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Results for “Environmental Entomology”

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31 records · Page 2Linked to original sources
USGS2019

Effect of corolla slitting and nectar robbery by the Eastern Carpenter Bee (Hymenoptera: Apidae) on fruit quality of Vaccinium corymbosum, L.; (Ericales: Ericaceae).

Eastern carpenter bees, Xylocopa virginica (L.) (Hymenoptera: Apidae), are among the most abundant native bee visitors to highbush blueberry, Vaccinium corymbosum L., flowers in the northeastern United States, and they sometimes display corolla-slitting behavior to rob nectar. We studied foraging behavior of X. virginica on 14 blueberry cultivars in an experimental planting in Rhode Island, and assessed factors related to slitting frequency, and the effects of slitting on fruit set and blueberry quality. Among 14 cultivars in bloom, an average of 35% (range 16–67%) of flowers were slit in 2017, and 39% (range 20–62%) in 2018. Factors that affected the proportion of corollas slit included cultivar, anther length, flower volume, and number of days in bloom at or above 15°C. Corolla slitting did not affect fruit set. Average weight and percent soluble solids of fruit resulting from slit and non-slit corollas did not differ significantly in two early- ( ‘ Bluehaven ’ , ‘ Earliblue ’ ), two mid- ( ‘ Collins ’ , ‘ Bluecrop ’ ), and two late-season ( ‘ Herbert ’ , ‘ Lateblue ’ ) ripening cultivars in 2017. In 2018, average fruit weight and percent soluble solids resulting from slit and non-slit flowers did not differ significantly in most cultivars, but slit corollas resulted in berries with greater mass in two cultivars, ‘ Bluehaven ’ and ‘ Collins ’ . ‘ Collins ’ fruit from non-slit corollas had a significantly higher percentage of soluble solids at maturity than fruit from slit corollas in 2018. Corolla slitting and nectar robbery by X. virginica did not have a significant negative effect on fruit quality under the described growing conditions and pollinator community.

Rhode Island↗
USGS2019

Effects of stream temperature and substrate type on emergence patterns of Plecoptera and Trichoptera from northeastern United States headwater streams

The timing and spatial distribution of aquatic insect emergence is linked to the abiotic and biotic environment in streams. Studies of aquatic insect emergence are needed to generate baseline data to identify potential shifts in phenology and habitat-related emergence with global change. The purpose of this study was to 1) compare the timing of Plecoptera (stonefly) species emergence between two streams with different thermal regimes and 2) characterize the distribution of emerging Plecoptera and Trichoptera (caddisflies) from wood, rock, gravel, and sand substrates in five forested, headwater streams. Emergence timing and duration varied among Plecoptera species, with Ostrocerca albidipennis (Walker) (Plecoptera: Nemouridae) emerging only in May and four species in the genus Leuctra (Plecoptera: Leuctridae) collectively emerging throughout the summer (May to September). We observed earlier emergence of Amphinemura nigritta (Provancher) (Plecoptera: Nemouridae) and a longer total emergence period for Leuctra ferruginea (Walker) (Plecoptera: Leuctridae) in the stream with ~1.5°C warmer temperatures, which suggested that some insects may experience phenological shifts in streams with subtle differences in temperature. The abundance of plecopteran and trichopteran taxa emerging from wood was generally greater than for gravel or sand, and sand was the least preferred emergence substrate. The results suggest that human actions that decrease large wood and increase fine sedimentation may decrease habitat quality for many insect larvae and limit preferred emergence substrates.

Massachusetts↗
USGS2019

Do the quality and quantity of honey bee-collected pollen vary across an agricultural land use gradient?

Pollen is the source of protein for most bee species, yet the quality and quantity of pollen is variable across landscapes and growing seasons. Understanding the role of landscapes in providing nutritious forage to bees is important for pollinator health, particularly in areas undergoing significant land-use change such as in the Northern Great Plains (NGP) region of the United States where grasslands are being converted to row crops. We investigated how the quality and quantity of pollen collected by honey bees ( Apis mellifera L. [Hymenoptera: Apidae]) changed with land use and across the growing season by sampling bee-collected pollen from apiaries in North Dakota, South Dakota, and Minnesota, USA, throughout the flowering season in 2015–2016. We quantified protein content and quantity of pollen to investigate how they varied temporally and across a land-use gradient of grasslands to row crops. Neither pollen weight nor crude protein content varied linearly across the land-use gradient; however, there were significant interactions between land use and sampling date across the season, particularly in grasslands. Generally, pollen protein peaked mid-July while pollen weight had two maxima in late-June and late-August. Results suggest that while land use itself may not correlate with the quality or quantity of pollen resources collected by honey bees among our study apiaries, the nutritional landscape of the NGP is seasonally dynamic, especially in certain land covers, and may impose seasonal resource limitations for both managed and native bee species. Furthermore, results indicate periods of qualitative and quantitative pollen dearth may not coincide.

Minnesota, North Dakota, South Dakota↗
USGS2002

Potential nontarget effects of Metarhizium anisopliae (Deuteromycetes) used for biological control of ticks (Acari: Ixodidae)

The potential for nontarget effects of the entomopathogenic fungus Metarhizium anisopliae (Metschnikoff) Sorokin, when used for biological control of ticks, was assessed in laboratory trials. Fungal pathogenicity was studied against convergent ladybird beetles, Hippodamia convergens Guérin-Méneville, house crickets, Acheta domesticus (L.), and the milkweed bugs Oncopeltus fasciatus (Dallas). Fungal spores applied with a spray tower produced significant mortality in H. convergens and A. domesticus , but effects on O. fasciatus were marginal. Placing treated insects with untreated individuals resulted in mortality from horizontal transmission to untreated beetles and crickets, but not milkweed bugs. Spread of fungal infection in the beetles resulted in mortality on days 4–10 after treatment, while in crickets mortality was on day 2 after treatment, suggesting different levels of pathogenicity and possibly different modes of transmission. Therefore, M. anisopliae varies in pathogenicity to different insects. Inundative applications can potentially affect nontarget species, but M. anisopliae is already widely distributed in North America, so applications for tick control generally would not introduce a novel pathogen into the environment. Pathogenicity in lab trials does not, by itself, demonstrate activity under natural conditions, so field trials are needed to confirm these results and to assess methods to minimize nontarget exposure.

Environmental Entomology↗
USGS2004

Woodland type and spatial distribution of nymphal Ixodes scapularis (Acari: Ixodidae)

Spatial distribution patterns of black-legged ticks, Ixodes scapularis , in deciduous and coniferous woodlands were studied by sampling ticks in different woodland types and at sites from which deer had been excluded and by quantifying movement patterns of tick host animals (mammals and birds) at the Lighthouse Tract, Fire Island, NY, from 1994 to 2000. Densities of nymphal ticks were greater in deciduous than coniferous woods in 3 of 7 yr. Only engorged ticks survived the winter, and overwintering survival of engorged larvae in experimental enclosures did not differ between deciduous and coniferous woods. Nymphs were not always most abundant in the same forest type as they had been as larvae, and the habitat shift between life stages differed in direction in different years. Therefore, forest type by itself did not account for tick distribution patterns. Nymphal densities were lower where deer had been excluded compared with areas with deer present for 3 yr after exclusion, suggesting that movement patterns of vertebrate hosts influenced tick distribution, but nymphal densities increased dramatically in one of the enclosures in the fourth year. Therefore, movements of ticks on animal hosts apparently contribute substantially to tick spatial distribution among woodland types, but the factor(s) that determine spatial distribution of nymphal I. scapularis shift from year to year.

New York↗
USGS2004

Effects of natural forest fragmentation on a Hawaiian spider community

The kipuka system, a network of forest fragments surrounded by lava flows on the island of Hawaii, offers an opportunity to study the natural, long-term fragmentation of a native ecosystem. We examined the impacts of habitat edges upon the community structure of nocturnally active native spiders, primarily in the genus Tetragnatha. We measured plant and spider species distributions across the edges of four small fragments and one large continuously forested area that were surrounded by a lava flow in 1855. Results indicated that an ???20 m edge ecotone surrounds core forest habitat. Spider community structure changed across the edge, with a decrease in total species richness and diversity at the forest/lava boundary, and a change in the dominant taxon from native Tetragnatha (Tetragnathidae) to native Cyclosa (Araneidae). Severe habitat restrictions were found for some spider species. In addition, nearly all of the spiders captured were endemic species, and the few introduced species were limited to the younger and more open lava flows. Our results suggest that species responses to edges can vary, and that core habitat specialists may decline in fragmented conditions.

Environmental Entomology↗
USGS2005

Longer-term effects of selective thinning on microarthropod communities in a late-successional coniferous forest

Microarthropod densities within late-successional coniferous forests thinned 16–41 yr before sampling were compared with adjacent unthinned stands to identify longer term effects of thinning on this community. Soil and forest floor layers were sampled separately on eight paired sites. Within the forest floor oribatid, mesostigmatid, and to a marginal extent, prostigmatid mites, were reduced in thinned stands compared with unthinned stands. No differences were found for Collembola in the forest floor or for any mite suborder within the soil. Family level examination of mesostigmatid and prostigmatid mites revealed significant differences between stand types for both horizons. At the species level, thinning influenced numerous oribatid mites and Collembola. For oribatid mites, significant or marginally significant differences were found for seven of 15 common species in the forest floor and five of 16 common species in soil. Collembola were affected less, with differences found for one of 11 common species in the forest floor and three of 13 common species in soil. Multivariate analysis of variance and ordination indicated that forest thinning had little influence on the composition of oribatid mite and collembolan communities within either the forest floor or soil. Differences in microclimate or in the accumulation of organic matter on the forest floor were likely most responsible for the observed patterns of abundance. Considering the role that microarthropods play in nutrient cycling, determining the functional response of a wide range of taxa to thinning may be important to effective ecosystem management.

Oregon↗
USGS2017

Potential concerns with analytical Methods Used for the detection of Batrachochytrium salamandrivorans from archived DNA of amphibian swab samples, Oregon, USA

Taxonomic identification of pollen has historically been accomplished via light microscopy but requires specialized knowledge and reference collections, particularly when identification to lower taxonomic levels is necessary. Recently, next-generation sequencing technology has been used as a cost-effective alternative for identifying bee-collected pollen; however, this novel approach has not been tested on a spatially or temporally robust number of pollen samples. Here, we compare pollen identification results derived from light microscopy and DNA sequencing techniques with samples collected from honey bee colonies embedded within a gradient of intensive agricultural landscapes in the Northern Great Plains throughout the 2010–2011 growing seasons. We demonstrate that at all taxonomic levels, DNA sequencing was able to discern a greater number of taxa, and was particularly useful for the identification of infrequently detected species. Importantly, substantial phenological overlap did occur for commonly detected taxa using either technique, suggesting that DNA sequencing is an appropriate, and enhancing, substitutive technique for accurately capturing the breadth of bee-collected species of pollen present across agricultural landscapes. We also show that honey bees located in high and low intensity agricultural settings forage on dissimilar plants, though with overlap of the most abundantly collected pollen taxa. We highlight practical applications of utilizing sequencing technology, including addressing ecological issues surrounding land use, climate change, importance of taxa relative to abundance, and evaluating the impact of conservation program habitat enhancement efforts.

Oregon↗
USGS2020

Practical considerations for the incorporation of insect-mediated contaminant flux into ecological risk assessments

Insect-mediated contaminant flux is truly an interdisciplinary concept that merges ideas from many technical areas of science (e.g., environmental chemistry, landscape ecology, and entomology). This chapter introduces risk assessors to this emerging and ecologically relevant concept by distilling the main mechanisms that drive insect-mediated contaminant flux and integrating them together so that more informed decisions can be made on whether the phenomenon presents a potential risk at a site.

Book chapter↗
USGS2016

Relationships between maternal engorgement weight and the number, size, and fat content of larval Ixodes scapularis (Acari: Ixodidae)

The relationship between engorgement weight of female Ixodes scapularis Say and characteristics of offspring was studied using field-collected females fed on rabbits in the laboratory. The number of eggs laid was positively related to maternal engorgement weight in one trial, and larval size (estimated by scutal area) was positively related to maternal engorgement weight in the other. These results suggest a trade-off in number of eggs produced versus average size of offspring, possibly determined during late engorgement. The adults for the two trials were collected from different sites in southern Rhode Island and in different seasons (the fall adults were newly emerged, while the spring adults had presumably lived through the winter), so it is not clear whether these results reflect genetic differences or subtle environmental differences between trials. Percent egg hatch and average fat content of larvae were not related to female engorgement weight. We present a modified method to measure lipid content of pooled larval ticks.

Journal of Medical Entomology↗
USGS2016

Modeling the geographic distribution of Ixodes scapularis and Ixodes pacificus (Acari: Ixodidae) in the contiguous United States

In addition to serving as vectors of several other human pathogens, the black-legged tick, Ixodes scapularis Say, and western black-legged tick, Ixodes pacificus Cooley and Kohls, are the primary vectors of the spirochete ( Borrelia burgdorferi ) that causes Lyme disease, the most common vector-borne disease in the United States. Over the past two decades, the geographic range of I. pacificus has changed modestly while, in contrast, the I. scapularis range has expanded substantially, which likely contributes to the concurrent expansion in the distribution of human Lyme disease cases in the Northeastern, North-Central and Mid-Atlantic states. Identifying counties that contain suitable habitat for these ticks that have not yet reported established vector populations can aid in targeting limited vector surveillance resources to areas where tick invasion and potential human risk are likely to occur. We used county-level vector distribution information and ensemble modeling to map the potential distribution of I. scapularis and I. pacificus in the contiguous United States as a function of climate, elevation, and forest cover. Results show that I. pacificus is currently present within much of the range classified by our model as suitable for establishment. In contrast, environmental conditions are suitable for I. scapularis to continue expanding its range into northwestern Minnesota, central and northern Michigan, within the Ohio River Valley, and inland from the southeastern and Gulf coasts. Overall, our ensemble models show suitable habitat for I. scapularis in 441 eastern counties and for I. pacificus in 11 western counties where surveillance records have not yet supported classification of the counties as established.

Journal of Medical Entomology↗
USGS1999

Preliminary survey for entomopathogenic fungi associated with Ixodes scapularis (Acari: Ixodidae) in southern New York and New England, USA

Free-living larval, nymphal, and adult Ixodes scapularis Say were collected from scattered locales in southern New England and New York to determine infection rates with entomopathogenic fungi. Infection rates of larvae, nymphs, males, and females were 0% (571), 0% (272), 0% (57), and 4.3% (47), respectively. Two entomopathogenic fungi were isolated from field-collected I. scapularis females from Fire Island, NY. Isolates were identified as Verticillium lecanii (Zimmermann) Viegas and Verticillium sp. (a member of the Verticillium lecanii species complex). Ixodes scapularis Say is the principal vector of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner ( Burgdorfer et al. 1982 , Johnson et al. 1984 ), the etiologic agent of Lyme disease in the northeastern and upper-midwestern United States. Control of I. scapularis is based on chemical treatment ( Mather et al. 1987b ; Schulze et al. 1987 , 1991 ), environmental management ( Wilson et al. 1988 , Schulze et al. 1995 ), and habitat modification ( Wilson 1986 ). These methods have shown variable success, and some potentially have negative environmental effects ( Wilson and Deblinger 1993 , Ginsberg 1994 ). Studies concerning natural predators, parasitoids, and pathogens of I. scapularis are rare. The use of ground-dwelling birds as tick predators has had only limited success ( Duffy et al. 1992 ). Nymphal I. scapularis are often infected with the parasitic wasp Ixodiphagus hookeri (Howard) ( Mather et al. 1987a , Hu et al. 1993 , Stafford et al. 1996 , Hu and Hyland 1997 ), but this wasp does not effectively control I. scapularis populations ( Stafford et al. 1996 ). The entomopathogenic nematodes Steinernema carpocapsae (Weiser) and S. glaseri (Steiner) are pathogenic only to engorged female I. scapularis, and thus have limited applicability ( Zhioua et al. 1995 ). In contrast, the entomogenous fungus Metarhizium anisopliae (Metschnikoff) Sorokin is highly pathogenic to all stages of I. scapularis, unfed as well as engorged, and thus has considerable potential as a microbial control agent ( Zhioua et al. 1997 ). European studies have suggested that entomopathogenic fungi might serve as natural controls of of Ixodes ricinus L. populations ( Samsinakova et al. 1974 , Eilenberg et al. 1991 , Kalsbeek et al. 1995 ). In the current study, we describe the isolation of entomopathogenic fungi from field-collected I. scapularis.

Journal of Medical Entomology↗
USGS2019

Differences in mosquito communities in six cities in Oklahoma

Vector-borne diseases in the United States have recently increased as a result of the changing nature of vectors, hosts, reservoirs, pathogens, and the ecological and environmental conditions. Current information on vector habitats and how mosquito community composition varies across space and time is vital to successful vector-borne disease management. This study characterizes mosquito communities in urban areas of Oklahoma, United States, an ecologically diverse region in the southern Great Plains. Between May and September 2016, 11,996 female mosquitoes of 34 species were collected over 798 trap nights using three different trap types in six Oklahoma cities. The most abundant species trapped were Culex pipiens L. complex (32.4%) and Aedes albopictus (Skuse) (Diptera: Culicidae) (12.0%). Significant differences among mosquito communities were detected using analysis of similarities (ANOSIM) between the early (May–July) and late (August–September) season. Canonical correlation analysis (CCA) further highlighted the cities of Altus and Idabel as relatively unique mosquito communities, mostly due to the presence of Aedes aegypti (L.) and salt-marsh species and absence of Aedes triseriatus (Say) in Altus and an abundance of Ae. albopictus in Idabel. These data underscore the importance of assessing mosquito communities in urban environments found in multiple ecoregions of Oklahoma to allow customized vector management targeting the unique assemblage of species found in each city.

Oklahoma↗