Ecological Archives E092-029-A1

Yao-Hua Law and Jay A. Rosenheim. 2011. Effects of combining an intraguild predator with a cannibalistic intermediate predator on a species-level trophic cascade. Ecology 92:333–341.

Appendix A. Laboratory and field data on cannibalism in Geocoris pallens, and predation rates of Zelus renardii on G. pallens.

TABLE A1. Mortality rates of G. pallens individuals of smaller stages when paired with individuals of larger stages in a 25 mL vial for 48 hours. Each replicate had a slice of green bean to provide nourishment and water for the G. pallens individuals. Experiment was conducted 7–9 July 2009.

Larger stage Smaller stage Number of replicates Mortality of smaller stage
(%; mean ± 1SE)
1st/2nd instar Egg 8 25 ± 16.4
3rd/4th instar Egg 9 77.8 ± 14.7
3rd/4th instar 1st/2nd instar 8 50 ± 18.9
Adult female Egg 10 30 ± 15.3
Adult female 1st/2nd instar 8 87.5 ± 12.5

FIG A1. Mortality of Geocoris pallens adults in the absence or presence of Zelus renardii in a short-term field experiment. Experimental conditions were qualitatively similar to the experiments described in the main text (Experiments 1 and 2) in terms of plant structures and arthropod communities examined. On 5 August 2009, field cages were constructed with spun polyester mesh plant sleeves (Fibe-AirTM, Kleen Test Products, WI, USA) enclosing the top five nodes of cotton plants. The cages enclosed both vegetative and reproductive structures. All visible predators were removed prior to caging. Ten Tetranychus urticae females were added to each cage immediately after caging. On 6 August, two Lygus hesperus females and two each of G. pallens males and females were added to each cage. One Z. renardii 4th instar nymph was added to half of the cages (N = 9), whereas the other cages were left without Z. renardii (N = 10). The experiment was ended five days later when all arthropods in the cages were counted.

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