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Publications

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Ecology of Asclepias brachystephana: a plant for roadside and right of way management.

Authors: Shaun M McCoshum and Anurag Agrawal 

Insect Systematics and Diversity

Declining insect abundance is occurring around the world, and some management projects are aiming to utilize roadsides and other right-of-ways as insect conservation areas. In the US, the decline of the monarch butterfly (Danaus plexippus Linnaeus [Nymphalidae]) populations has led to multiple studies focusing on a small number of milkweed species (Asclepias [Apocynaceae]) that occur in the major flyways. Here we survey a poorly studied milkweed, bract milkweed (A. brachystephana Engelm. ex Torr.), to document where it grows, which organisms make use of the plants, seed production, and concentrations of milkweed toxins (cardenolides) and to investigate if this species is suitable for roadside or right-of-ways management projects. Our results show that the range of A. brachystephana includes the Chihuahuan Desert and neighboring ecoregions. Plant populations were also observed occurring on roadsides and right-of-ways, rarely spreading into neighboring habitats. We document a variety of native pollinators utilizing floral resources and a few herbivores feeding on plant tissue. Chemical analyses show wild plants produce higher concentrations of toxic cardenolide than many other milkweed species. These data suggest A. brachystephana should be considered for roadside and right-of-way plantings, restoration projects, or seeding throughout the Chihuahuan Desert and adjoining ecoregions.

 
Phylogeny, Phenology, and Forage of Ashmeadiella (Hymenoptera: Megachilidae).

Authors: Elizabeth A Murray, Laurelin Evanhoe, Silas Bossert, Monica A Geber, Terry Griswold, and Shaun M McCoshum 

Insect Systematics and Diversity

Ashmeadiella (Megachilidae: Osmiini) is a bee genus endemic to North America, with greatest richness in arid and Mediterranean regions of the southwestern United States. The last time the species relationships of Ashmeadiella were analyzed was in the 1950s, when Robert Sokal and Charles Michener developed a novel statistical clustering method for classification called numerical taxonomy. We built a molecular phylogeny to revisit the species groups they established that included all five subgenera in our sampling. We also assembled life history data to lay the foundation for future conservation programs for these bees. We chose three aspects of bee biology that can inform conservation strategies: documenting periods of the year adult bees are flying, assembling data for the flowers each species visits, and compiling the localities and ecoregions where they have been collected. Our results suggest that Ashmeadiella subgenera need to be revised and that some species may need to be synonymized. Museum collection records reveal that: adult flight periods range from a few months to most of the year; most species are polylectic; and, over half of the species’ ranges extend into the Mojave Desert.

Land Conversion for Solar Facilities and Urban Sprawl in Southwest Deserts Causes Different Amounts of Habitat Loss for Ashmeadiella Bees

Authors:Shaun M McCoshum and Dr. Monica A Geber

Journal of the Kansas Entomological Society

Land conversion for human use poses one of the greatest threats to terrestrial ecosystems and causes habitat loss for a myriad of species. The development of large solar energy facilities and urban sprawl are converting wild lands in the Southwest deserts of the USA for human use and resulting in habitat loss for desert species. This is in part due to the Southwest deserts being identified as having high renewable energy potential while urban areas expand into areas supporting high biodiversity. Previous studies have quantified development within some of these biodiversity hotspots, but none have investigated direct species-specific habitat loss for different species of pollinators. Native bees are poorly studied, and therefore it is difficult to know how much habitat has been lost. We quantified the amount of land conversion occurring between 2010 and 2015 in Clark County, NV, Mojave County, AZ, and San Bernardino County, CA to assess direct loss of potential-habitat for species in the Southwest deserts. Using Satellite images, we quantified the direct habitat loss to solar facilities and estimated other land conversion due to urban sprawl using USDA land cover data. We created eco-niche models in MaxENT for ten Ashmeadiella bees, to estimate the amount of direct, potential-habitat loss caused by solar development and urban expansion. Our data suggest species are not equally affected by land conversion in the Southwest deserts and direct, potential-habitat loss to urban sprawl is much greater than the loss due to solar facilities. Furthermore, our data show each species incurs different amounts of habitat loss to both solar development and urban expansion as well as between counties. These results should assist in pollinator conservation program development by illustrating land conversion can vary between local governments and pollinator species. 

 
 
Landscape predictors of pathogen prevalence and range contractions in US bumblebees

Authors: Scott H. McArt, Christine Urbanowicz, Shaun McCoshum, Rebecca E. Irwin, and Lynn S. Adler

Proceedings B

Several species of bumblebees have recently experienced range contractions and possible extinctions. While threats to bees are numerous, few analyses have attempted to understand the relative importance of multiple stressors. Such analyses are critical for prioritizing conservation strategies. Here, we describe a landscape analysis of factors predicted to cause bumblebee declines in the USA. We quantified 24 habitat, land-use and pesticide usage variables across 284 sampling locations, assessing which variables predicted pathogen prevalence and range contractions via machine learning model selection techniques. We found that greater usage of the fungicide chlorothalonil was the best predictor of pathogen (Nosema bombi) prevalence in four declining species of bumblebees. Nosema bombi has previously been found in greater prevalence in some declining US bumblebee species compared to stable species. Greater usage of total fungicides was the strongest predictor of range contractions in declining species, with bumblebees in the northern USA experiencing greater likelihood of loss from previously occupied areas. These results extend several recent laboratory and semi-field studies that have found surprising links between fungicide exposure and bee health. Specifically, our data suggest landscape-scale connections between fungicide usage, pathogen prevalence and declines of threatened and endangered bumblebees.

Direct and indirect effects of sunscreen exposure on reef biota

Authors: Shaun M McCoshum, Alicia Schlarb and Kristen A. Baum 

Hydrobiologia

Coral reefs are ecologically and economically important, contributing to both fishing and ecotourism economies around the world. Tourism and recreational activities have increased in coastal areas and so has the use of sunscreen. Sunscreen reduces human exposure to harmful UV rays, but washes off during aquatic recreational activities, which may negatively affect reef biota. To evaluate how sunscreen affects coral reef ecosystems, we added sunscreen at concentrations similar to previous studies to growing environments containing flatworms (Convolutriloba macropyga) with symbiotic algae, photosynthetic diatoms (Nitzschia sp.), Aiptasia anemones, and pulse corals (Xenia sp.). Using behavioral observations and estimates of population and colony growth, we show nominal concentrations of sunscreen negatively affect all of the studied species. Furthermore, we show that mobile flatworms do not avoid water which contains sunscreen and flatworms exposed to sunscreen prefer darker conditions. Based on our results, beach goers should limit use of sunscreens when near coral reefs and consider alternative protective measures, such as the utilization of sun-protective clothing.

 

Species distribution models for natural enemies of monarch butterfly (Danaus plexippus) larvae and pupae: distribution patterns and implications for conservation 

Authors: Shaun M McCoshum, Shannon L. Andreoli, Carl M. Stenoien, Karen S. Oberhauser, and Kristen A. Baum.

Journal of Insect Conservation

ABSTRACT: Prey populations can be strongly influenced by predators and parasitoids, and migratory prey whose distributions vary geographically throughout their breeding seasons encounter different combinations of predators and parasitoids throughout their range. North American monarch butterflies (Danaus plexippus) are susceptible to a wide variety of natural enemies, but the distribution of these natural enemies has not been quantified. We developed ecological niche models using environmental data to identify areas with suitable abiotic conditions for eight known natural enemies of monarchs, including six predators: Arilus cristatus, Harmonia axyridis, Monomorium minimum, Podisus maculiventris, Polistes spp., and Solenopsis geminata; and two parasitoids: Lespesia archippivora and Pteromalus cassotis. We combined correlated suitable areas for individual predators and parasitoids to identify regions with the most predator and parasitoid species potential. The Gulf Coast, West Coast, Florida, and parts of the eastern United States are predicted to have the most natural enemy species. We suggest that future research should assess monarch mortality rates in these areas, and that monarch conservation strategies consider pressure from natural enemies.

 

New reports that monarch butterflies (Lepidoptera: Nymphalidae, Danaus plexippus Linnaeus) are hosts for a pupal parasitoid (Hymenoptera: Chalcidoidae, Pteromalus cassotis Walker

Authors: Carl Stenoien, Shaun M McCoshum, Wendy Caldwell, Alma de Anda Karen S. Oberhauser

Journal of the Kansas Entomological Society

ABSTRACT: Monarch butterflies are one of the best studied non-pest lepidopterans, serving as a model for migration, chemical ecology, and insect conservation. Despite the intensity with which the larvae and adults have been studied, the cryptic pupal stage is often difficult to study in the wild. It is perhaps due to this difficulty that researchers have largely overlooked monarchs’ interactions with a pupal parasitoid, Pteromalus cassotis. Using field experiments in the northern U.S. and observational data from wild collected pupae in the southern U.S., we report occurrences of this host-parasitoid interaction at sites Minnesota, Georgia, Oklahoma, Texas, and Wisconsin. At sites in Minnesota, rates of parasitism of experimentally placed monarch were highly variable, ranging from 60% in 2010 to 0% in 2013 and 2014. Observations of wild-collected pupae suggest that rates of parasitism may near 100% at some sites in the southern U.S. The number of wasps emerging from a single host ranged from 1–425 (mean = 71). Later dissections of hosts revealed that, in some cases, dead parasitoids remained inside the host as larvae, pupae, and/or adults. Within a host, wasp sex ratios were typically female biased (median = 91% female), as is common in gregarious parasitic hymenopterans. Infected monarch pupae at a site in Oklahoma produced more wasps per host, more male-biased sex ratios, and had higher survival than hosts from other sites. We discuss the possibility that P. cassotis is a specialist on monarchs and perhaps closely related species, based on monarchs’ sequestered cardenolides, published host records, and evidence for correlated population dynamics of this host and parasitoid.

 
Sex ratios and Ophryocystis elektroscirrha infection levels of Danaus plexippus during spring migration through Oklahoma

Authors: Shaun M McCoshum and Kristen Baum

Entomologia Experimentalis Applicata

ABSTRACT:Monarch butterflies (Danaus plexippus; Lepidoptera: Nymphalidae) have a multiple brood migration in the spring as they move between their overwintering grounds and summer breeding grounds. In Oklahoma, monarchs produce at least one generation in the spring, which develop and continue the northward migration, leaving Oklahoma without a breeding population during the hot summer months. Female monarchs leave the overwintering grounds prior to males, but it is not clear whether females re-colonize areas along the migration route prior to, or at the same time as males. Studies have documented similar male to female ratios at emergence, but have identified a male biased sex ratio in the field. Both males and females are susceptible to infections from the neo-gregarine parasite, Ophryocystis elektroscirrha (OE), which is an obligate spore-forming protist that reduces the flight abilities and life spans of infected individuals. We examine the number of male and female monarchs during the spring migration through Oklahoma and whether sex ratios or OE infection estimates vary with capture technique (active or passive). Our data suggest populations are male biased during the first week of spring migration in Oklahoma, but shift to female biased by the third week in both cool and warm springs. Therefore, males may leave southern areas prior to females or migrate longer distances per day. Active sampling (i.e., netting) did not lead to more males than females being caught compared to passive sampling (i.e., sticky traps). Significantly fewer OE carrying monarchs (with 2 or more spores) were captured via netting than by sticky traps which may be caused by sticky trap glue affecting tape sampling effectiveness, but there was no difference in the number of heavily infected individuals (more than 100 spores). Therefore, data from netted monarchs may underestimate OE infection rates within populations.

 
Introduced Sap Beetles (Coleoptera: Nitidulidae) on Santa Catalina Island, California

Authors. Shaun M McCoshum, Andy Cline, and Michael Caterino

The Coleopterists Bulletin

​SUMMARY: In 2010, two non-native Sap Beetles were collected in the interior of the  island. One species is a new state record for California, the other has been found in California but not on Catalina.

 
Green light affects blue-light-based phototropism in hypocotyls of Arabidopsis thaliana​

Authors: Shaun M McCoshum and John Z. Kiss

The  Journal of the Torrey Botanical Society

ABSTRACT: Light affects all aspects of plant growth and development from seed germination to senescence. While there has been intensive investigation of the effects of blue and red light on development and tropisms, much less is known about the specific effects of green light exposure in plants. Several recent studies demonstrate that monochromatic green light has a number of physiological effects including antagonizing light-mediated growth inhibition in hypocotyls and reversing blue-light-induced stomatal opening. In this paper, we report on the effects of green light pulses on phototropism in both light- and dark-grown seedlings of Arabidopsis thaliana. Green light had no effect on either red-light or blue-light-based phototropism in roots. However, in hypocotyls of dark-grown seedlings, pulses of green light significantly reduced blue-light positive phototropism while the growth rate was increased. In contrast, in hypocotyls of light-grown seedlings, green pulses significantly increased positive phototropic curvature while there was no significant effect on growth rate. The observed effects of green light may occur by perception through the phytochromes or via a novel undiscovered green light receptor. Taken together, these results suggest that care should be taken when green illumination is used as a “safe” light in studies of plant development. While green light effects may be more subtle compared to red and blue effects, monochromatic green illumination can influence the growth and development of seedlings.

Shaun McCoshum

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