March 12 lecture handout

March 12 lecture handout - 3/9/2012 Dispersal Movement that...

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3/9/2012 1 Dispersal • Movement that results in an increase in the mean distance between individuals (Dingle, 1996) – Includes migratory and trivial flight (insects can disperse by either behavior, or by random locomotion) Trivial Flight • Flight that has no migratory component • Usually defined in crop pests as short flights between hosts – Example: soybean aphids moving between plants during the summer Movements directed by resources and/or Home Range Station keeping: like central place foraging : – Foraging – Commuting (periodic movements) – Territorial behavior (patrolling) Ranging – Movement to explore an area – Establish the boundary of a territory
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3/9/2012 2 Life Stages: Remember Tinbergen’s Questions • Not all life stages disperse; not all are mobile Only adults have wings; but not all adults have wings Specialized Dispersal Stages • Eggs: – Inside parasitized host • Larvae: – As “crawlers” • Pupae: – Inside fruit, hosts • Adults Triggers of Dispersal Behavior Visual Cues – Color – Search image Olfactory Cues – Pheromones Photoperiod Crowding
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3/9/2012 3 What causes this transformation? Why Disperse? • Limited resources – Competition • Between individuals • Among family members – Food – Mates – Shelter • Weather – Season • Disaster More reasons to disperse • Decline in conditions (reversible or not) – Pesticide application – Everything already eaten – Patch quality declines (marginal value theorem) • Change in territory • Change in resource needs – small larvae eat different food from large larvae
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3/9/2012 4 Natal Dispersal • Movement of a young animal from birthplace before mating • Benefits – Avoid inbreeding – Avoid competing with parents and siblings •Cos
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This note was uploaded on 03/21/2012 for the course ENTOMOLOGY 104 taught by Professor Lewis during the Spring '12 term at UC Davis.

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March 12 lecture handout - 3/9/2012 Dispersal Movement that...

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