Discarded vehicle tire casings are an important artificial habitat for the developmental stages of numerous vector mosquitoes. Discarded vehicle tires degrade under ultraviolet light and leach numerous soluble metals (e.g., barium, cadmium, zinc) and organic substances (e.g., benzothiazole and its derivatives [BTs], polyaromatic hydrocarbons [PAHs]) that could affect mosquito larvae that inhabit the tire casing. This study examined the relationship between soluble zinc, a common marker of tire leachate, on mosquito densities in tire habitats in the field, and tested the effects of tire leachate on the survival and development of newly hatched Aedes albopictus and Aedes triseriatus larvae in a controlled laboratory dose-response experiment. In the field, zinc concentrations were as high as 7.26 mg/L in a single tire and averaged as high as 2.39 (SE±1.17) mg/L among tires at a single site. A. albopictus (37/42 tires, 81.1%) and A. triseriatus (23/42, 54.8%) were the most widespread mosquito species, co-occurred in over half (22/42, 52.4%) of all tires, and A. triseriatus was only collected without A. albopictus in one tire. A. triseriatus was more strongly negatively associated with zinc concentration than A. albopictus, and another common mosquito, C. pipiens, which was found in 17 tires. In the laboratory experiment, A. albopictus per capita rate of population change (l') was over 1.0, indicating positive population growth, from 0 to 10,000 mg/L tire leachate, corresponding to 8.9 mg/L zinc concentration, but steeply declined to zero from 50,000 to 100,000 mg/L tire leachate (44.5-89.0 mg/L zinc). In contrast, A. triseriatus l' declined at the lower concentration of 100 mg/L tire leachate (0.05 mg/L zinc), and was zero at 500, 10,000, 50,000 and 100,000 mg/L tire leachate. These results indicate that tire leachate can have severe negative effects on populations of container utilizing mosquitoes at concentrations commonly found in the field. Superior tolerance to tire leachate of A. albopictus compared to A. triseriatus, and possibly other native mosquito species, may have facilitated the replacement of these native species as A. albopictus has invaded North America and other regions around the PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.3065v1 | CC BY 4.0 Open Access | rec Abstract 15 Discarded vehicle tire casings are an important artificial habitat for the developmental stages of 16 numerous vector mosquitoes. Discarded vehicle tires degrade under ultraviolet light and leach 17 numerous soluble metals (e.g., barium, cadmium, zinc) and organic substances (e.g., 18 benzothiazole and its derivatives [BTs], polyaromatic hydrocarbons [PAHs]) that could affect 19 mosquito larvae that inhabit the tire casing. This study examined the relationship between 20 soluble zinc, a common marker of tire leachate, on mosquito densities in tire habitats in the field, 21 and tested the effects of tire leachate on the survival and development of newly hatched Aedes 22 albopictus and Aedes triseriatus larvae in a cont...

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Aspects of population growth rates are examined for cohorts of the treeholes mosquito Aedes triseriatus, reared in field containers under different conditions of larval density, concentration of natural treehole fluid, and in the presence or absence of a late—hatching cohort of larvae. Density and fluid concentration produced similar and independent significant competitive effects on each measure of cohort success, including female mass, development time, and survival to the adult stage, as well as on a composite index of performance. The sensitivity of first—cohort development time to high density and dilute fluid was reduced by the presence of the second cohort, and first—cohort survivorship responses to fluid concentration and density suggest an enhanced performance in dilute medium and intermediate density due to the addition of the second cohort. A composite index did not detect these complex interactions of experimental factors, suggesting that overall population growth rates for the first cohort respond to density and food in a very simple manner. The second cohort experienced total mortality in the presence of high first—cohort density, dilute medium, or the incidental oviposition of another treehole mosquito, Anopheles barberi, and never matched the success of the first cohort, even under conditions of low density and concentrated fluid.

We provide an analysis of the invasion and spread of the container inhabiting mosquitoes Aedes aegypti and Aedes albopictus in the Bermuda Islands. Considered eradicated in the mid-1960s, A. aegypti was redetected in 1997, and A. albopictus was first detected in 2000. Based on weekly ovitrap data collected during the early stages of the invasion, we mapped the spread of Aedes throughout the islands. We analyzed the effects of buildings and roads on mosquito density and found a significant association between density and distance to roads, but not to buildings. We discuss the potential role of human transport in the rapid spread in the islands. The temporal correlation in ovitrap collection values decreased progressively, suggesting that habitat degradation due to control efforts were responsible for local shifts in mosquito densities. We report a sharp decrease in A. aegypti presence and abundance after the arrival of A. albopictus in the year 2000. Possible mechanisms for this rapid decline at relatively low density of the second invader are discussed in the context of classical competition theory and earlier experimental results from Florida, as well as alternative explanations. We suggest that support for the competition hypothesis to account for the decline of A. aegypti is ambiguous and likely to be an incomplete explanation.

Summary 0[ We tested a set of hypotheses to predict egg!laying behaviour in Aedes triseriatus in the _eld in Massachusetts[ These hypotheses re~ect three main themes] females avoid competitive or predatory threats to their larvae^females judge larvae or eggs as cues to future permanence or productivity within a treehole^and females are either opportunistic ovipositors\ or hedge their bets by scattering their eggs in multiple habitats[ We predicted that mosquitoes might vary in their response depending on whether their o}spring will hatch immediately or enter diapause and hatch the next year[ 1[ We stocked arti_cial treeholes with larvae at four densities ranging from 9 to 89 larvae per habitat for four trials in 0881 and eight trials in 0883[ In 0881\ we added predatory Anopheles barberi larvae to half the replicates of each density level[ In 0883\ we tested for an interaction between egg and larval density by stocking additional traps with eggs in batches of 9\ 19 and 199\ and larvae in densities as in the previous trials[ 2[ The population revealed a signi_cant interaction between time of year and larval density[ More eggs accumulated in traps stocked with fewer larvae "9 or 04# early in the season\ but females showed a slight positive response to higher densities "34 or 89# later on\ after their o}spring were all likely to enter diapause[ These results suggest that potential ambiguities of larval cues\ with indications of habitat permanence as well as adversity of future competition\ are resolved by females[ Females did not respond di}erentially to the predatory Anopheles barberi larvae[ 3[ The estimated batch size obtained in oviposition traps did not di}er from the fecundity of _eld!caught females allowed to oviposit under con_nement in laboratory vials\ suggesting that bet!hedging by scattering of eggs among multiple habitats did not occur[ 4[ An unexpected result\ a positive response to higher egg densities\ is discussed in light of studies on other insects[ This result con~icts with our predictions based on females choosing less competitive environments for their larvae and also con~icts with previously published accounts of avoidance of eggs in this species[ Preference for habitats with conspeci_c eggs might be explained if eggs re~ect habitat stability or if larvae gain an advantage from being in an aggregation[ Neither hypothesis is resolved by the present study[