Insect Pollinators in the Anthropocene: How Multiple Environmental Stressors Are Shaping Pollinator Health

Editorial

07 September 2023

Editorial: Insect pollinators in the Anthropocene: how multiple environmental stressors are shaping pollinator health

Pierre Lau

Fabio Sgolastra

Geoffrey R. Williams

and

Lars Straub

2,185 views

2 citations

Editors

Lars Straub

University of Bern

Fabio SGOLASTRA

University of Bologna

Pierre Lau

United States Department of Agriculture (USDA)

Geoffrey Williams

Auburn University

Impact

Original Research

05 May 2023

Impact of landscape configuration and composition on pollinator communities across different European biogeographic regions

Irene Bottero

, 26 more and

Jane C. Stout

Introduction: Heterogeneity in composition and spatial configuration of landscape elements support diversity and abundance of flower-visiting insects, but this is likely dependent on taxonomic group, spatial scale, weather and climatic conditions, and is particularly impacted by agricultural intensification. Here, we analyzed the impacts of both aspects of landscape heterogeneity and the role of climatic and weather conditions on pollinating insect communities in two economically important mass-flowering crops across Europe.

Methods: Using a standardized approach, we collected data on the abundance of five insect groups (honey bees, bumble bees, other bees, hover flies and butterflies) in eight oilseed rape and eight apple orchard sites (in crops and adjacent crop margins), across eight European countries (128 sites in total) encompassing four biogeographic regions, and quantified habitat heterogeneity by calculating relevant landscape metrics for composition (proportion and diversity of land-use types) and configuration (the aggregation and isolation of land-use patches).

Results: We found that flower-visiting insects responded to landscape and climate parameters in taxon- and crop-specific ways. For example, landscape diversity was positively correlated with honey bee and solitary bee abundance in oilseed rape fields, and hover fly abundance in apple orchards. In apple sites, the total abundance of all pollinators, and particularly bumble bees and solitary bees, decreased with an increasing proportion of orchards in the surrounding landscape. In oilseed rape sites, less-intensively managed habitats (i.e., woodland, grassland, meadows, and hedgerows) positively influenced all pollinators, particularly bumble bees and butterflies. Additionally, our data showed that daily and annual temperature, as well as annual precipitation and precipitation seasonality, affects the abundance of flower-visiting insects, although, again, these impacts appeared to be taxon- or crop-specific.

Discussion: Thus, in the context of global change, our findings emphasize the importance of understanding the role of taxon-specific responses to both changes in land use and climate, to ensure continued delivery of pollination services to pollinator-dependent crops.

6,800 views

13 citations

Average Varroa destructor population growth expressed as number of mites/100 bees after 6 months for each season. These results combine data from both trials 1 and 2. The dashed red line represents the standard economical threshold of 3 mites/100 bees. There was a significant impact of season treatment was administered on the mites/100 bees (P ≤ 0.05). Significant differences between means are indicated with different letters (α = 0.05; a > b > c).

Original Research

17 April 2023

Seasonal differences in Varroa destructor population growth in western honey bee (Apis mellifera) colonies

Cameron J. Jack

, 2 more and

James D. Ellis

3,920 views

9 citations

Original Research

05 May 2023

Effects of geographic origin and temperature on survival, development, and emergence of the managed pollinator Osmia lignaria

Morgan B. Scalici

, 2 more and

Theresa L. Pitts-Singer

2,609 views

4 citations

Original Research

30 June 2023

Deformed wing virus prevalence in solitary bees put to the test: an experimental transmission study

Alexandria Schauer

, 4 more and

Peter Neumann

4,095 views

1 citations

Original Research

23 February 2023

Planted pollinator habitat in agroecosystems: How does the pollinator community respond?

Hannah K. Levenson

and

David R. Tarpy

Pollinators are important both ecologically and economically. Nonetheless, documented pollinator population decline threatens ecosystem functioning and human well-being. In response, conservation methods such as augmented pollinator habitat are becoming popular tools to combat pollinator losses. While previous research has shown added habitat can benefit bee communities, there are still aspects of the habitat implementation that require further research, particularly how this will impact bee communities in real-world settings beyond researcher-led efforts. In our study, we use a 2016 initiative mandating the planting of pollinator habitat on research stations across North Carolina, United States to act as an outdoor laboratory to investigate this exact question. From 2016 to 2018, we found significant increases in bee abundance and diversity. However, these increases depended on the quality of habitat, with areas of higher flower cover and diversity supporting larger, more diverse bee communities. Although the habitats positively supported bee communities, we found that resources within the habitats were lower later in the sampling season, highlighting the need of developing seed mixes that include late season resources. Weedy plants were documented to establish within the habitats, demonstrating the need for regular upkeep and maintenance of pollinator habitat in order to appropriately support bee communities. It is likely that planting pollinator habitat will not be a one-size-fits-all conservation solution, as bee species can respond differently to some habitat characteristics. Future long-term studies on pollinators will be important as natural fluctuations in bee populations may limit findings and many knowledge gaps on native bees still persist.

5,655 views

5 citations

Mathematical model that predicts the number of honey bee exits from the hive according to ambient temperature. The curves depict the results of linear models, all significant, established based on recordings of RFID transponder-labelled workers (n = 1,330 bees in total; Requier, 2013). (A) Number of exits by bee and by day. (B) Average duration of trips by bee and by day in second. The amplitude of daily temperatures recorded in April, May, June, July, August, and September were, respectively, 10.2–20.7, 12.9–27.6, 13.7–27.6, 15.1–26.1, 13.3–26.1, and 12.0–22.3°C. The number of recorded bees per month ranged from 90 to 308.

Policy and Practice Reviews

17 February 2023

Decision-making criteria for pesticide spraying considering the bees’ presence on crops to reduce their exposure risk

Axel Decourtye

, 5 more and

Mickaël Henry

2,913 views

4 citations

Original Research

02 February 2023

Increased survival of honey bees consuming pollen and beebread is associated with elevated biomarkers of oxidative stress

Liudmyla S. Yazlovytska

, 4 more and

Roman A. Volkov

Introduction: Significant losses of honey bee colonies have been observed worldwide in recent decades. Inadequate nutrition is considered to be one of the factors that can reduce honey bee resistance to abiotic and biotic environmental stresses. Accordingly, we assessed the impact of food composition on worker bee survival.

Methods: Bees in cages were fed six different diets, and then their survival, levels of thiobarbituric acid reactive substances and protein carbonyl groups, catalase and lysozyme activities were evaluated.

Results and Discussion: After 17 days of feeding, the lowest mortality was observed in the group of bees that received sucrose solution with the addition of willow pollen or artificial rapeseed beebread or artificial willow beebread (diets 4–6). The highest mortality was found in bees that consumed only sucrose solution (diet 1) or the sucrose solution supplemented with a mixture of amino acids (diet 2), which can be explained by the lack of vitamins and microelements in these diets. In the group of bees that received the sucrose solution with rapeseed pollen (diet 3), mortality was intermediate. To check whether the decrease in insect survival could be related to oxidative damage, we evaluated biomarkers of oxidative stress. Consumption of pollen (diets 3 and 5) and artificial beebread (diets 4 and 6) enhances protein carbonylation in worker bees. Feeding bees artificial beebread also resulted in increase in lipid peroxidation and catalase activity, which is probably due to the presence of hydrogen peroxide in the honey contained in beebread. Remarkably, the increase in biomarkers of oxidative stress was not accompanied by adverse but positive effects on insect survival. A lack of amino acids and proteins in the diet 1 did not cause oxidative stress, but led to an increase in lysozyme activity in hemolymph, a biomarker of immune system status. In conclusion, we believe that the increase in oxidative stress biomarkers we found do not indicate oxidative damage, but rather reflect the changes in redox balance due to consumption of certain dietary options.