PARENT SESSION
Poster Session # 20: Predator - Prey / Mutualism - Parasitism Ecology.

Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Functional responses and species coexistence in members of a treehole community.

Griswold, Marcus^*,1, Lounibos, L², ¹ University of Florida, Gainesville, FL² University of Florida, Vero Beach, FL

ABSTRACT- Larvae of Toxorhynchites rutilus and Corethrella appendiculata are aquatic invertebrate predators commonly found in treeholes and artificial containers in the southeastern U.S. Both predators may co-occur. The functional responses of each predator to two prey species, Aedes albopictus and Ochlerotatus triseriatus, were estimated in laboratory experiments. Relative prey vulnerability was also determined by offering the two prey species to the predators in seven fixed ratios with a fixed total density of 100 prey larvae. Both T. rutilus and C. appendiculata exhibited an inversely density-dependent Type II functional response to each prey species, taken alone. This protocol provides a null model for examining the functional responses on both prey, when encountered together. Analyses using Manly's suggest that the full functional response may be more complex than predicted from the null model. These results may help to explain the coexistence of the native treehole species O. triseriatus with the invasive A. albopictus. Although A. albopictus escapes some predation by developing at a faster rate than O. triseriatus, the greater vulnerability of A. albopictus to both predators in early instars counteracts the developmental advantage that A. albopictus has over O. triseriatus.

Key words: prey, predator, vulnerability, mosquitoes