ch18ppt - Lecture 18 Pest Management Pest Management...

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Lecture 18 Pest Management
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Pest Management Insects are pests when they conflict with our welfare, aesthetics and/or profits Basically, its any animal we don’t like. Pests compete with us for food, feed on us or our animals & transmit disease
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Determining Pest Impact Measure the impact of insects in crops Need to analyze each situation: Determine size of pest population Cost of controlling pest Economic losses that will occur without control Determination of the Economic Injury Level
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Economic Injury Level Calculated using: Cost of control Market value of crop Estimated loss based on number of insects Effectiveness of control measures Pest No. Time Equilibrium point Equilibrium point Economic Threshhold Parasite introduction
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Why do Insects Become Pests? 1. Introduced into region w/o regulatory agents parasites, predators and pathogens 2. Insect vectors pathogen in new situation 3. Native insect shifts onto introduced plant species 4. Monocultural agroecosystems 5. Overuse of insecticides Leads to resistance Eliminates natural enemies May actually stimulate pest populations
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Pest Species The pest status of an insect depends on: 1. Abundance of individuals in an area 2. Kind of injury it causes 3. Specific characteristics of insect high reproductive rate short generation times inhabit unstable habitats polyphagous highly adaptable great dispersers
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Houseflies One female lays 100 eggs in her lifetime Generation time depends on temperature as short as 2 wks at temperatures over 80°F. Eggs simply dropped onto food Can reach huge populations in short period Davis in fall – huge housefly populations from rotting tomatoes in local fields
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Aphids One female aphid can produce 100’s of offspring Offspring can each produce 100’s of offspring All in a couple of weeks Almost born pregnant Largely parthenogenetic May specialize on few hosts but these are often crop plants
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Contrast with Non-pest Species Monarch butterfly – one female lays 10-20 eggs/year may live 2-3 years places eggs only on milkweeds only one generation/yr Jewel beetles (Buprestidae) – one female lays 20-30 eggs in lifetime generation time up to 20 yrs record holder 70 years!
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Population Regulation Intrinsic mechanisms density dependent factors interactions among individuals in population, include intraspecific competition cannibalism interference competition scramble competition. Extrinsic mechanisms
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This note was uploaded on 12/03/2009 for the course ENT 100 taught by Professor Kimsey,r during the Fall '08 term at UC Davis.

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ch18ppt - Lecture 18 Pest Management Pest Management...

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