Does Nutrient Availability and Larval Competition Alter Chikungunya Virus Infection in the Mosquito Aedes albopictus?

Abstract

Aedes albopictus is a mosquito that has spread rapidly in the United States and is considered an important vector for arbovirus transmission to humans in several countries. Larval interactions and environmental conditions can influence mosquitoes and their ability to transmit pathogens as adults. We investigated whether intraspecific larval competition among Ae. albopictus mosquitoes from Florida, combined with varying food availability, affects vector competence for Chikungunya virus (CHIKV). We reared larvae under four competition treatment densities and two food levels. Measurements were taken for larval development duration, survival rate, and female wing length. Mosquitoes from each treatment group were orally challenged with CHIKV. Our results showed that development time was longer for both female and male Ae. albopictus under high-competition conditions and appeared as the most important factor, followed by survivorship. Survival rates were highest under low-density conditions compared to those reared under high-density conditions. Mosquitoes reared with a low amount of food had the lowest survivorship and longest development times compared to those provided with high food levels. Our results also showed susceptibility infection and disseminated infection of CHIKV was influenced by an interaction of density and food availability. Mosquitoes from the high-food, high-density treatment group exhibited lower CHIKV infection and dissemination rates compared to other treatment combinations. These findings highlight the role of larval competition and nutritional stress during immature stages in shaping adult mosquito traits, with important epidemiological implications for CHIKV transmission.

Keywords: Aedes albopictus; Chikungunya virus; intraspecific larval competition; nutrient availability; susceptibility to infection.

Figure 1

Schematic overview of experimental design. Mosquito population growth correlates (development time, adult eclosion rates, and adult size) were determined for mosquitoes from each experimental treatment. Adult female mosquitoes from each treatment were orally challenged with CHIKV infected blood to determine infection rate (IR), dissemination rate (DR), and whether larval competition and nutrition altered the course of infection.

Figure 1

Schematic overview of experimental design. Mosquito population growth correlates (development time, adult eclosion rates, and adult size) were determined for mosquitoes from each experimental treatment. Adult female mosquitoes from each treatment were orally challenged with CHIKV infected blood to determine infection rate (IR), dissemination rate (DR), and whether larval competition and nutrition altered the course of infection.

Figure 2

Analysis of the effects of larval density treatment on survivorship and development time of Ae. albopictus males (in circles) and females (in squares). Bivariate least-squares means (±standard error) are shown for dependent variables contributing the most to significant multivariate treatment effects. Means followed by different letters show significant differences (development time, capital letters; survivorship, lower-case letters).

Figure 3

Analysis of the effects of food treatment on survivorship and development time of Ae. albopictus males. Bivariate least-squares means (±standard error) are shown for the dependent variables which had the greatest contribution to the multivariate effect. Means followed by different letters show significant differences (development time, capital letters, survivorship, lower-case letters).

Figure 4

CHIKV viral titer in Ae. albopictus (A) bodies and (B) legs at 7 days post-infection. Statistical analysis was performed by a two-way ANOVA, bars represent means ± standard error of the means.