In field-based diversity surveys that continued and expanded upon work done in the summer of 2014, we sampled adult and larval mosquito populations at five Boston-area study sites. Though a summer drought hindered our initial goal of comparing island and mainland mosquito populations, the dry conditions promoted the success of our larval sampling, which made use of black plastic “ovitraps” to mimic natural tree hole oviposition sites.
Over five months of larval sampling, we collected and identified both native and exotic species, as well as species thought to be rare in Massachusetts (Anopheles barberi, Culex erraticus, and possibly Aedes punctor). Additionally, we collected probable hybrid specimens from tree holes and ovitraps frequented by both Aedes triseriatus and Aedes hendersoni females, revealing a close ecological relationship that merits further molecular analysis. The findings of our surveys have implications for climate change-driven shifts in species distribution, as well as more local effects of niche partitioning. After the conclusion of the field season, we finished rearing the late-hatching larval batches in the lab. Now that all specimens have been processed and identified, samples of Ae. triseriatus and Ae. hendersoni will be tested with a novel hybridization primer developed by Wilson et al., and species identifications will be verified with selective DNA barcoding using the COI region.
Our datasets include a record of adult mosquito abundance and diversity at Thompson island; seasonal fecundity rates based on egg-collecting ovitraps at our several mainland sites; still-pending genomic data including the COI-region sequences of sample specimens of each species; and a forthcoming molecular assay for the presence or absence of hybrid DNA among Ae. hendersoni/triseriatus populations. Statistical analysis of these data (still to be completed) will depend on the results of the molecular hybridization assay: if hybrid DNA is confirmed within a single individual, we will proceed in determining the maternal DNA of the specimen and potentially also develop a metric for the degree/extent of hybridization within a site. If we find that specimens identified as potential hybrids based on morphology alone turn out to be pure-bred individuals, we may consider other hypotheses for their phenotypic differences.
Outside this species pairing, our larval surveys revealed interesting distribution patterns in populations of Ae. japonicus, which we hypothesize may be related to proximity to human disturbance. This theory could be tested with the application of GIS software to determine distance to the nearest inhabited site, which would be regressed against Ae. japonicus collection rates at a site.
Our observations on the distribution of species (like Ae. japonicus, Anopheles barberi, and Culex erraticus) represent in themselves a noteworthy advancement in regional mosquito ecology. It is likely that our continued analysis of our samples from the field will reveal further enlightening information on these species and their interactions in the wild.
