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1. Climate‐related geographical variation in performance traits across the invasion front of a widespread non‐native insect

   https://doi.org/10.1111/jbi.14005  

   Thompson, Lily M. ; Powers, Sean D. ; Appolon, Ashley ; Hafker, Petra ; Milner, Lelia ; Parry, Dylan ; Agosta, Salvatore J. ; Grayson, Kristine L. ( November 2020 , Journal of Biogeography)

   Invasive species are ideal systems for testing geographical differences in performance traits and measuring evolutionary responses as a species spreads across divergent climates and habitats. The European gypsy moth,Lymantria dispar disparL. (Lepidoptera: Erebidae), is a generalist forest defoliator introduced to Medford, Massachusetts, USA in 1869. The invasion front extends from Minnesota to North Carolina and the ability of this species to adapt to local climate may contribute to its continuing spread. We evaluated the performance of populations along the climatic gradient of the invasion front to test for a relationship between climate and ecologically important performance traits.

   Eastern United States of America

   Lymantria dispar disparL. (Lepidoptera: Erebidae)

   Insects from 14 populations across the US invasion front and interior of the invasive range were reared from hatch to adult emergence in six constant temperature treatments. The responses of survival, pupal mass and larval development time were analysed as a function of source climate (annual mean normal temperature), rearing temperature and their interaction using multiple polynomial regression.

   With the exception of female development time, there were no significant interactions between source climate and rearing temperature, indicating little divergence in the shape of thermal reaction norms among populations. Source population and rearing temperature were significant predictors of survival and pupal mass. Independent of rearing temperature, populations from warmer climates had lower survival than those from colder climates, but attained larger body size despite similar development times. Larval development time was dependent on rearing temperature, but there were not consistent relationships with source climate.

   Thermal adaptation can be an important factor shaping the spread of invasive species, particularly in the context of climate change. Our results suggest thatL. d. disparis highly plastic, but has undergone climate‐related adaptation in thermal performance and life‐history traits as it spread across North America.

    

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2. Characterizing seasonal changes in the reproductive activity of Culex mosquitoes throughout the fall, winter, and spring in Ohio

   https://doi.org/10.1186/s13071-023-05806-0  

   Siperstein, Alden ; Pomeroy, Laura W. ; Robare, Sydney ; Sarko, Lucas ; Dehus, Hannah ; Lowmiller, Taylor ; Fyie, Lydia ; Meuti, Megan E. ( May 2023 , Parasites & Vectors)

   Culexmosquitoes are the primary vectors of West Nile virus (WNV) across the USA. Understanding when these vectors are active indicates times when WNV transmission can occur. This study determined the proportion of femaleCulexmosquitoes that were in diapause during the fall and winter and when they terminated diapause and began blood feeding in the spring.

   Mosquitoes were collected from parks using various traps and/or aspirated from culverts in Franklin County, Ohio, from October to mid-May from 2019 to 2022.Culexmosquitoes were morphologically identified to species, and the ovaries of females were dissected to determine their diapause and parity statuses.

   By early October 2021, roughly 95% ofCulex pipienscollected in culverts were in diapause and 98% ofCx. erraticuswere in diapause. Furthermore, gravid and blood-fedCulex salinarius,Cx. pipiens, andCx. restuanswere collected in late November in 2019 and 2021 in standard mosquito traps. In the winter of 2021, the proportions of non-diapausingCulexdecreased within culverts. The last non-diapausingCx. erraticuswas collected in late December 2021 while the final non-diapausingCx. pipienswas collected in mid-January 2022, both in culverts. Roughly 50% ofCx. pipiensterminated diapause by mid-March 2022, further supported by our collections of gravid females in late March in all 3 years of mosquito collection. In fact, male mosquitoes ofCx. pipiens,Cx. restuans, andCx. territanswere collected by the 1st week of May in 2022, indicating that multiple species ofCulexproduced a second generation that reached adulthood by this time.

   We collected blood-fed and gravidCulexfemales into late November in 2 of the 3 years of our collections, indicating that it might be possible for WNV transmission to occur in late fall in temperate climates like Ohio. The persistence of non-diapausingCx. pipiensandCx. erraticusthroughout December has important implications for the winter survival of WNV vectors and our overall understanding of diapause. Finally, determining whenCulexterminate diapause in the spring may allow us to optimize mosquito management programs and reduce the spread of WNV before it is transmitted to humans.

    

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3. Resistance from a resident heterospecific affects establishment success of a globally invasive freshwater fish

   https://doi.org/10.1111/fwb.14035  

   Deacon, Amy E. ; Fraser, Douglas F. ; Farrell, Aidan D. ( December 2022 , Freshwater Biology)

   The role of biotic resistance is a subject of debate in our understanding of invasions. We used a well‐known system in the Northern Range of Trinidad, where ephemeral conditions in small pool habitats lead to repeated colonisation by two native species (guppies,Poecilia reticulata, and killifish,Anablepsoides hartii), to ask questions about the role of biotic resistance and intraguild predation in natural, small‐water habitats.

   Using horticultural containers under forest cover, alongside constructed bankside mesocosms, we established populations of each species to test hypotheses concerning the conditions under which the guppy, a globally successful invasive species with the potential to establish populations from a single female, could be excluded by a resident intraguild predator, the killifish.

   Recruitment success of the guppy depended on founder numbers (propagule size) and introduction order (whether first or last to arrive in the habitat). Single founder guppies always failed to recruit in pools with resident killifish, which we posit is directly attributable to biotic resistance from the resident. However, increased propagule pressure (introduction attempts and propagule number) greatly increased the probability of successful invasion.

   Our results have two main implications. The first is that guppies are capable of being successful colonisers even in the presence of a resident intraguild predator. The second is to highlight the role that biotic resistance can play in preventing establishment in small‐water habitats, especially under circumstances of low propagule pressure.

   While previous studies have shown that guppies are strong colonisers outside of their native range, our findings suggest that this may not always be the case when there are other small‐bodied fish present. Accordingly, we argue that in small‐water habitats, biotic resistance and intraguild predation relationships should be important considerations when the ability to establish is being assessed for a taxon.

    

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4. Heterocypris incongruens maintains an egg bank in stormwater habitats and influences the development of larval mosquito, Culex restuans

   https://doi.org/10.1002/ece3.10445  

   Trujillo, Jacqueline ; Schwing, Cameron D. ; Muturi, Ephantus J. ; Cáceres, Carla E. ( August 2023 , Ecology and Evolution)

   Dormant propagules can provide a rapid colonization source for temporary aquatic habitats and set the trajectory for community dynamics, yet the egg banks of stormwater management systems have received little attention. We asked which species hatched from the sediment of drainage ditches in Champaign County, IL, and found bdelloid rotifers and ostracods (Heterocypris incongruens) to be the most common taxa. These sites also are colonized by mosquitoes, and we established laboratory experiments to examine interspecific interactions between common co‐occurring taxa.Culex restuanslarvae were reared in the presence or absence ofH. incongruensat two intra‐ and interspecific densities (20 or 40 total individuals) and their survivorship to adulthood, development time to adulthood, adult body size, and sex ratio were determined. Survival forCx. restuanswas significantly lower at high larval density than at low larval density in both treatments.Culex restuanslarvae reared in the presence ofH. incongruenshad a shorter development time to adulthood and emerged as larger adults compared to those reared in the absence ofH. incongruens. The sex ratios in theH. incongruenstreatments were female‐biased whereas those in theCulex‐only treatments were male‐biased. These differences may have epidemiological implications, as only female mosquitoes serve as disease vectors. Our results emphasize the importance of understanding interspecific interactions in influencing larval mosquito development traits.

    

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5. Baltimore Ecosystem Study: Physical, chemical and biological properties of forest and home lawn soils

   https://doi.org/10.6073/pasta/3847c58578bd9d5987a49e55066b497b  

   Groffman, Peter M ; Raciti, Steve ( January 2020 , Environmental Data Initiative)

   Abstract: One-meter soil cores were taken to evaluate soil texture, bulk density, carbon and nitrogen pools, microbial biomass carbon and nitrogen content, microbial respiration, potential net nitrogen mineralization, potential net nitrification and inorganic nitrogen pools in 32 residential home lawns that differed by previous land use and age, but had similar soil types. These were compared to soils from 8 forested reference sites. Purpose: Soil cores were obtained from residential and forest sites in the Baltimore, MD USA metropolitan area. The residential sites were mostly within the Gwynns Falls Watershed (-76.012008W, -77.314183E, 39.724847N, 38.708367S and approximately 17 km2) Lawns on residential sites were dominated by a variety of cool season turfgrasses. Forest soil cores were taken from permanent forest plots of the Baltimore Ecosystem Study (BES) LTER (Groffman et al. 2006). These remnant forests are over 100 years old with soils that were comparable in type and texture to those underlying the residential study sites. Soils from all sites were from the Manor series (coarse-loamy, micaceous, mesic Typic Dystrudepts), which are well-drained upland soils with loamy textures and bedrock at 5 to 10 feet below the soil surface. To aid the site selection process we used neighborhoods in the Baltimore City metropolitan area that have been mapped using HERCULES, a high resolution land cover classification system designed to assist in the study of human-ecological systems (Cadenasso et al. 2007). Using HERCULES and additional data sources, we identified residential sites that were similar except for single factors that we hypothesized to be important predictors of ecosystem dynamics. These factors included land use history (agriculture and forest, n = 10 and n = 22), housing density (low and medium/high, n = 9 and n = 23), and housing age (4 to 58 yrs old, n = 32). Housing age was acquired from the Maryland Property View database. Prior land use was determined based on land use change maps developed by integrating aerial photos from 1938, 1957, 1971, and 1999 into a geographic information system. Once a list of residential parcels meeting the predefined criteria were identified, we sent mailings to property owners chosen at random from each of the factor groups with the goal of recruiting 40 property owners for a 3 year study (of which this work is a part). We had recruited 32 property owners at the time that soil cores were obtained. Data have been published in Raciti et al. (2011a, 2011b) References Cadenasso, M. L., S. T. A. Pickett, and K. Schwarz. 2007. Spatial heterogeneity in urban ecosystems: reconceptualizing land cover and a framework for classification. Frontiers in Ecology and the Environment 5:80-88. Groffman, P. M., R. V. Pouyat, M. L. Cadenasso, W. C. Zipperer, K. Szlavecz, I. D. Yesilonis, L. E. Band, and G. S. Brush. 2006. Land use context and natural soil controls on plant community composition and soil nitrogen and carbon dynamics in urban and rural forests. Forest Ecology and Management 236:177-192. Raciti, S. R., P. M. Groffman, J. C. Jenkins, R. V. Pouyat, and T. J. Fahey. 2011a. Controls on nitrate production and availability in residential soils. Ecological Applications:In press. Raciti, S. R., P. M. Groffman, J. C. Jenkins, R. V. Pouyat, T. J. Fahey, M. L. Cadenasso, and S. T. A. Pickett. 2011b. Accumulation of carbon and nitrogen in residential soils with different land use histories. Ecosystems 14:287-297. 

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