine requirements.
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  Importance of Post-harvestEntomology • Reduces quantitative and qualitative losses. • Maintains nutritional and market quality. • Prevents contamination of produce. • Extends storage life. • Meets export quarantine standards. • Increases farmers' income. • Reduces post-harvest losses.
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  Types of InsectPests Affecting Harvested Produce A. Field-to-Storage Pests • These insects infest crops in the field and continue damaging produce during storage. • Examples: Fruit flies Mango seed weevil Mealybugs B. Storage Pests • These insects attack produce after harvesting. • Examples: Beetles Moths Weevils Mites
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  Mealy bugs Potato tubermoth
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  Important Insect Pestsof Horticultural Produce Insect Pest Scientific Name Host Crop Nature of Damage Oriental fruit fly Bactrocera dorsalis Mango, Guava, Citrus Larvae feed inside fruits causing rotting Melon fruit fly Bactrocera cucurbitae Cucurbits Maggots tunnel into fruits Mango Seed weevil Sternochetus mangiferae Mango Larvae feed inside seed Onion thrips Thrips tabaci Onion Surface injury and reduced storage quality Potato tuber moth Phthorimaea operculella Potato Larvae tunnel inside tubers Pulse beetle Callosobruchus chinensis Pulses Seed damage during storage Warehouse beetle Trogoderma variabile Stored products Feeding damage and contamination Flour moth Plodia interpunctella Stored dried produce Feeding and webbing
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  Oriental Fruit flyMelon Fruit fly
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  Mango Seed weevil Onionthrips
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  Potato Tuber mothPulse beetles
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  Nature of DamageCaused by Insect Pests • Feeding holes • Internal tunneling • Fruit rotting • Contamination with insect excreta • Weight loss • Reduction in nutritional quality • Reduced seed viability • Premature ripening • Secondary fungal and bacterial infections • Loss of export quality
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  A. Protective Measuresin the Field to Control Insect Pests • Field management is the first step in preventing post-harvest insect infestation. A. Cultural Practices • Maintain orchard sanitation. • Remove fallen and infested fruits. • Destroy crop residues. • Harvest at proper maturity. • Follow crop rotation where applicable. • Use resistant or tolerant varieties.
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  B. Mechanical Control •Collect and destroy infested fruits • Fruit bagging • Pheromone trap Oriental fruit fly (Fruits-Bactocera dorsalis): Methyl Eugenol trap Melon Fruit fly (Cucumber-Bactrocera/Zeugodacus cucurbitae): Cuelure • Use insect-proof nets • Prune infected plant parts C. Biological Control • Use natural enemies such as: Parasitoids Predators Entomopathogenic fungi • Examples: Trichogramma spp. Ladybird beetles Beauveria bassiana Metarhizium anisopliae
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  Methyl Eugenol Trap Cuelure
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  Difference between CueLure and Methyl Eugenol Trap Feature Cue-Lure Trap Methyl Eugenol Trap Chemical attractant Cue-lure (4-(p-acetoxyphenyl)-2-butanone) Methyl eugenol (4-allyl-1,2-dimethoxybenzene) Target insects Male fruit flies of many Zeugodacus and some Bactrocera species Male fruit flies of several Bactrocera species Main species attracted Zeugodacus cucurbitae (melon fruit fly), Zeugodacus tau Bactrocera dorsalis (oriental fruit fly), Bactrocera correcta Major crops protected Cucurbits (bitter gourd, cucumber, pumpkin, bottle gourd, squash, etc.) Mango, guava, citrus, papaya, banana, peach and other fruit crops Purpose Monitoring and mass trapping of cucurbit fruit flies Monitoring and mass trapping of oriental fruit flies in fruit orchards Trap contents Cue-lure + insecticide (e.g., DDVP strip or malathion) Methyl eugenol + insecticide (e.g., DDVP strip or malathion) Field placement Hung 1–2 m above ground in cucurbit fields Hung 1.5–2.5 m high in fruit trees Effect on females Does not attract females Does not attract females Simple memory trick Cue-lure → Cucurbits (vegetables). Methyl eugenol → Mango and other fruit trees (orchards).
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  D. Chemical Control •Apply recommended insecticides only when necessary. • Observe pre-harvest intervals (PHI). • Rotate insecticides to delay resistance. • Follow label recommendations and residue limits. E. Orchard Hygiene • Remove fallen fruits regularly. • Eliminate alternate hosts. • Maintain weed control. • Sanitize harvesting equipment.
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  B. Post-harvest PreventiveMeasures • Harvest healthy produce only. • Avoid mechanical injury. • Use clean harvesting containers. • Remove damaged produce. • Wash and sanitize produce where appropriate. • Maintain proper storage conditions. • Inspect produce regularly. • Use insect-proof packaging.
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  1. Cold Treatment •Cold treatment is a quarantine method in which harvested produce is stored at a prescribed low temperature for a specified period to kill or suppress insect pests without affecting produce quality. Objectives • Kill eggs, larvae, and pupae. • Prevent insect development. • Meet export quarantine requirements. • Extend shelf life. Principle • Low temperatures slow insect metabolism and eventually cause mortality while preserving produce quality.
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  Common Temperature Requirements CropTemperature Duration Target Pest Citrus 0–2°C 14–18 days Fruit flies Mango 1–2°C (where crop tolerance allows) 14–21 days Fruit flies Grapes 0–1°C 10–14 days Storage insects Note: Treatment schedules vary depending on the importing country's quarantine regulations and the commodity's tolerance to cold.
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  Advantages • Chemical-free method. •Environmentally friendly. • Suitable for export commodities. • Maintains produce quality. Limitations • Requires cold storage facilities. • Some tropical fruits are susceptible to chilling injury. • Treatment duration can be lengthy.
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  Fumigation • Fumigation isthe treatment of harvested produce with approved gaseous pesticides in an enclosed space to destroy insect pests. Objectives • Eliminate insects. • Prevent pest spread. • Meet quarantine regulations. • Protect stored produce.
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  Common Fumigants Fumigant TargetPest Remarks Phosphine (PH ) ₃ (Aluminium Phosphide-Celphos) Storage insects Widely used for stored commodities Sulfuryl fluoride Storage insects Used for certain stored products and structures Sulfur dioxide Grapes Controls fungal diseases and some pests; used under specific conditions Note: Some fumigants that were widely used historically (e.g., methyl bromide) are now highly restricted or phased out in many countries because of environmental concerns. Always follow current national regulations and quarantine requirements.
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  Advantages • Highly effective. •Penetrates packaged produce. • Controls hidden insect stages. • Suitable for quarantine treatment. Limitations • Requires trained personnel. • Some fumigants leave residue concerns or have regulatory restrictions. • Specialized equipment is required.
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  2. Irradiation • Irradiationis the application of controlled doses of ionizing radiation to harvested produce to kill or sterilize insect pests and prevent their reproduction without making the food radioactive. Radiation Sources • Gamma rays (Cobalt-60 & Cesium-137-Both emits gamma rays-Widely used) • Electron beams (E-beam) • X-rays Objectives • Destroy insect pests. • Delay insect development. • Meet quarantine regulations. • Extend shelf life. • Reduce pesticide use.
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  Common Crops • Mango •Papaya • Guava • Dragon fruit • Spices • Cut flowers Advantages • No chemical residues. • Effective against internal insect stages. • Suitable for export. • Can be applied after packaging. • Environmentally friendly. Limitations • High installation cost. • Requires specialized facilities. • Subject to regulatory approval and consumer acceptance.
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  Comparison of ColdTreatment, Fumigation, and Irradiation Feature Cold Treatment Fumigation Irradiation Method Low temperature Gaseous pesticide Ionizing radiation Chemical residue None Possible, depending on fumigant None Export use Very common Common Increasingly adopted Target Mainly fruit flies and storage insects Broad range of insects All life stages of many insects Cost Moderate Moderate High initial investment Environmental impact Low Depends on fumigant Low
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  Integrated Pest Management(IPM) in Post-harvest Produce • Integrated Pest Management combines preventive, cultural, biological, physical, and chemical methods to minimize insect damage. Components • Field sanitation. • Resistant varieties. • Timely harvesting. • Proper grading and sorting. • Cold chain maintenance. • Monitoring and inspection. • Cold treatment. • Fumigation where appropriate. • Irradiation for quarantine purposes. • Safe storage and packaging.
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  3. Quarantine Measures •Plant quarantine is the set of legal measures adopted to prevent the introduction and spread of harmful insect pests and diseases across regions or countries. Importance • Prevents invasive pests. • Protects agriculture. • Facilitates international trade. • Meets import and export regulations.
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  General Preventive Measures BeforeHarvest • Maintain orchard sanitation. • Control field insect pests. • Use recommended insecticides judiciously. • Follow integrated pest management practices. • Harvest at proper maturity. After Harvest • Handle produce carefully to avoid injuries. • Sort and remove infested produce. • Wash and sanitize where appropriate. • Pre-cool promptly. • Store at recommended temperature and humidity. • Use insect-proof storage and packaging. • Inspect produce regularly during storage.
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  Summary of ImportantInsect Pests Crop Insect Pest Nature of Damage Main Control Measure Mango Oriental fruit fly Internal fruit feeding Orchard sanitation, trapping, cold treatment, irradiation Mango Mango seed weevil Seed damage Field sanitation and quarantine measures Cucurbits Melon fruit fly Fruit tunneling Fruit bagging, baiting, sanitation Potato Potato tuber moth Tuber tunneling Proper storage, sanitation Onion Onion thrips Surface damage Field management and proper storage Stored products Warehouse beetles Feeding and contamination Clean storage, fumigation Pulses Pulse beetles Seed damage Airtight storage and fumigation
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  Key Points • Post-harvestentomology deals with insect pests that damage horticultural produce after harvest. • Major post-harvest insect pests include fruit flies, potato tuber moth, mango seed weevil, onion thrips, warehouse beetles, and pulse beetles. • Effective field protection includes orchard sanitation, resistant varieties, biological control, mechanical methods, and judicious insecticide use. • Cold treatment uses prescribed low temperatures for specific durations to eliminate quarantine pests, especially fruit flies. • Fumigation uses approved gaseous pesticides such as phosphine to control storage insects and meet quarantine requirements. • Irradiation employs gamma rays, electron beams, or X-rays to sterilize or eliminate insect pests without leaving chemical residues. • An Integrated Pest Management (IPM) approach—combining sanitation, careful handling, monitoring, cold chain maintenance, and appropriate quarantine treatments—is the most sustainable and effective strategy for protecting harvested horticultural produce from insect pests.