Making connections between container mosquito performance and detrital decay using stable isotope analysis across different food environments: A study of Aedes albopictus and Culex restuans

Aedes albopictus, an invasive species from Asia, often interacts in containers with other species including Culex restuans. Past work has revealed differences in larval feeding behavior, with Culex filtering in the water column at the surface and Aedes browsing on surfaces. We hypothesized that these behaviors and other factors would produce differences between species in, 1) mass, survival, and development times depending on detritus type, 2) degree of detrital decay, and 3) nutrient isotopic signatures. We grew larvae of both species in ratios of two common detritus types (leaf and animal). We used 6 combinations of detritus types with amounts expressed in relative terms (1 unit of detritus equaled 0.05 g). Single (ratio of animal:leaf, 1:0, 2:0, 0:1, 0:10) and mixed (1:1,1:10) ratios were used. Culex restuans or Ae. albopictus were monitored for survival and sex-specific adult development time and mass. Survival only differed between species for one ratio (0:10), where Ae. albopictus had higher survival compared to Cx. restuans. Male and female Cx. restuans performed poorly in the 0:10 ratio, which produced the longest development times and smallest adults. Female Ae. albopictus development time was the slowest in single versus mixed detritus ratios, with males invariant. Aedes albopictus amplified detrital decay in two ratios (0:1, 1:10) compared to Cx. restuans. Stable isotope analysis revealed that Ae. albopictus were more enriched in nitrogen across all ratios compared to Cx. restuans Our findings supported our three hypotheses and provide further insights into the well-established superior competitive ability of Ae. albopictus.