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Dahake A, Persaud SG, Jones MN, Goyret J, Davidowitz G, Raguso RA. Dying of thirst: Osmoregulation by a hawkmoth pollinator in response to variability in ambient humidity and nectar availability. JOURNAL OF INSECT PHYSIOLOGY 2024; 159:104700. [PMID: 39255897 DOI: 10.1016/j.jinsphys.2024.104700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 07/23/2024] [Accepted: 09/04/2024] [Indexed: 09/12/2024]
Abstract
Climate-induced shifts in flowering phenology can disrupt pollinator-floral resource synchrony, especially in desert ecosystems where rainfall dictates both. However, baseline metrics to gauge pollinator health in the wild amidst rapid climate change are lacking. Our laboratory-based study establishes a baseline for pollinator physiological state by exploring how osmotic conditions influence survivorship in a desert hawkmoth pollinator, Manduca sexta. We sampled hemolymph osmolality from over 1000 lab-grown moths at 20 %, 50 %, and 80 % ambient humidity levels. Starved moths maintained healthy osmolality of 350-400 mmol/kg for 1-3 days after eclosion regardless of ambient humidity, but it sharply rose to 550 mmol/kg after 4-5 days in low and moderate humidity, and after 5 days in high humidity. Starved moths in low humidity conditions perished within 5 days, while those in high humidity survived twice as long. Moths fed synthetic Datura wrightii nectar, synthetic Agave palmeri nectar, or water, maintained osmolality within a healthy range of 350-400mmol/kg. The same was true for moths fed authentic floral nectars from Datura and Agave plants, although moths consumed more synthetic than authentic nectars, possibly due to non-sugar constituents. Simulating a 4-day mismatch between pollinator emergence and nectar availability, a single nectar meal osmotically rescued moths under dry ambient conditions. Our findings highlight hemolymph osmolality as a rapid and accurate biomarker distinguishing dehydrated from hydrated states in insect pollinators.
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Affiliation(s)
- Ajinkya Dahake
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14850, USA.
| | - Steven G Persaud
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14850, USA
| | - Marnesha N Jones
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA
| | - Joaquín Goyret
- Department of Biology, University of Tennessee, Martin, TN 38237, USA
| | - Goggy Davidowitz
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14850, USA
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Jones LJ, Miller DA, Schilder RJ, López‐Uribe MM. Body mass, temperature, and pathogen intensity differentially affect critical thermal maxima and their population-level variation in a solitary bee. Ecol Evol 2024; 14:e10945. [PMID: 38362170 PMCID: PMC10867875 DOI: 10.1002/ece3.10945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 10/16/2023] [Accepted: 12/21/2023] [Indexed: 02/17/2024] Open
Abstract
Climate change presents a major threat to species distribution and persistence. Understanding what abiotic or biotic factors influence the thermal tolerances of natural populations is critical to assessing their vulnerability under rapidly changing thermal regimes. This study evaluates how body mass, local climate, and pathogen intensity influence heat tolerance and its population-level variation (SD) among individuals of the solitary bee Xenoglossa pruinosa. We assess the sex-specific relationships between these factors and heat tolerance given the differences in size between sexes and the ground-nesting behavior of the females. We collected X. pruinosa individuals from 14 sites across Pennsylvania, USA, that varied in mean temperature, precipitation, and soil texture. We measured the critical thermal maxima (CTmax) of X. pruinosa individuals as our proxy for heat tolerance and used quantitative PCR to determine relative intensities of three parasite groups-trypanosomes, Spiroplasma apis (mollicute bacteria), and Vairimorpha apis (microsporidian). While there was no difference in CTmax between the sexes, we found that CTmax increased significantly with body mass and that this relationship was stronger for males than for females. Air temperature, precipitation, and soil texture did not predict mean CTmax for either sex. However, population-level variation in CTmax was strongly and negatively correlated with air temperature, which suggests that temperature is acting as an environmental filter. Of the parasites screened, only trypanosome intensity correlated with heat tolerance. Specifically, trypanosome intensity negatively correlated with the CTmax of female X. pruinosa but not males. Our results highlight the importance of considering size, sex, and infection status when evaluating thermal tolerance traits. Importantly, this study reveals the need to evaluate trends in the variation of heat tolerance within and between populations and consider implications of reduced variation in heat tolerance for the persistence of ectotherms in future climate conditions.
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Affiliation(s)
- Laura J. Jones
- Intercollege Graduate Degree Program in EcologyThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
- Department of Entomology, Center for Pollinator ResearchThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
| | - Douglas A. Miller
- Earth and Environmental Systems InstituteThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
| | - Rudolf J. Schilder
- Intercollege Graduate Degree Program in EcologyThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
- Department of Entomology, Center for Pollinator ResearchThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
- Department of BiologyThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
| | - Margarita M. López‐Uribe
- Intercollege Graduate Degree Program in EcologyThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
- Department of Entomology, Center for Pollinator ResearchThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
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Zbrozek M, Fearon ML, Weise C, Tibbetts EA. Honeybee visitation to shared flowers increases Vairimorpha ceranae prevalence in bumblebees. Ecol Evol 2023; 13:e10528. [PMID: 37736280 PMCID: PMC10511299 DOI: 10.1002/ece3.10528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 08/16/2023] [Accepted: 08/31/2023] [Indexed: 09/23/2023] Open
Abstract
Vairimorpha (=Nosema) ceranae is a widespread pollinator parasite that commonly infects honeybees and wild pollinators, including bumblebees. Honeybees are highly competent V. ceranae hosts and previous work in experimental flight cages suggests V. ceranae can be transmitted during visitation to shared flowers. However, the relationship between floral visitation in the natural environment and the prevalence of V. ceranae among multiple bee species has not been explored. Here, we analyzed the number and duration of pollinator visits to particular components of squash flowers-including the petals, stamen, and nectary-at six farms in southeastern Michigan, USA. We also determined the prevalence of V. ceranae in honeybees and bumblebees at each site. Our results showed that more honeybee flower contacts and longer duration of contacts with pollen and nectar were linked with greater V. ceranae prevalence in bumblebees. Honeybee visitation patterns appear to have a disproportionately large impact on V. ceranae prevalence in bumblebees even though honeybees are not the most frequent flower visitors. Floral visitation by squash bees or other pollinators was not linked with V. ceranae prevalence in bumblebees. Further, V. ceranae prevalence in honeybees was unaffected by floral visitation behaviors by any pollinator species. These results suggest that honeybee visitation behaviors on shared floral resources may be an important contributor to increased V. ceranae spillover to bumblebees in the field. Understanding how V. ceranae prevalence is influenced by pollinator behavior in the shared floral landscape is critical for reducing parasite spillover into declining wild bee populations.
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Affiliation(s)
- Maryellen Zbrozek
- Department of Ecology & Evolutionary BiologyUniversity of MichiganAnn ArborMichiganUSA
| | - Michelle L. Fearon
- Department of Ecology & Evolutionary BiologyUniversity of MichiganAnn ArborMichiganUSA
| | - Chloe Weise
- Department of Ecology & Evolutionary BiologyUniversity of MichiganAnn ArborMichiganUSA
| | - Elizabeth A. Tibbetts
- Department of Ecology & Evolutionary BiologyUniversity of MichiganAnn ArborMichiganUSA
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Orlova M, Porter M, Hines HM, Amsalem E. Symptomatic Infection with Vairimorpha spp. Decreases Diapause Survival in a Wild Bumble Bee Species ( Bombus griseocollis). Animals (Basel) 2023; 13:ani13101656. [PMID: 37238086 DOI: 10.3390/ani13101656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 04/27/2023] [Accepted: 05/05/2023] [Indexed: 05/28/2023] Open
Abstract
Vairimorpha, a microsporidian parasite (previously classified as Nosema), has been implicated in the decline of wild bumble bee species in North America. Previous studies examining its influence on colony performance have displayed variable results, from extremely detrimental effects to no observable influence, and little is known about the effects it has on individuals during the winter diapause, a bottleneck for survival in many annual pollinators. Here, we examined the effect of Vairimorpha infection, body size, and mass on diapause survival in Bombus griseocollis gynes. We demonstrate that gyne survival length in diapause is negatively affected by symptomatic Vairimorpha infection of the maternal colony but does not correlate with individual pathogen load. Our findings further indicate that increased body mass offers a protective effect against mortality during diapause in infected, but not in healthy, gynes. This suggests that access to adequate nutritional resources prior to diapause might offset the harmful effect of Vairimorpha infection.
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Affiliation(s)
- Margarita Orlova
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA
- Department of Biology and Chemistry, College of Arts and Sciences, State University of New York Polytechnic Institute, Utica, NY 13502, USA
| | - Monique Porter
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Heather M Hines
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Etya Amsalem
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA
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Gratton EM, McNeil DJ, Grozinger CM, Hines HM. Local habitat type influences bumble bee pathogen loads and bee species distributions. ENVIRONMENTAL ENTOMOLOGY 2023:7150786. [PMID: 37133965 DOI: 10.1093/ee/nvad027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 01/26/2023] [Accepted: 03/30/2023] [Indexed: 05/04/2023]
Abstract
Bumble bees (Hymenoptera: Apidae, Bombus Latreille) perform important ecological services in both managed and natural ecosystems. Anthropogenically induced change has altered floral resources, climate, and insecticide exposure, factors that impact health and disease levels in these bees. Habitat management presents a solution for improving bee health and biodiversity, but this requires better understanding of how different pathogens and bee species respond to habitat conditions. We take advantage of the washboard of repeated ridges (forested) and valleys (mostly developed) in central Pennsylvania to examine whether local variation in habitat type and other landscape factors influence bumble bee community composition and levels of 4 leading pathogens in the common eastern bumble bee, Bombus impatiens Cresson. Loads of viruses (DWV and BQCV) were found to be lowest in forest habitats, whereas loads of a gut parasite, Crithidia bombi, were highest in forests. Ridgetop forests hosted the most diverse bumble bee communities, including several habitat specialists. B. impatiens was most abundant in valleys, and showed higher incidence in areas of greater disturbance, including more developed, unforested, and lower floral resource sites, a pattern which mirrors its success in the face of anthropogenic change. Additionally, DNA barcoding revealed that B. sandersoni is much more common than is apparent from databases. Our results provide evidence that habitat type can play a large role in pathogen load dynamics, but in ways that differ by pathogen type, and point to a need for consideration of habitat at both macro-ecological and local spatial scales.
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Affiliation(s)
- Elena M Gratton
- Department of Entomology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
| | - Darin J McNeil
- Department of Forestry and Natural Resources, University of Kentucky, Lexington, KY, USA
| | - Christina M Grozinger
- Department of Entomology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
| | - Heather M Hines
- Department of Entomology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
- Department of Biology, Pennsylvania State University, University Park, PA, USA
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