Decaying Invertebrate Carcasses Increase Growth of <I>Aedes triseriatus</I> (Diptera: Culicidae) When Leaf Litter Resources Are Limiting

Abstract

Treeholes are detritus-based communities, and resource quantity and quality play a large role in structuring such communities. The primary resource is leaf litter, but decaying invertebrates also are a resource to treehole inhabitants. These communities are subject to a variety of disturbances, which may affect resources or cause widespread mortality. When dead inhabitants decay, they provide a potentially high-quality resource to survivors or subsequent colonists. We predicted that variation in decaying larvae (0, 7.3, and 29.2 mg/liter) and leaf litter (1, 5, and 10 g/liter) would influence the performance of populations of Aedes triseriatus (Say), the eastern treehole mosquito. We tested this prediction in field mesocosms, which were subjected to a freezing event causing widespread mortality of the scirtid beetle Helodes pulchella Guerin. We then added a cohort of first instar mosquitoes to mesocosms, and we monitored their development from March until June 2005. At the highest leaf litter level, survival, adult mass, and time to complete development were unaffected by decaying scirtids, and they were different from treatments with lower levels of leaf litter. In treatments with 1 and 5 g/liter leaf litter and decaying scirtids, mosquito survival and adult mass were higher than in treatments with 1 and 5 g/liter leaf litter and no decaying scirtids. At 5 g/liter leaf litter, a higher mass of dead scirtids was required to significantly increase adult mass. Faster decay of carcasses and release of limiting nutrients likely spur growth of microorganisms, upon which mosquitoes feed. Invertebrate populations in high-disturbance communities may be subject to high mortality, and mosquitoes hatching after the disturbance will benefit, but only when other resources are limiting.

Variation in performance of two co‐occurring mosquito species across diverse resource environments: insights from nutrient and stable isotope analyses

“…Consistent with previous findings (Fish & Carpenter, 1982;Daugherty et al, 2000;Yee & Juliano, 2006;Harshaw et al, 2007;Yee et al, 2007a;Murrell & Juliano, 2008), mosquitoes in this study performed better under ratios containing some animal detritus versus leaf-only containers (Figs 1a,b and 2), and mixed detritus compared with single detritus environments generally promoted higher survival (Fig. 2).…”

Stable isotope analysis reveals detrital resource base sources of the tree hole mosquito, Aedes triseriatus

“…Our results indicate that invertebrate detritus may contribute proportionately more to nitrogen-containing compounds in pupal biomass than plant material, consistent with the observations that mosquito isotope values changed during the season and that invertebrate carcass influence on growth of Ae. triseriatus in tree holes is most pronounced when plant material resources are limiting (Harshaw et al 2007). That carbon may come primarily from one diet source while nitrogen comes from another is not surprising ((Stenroth et al 2006)), but the ecological consequences of this have not often been addressed.…”

“…Although tree holes are consistent recipients of plant detritus in the form of senescent leaf material (Carpenter 1983, Lounibos et al 1992; Leonard & Juliano 1995), other inputs include flower parts, twigs, and terrestrial invertebrate carcasses (Lounibos et al 1992; Yee et al 2007a, b). Recent studies have emphasized the potential importance of animal (invertebrate) detritus inputs as they relate to container-breeding mosquito nutrition and to outcomes of larval competition (Daugherty & Juliano 2000; Yee & Juliano 2006; Harshaw et al 2007; Yee et al 2007a, b; Murrell and Juliano 2008). Insect carcasses appear to be roughly tenfold higher in food value for mosquito larvae compared to senescent leaf material (Yee & Juliano 2006; Yee et al 2007b), potentially allowing co-existence of competing larval species in tree holes and increased production of Ae.…”

“…Insect carcasses appear to be roughly tenfold higher in food value for mosquito larvae compared to senescent leaf material (Yee & Juliano 2006; Yee et al 2007b), potentially allowing co-existence of competing larval species in tree holes and increased production of Ae. triseriatus from these habitats (Harshaw et al 2007; Yee et al . 2007b).…”

Senescent leaf exudate increases mosquito survival and microbial activity

“…These inputs consist primarily of plant material, with leaf litter as the major source of coarse particulate organic matter (CPOM), fine particulate organic matter (FPOM), and dissolved organic matter (DOM) (Fish & Carpenter, 1982: Leonard & Juliano, 1995; Walker et al , 1997). In addition to plant detritus, stemflow (Kitching, 1971; Fish, 1983; Carpenter, 1982b; Walker et al , 1991; Kaufman et al , 1999, 2002; Kaufman & Walker, 2006) and animal detritus (Daugherty et al , 2000; Yee & Juliano, 2006; Harshaw et al , 2007) contribute to allochthonous nutrient pools. Water runoff during rain events collects in tree holes, introducing critical soluble nutrients (e.g.…”