Bumble bees damage plant leaves and accelerate flower production when pollen is scarce

Science ◽  
2020 ◽  
Vol 368 (6493) ◽  
pp. 881-884 ◽  
Author(s):  
Foteini G. Pashalidou ◽  
Harriet Lambert ◽  
Thomas Peybernes ◽  
Mark C. Mescher ◽  
Consuelo M. De Moraes
Keyword(s):  
Environmental Change ◽  
Bumble Bees ◽  
Floral Resources ◽  
Bumble Bee ◽  
Laboratory Studies ◽  
Plant Leaves ◽  
Flower Production ◽  
Worker Behavior ◽  
Phenological Synchrony ◽  
Outdoor Experiments

Maintaining phenological synchrony with flowers is a key ecological challenge for pollinators that may be exacerbated by ongoing environmental change. Here, we show that bumble bee workers facing pollen scarcity damage leaves of flowerless plants and thereby accelerate flower production. Laboratory studies revealed that leaf-damaging behavior is strongly influenced by pollen availability and that bee-damaged plants flower significantly earlier than undamaged or mechanically damaged controls. Subsequent outdoor experiments showed that the intensity of damage inflicted varies with local flower availability; furthermore, workers from wild colonies of two additional bumble bee species were also observed to damage plant leaves. These findings elucidate a feature of bumble bee worker behavior that can influence the local availability of floral resources.

scholarly journals Cross-infectivity of honey and bumble bee-associated parasites across three bee families

Parasitology ◽  
2020 ◽  
Vol 147 (12) ◽  
pp. 1290-1304 ◽  
Author(s):  
Lyna Ngor ◽  
Evan C. Palmer-Young ◽  
Rodrigo Burciaga Nevarez ◽  
Kaleigh A. Russell ◽  
Laura Leger ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Bumble Bees ◽  
Floral Resources ◽  
Bumble Bee ◽  
Broad Host Range ◽  
Osmia Lignaria ◽  
Social Bees ◽  
Crithidia Bombi ◽  
Halictus Ligatus ◽  
Parasite Replication

AbstractRecent declines of wild pollinators and infections in honey, bumble and other bee species have raised concerns about pathogen spillover from managed honey and bumble bees to other pollinators. Parasites of honey and bumble bees include trypanosomatids and microsporidia that often exhibit low host specificity, suggesting potential for spillover to co-occurring bees via shared floral resources. However, experimental tests of trypanosomatid and microsporidial cross-infectivity outside of managed honey and bumble bees are scarce. To characterize potential cross-infectivity of honey and bumble bee-associated parasites, we inoculated three trypanosomatids and one microsporidian into five potential hosts – including four managed species – from the apid, halictid and megachilid bee families. We found evidence of cross-infection by the trypanosomatids Crithidia bombi and C. mellificae, with evidence for replication in 3/5 and 3/4 host species, respectively. These include the first reports of experimental C. bombi infection in Megachile rotundata and Osmia lignaria, and C. mellificae infection in O. lignaria and Halictus ligatus. Although inability to control amounts inoculated in O. lignaria and H. ligatus hindered estimates of parasite replication, our findings suggest a broad host range in these trypanosomatids, and underscore the need to quantify disease-mediated threats of managed social bees to sympatric pollinators.

scholarly journals Bumble bees in landscapes with abundant floral resources have lower pathogen loads

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Darin J. McNeil ◽  
Elyse McCormick ◽  
Ashley C. Heimann ◽  
Melanie Kammerer ◽  
Margaret R. Douglas ◽  
...  
Keyword(s):  
Honey Bee ◽  
Geographic Region ◽  
Bumble Bees ◽  
Floral Resources ◽  
Bumble Bee ◽  
Population Declines ◽  
Pollination Services ◽  
Deformed Wing Virus ◽  
Wild Bee ◽  
Nesting Resources

AbstractThe pollination services provided by bees are essential for supporting natural and agricultural ecosystems. However, bee population declines have been documented across the world. Many of the factors known to undermine bee health (e.g., poor nutrition) can decrease immunocompetence and, thereby, increase bees’ susceptibility to diseases. Given the myriad of stressors that can exacerbate disease in wild bee populations, assessments of the relative impact of landscape habitat conditions on bee pathogen prevalence are needed to effectively conserve pollinator populations. Herein, we assess how landscape-level conditions, including various metrics of floral/nesting resources, insecticides, weather, and honey bee (Apis mellifera) abundance, drive variation in wild bumble bee (Bombus impatiens) pathogen loads. Specifically, we screened 890 bumble bee workers from varied habitats in Pennsylvania, USA for three pathogens (deformed wing virus, black queen cell virus, and Vairimorpha (= Nosema) bombi), Defensin expression, and body size. Bumble bees collected within low-quality landscapes exhibited the highest pathogen loads, with spring floral resources and nesting habitat availability serving as the main drivers. We also found higher loads of pathogens where honey bee apiaries are more abundant, a positive relationship between Vairimorpha loads and rainfall, and differences in pathogens by geographic region. Collectively, our results highlight the need to support high-quality landscapes (i.e., those with abundant floral/nesting resources) to maintain healthy wild bee populations.

scholarly journals Landscape Enhancements in Apple Orchards: Higher Bumble Bee Queen Species Richness, but No Effect on Apple Quality

Insects ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 421
Author(s):  
Amélie Gervais ◽  
Marc Bélisle ◽  
Marc J. Mazerolle ◽  
Valérie Fournier
Keyword(s):  
Species Richness ◽  
Bumble Bees ◽  
Bumble Bee ◽  
Pesticide Use ◽  
Apple Orchards ◽  
Seed Number ◽  
Apple Production ◽  
Apple Quality ◽  
Effective Pollinators ◽  
Quality Weight

Bumble bees are among the most effective pollinators in orchards during the blooming period, yet they are often threatened by the high levels of pesticide use in apple production. This study aimed to evaluate the influence of landscape enhancements (e.g., hedgerows, flower strips) on bumble bee queens in apple orchards. Bumble bee queens from 12 orchards in southern Québec (Canada) were marked, released, and recaptured in the springs and falls of 2017 to 2019. Half of the 12 orchards had landscape enhancements. Apples were harvested in 2018 and 2019 to compare their quality (weight, diameter, sugar level, and seed number) in sites with and without landscape enhancements. Species richness, as well as the occurrence of three species out of eight, was higher in orchards with landscape enhancements than in orchards without such structures. The occurrence of Bombus ternarius was lower in orchards with high levels of pesticide use. Apples had fewer seeds when collected in orchards with landscape enhancements and were heavier in orchards that used more pesticides. Our work provides additional evidence that landscape enhancements improve bumble bee presence in apple orchards and should therefore be considered as a means to enhance pollination within farms.

scholarly journals Olfactory coding in the antennal lobe of the bumble bee Bombus terrestris

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marcel Mertes ◽  
Julie Carcaud ◽  
Jean-Christophe Sandoz
Keyword(s):  
Honey Bees ◽  
Antennal Lobe ◽  
Bombus Terrestris ◽  
Bumble Bees ◽  
Foraging Strategies ◽  
Bumble Bee ◽  
Carbon Chain Length ◽  
Olfactory Coding ◽  
Major Transitions

AbstractSociality is classified as one of the major transitions in evolution, with the largest number of eusocial species found in the insect order Hymenoptera, including the Apini (honey bees) and the Bombini (bumble bees). Bumble bees and honey bees not only differ in their social organization and foraging strategies, but comparative analyses of their genomes demonstrated that bumble bees have a slightly less diverse family of olfactory receptors than honey bees, suggesting that their olfactory abilities have adapted to different social and/or ecological conditions. However, unfortunately, no precise comparison of olfactory coding has been performed so far between honey bees and bumble bees, and little is known about the rules underlying olfactory coding in the bumble bee brain. In this study, we used in vivo calcium imaging to study olfactory coding of a panel of floral odorants in the antennal lobe of the bumble bee Bombus terrestris. Our results show that odorants induce reproducible neuronal activity in the bumble bee antennal lobe. Each odorant evokes a different glomerular activity pattern revealing this molecule’s chemical structure, i.e. its carbon chain length and functional group. In addition, pairwise similarity among odor representations are conserved in bumble bees and honey bees. This study thus suggests that bumble bees, like honey bees, are equipped to respond to odorants according to their chemical features.

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