Predation by Coccinellid Beetles: Experiments on Switching
1973
Murdoch, William W. | Marks, J. R.
The predatory behavior of a ladybird, Coccinella, was examined as it preyed upon varying ratios of two aphid species, Acrythosiphon pisum and Aphis fabae. Experiments were done in petri dishes and on bean plants. The ladybirds attacked the two prey species in direct proportion to their relative abundance. There was little variability among predators in a given treatment. Training had no effect on the subsequent diets of the predators, and all treatments provided a very good fit to a simple ₙo—switching" model. Predation on each species was density independent. This simple type of predation contrasts markedly with the results of earlier experiments on predatory snails in which variability among predators and a strong training effect produce switching.
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