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The relationship between (a) the structure and composition of the landscape around an individual's home and (b) environmental perceptions and health outcomes has been well demonstrated (eg the value of vegetation cover to well‐being). Few studies, however, have examined how multiple landscape features (eg vegetation and water cover) relate to perceptions of multiple environmental problems (eg air or water quality) and whether those relationships hold over time. We utilized a long‐term dataset of geolocated telephone surveys in Baltimore, Maryland, to identify relationships between residents’ perceptions of environmental problems and nearby landcover. Residents of neighborhoods with more vegetation or located closer to water were less likely to perceive environmental problems. Water quality was one exception to this trend, in that people were more likely to perceive water‐quality problems when nearby water cover was greater. These trends endured over time, suggesting that these relationships are stable and therefore useful for informing policy aimed at minimizing perceived environmental problems.

 

Abstract Environmental conditions associated with urbanization are likely to influence the composition and abundance of mosquito (Diptera, Culicidae) assemblages through effects on juvenile stages, with important consequences for human disease risk. We present six years (2011–2016) of weekly juvenile mosquito data from distributed standardized ovitraps and evaluate how variation in impervious cover and temperature affect the composition and abundance of container-breeding mosquito species in Maryland, USA. Species richness and evenness were lowest at sites with high impervious cover (>60% in 100-m buffer). However, peak diversity was recorded at sites with intermediate impervious cover (28–35%). Four species were observed at all sites, including two recent invasives (Aedes albopictus Skuse, Ae. japonicus Theobald), an established resident (Culex pipiens L), and one native (Cx. restuans Theobald). All four are viral vectors in zoonotic or human transmission cycles. Temperature was a positive predictor of weekly larval abundance during the growing season for each species, as well as a positive predictor of rapid pupal development. Despite being observed at all sites, each species responded differently to impervious cover. Abundance of Ae. albopictus larvae was positively associated with impervious cover, emphasizing that this medically-important vector not only persists in the warmer, impervious urban landscape but is positively associated with it. Positive temperature effects in our models of larval abundance and pupae occurrence in container habitats suggest that these four vector species are likely to continue to be present and abundant in temperate cities under future temperature scenarios. 

Tree Baltimore (treebaltimore.org) hired Davey Tree to conduct a census of all publicly owned trees and tree pits in the city of Baltimore. This census was completed by arborists in 2017-2018, documenting over 192,000 trees and potential tree sites that reflect the public component of Baltimore’s urban forest. Entries in this dataset include trees in parkways (street trees), mown areas of public parks (forest patches excluded), meridian trees, and vacant spaces for tree planting. Data is continuously updated and the current vintage can be found at https://baltimore.maps.arcgis.com/apps/webappviewer/index.html?id=d2cfbbe9a24b4d988de127852e6c26c8. 

Tree canopy cover is a critical component of the urban environment that supports ecosystem services at multiple spatial and temporal scales. Increasing tree canopy across a matrix of public and private land is challenging. As such, municipalities often plant trees along streets in public rights‐of‐way where there are fewer barriers to establishment, and composition and biomass of street trees are inextricably linked to human decisions, management, and care. In this study, we investigated the contributions of street trees to the broader urban forest, inclusive of tree canopy distributed across both public and private parcels in Baltimore, MD, USA. We assess how species composition, biodiversity, and biomass of street trees specifically augment the urban forest at local and citywide scales. Furthermore, we evaluate how street tree contributions to the urban forest vary with social and demographic characteristics of local residential communities. Our analyses demonstrate that street trees significantly enhanced citywide metrics of the urban forests' richness and tree biomass, adding an average six unique species per site. However, street tree contributions did not ameliorate low tree canopy locations, and more street tree biomass was generally aligned with higher urban forest cover. Furthermore, species richness, abundance, and biomass added by street trees were all positively related to local household income and population density. Our results corroborate previous findings that wealthier urban neighborhoods often have greater tree abundance and canopy cover and, additionally, suggest that investment in municipally managed street trees may be reinforcing inequities in distribution and function of the urban forest. This suggests a need for greater attention to where and why street tree plantings occur, what species are selected, and how planted tree survival is maintained by and for residents in different neighborhoods.

 

Condition-specific competition, when environmental conditions alter the outcome of competition, can foster the persistence of resident species after the invasion of a competitively superior invader. We test whether condition-specific competition can facilitate the areawide persistence of the resident and principal West Nile virus vector mosquito Culex pipiens with the competitively superior invasive Aedes albopictus in water from different urban container habitats. (2) Methods: We tested the effects of manipulated numbers of A. albopictus on C. pipiens’ survival and development in water collected from common functional and discarded containers in Baltimore, MD, USA. The experiment was conducted with typical numbers of larvae found in field surveys of C. pipiens and A. albopictus and container water quality. (3) Results: We found increased densities of A. albopictus negatively affected the survivorship and development of C. pipiens in water from discarded containers but had little effect in water from functional containers. This finding was driven by water from trash cans, which allowed consistently higher C. pipiens’ survival and development and had greater mean ammonia and nitrate concentrations that can promote microbial food than other container types. (4) Conclusions: These results suggest that the contents of different urban containers alter the effects of invasive A. albopictus competition on resident C. pipiens, that trash cans, in particular, facilitate the persistence of C. pipiens, and that there could be implications for West Nile virus risk as a result. 

Abstract The temperate United States has experienced increasing incidence of mosquito-borne diseases. Recent studies conducted in Baltimore, MD have demonstrated a negative relationship between abundances of Aedes albopictus (Skuse) and Culex mosquitoes and mean neighborhood income level, but have not looked at the presence of pathogens. Mosquitoes collected from five socioeconomically variable neighborhoods were tested for infection by West Nile, chikungunya, and Zika viruses in 2015 and 2016, and again from four of the neighborhoods in 2017. Minimum infection rates of pooled samples were compared among neighborhoods for each year, as well as among individual blocks in 2017. West Nile virus was detected in both Ae. albopictus and Culex pools from all neighborhoods sampled in 2015 and 2017. No infected pools were detected in any year for chikungunya or Zika viruses, and none of the target viruses were detected in 2016. Infection rates were consistently higher for Culex than for Ae. albopictus. Minimum infection rate was negatively associated with mean neighborhood income for both species in 2015. Although earlier work has shown a positive association between block-level abandonment and mosquito abundance, no association was detected in this study. Still, we demonstrate that viral infection in mosquito pools can differ substantially across adjacent urban neighborhoods that vary by income. Though trap security and accessibility often inform city sampling locations, detecting and managing arboviral risk requires surveillance across neighborhoods that vary in socioeconomics, including lower income areas that may be less accessible and secure but have higher infection rates. 

Species interactions that influence the performance of the exotic mosquito Culex pipiens can have important effects on the transmission risk of West Nile virus (WNV). Invasive plants that alter the vegetation communities of ephemeral ground pools may facilitate or resist the spread of C. pipiens (L.) by altering allochthonous inputs of detritus in those pools. To test this hypothesis, we combined field surveys of roadside stormwater ditches with a laboratory microcosm experiment to examine relationships between C. pipiens performance and water quality in systems containing detritus from invasive Phragmites australis (Cav.) Trin. Ex Steud., introduced Schedonorus arundinaceus (Schreb.) Dumort., or native Juncus effusus L. or Typha latifolia L. In ditches, C. pipiens abundance was unrelated to detritus species but female C. pipiens were significantly larger from ditches with S. arundinaceus and smaller with J. effusus. Larger and smaller C. pipiens were also produced in microcosms provisioned with S. arundinaceus and J. effusus, respectively, yet the per capita rate of population of change did not vary. Larger females from habitats with S. arundinaceus were likely caused by faster decay rates of S. arundinaceus and resultant increases in microbial food, but lower survival as a result of fouling and higher tannin-lignin concentrations resulted in little changes to overall population performance. Larger female mosquitoes have been shown to have greater potential for transmitting arboviruses. Our findings suggest that changed community-level interactions from plant invasions in urban ephemeral ground pools can affect the fitness of C. pipiens and possibly increase WNV risk. 

Abstract Mosquitoes pose an increasing risk in urban landscapes, where spatial heterogeneity in juvenile habitat can influence fine-scale differences in mosquito density and biting activity. We examine how differences in juvenile mosquito habitat along a spectrum of urban infrastructure abandonment can influence the adult body size of the invasive tiger mosquito, Aedes albopictus (Skuse) (Diptera: Culicidae). Adult Ae. albopictus were collected across 3 yr (2015–2017) from residential blocks in Baltimore, MD, that varied in abandonment level, defined by the proportion of houses with boarded-up doors. We show that female Ae. albopictus collected from sites with higher abandonment were significantly larger than those collected from higher income, low abandonment blocks. Heterogeneity in mosquito body size, including wing length, has been shown to reflect differences in important traits, including longevity and vector competence. The present work demonstrates that heterogeneity in female size may reflect juvenile habitat variability across the spatial scales most relevant to adult Aedes dispersal and human exposure risk in urban landscapes. Previous work has shown that failure to manage abandonment and waste issues in impoverished neighborhoods supports greater mosquito production, and this study suggests that mosquitoes in these same neighborhoods could live longer, produce more eggs, and have different vector potential.