predators and parasites as biological control.pptx

predators and parasites as biological control.pptx

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  BIOLOGICAL CONTROL
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  • Some insectscan be considered pests at certain times and beneficial at other times. An insect is usually considered a pest when it is in competition with humans for some resource, and when significant numbers are present. Insects can be managed, Pest management is the intelligent selection and use pest control actions Pest control actions include the monitoring of pest increase
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  Natural control • refersto the maintenance of pest populations within certain limits by environmental conditions, or factors. These include: • 1. Physical factors such as weather (e.g. cold winters can reduce some insect populations). • 2. Quality and quantity of available food. • 3. Competition between species or among individuals of the same species. • 4. Amount and quality of living space or territory. • 5. Natural enemies such as predators, parasites and other microorganisms
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  BIOLOGICAL CONTROL The useof living natural enemies to •control pests. Includes: • Predators • Parasitoids • Pathogens
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  • Applied biologicalcontrol can involve classical importation and establishment of natural enemies, augmentation, or conservation. While complete biological control (integrated pest management, IPM) is always desired. • Factors causing outbreaks in pest population: • Natural factors as migration, and environmental changes that allow the pest to increase in number.
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  1.Man induced factors: a.Introductionof a new species to new areas without their natural enemies, the pest survive and reproduce rapidly in their new environment. b.Change in crop management. c.Alteration of the habitat. d.Side effects of pesticide used. e.Monoculture or continuous cropping that provides a concentrated food source for species that can survive and reproduce in them.
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  PREDATORS • An insectpredator is a free-living as a larva, kills it host immediately by direct attack, and requires a number of prey individuals to provide sufficient food for growth. • Some are predators as immatures, but feed on alternative foods as adults (e.g. nectar and honeydew). Some are obligatory predators in both immature and adult stages.
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  SOME IMPORTANT INSECTPREDATORS IN BIOLOGICAL CONTROL: • Ground beetles: • Order Coleoptera • Family Carabidae • Life History: Nocturnal, in or on soil, some live up to four years. Prey: Caterpillars, soil and tree insects, earthworms. • They are generalist predators and may feed on a wide variety of insects. Most are predaceous on insects in and on the soil as adults and larvae. Some species leave the soil and climb and feed on plant foliage. E.g. Calosoma sp.
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  1. Tiger beetles: OrderColeoptera Family Cicindellidae Life history: stalking predators as larvae, fast runners as adults. Prey: whatever they can catch. They are a large group of beetles known for their aggressive predatory habits and running speed. They are also generalist predators; all are predatory, both as adults and as larvae. The larvae of tiger beetles live in cylindrical burrows in the soil. They capture prey insects that wander over the ground. E.g. Cicindela sp.
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  • Lady beetles: •Order Coleoptera • Family Coccinellidae • Life history: predaceous as adults and larvae. • Prey: aphids, scale insects, eggs of various insects, spider mites and other soft bodies pests. • Various larger species of Coccinellidae attack caterpillars and other beetle larvae. Besides the prey they favour, most predatory coccinellids include other items in their diets, including honeydew, pollen, plant sap, nectar, and various fungi. Apart from the generalist aphid and scale predators and incidental substances of botanical origin, many Coccinellidae do favour or even specialise in certain prey types. This makes some of them particularly valuable as agents in biological control programmes. E.g. the larva of the Rodolia cardinalis is a specialist predator on a few species of Icerya purchasi
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  • Syrfid orhover flies: • Order Diptera. • Family Syrfidae • Life history: Adults feed on nectar and pollen, larvae are predaceous. • Prey: aphids, scale insects, and other small insects. • These flies are called by several names, such as flower flies or hover flies. Usually they can be seen feeding on flowers. • Larval stage of the syrphid fly preys on insects. They crawl over foliage and can eat dozens of small, soft-bodied insects each day. • Syrphid flies are particularly important in controlling aphid infestations early in the season, when cooler temperatures may
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  • Assassin bugs •Order Hemiptera • Family Reduviidae • Life history: Assassin bugs feed by piercing prey with their beaks to suck out juices. • Prey: Caterpillars, small flying insects, aphids, and leafhoppers. • Assassin bugs are named that way because of the proficient predatory life style. They are waiting for the prey in ambush, but once the prey is identified chances of escape are minimal. • Assassin bugs usually eat different type of insects. Some species feed on the blood of birds, reptiles and mammals.
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  • Vespid Wasps(Hunting wasps) • Order Hymenoptera • Family Vespidae • Life history: Many have annual colonies with queens, workers, and males. • Prey: Caterpillars and other insects. • A large number of wasps from several families prey on insect pests. Many take their prey, whole or in pieces, back to their mud, soil or paper nests to feed to the immature wasps. • Sand wasp: is an example of hunting wasp which take its prey to the nests to feed to the immature wasps. First sand wasp paralyses the host insect, then it wait a few minutes and finally it uses her forelegs to carry the host insect to the nest.
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  • Green Lacewings •Order Neuroptera • Family Chrysopidae • Life history: Oval, white eggs laid singly on stalks 8 mm long. Small gray larvae spin cocoons and pupate on undersides of leaves. • Prey: larvae feed on aphids and other small insects. Adults feed on honeydew and pollen. • Adults have thin, green bodies and green wings with lacy veins; they are not predators. Larvae are predators, with long, curved mandibles that they use to suck the fluids out of prey. Larvae are about ¼ inch long, and feed on most small soft bodied insects.