Competitive Outcomes of Aquatic Container Diptera Depend on Predation and Resource Levels

Abstract

Resources and predation are both known to be important in structuring communities; however the strength of one factor may be affected by the intensity of the other. This study used a fully crossed factorial experiment in laboratory microcosms to examine the ability of a predator, Corethrella appendiculata (Grabham), and basal resources (leaf litter) to differentially affect two competing species of mosquito prey. Increased resources resulted in shorter developmental time and increased survivorship, mass, and population performance for both prey species, except when predation levels were high. Increased levels of predation and resources reduced the negative competitive effects of Aedes albopictus (Skuse) on Ochlerotatus triseriatus (Say). At low levels of resources and predation, the superior competitor, A. albopictus had the higher survivorship, and at high levels of resources and predation, the inferior competitor's survival was greater. Predators in high-resource treatments emerged larger than those in low resources, suggesting the occurrence of a bottom-up cascade or alternative feeding method. This study suggests that survival and coexistence of the two prey species may depend on the interaction of resources and predation, in that high levels of predation are important for the coexistence of both species.

Habitat complexity and sex-dependent predation of mosquito larvae in containers

“…appendiculata compared to A. albopictus (Fig. 6), as shown by others (Griswold and Lounibos 2005c). Studies have shown that direct effects of predation (e.g., predator-mediated release from competition) (e.g., Morin 1981), as well as trait-mediated indirect effects of predation (e.g., morphology and behavior) (Werner and Anholt 1996;Relyea 2000) may reverse the outcome of competition.…”

“…Studies have shown that direct effects of predation (e.g., predator-mediated release from competition) (e.g., Morin 1981), as well as trait-mediated indirect effects of predation (e.g., morphology and behavior) (Werner and Anholt 1996;Relyea 2000) may reverse the outcome of competition. In the current study, predator-mediated release from interspecific competition as well as behavioral differences among the prey in the presence of a predator may largely be responsible (Morin 1981;Werner and Anholt 1996;Griswold and Lounibos, 2005c).…”

Do natural container habitats impede invader dominance? Predator-mediated coexistence of invasive and native container-dwelling mosquitoes

“…Behavioral responses of A. albopictus to water-borne cues to risk of predation are either absent (Kesavaraju and Juliano 2004) or of much smaller magnitude than those of native O. triseriatus (Kesavaraju et al 2007a). This likely contributes to greater vulnerability of A. albopictus to predation by C. appendiculata (and to other predators like Toxorhynchites rutilus (order, Diptera; family, Culicidae) compared to O. triseriatus (Lounibos et al 2001;Griswold and Lounibos 2005a;Griswold and Lounibos 2005b).…”

“…Previous studies have shown that A. albopictus is more vulnerable to C. appendiculata predation than is O. triseriatus Lounibos 2005a, Griswold andLounibos 2005b;Kesavaraju et al 2007a), but follow up studies on how vulnerability affects distribution in the field were lacking. Our study shows that in natural container habitats like tree holes, C. appendiculata is more abundant than in artiWcial container habitats, and may be impeding dominance by A. albopictus.…”

Testing Developmental Plasticity in Aquatic Larvae ofCorethrella appendiculata(Diptera: Corethrellidae)

“…The family Corethrellidae is closely related to the Culicidae with a similar life cycle including an aquatic larva and pupa followed by an adult, females of which typically feed on frog blood to gain nutrients for egg production. C. appendiculata larvae are predatory occupants of container habitats (Griswold andLounibos 2005, Kesavaraju et al 2007) and may be found at high densities in the Þeld (Lounibos 1983). The experimental advantages of this species include discrete prey allowing for easy measurement of food consumption, ability to be reared in large numbers, and lengthy development time, facilitating detectability of treatment effects.…”