Mechanisms of interference competition in the western tree-hole mosquito, Aedes sierrensis |
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Authors: | KENDAL S BROADIE WILLIAM E BRADSHAW |
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Institution: | Department of Biology, University of Oregon |
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Abstract: | Abstract. - 1 Mechanisms of interference competition affecting Aedes sierrensis (Ludlow) were investigated in laboratory microcosms using reconstituted, natural tree-hole detritus as food and substrate.
- 2 Pupation success, larval development time, and pupal weight were all affected by larval density but not by surface area:volume ratio of the microcosm.
- 3 Mature fourth instars affected pupation success, pupal weight, and development time of developing cohorts separated from them by a 2 μm pore membrane impermeable to bacteria, indicating that chemical competition is proportional to density of at least older instars.
- 4 Cannibalism does not occur, regardless of the presence or absence of food or physical complexity.
- 5 Fourth instars inhibited each other's feeding at densities of 64 larvae/ml or greater. Feeding inhibition due to physical contact (encounter competition) was abated but not eliminated by increasing physical complexity of the microcosm by the addition of leaves.
- 6 Levels of detritus and larval density both affect weight of day-1 fourth instars. Resistance to encounter competition is proportional to fourth instar weight and weight-specific resistance is correlated with rank weight within a developing cohort.
- 7 At densities around the population equilibrium in nature, encounter competition should be taking place, especially in tree holes with few leaves or other large litter.
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Keywords: | Competition mechanisms chemical inhibition encounter competition habitat surface/volume ratio insect development physical interference cannibalism |
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