Effect of Larval Competition on Extrinsic Incubation Period and Vectorial Capacity of Aedes albopictus for Dengue Virus

Abstract

Despite the growing awareness that larval competition can influence adult mosquito life history traits including susceptibility to pathogens, the net effect of larval competition on human risk of exposure to mosquito-borne pathogens remains poorly understood. We examined how intraspecific larval competition affects dengue-2 virus (DENV-2) extrinsic incubation period and vectorial capacity of its natural vector Aedes albopictus. Adult Ae. albopictus from low and high-larval density conditions were orally challenged with DENV-2 and then assayed for virus infection and dissemination rates following a 6, 9, or 12-day incubation period using real-time quantitative reverse transcription PCR. We then modeled the effect of larval competition on vectorial capacity using parameter estimates obtained from peer-reviewed field and laboratory studies. Larval competition resulted in significantly longer development times, lower emergence rates, and smaller adults, but did not significantly affect the extrinsic incubation period of DENV-2 in Ae. albopictus. Our vectorial capacity models suggest that the effect of larval competition on adult mosquito longevity likely has a greater influence on vectorial capacity relative to any competition-induced changes in vector competence. Furthermore, we found that large increases in the viral dissemination rate may be necessary to compensate for small competition-induced reductions in daily survivorship. Our results indicate that mosquito populations that experience stress from larval competition are likely to have a reduced vectorial capacity, even when susceptibility to pathogens is enhanced.

Keystone nonconsumptive effects within a diverse predator community

“…For example, our study found that particular predator combinations altered mosquito longevity by 5 days or more (Figure c). Extrinsic incubation periods for many pathogens that impact humans (e.g., malaria parasites, West Nile virus, and Dengue virus) often are relatively long when compared to the life spans of their mosquito vectors (Bara, Rapti, Cáceres, & Muturi, ). This means that relatively modest increases or decreases in vector life spans can have fairly dramatic impacts on whether vectors regularly live long enough to transmit pathogens to new hosts (e.g., LaDeau, Allan, Leisnham, & Levy, ; McMeniman et al., ; Shapiro, Murdock, Jacobs, Thomas, & Thomas, ).…”

“…For example, our study found that particular predator combinations altered mosquito longevity by 5 days or more ( Figure 2c). Extrinsic incubation periods for many pathogens that impact humans (e.g., malaria parasites, West Nile virus, and Dengue virus) often are relatively long when compared to the life spans of their mosquito vectors (Bara, Rapti, Cáceres, & Muturi, 2015).…”

Zika and chikungunya: mosquito‐borne viruses in a changing world

“…Murrel and Juliano demonstrated that the competition winner or even the presence of competition itself depended on the type of detritus in the larval environment. Competition can also enhance susceptibility of infection to arboviruses, although, since competition also may shorten adult longevity, the net effect of this interaction on vector competence remains unclear.…”

Effect of food types on competitive interaction between Aedes aegypti (LINNAEUS, 1762) and Ae. albopictus (SKUSE, 1894) (Diptera, Culicidae): a proximate level appraisal

“…albopictus and Ae. aegypti with variations in the food substrates (DAUGHERTY et al 2000, YEE et al 2007, MURRELL & JULIANO 2008, BARA et al 2014, COURET et al 2014. The outcome of the competitive interactions was in favour of Ae.…”