Abstract:Plants may benefit from limiting the community of generalist floral visitors if the species that remain are more effective pollinators and less effective pollenivores. Plants can reduce access to pollen through altered floral cues or morphological structures, but can also reduce consumption through direct pollen defenses. We observed that Eucera (Peponapis) pruinosa, a specialist bee on Cucurbita plants, collected pure loads of pollen while generalist honey bees and bumble bees collected negligible amounts of … Show more
“…Wild bees that specialize on cucurbits (e.g. squash bees) may be disproportionately impacted, since honeybees and some bumblebees are known to avoid cucurbit pollen due to fitness trade-offs (Brochu et al, 2020). When parsed from solitary bees, we found modest evidence indicating that bumblebee visitation was reduced by landscape-level fungicide hazards.…”
Pesticides threaten ecosystem services by reducing the abundance and diversity of beneficial arthropods, including pollinators, in agroecosystems (Carvalho, 2017). Pesticide use can result in hazards to honeybees Apis mellifera L. and wild bee species, and is considered a factor contributing to pollinator decline (Zioga et al., 2020). These non-target effects reduce crop visitation, disrupt pollination and can reduce yields (Stanley et al., 2015). However, the impacts of pesticides on pollinators are rarely studied beyond the focal field, or local level, despite the fact that some bees forage widely (Greenleaf et al., 2007) and thus pesticide exposure occurs at a larger spatial
“…Wild bees that specialize on cucurbits (e.g. squash bees) may be disproportionately impacted, since honeybees and some bumblebees are known to avoid cucurbit pollen due to fitness trade-offs (Brochu et al, 2020). When parsed from solitary bees, we found modest evidence indicating that bumblebee visitation was reduced by landscape-level fungicide hazards.…”
Pesticides threaten ecosystem services by reducing the abundance and diversity of beneficial arthropods, including pollinators, in agroecosystems (Carvalho, 2017). Pesticide use can result in hazards to honeybees Apis mellifera L. and wild bee species, and is considered a factor contributing to pollinator decline (Zioga et al., 2020). These non-target effects reduce crop visitation, disrupt pollination and can reduce yields (Stanley et al., 2015). However, the impacts of pesticides on pollinators are rarely studied beyond the focal field, or local level, despite the fact that some bees forage widely (Greenleaf et al., 2007) and thus pesticide exposure occurs at a larger spatial
“…For example, it has been shown experimentally that bumble bees ( Bombus terrestris ) performed significantly less pollen foraging on plants which have large, echinate pollen grains (three Malvaceae species and Knautia arvensis (Dipsacaceae)) (Konzmann et. al., 2019), but studies of pollen foraging on Cucurbita (Cucurbitaceae) by the generalist bumble bee Bombus impatiens have shown it is likely that combinations of morphological (large size and pronounced echinae in this example), nutritional and chemical pollen traits could allow plants to selectively attract and deter particular suites of pollinators (Brochu et al., 2020). It seems unlikely that pollinators could perceive subtle differences in pollen morphology, especially those on a micrometric scale, but further experimental work could test whether the micro‐morphological landscape provided by pollen grains is functionally significant for bees and other insects during pollination.…”
Section: Discussionmentioning
confidence: 99%
“…This hypothesis provides a link between pollination ecology and pollen morphology and could be tested using foraging experiments such as those of Konzmann, Koethe, and Lunau (2019) and Brochu et al. (2020).…”
Section: Discussionmentioning
confidence: 99%
“…However, by analogy with the role of morphological diversity among flowers in pollination (e.g., Ghazoul, 2006), we hypothesize that pollen grains may contribute to the overall phenotypic diversity that is presented by plants to pollinators. This hypothesis provides a link between pollination ecology and pollen morphology and could be tested using foraging experiments such as those of Konzmann, Koethe, and Lunau (2019) and Brochu et al (2020).…”
Morphology varies enormously across clades, and the morphology of a trait may reflect ecological function or the retention of ancestral features. We examine the tension between ecological and phylogenetic correlates of morphological diversity through a case study of pollen grains produced by angiosperms in Barro Colorado Island, Panama (BCI). Using a molecular phylogeny of 730 taxa, we demonstrate a statistically significant association between morphological and genetic distance for these plants. However, the relationship is non‐linear, and while close relatives share more morphological features than distant relatives, above a genetic distance of ~ 0.7 increasingly distant relatives are not more divergent in phenotype. The pollen grains of biotically pollinated and abiotically pollinated plants overlap in morphological space, but certain pollen morphotypes and individual morphological traits are unique to these pollination ecologies. Our data show that the pollen grains of biotically pollinated plants are significantly more morphologically diverse than those of abiotically pollinated plants.
Abstract in Spanish is available with online material.
“…Although biotic and abiotic stressors may not immediately affect the survival of exposed individuals, they challenge the immune system and impair general fitness 7 , 10 , 26 . Honeybees are social insects, and may therefore compensate for their comparably small repertoire of immunity-related genes 27 , 28 and cellular immune responses 29 by developing behavioral mechanisms that limit intoxication via the avoidance and dilution of certain food sources, and the co-cultivation of beneficial microbes synergistically supporting the detoxification of plant metabolites 30 .…”
Honeybees are essential pollinators of many agricultural crops and wild plants. However, the number of managed bee colonies has declined in some regions of the world over the last few decades, probably caused by a combination of factors including parasites, pathogens and pesticides. Exposure to these diverse biotic and abiotic stressors is likely to trigger immune responses and stress pathways that affect the health of individual honeybees and hence their contribution to colony survival. We therefore investigated the effects of an orally administered bacterial pathogen (Pseudomonas entomophila) and low-dose xenobiotic pesticides on honeybee survival and intestinal immune responses. We observed stressor-dependent effects on the mean lifespan, along with the induction of genes encoding the antimicrobial peptide abaecin and the detoxification factor cytochrome P450 monooxygenase CYP9E2. The pesticides also triggered the immediate induction of a nitric oxide synthase gene followed by the delayed upregulation of catalase, which was not observed in response to the pathogen. Honeybees therefore appear to produce nitric oxide as a specific defense response when exposed to xenobiotic stimuli. The immunity-related and stress-response genes we tested may provide useful stressor-dependent markers for ecotoxicological assessment in honeybee colonies.
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