Consequences of secondary nectar robbing for male components of plant reproduction

Richman, Sarah K.; Irwin, Rebecca E.; Bosak, Johannes; Bronstein, Judith L.

doi:10.1002/ajb2.1082

Cited by 6 publications

(11 citation statements)

References 55 publications

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“…Costs of primary robbing and, to a lesser extent, secondary robbing have been documented in detail for some plant species, including ones robbed by B. occidentalis at or near our study sites (Irwin & Brody 1998, Irwin & Maloof 2002, Burkle et al 2007. Negative effects can be attributed, for instance, to pollinator avoidance of robbed flowers, direct damage to ovules, and reduced pollen quantity or quality (Irwin et al 2010;Richman et al 2018). In our experimental manipulations of nectar robbing, we found evidence that A. caerulea fruit set was significantly lower when subjected to high rates of robbing, suggesting a potential benefit to the absence of this robber.…”

Section: Discussionmentioning

confidence: 77%

“…In some well-studied systems, robbing is detrimental to both female and male reproductive function (Irwin et al 2010). In other systems, female function alone is affected (Richman et al 2018). Increased reproductive success resulting from nectar robbing has also been reported, although this appears to be less common than documented negative consequences (Higashi et al 1988;Navarro 2000;Zhu et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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What are the plant reproductive consequences of losing a nectar robber?

Ledbetter

Richman²,

Irwin

et al. 2022

J Poll Ecol

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Pollinator declines worldwide are detrimental for plants. Given the negative effects that antagonisitc visitors, including nectar robbers, can sometimes inflict, might declines in their populations instead confer benefits? During the 1970s, reproductive biology of the Colorado columbine, Aquilegia caerulea (Ranunculaceae), was documented near Gothic, Colorado. At that time, Bombus occidentalis, the Western Bumble bee, was one of its many pollinators, but more commonly acted as its only known nectar robber. Bombus occidentalis abundance has declined precipitously throughout the Western USA since the 1970s. In 2016, we documented floral visitors at sites near those used in the original survey. We then experimentally quantified the effects of nectar robbing, allowing us to estimate the reproductive consequences of losing B. occidentalis. We also quantified the potential pollination services of muscid flies (Muscidae, Diptera). The floral visitor community was dramatically different in 2016 compared to the 1970s. Bombus occidentalis was infrequently observed, and nectar robbing was negligible. Our experiments suggested that a high level of nectar robbing would lead to significantly reduced fruit set, although not seeds per fruit. Fly visits to flowers were dramatically higher in 2016 compared to the 1970s. In the absence of bumble bees, muscid flies significantly reduced fruit set below the self-pollination rate. The negative effect of the increase in these flies likely outweighed any positive effects A. caerulea experienced from the absence of its nectar robber. Although the field observations were conducted in a single year, when interpreted in combination with our manipulative experiments, they suggest how A. caerulea may fare in a changing visitation landscape.

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Section: Discussionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

What are the plant reproductive consequences of losing a nectar robber?

Ledbetter

Richman²,

Irwin

et al. 2022

J Poll Ecol

View full text Add to dashboard Cite

show abstract

“…Other studies found that nectar robbing can include a cost to the male component of fitness in some species (Castro et al, 2008;Irwin & Brody, 1999;Irwin & Maloof, 2002;Richardson, 2004) but not in others (Maloof, 2001;Morris, 1996;Richman et al, 2018). With the method we used here, it is unclear how much of the pollen released from anthers ultimately reaches stigmas of conspecific plants.…”

Section: Discussionmentioning

confidence: 90%

Novel nectar robbing negatively affects reproduction in Digitalis purpurea

Mackin

Goulson

Castellanos

2021

Preprint

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With many plant-pollinator interactions undergoing change, we require a better understanding of how the addition of new interacting partners, such as antagonists, can affect plant reproduction. One such group of antagonistic floral visitors, nectar robbers, can deplete plants of nectar rewards without contributing to pollination. The addition of nectar robbing to the floral visitor assemblage could therefore have costs to the plant´s reproductive output. We focus on a recent plant colonist, Digitalis purpurea, a plant that in its native range is rarely robbed, but experiences intense nectar robbing in areas it has been introduced to. Here, we test the costs to reproduction following experimental nectar robbing. To identify any changes in the behaviour of the principal pollinators in response to nectar robbing, we measured visitation rates, visit duration, proportion of flowers visited and rate of rejection of inflorescences. To find the effects of robbing on fitness, we used proxies for female and male components of reproductive output, by measuring the seeds produced per fruit and the pollen export respectively. Nectar robbing significantly reduced the rate of visitation and lengths of visits by bumblebees. Additionally, bumblebees visited a lower proportion of flowers on an inflorescence that had robbed flowers. We found that flowers in the robbed treatment produced significantly fewer seeds per fruit on average but did not export fewer pollen grains. Our finding that robbing leads to reduced seed production could be due to fewer and shorter visits to flowers leading to less effective pollination. We discuss the potential consequences of new pollinator environments, such as exposure to nectar robbing, for plant reproduction.

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“…We found that nectar robbing did not negatively affect the male component of reproduction through pollen removal by bumblebees. Other studies found that nectar robbing can include a cost to the male component of fitness in some species (Castro et al., 2008 ; Irwin & Brody, 1999 ; Irwin & Maloof, 2002 ; Richardson, 2004 ) but not in others (Maloof, 2001 ; Morris, 1996 ; Richman et al., 2018 ). With the method we used here, it is unclear how much of the pollen released from anthers ultimately reaches stigmas of conspecific plants.…”

Section: Discussionmentioning

confidence: 95%

“…During nectar robbing, a floral visitor bites a hole in the corolla ("primary robbing") or utilizes an existing hole previously created by another robber ("secondary robbing") to feed from nectar, which often results in no contact with the stigmas or anthers and hence no contribution to pollination (Inouye, 1983;Rojas-Nossa et al, 2016). Some previous studies found limited or no negative fitness consequences of robbing for the plant (Richman et al, 2018;Stout et al, 2000) with some examples of robbing increasing plant fitness through increasing pollen flow and dispersal distance (Higashi et al, 1988;Maloof & Inouye, 2000) and increasing the frequency of visitation from legitimate pollinators (Stout et al, 2000). However, other studies have reported detrimental effects on at least one component of the plant's reproductive success (Adler et al, 2016;Burkle et al, 2007;Castro et al, 2008;Irwin & Brody, 1999;Lara & Ornelas, 2001).…”

mentioning

confidence: 99%

Novel nectar robbing negatively affects reproduction in Digitalis purpurea

Mackin

Goulson

Castellanos

2021

Ecology and Evolution

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Many plant-pollinator interactions are undergoing change due to multiple anthropogenic influences (González-Varo et al., 2013;Goulson et al., 2015). At present, we have a limited understanding of how novel interactions affect plant reproductive success, for example, after plant invasion (Barrett et al., 2008;Chalcoff et al., 2019;Richardson et al., 2000). One interaction with consequences for plants is nectar robbing, where plants have their mutualism with pollinators bypassed by floral visitors (robbers) that consume nectar rewards without pollinating (Irwin et al., 2010). In the same way as pollination mutualisms, this interaction between

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Consequences of secondary nectar robbing for male components of plant reproduction

Abstract: Combined with prior research, this study suggests that secondary robbing is less costly to a component of male fitness than to female fitness in Ipomopsis, broadening our knowledge of the overall costs of mutualism exploitation to total plant fitness.

Cited by 6 publications

References 55 publications

What are the plant reproductive consequences of losing a nectar robber?

What are the plant reproductive consequences of losing a nectar robber?

Novel nectar robbing negatively affects reproduction in Digitalis purpurea

Novel nectar robbing negatively affects reproduction in Digitalis purpurea

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