Open-top warming chambers reduce animal pollination of two subalpine herbs

Open top chambers (OTCs) are a popular method for studying the biological effects of climate change through passive heating, but their effects on biotic interactions are poorly understood, especially for pollination. Here we use the subalpine plants Delphinium nuttallianum and Potentilla pulcherrima to examine the possibility that the effects of OTCs on plant reproduction are not the result of warming but rather OTCs acting as barriers to pollinator movement. Pollinator observations were conducted and stigmas collected from plants inside and outside of OTCs in a meadow in the Rocky Mountains of Colorado, USA. Very few visitors were observed inside of OTCs, which led to severe reductions in visitation rates, by 92% in Delphinium and 85% in Potentilla. The number of conspecific pollen grains on stigmas was 73% lower in OTCs for Delphinium but not Potentilla, likely because it is capable of autogamous self-pollination. This study clearly shows that OTCs can reduce animal pollination, which is also likely to reduce plant reproductive output of outcrossing plants via decreases in the quantity or quality of pollen. OTCs may therefore confound effects of warming on plant reproduction with pollination effects. Although the unintended effects of OTCs on abiotic conditions are well-studied, this study highlights that their effects on biotic interactions require further investigation.

Contribution of animal pollination to food nutrient production in Benin-West Africa

Background Pollinators play a key role in human food production by improving the yield and quality of crops. Several studies assessed the economic value of pollination services delivered by animals through yield improvement. However, little is known about the contribution of animal pollinators to nutrient production. This study assessed the contribution of animal pollination to nutrient production in Benin. Food and Agriculture Organization data on crop production and United States Department of Agriculture crop composition data of 37 leading crops were used. These crops were categorized into five classes, depending on their degree of dependence on animal pollinators for fruit production. Results The study showed that more than half of the studied crops (56.75%) relies at different levels on animal pollination for fruit production. Minerals, namely fluoride (83.92%) and selenium (52.62%), were the most delivered by animal-pollinated crops. Roughly 50% of lipids outputs and 24% of proteins outputs were obtained from pollinator-dependent crops. Significant outputs of fat-soluble vitamins up to 65% were also attributed to animal pollination. A low contribution of animal pollination (up to 8%) was reported for water-soluble vitamins. Conclusion Animal-pollinated crops significantly contribute to the supply of nutrients and consequently to nutritional and food security in Benin. Conservation of pollinators should be considered as an important component of food security programs in the country.

Spontaneous choices for insect-pollinated flower shapes by wild non-eusocial halictid bees

The majority of angiosperms require animal pollination for reproduction and insects are the dominant group of animal pollinators. Bees are considered one of the most important and abundant insect pollinators. Research into bee behaviour and foraging decisions has typically centred on managed eusocial bee species, Apis mellifera and Bombus terrestris. Non-eusocial bees are understudied with respect to foraging strategies and decision-making, such as flower preferences. Understanding whether there are fundamental foraging strategies and preferences which are features of insect groups can provide key insights into the evolution of flower-pollinator co-evolution. In the current study, Lasioglossum (Chilalictus) lanarium and L. (Parasphecodes) sp., two native Australian generalist halictid bees, were tested for flower shape preferences between native insect-pollinated and bird-pollinated flowers. Each bee was presented with achromatic images of either insect-pollinated or bird-pollinated flowers in a circular arena. Both native bee species demonstrated a significant preference for images of insect-pollinated flowers. These preferences are similar to those found in A. mellifera, suggesting that flower shape preference may be a deep-rooted evolutionary occurrence within bees. With growing interest in the sensory capabilities of non-eusocial bees as alternative pollinators, the current study also provides a valuable framework for further behavioural testing of such species.

Pollination interactions promoting plant invasions.

Most plant species rely on, or benefit from, animal pollination. Therefore, pollination interactions are expected to play a key role in the reproduction and invasion success of non-native plants in their new areas. Understanding this role will allow us to better predict certain plant invasions. Also, it will allow us to explore the potential of invasion management measures based on disrupting or avoiding pollination interactions. In this chapter we review the available information on reproductive systems and their degree of dependence on animal-mediated pollination of non-native plant species. We review the characteristics of resident pollinators feeding on non-native plants and the different environmental setups that allow or impede non-native plants to reproduce in their new areas. Finally, we explore the scarce literature on invasion management measures based on disrupting pollination interactions and discuss their potentiality. Evidence so far shows that animal pollination does not usually act as an effective barrier to invasion. Most introduced plants are able to receive suitable pollination service from resident pollinators, while others are able to minimize their reliance on pollinators through different mechanisms (e.g. selfing or asexual reproduction). The environmental settings where the introduction occurs (for instance, the presence of neighbours with similar or dissimilar flower morphologies), can play an important role on the success or failure of non-native plants overcoming reproductive barriers. Although it seems that most introduced plants do not face pollination barriers, we consider that, for certain species, the disruption or avoidance of pollination interactions as control or prevention measures deserve further exploration.

Crop Pollination in Small-Scale Agriculture in Tanzania: Household Dependence, Awareness and Conservation

Global economic value of agriculture production resulting from animal pollination services has been estimated to be $235–$577 billion. This estimate is based on quantification of crops that are available at the global markets, and mainly originates from countries with precise information about quantities of agriculture production, exports, and imports. In contrast, knowledge about the contribution of pollinators to household food and income in small-scale farming at local and regional scales is still lacking, especially for developing countries where the availability of agricultural statistics is limited. Although the global decline in pollinator diversity and abundance has received much attention, relatively little effort has been directed towards understanding the role of pollinators in small-scale farming systems, which feed a substantial part of the world’s population. Here, we have assessed how local farmers in northern Tanzania depend on insect-pollinated crops for household food and income, and to what extent farmers are aware of the importance of insect pollinators and how they can conserve them. Our results show that local farmers in northern Tanzania derived their food and income from a wide range of crop plants, and that 67% of these crops depend on animal pollination to a moderate to essential degree. We also found that watermelon—for which pollination by insects is essential for yield—on average contributed nearly 25% of household income, and that watermelons were grown by 63% of the farmers. Our findings indicate that local farmers can increase their yields from animal pollinated crops by adopting more pollinator-friendly farming practices. Yet, we found that local farmers’ awareness of pollinators, and the ecosystem service they provide, was extremely low, and intentional actions to conserve or manage them were generally lacking. We therefore urge agriculture authorities in Tanzania to act to ensure that local farmers become aware of insect pollinators and their important role in agriculture production.

Pollination interactions promoting plant invasions.

Most plant species rely on, or benefit from, animal pollination. Therefore, pollination interactions are expected to play a key role in the reproduction and invasion success of non-native plants in their new areas. Understanding this role will allow us to better predict certain plant invasions. Also, it will allow us to explore the potential of invasion management measures based on disrupting or avoiding pollination interactions. In this chapter we review the available information on reproductive systems and their degree of dependence on animal-mediated pollination of non-native plant species. We review the characteristics of resident pollinators feeding on non-native plants and the different environmental setups that allow or impede non-native plants to reproduce in their new areas. Finally, we explore the scarce literature on invasion management measures based on disrupting pollination interactions and discuss their potentiality. Evidence so far shows that animal pollination does not usually act as an effective barrier to invasion. Most introduced plants are able to receive suitable pollination service from resident pollinators, while others are able to minimize their reliance on pollinators through different mechanisms (e.g. selfing or asexual reproduction). The environmental settings where the introduction occurs (for instance, the presence of neighbours with similar or dissimilar flower morphologies), can play an important role on the success or failure of non-native plants overcoming reproductive barriers. Although it seems that most introduced plants do not face pollination barriers, we consider that, for certain species, the disruption or avoidance of pollination interactions as control or prevention measures deserve further exploration.

In situ modeling of multimodal floral cues attracting wild pollinators across environments

With more than 80% of flowering plant species specialized for animal pollination, understanding how wild pollinators utilize resources across environments can encourage efficient planting and maintenance strategies to maximize pollination and establish resilience in the face of environmental change. A fundamental question is how generalist pollinators recognize “flower objects” in vastly different ecologies and environments. On one hand, pollinators could employ a specific set of floral cues regardless of environment. Alternatively, wild pollinators could recognize an exclusive signature of cues unique to each environment or flower species. Hoverflies, which are found across the globe, are one of the most ecologically important alternative pollinators after bees and bumblebees. Here, we have exploited their cosmopolitan status to understand how wild pollinator preferences change across different continents. Without employing any a priori assumptions concerning the floral cues, we measured, predicted, and finally artificially recreated multimodal cues from individual flowers visited by hoverflies in three different environments (hemiboreal, alpine, and tropical) using a field-based methodology. We found that although “flower signatures” were unique for each environment, some multimodal lures were ubiquitously attractive, despite not carrying any reward, or resembling real flowers. While it was unexpected that cue combinations found in real flowers were not necessary, the robustness of our lures across insect species and ecologies could reflect a general strategy of resource identification for generalist pollinators. Our results provide insights into how cosmopolitan pollinators such as hoverflies identify flowers and offer specific ecologically based cues and strategies for attracting pollinators across diverse environments.