Generalist Feeding Behaviors of Aedes sierrensis Larvae and Their Effects on Protozoan Populations

Abstract

The generalist feeding strategy of larvae of the western tree hole mosquito, Aedes sierrensis, is central to understanding the community-level effects of the tritrophic interactions among mosquito larvae, midsized organisms (such as protozoa), and lowerlevel organisms (such as bacteria and fungi) in west coast phytotelmata. Laboratory microcosm experiments were conducted to characterize the feeding strategies of Ae. sierrensis larvae in the presence of multiple resource types (free-swimming protozoa and substratebound particulate material). In our experiment, we quantified the effects of varying instar numbers and profile, resource type, and refuge size on predation of protozoa. Refugia were explicitly modeled in our microcosms, representing the interstitial spaces of leaf litter and the wood lining of natural tree holes. Results from these microcosm experiments suggested that: (1) Even in the absence of larvae, the majority of protozoa resided in the small-volume, resource-rich refugia. There was, however, a strong nonlinear and negative relationship between larval densities in the upper compartment and the protozoan densities in the refuge, suggesting that there was continual movement of protozoa between the two spaces. (2) Fourth instars harvested resources by filter-feeding at a higher rate than second instars. (3) As the level of substrate-bound particulate food was increased, the predation pressure by filter-feeding on the protozoa decreased. (4) As the refuge volume increased, the predation pressure on the protozoa decreased.We constructed a three-state-variable mathematical model describing the generalist feeding behavior of Ae. sierrensis larvae. The model system, with constant predator densities and two prey groups, exhibited full cooperativity; i.e., an increase in protozoa density resulted in a shift toward predation by filter feeding, while an increase in substrate-bound resources resulted in a shift toward predation by browsing. This indirect mutualism is mechanistically distinct from previously published systems and provides a potential mechanism for protozoan persistence in the presence of larval predation.

Ecological Suitability and Spatial Distribution of Five Anopheles Species in Amazonian Brazil

“…6,62 The larvae of some species seem able to tolerate only a narrow ecological range, whereas larvae of other widely distributed species may be more broadly adapted. 63,64 Of the five species of anophelines examined, An. triannulatus appears the most likely habitat generalist as it demonstrates both widespread distribution and little if any environmental constraints.…”

Environmental Correlates of Abundances of Mosquito Species and Stages in Discarded Vehicle Tires

“…1 and 2). Protozoans often are important prey for mosquito larvae (Conchran-Stafira and von Ende 1998, Eisenberg et al 2000, Kaufman et al 2002, Kneitel 2007, Yee et al 2007c, although there are no data testing whether protozoans affect patterns of oviposition. Gravid females of several species of container mosquitoes prefer substrates with bacteria for oviposition (Maw 1970, Ikeshoji et al 1975, Trexler et al 2003, and our data identified bacterial productivity (PS) as important for both early and late instars of Aedes during spring (Fig.…”

Soluble nutrient effects on microbial communities and mosquito production in Ochlerotatus triseriatus habitats

“…The few studies that have addressed microbial populations in treeholes (Washburn et al 1988, Paradise & Dunson 1998, Kaufman et al 1999, Eisenberg et al 2000 have generally provided evidence for strong larval control. Except for temporary reduction of water column bacterial populations through dilution , stemflow effects are thought to be minor compared to larval effects (Kaufman et al 1999).…”