Some exclusion cages do not exclude predators

0371607 - ÚVGZ 2012 RIV CZ eng J - Článek v odborném periodiku
Ameixa, Olga - Kindlmann, Pavel
Some exclusion cages do not exclude predators.
European Journal of Environmental Sciences. Roč. 1, č. 1 (2011), s. 67-69. ISSN 1805-0174
Výzkumný záměr: CEZ:AV0Z60870520
Klíčová slova: predator effectiveness * exclusion cages * ladybirds * aphids
Kód oboru RIV: EH - Ekologie - společenstva

Exclusion techniques, such as cages, are the most frequently used means of evaluating the efficiency of natural enemies in suppressing the abundance of their prey. The growth rates and peak densities of aphid populations within cages are usually larger than those in uncaged populations. However, cages change the microenvironment and prevent aphids from emigrating. Attempts were made to avoid the change in the microenvironment by using cages with a large (8 mm) mesh. Here we test the hypothesis that because of the large mesh size, predators can easily penetrate into such cages during an experiment. Our results have shown that cages with a large (8 mm) mesh size do not prevent predators from entering the cages and therefore cannot be used as “exclusion cages” for measuring the effect of predators on aphid numbers. Other methods of assessing the effectiveness of natural enemies in reducing the abundance of their prey, like removing the predators or direct observations, should be used instead.
Trvalý link: http://hdl.handle.net/11104/0205083