Discovery and exploitation of a natural ecological trap for a mosquito disease vector. leaf litter metagenome

Ecological traps occur due to a mismatch between a habitat’s attractiveness and quality, wherein organisms show preference for low-quality habitats over other available high-quality habitats. Our previous research identified leaf litter from common blackberry (Rubus allegheniensis) as a natural ecological trap for an important mosquito vector for West Nile virus (Culex pipiens), attracting mosquitoes to oviposit in habitats deleterious to the survival of their larvae. In an experiment designed to elucidate the mechanisms that explain the attractiveness and nutritional quality of leaf litter subsidies to mosquitoes, we prepared infusions from mixtures of leaves from four different plant species: common blackberry (Rubus allegheniensis), Amur honeysuckle (Lonicera maackii), elderberry (Sambucus canadensis), and autumn olive (Elaeagnus umbellata). To investigate differences in microbial communities among the leaf litter mixtures, 75 DNA extracts were sequenced using Illumina MiSeq Bulk v3 analysis bacterial operational taxonomic units (OTUs) were profiled across the 15 leaf litter mixtures. We targeted three hypervariable regions of the 16S rRNA gene. Our analyses suggest that oviposition site selection by Cx. pipiens is mediated primarily by chemical cues as leaves decompose. However, we also show here that juvenile mosquito survival mainly is related to the suitability of the bacterial community in the aquatic habitat for mosquito nutritional needs, which does not appear to create a cue that influences oviposition choice. This mismatch between oviposition cues and drivers of larval habitat quality may account for the ecological trap phenomenon detected in this study. Collectively, our findings provide new insights into potential mechanistic pathways by which ecological traps may occur in nature and experimental proof-of-concept for an environmentally safe and effective ‘attract-and-kill’ tool for mosquito control