López-Uribe Lab

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  • Results 2024 IRES Pollinators in Changing Climates

    Results 2024 IRES Pollinators in Changing Climates

    For our 2024 NSF-IRES Pollinators in Changing Climates Program, students traveled to Peru with another IRES group working on “Manifestations of Climate Change in Extreme Events, Social and Biological Systems”. Two groups worked on topics around pollinators and climate change. 

    Group 1 investigated the effect of microclimate (sun and shade) on the thermal ecology of pollinators and the community assembly of pollinating bees. Specifically, they tested the following three hypotheses:

    H1. Microclimate shapes bee community composition mediated by body size;

    H2. Body size is positively associated with the bee’s ability to generate heat; and

    H3. Floral morphology shapes microclimatic conditions for foraging bees.

    They sampled bees under sun and shade spots across three sites at different altitudes. Their results indicate that (1) elevational gradients (not microclimate) have an effect on the body size of bees; (2) bees’ thoracic temperatures are greater when foraging under the sun; and (3) flower morphology does not impact bees’ body temperatures.

    Check out this video to learn more about what they found.

    https://www.youtube.com/watch?v=1Y5dHc9KRVA

    Group 2 collaborated with the drawdown project, an international project that aims to support strategies that will help reverse climate change and eventually reduce global average temperatures. The IRES group working on this project investigated how reducing food waste would release pressure on bees for crop pollination services. They found that, for example, by reducing waste in apple production by 50%, that would reduce the amount of bee visits necessary for apple production by more than 10 billion. More details about their results are in the following video (aquí versión en Español).

    https://www.youtube.com/watch?v=N2tP-FmOqVQ

    Because of our collaboration with the “Manifestations of Climate Change in Extreme Events, Social and Biological Systems”, we are happy to report their results in this blog as well. Their project focused on the spatio-temporal variability of trace gases and solar radiation across elevational gradients in Peru. Their results demostrate evidence of rising temperatures across all sites investigated but that these effects have been more produced at sites in lower elevations. Indeed, the year 2023 was the hottest year in Peru compared to the previous 50 years. These results are among the first ones to be reported for these areas of Peru.

    https://www.youtube.com/watch?v=HGM87JtY5bU

     

    Projects funded by NSF OISE-1952470 and administered by the López-Uribe Lab in the Department of Entomology at Penn State University

    Contributed post by

    Margarita M. López-Uribe

    Associate Professor in Pollinator Health

    Pennsylvania State University

  • Temperature, size, and pathogen load affect wild bee heat tolerance

    Temperature, size, and pathogen load affect wild bee heat tolerance

    Evaluating species’ thermal tolerance is important now more than ever given the ongoing threats to biodiversity under climate change. Species vary widely in heat tolerance, but the degree of variability in their heat tolerance, and the drivers of this variability among populations, are less understood. We expect that some of this variation in bees may be attributed to microclimate, physical differences among individuals, or differences in their infection status. Among “cold-blooded” animals (internal body temperatures are not regulated), larger organisms tend to be more thermally tolerant, and so size likely explains some heat tolerance variation. For individuals in the wild, other factors may impact thermal tolerance, such as infection.

     

    Bees are cold-blooded animals that pollinate the majority of plants in both natural and agricultural ecosystems. Several bee species are known to be in decline, and stressors such as climate variability and pathogen pressure, among others, are drivers of these declines. However, how these factors impact heat tolerance in bees has not been characterized for wild populations. In this study, we asked, (1) is variation in heat tolerance among populations explained by temperature?, (2) are there size differences among individuals that relate to differences in heat tolerance?, and finally, (3) does pathogen infection reduce heat tolerance?

     

    We evaluated the heat tolerance of squash bee (Xenoglossa pruinosa) populations across a thermally variant gradient in Pennsylvania, USA. To determine a bee’s heat tolerance, we measured its critical thermal maximum (CTmax), which gives us a proxy for the highest temperature that individuals can withstand. We also weighed the bees and screened them for three common parasite groups – trypanosomes (e.g., Crithidia mellificae), Spiroplasma apis (mollicute bacteria), and Vairimorpha apis (microsporidian, formerly Nosema apis) – to see if body size or pathogen load impacted their heat tolerance.

     

     

    We found that temperature did not predict heat tolerance in our squash bee populations. However, we found a strong association between temperature and population-level variation in heat tolerance. Specifically, sites with higher daily temperatures excluded bees with low or high heat tolerance, suggesting that heat stress reduces variation in this trait. Regarding size, we found that larger squash bees were more heat tolerant in congruence with previous studies, but interestingly, males were twice as sensitive to this size effect compared to females! Male squash bees were 40% smaller than females, and so this finding suggests that smaller individuals may be more vulnerable to heat stress. Lastly, we only found that one parasite group, trypanosomes, reduced heat tolerance in highly infected individuals – and again, this effect was sex-dependent! It seems that female squash bees have a harder time tolerating heat when they are hosting a lot of trypanosome parasites in their guts, whereas male heat tolerance isn’t affected by the extra company.

     

    So, what do our findings mean for understanding variation in heat tolerance among bees and their response to heat stress in the future? First of all, this study provides preliminary evidence that extreme heat can reduce variation in heat tolerance within populations, even if it doesn’t reduce mean heat tolerance at those sites. This is relevant for understanding if populations will be able to buffer themselves against future climate regimes, as it suggests that heat stress is already excluding squash bees with low heat tolerance from sites and reducing heat tolerance for the others that are there. Our results also reveal an important gap in most studies of heat tolerance variation among insects and other taxa – sexes may vary in how size and infection status impact heat tolerance. In our system, we know that the sexes differ physically, behaviorally, and physiologically. For example, female squash bees dig nests underground to lay their eggs, spend their mornings collecting pollen for their young, and go to sleep in their nests by midday. In contrast, the smaller male squash bees do not need to collect pollen for their offspring, and instead look for mates in the morning and then go to sleep in wilted squash flowers. So, the squash bee sexes are expending energy differently (i.e., differences in parental care) and are exposed to different microclimates (i.e., females nest underground). Given the known differences in physical, behavioral, and physiological phenotypes among sexes for many species, the López-Uribe lab will continue to consider sex when evaluating bee thermal tolerance in current and future studies.

     

    For more details, check out the full article here:

    Jones, L. J., Miller, D. A., Schilder, R. J., López-Uribe, M. M. (2024). Body mass, temperature, and pathogen intensity differentially affect critical thermal maxima and their population-level variation in a solitary bee. Ecology and Evolution, 14(2), e10945

     

    Contributed post and photography by

    Laura J. Jones

    Postdoctoral Fellow of Plant-Pollinator Ecology

    Department of Integrative Biology at UT Austin

     

    This study was funded by the USDA-NIFA-AFRI Pollinator Health Program, Project 2022-67013-36274

    Questions? Contact Laura Jones via email at laura.jones@austin.utexas.edu or the López-Uribe lab at lopezuribelab@gmail.com

  • Habitat management is needed to conserve wild lupine populations and associated pollinators

    Habitat management is needed to conserve wild lupine populations and associated pollinators

    Wild lupine is a fire-adapted, perennial wildflower found throughout North America. Due to the loss of its primary habitat, wild lupine is currently of conservation concern in roughly 60% of its range. Lack of disturbance and land management that aims to preserve forests (not open habitats) are contributing factors to its habitat loss. In the midwest, large populations of wild lupine can still be found in oak savanna habitats. In contrast, its populations on the east coast are constrained to early successional edge habitats that are managed for infrastructure like roadsides and powerline rights-of-ways. These human-created habitats are not only refugia for wild lupine but also many other open-habitat associated species of conservation concern.

    Habitat comparisons between the natural (A) and human-made (B–C) habitats where Lupinus perennis grows. Habitat depictions include savanna habitat (A), roadside habitat (B), and powerline right-of-way habitat (C). Boxes are not to scale. Created with https://www.biorender.com

    Wild lupine habitat supports several specialist insect herbivores, and many floral visitors and pollinators. Three endangered butterfly species depend on wild lupine for reproduction, including the Karner blue butterfly (Lycaeides melissa samuelis), the Frosted elfin (Callophrys irus), and the Persis dusky wing (Erynais persius). These butterflies feed on wild lupine leaves as caterpillars and depend on this food source to survive. Other insects such as mason bees (Osmia spp.) and bumble bees (Bombus spp.) visit wild lupine for pollen and nectar resources and are the primary pollinators of wild lupine in Pennsylvania.

    To aid in the conservation efforts of wild lupine and associated insects, we summarize the existing literature about wild lupine biology and habitat management in our recent paper. Wild lupine prefers open or partially shaded habitat conditions, with a canopy cover of 50% or less, sandy, well-drained soils, and reduced woody vegetation. Previous research suggests that habitat restoration and management can achieve optimal wild lupine habitat with prescribed fire, canopy removal, and herbicide use. Additionally, fences can exclude herbivores like white-tailed deer that consume wild lupine. These management practices do not have substantial negative effects on associated pollinators. Specifically following prescribed fire, studies have shown neutral or positive effects on bee abundance and diversity. Management practices can also be aided through a better understanding of the patterns of genetic diversity in lupine populations (e.g., avoiding inbreeding depression and conserving locally adapted populations). We are currently investigating the effects of prescribed fire and herbivore exclusion fencing on wild lupine fitness and pollinator visitation throughout Pennsylvania. Furthermore, we are assessing the population genetics of wild lupine in varying habitats throughout its range in efforts to conserve wild lupine habitat.

    Wild lupine blooms following a prescribed burn applied in the previous dormant season. Photo: Isabella Petitta

    You can read more about this research in our paper published in Plant Ecology: 

    Petitta IR, López-Uribe MM, Sabo AE. Biology and management of wild lupine (Lupinus perennis L.): a case study for conserving rare plants in edge habitat. Plant Ecology.

  • López-Uribe Lab at 2022 ESA Meeting #EntSoc22

    López-Uribe Lab at 2022 ESA Meeting #EntSoc22

    Many members of the López-Uribe Lab are presetting at the upcoming 2022 Entomological Society Meeting. Here are all the details, hope to see you there.

    Dr. Margarita López-Uribe 
    Recent history and future trends in entomology concerning bees.

    Sunday, November 13, Room 122 @ 9:50 am

    Adaptive processes in agricultural pollinators: The case study of the squash bee Eucera pruinosa.

    Tuesday, November 15, Room 203 @ 2:50 pm

    Grace Gutierrez
    Introduced mason bee species have comparable thermal tolerances to a native species.

    Monday, November 14. Room 220 @ 11:30 am

    Isabella Petitta
    Pollinator abundance and diversity across varying populations of Lupinus perennis in Pennsylvania.

    Monday, November 14, Room 116/117 @ 11:42 am

    Avehi Singh
    Comparative genomics sheds light on the evolutionary consequences of pollen specialization in the sensory genes of bees.

    Tuesday, November 15, Room 119/120 @ 10:00 AM

    Stephania Sandoval
    Non-aggressive interactions in the squash bee Eucera pruinosa and its brood parasite Tripeolus remigatus.

    Monday, November 14

    Phylogenomics reveals within species diversification but incongruence with color phenotypes in widespread orchid bees.

    Wednesday, November 16, Room 119/120 @ 3:56 pm

    Sydney Bird
    Polyandry in the common eastern bumble bee (Bombus impatiens) and its implication for conservation.

    Monday, November 14, Room 220 @ 12:18 pm

    Dr. Nash Turley
    Studying bee population dynamics using 10 years of standardized sampling.

    Tuesday, November 15, Room 210 @ 4:20 pm

    Laura Jones
    Squash cultivation and adaptation in cold tolerance aided the northward range of a solitary bee.

    Wednesday, November 16, Room 202 @ 11:05 pm

  • Spotted Lanternflies and Beekeeping

    Spotted Lanternflies and Beekeeping

    by Robyn Underwood

     

     

    The Spotted Lanternfly (SLF), Lycorma delicatula, is an introduced plant hopper from China that is rapidly expanding its range in the United States. Since arriving in Berks County, Pennsylvania in 2014, lanternflies have spread to and become established in 13 states (CT, DE, IN, MA, MD, MI, NC, NJ, NY, OH, PA, RI, and VA). This invasive insect is a significant economic threat, as it feeds on and damages grapevines and stresses trees. In addition, lanternflies are a major nuisance to humans, especially in the late summer and early fall when the adults aggregate and are very noticeable. Adult lanternflies, found in abundance on the trunks of trees, such as maples and tree-of-heaven, excrete large quantities of sticky, sweet honeydew as they feed on plant sap August-October. The honeydew covers the trunk of the tree and vegetation nearby, attracts sugar-loving insects, including honey bees, and promotes the growth of black sooty mold.

     

    To reduce the spread of these insects, a few things are important to know for beekeepers. Lanternfly eggs can be laid on hive boxes, lids, bottom boards, stands, pallets, etc. In addition, adult lanternflies often jump into vehicles. Beekeepers should check equipment, vehicles, trailers, etc. for lanternflies and their egg masses prior to moving the equipment. Inspection of hive equipment and removal of any life stages of SLF prior to movement is critical to avoid spreading it to new areas.

     

    In addition, once lanternflies become established in an area, beekeepers begin to notice an unusual late season honey collecting in their hives. The honeydew is a sugary liquid that accumulates where there are aggregations of lanternfly adults. Honey bees readily collect this honeydew and process it as honey. The taste of the honey depends on several factors including the plant the lanternflies are feeding on and the abundance of honeydew versus floral nectar in the processed honey.

     

    Answers to beekeepers’ frequently asked questions

     

    1. Is honey made from spotted lanternfly honeydew safe for consumption?

    Yes, the honeydew honey is safe for consumption by both bees and humans. Preliminary results of laboratory testing show that the levels of pesticides from lanterfly treatment efforts found in honeydew honey are exceedingly small and well below any level of concern. In addition, beekeepers in areas where lanterflies have been established for several years see that honey bees overwinter very well on this type of stored food.

     

    2. How can I recognize spotted lanternfly honeydew honey?

    Honey made from spotted lanternfly honeydew has a distinct smokey odor. The color is dark brown, but not nearly as dark or black as buckwheat honey. The honeydew honey is not as sweet as other honeys and it has a lingering aftertaste.

     

    3. Can I sell lanternfly honeydew honey?

    Yes! This honey is marketable. Bakeries readily purchase this honey for use. In unofficial taste tests, half or more of the people that try this honey think it tastes great. Similar to the differing opinions about the flavor of other distinct honeys, such as buckwheat honey, opinions vary.  In addition, clever marketing can make this a popular novelty.

     

    4. I don’t like the taste of honeydew honey and I don’t want to sell it. What can I do?

    To avoid extracting this honey, remove the honey you collected in spring and summer by the end of July. Honeydew honey begins to be collected by bees as lanternflies emerge as adults, usually in August. Do not place supers on colonies for fall honey collection. Instead, allow the bees to provision their hives with honeydew honey as winter feed. By spring, the bees will have turned that honey into new bees.

     

    Questions or comments? Contact Robyn Underwood at rmu1@psu.edu or 484-268-5208