Annual diversity of honeybee pollen sources in two pumpkin growing landscapes, Machakos County, Kenya

A honeybee (Apis mellifera scutellata) visiting
the flower of the country mallow (Abutilon
indicum) (Family: Malvaceae)

By Nang’oni et al.

Honey bees (Apis mellifera) play an indispensable role in ecosystems—not only by providing income through hive products but also by pollinating many cultivated crops. Their pollination activities significantly contribute to fruit and seed production, directly enhancing crop yields. As they go about their routine of collecting pollen and nectar, these remarkable insects unintentionally yet effectively support crop production through pollination services.

In our study, we turned our focus to rural farmlands in Machakos County, Kenya, which we categorised into two landscape types: those with low vegetation cover and those with medium vegetation cover. Our objective was to identify the annual sources of pollen that honeybees rely on in these distinct settings, based on colonies strategically placed throughout the study area. To achieve this, we collected pollen samples fortnightly from worker bees returning to their hives over a 14-month period, ensuring we captured the effects of both biophysical and climatic factors across the year. Leveraging these findings, we created a floral calendar for each region, highlighting the predominant pollen sources harvested by the bees.

Our research revealed notable differences between the two landscapes. In areas with low vegetation cover, honeybees predominantly collected pollen from seven plant families, including Asteraceae, Poaceae, Typhaceae, Combretaceae, Acanthaceae, Boraginaceae, and Amaranthaceae. In contrast, bees in areas with medium vegetation cover accessed a more diverse range of pollen sources from ten plant families, such as Asteraceae, Combretaceae, Poaceae, Malvaceae, Fabaceae, Salvadoraceae, Solanaceae, Euphorbiaceae, Liliaceae, and Scrophulariaceae. Interestingly, only four plant families served as major pollen sources for honeybees throughout the year in both landscapes. We also observed a higher diversity of plants providing over 45% of pollen to honeybees in areas with medium vegetation cover compared to those with low vegetation cover. Furthermore, honeybees in low vegetation cover landscapes at any given time collected more than double the amount of pollen from Poaceae and Typhaceae, compared to their counterparts in medium vegetation cover areas.

These findings highlight the ecological variations in forage sources available to honeybees, underscoring the importance of tailored conservation and management strategies. We believe it is essential for land use and management practices in these regions to prioritise the needs of honeybees to sustain livelihoods for beekeepers and farmers alike. At the farm level, we recommend aligning honeybee forage care practices with the developed floral calendars to ensure the effective protection of these vital pollinators.

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Spatial occupancy patterns of the nursery pollinator Derelomus chamaeropis at its host plant, Chamaerops humilis (Arecaceae)

Weevil Derelomus on the dwarf palm Chamaerops

By Moreno et al.

This study investigated how the weevil Derelomus chamaeropis—a specialist pollinator—and its host, the dioecious (individuals with separated sexes) dwarf palm (Chamaerops humilis), interact in nature. In particular, we evaluated how the spatial arrangement of these palms affects pollination and fruit production. We discovered that weevils prefer female palms and while the small-scale clustering of palms affects where weevils choose to settle, the dense groups of palms help improve fruiting. This study highlights how both the behavior of pollinators and the way plants are arranged can significantly influence pollination outcomes. 

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A survey of summer pollinator assemblies in two contiguous Richmond, Virginia (U.S.A.), urban green spaces

 By Ruppel & Trapp

A carder bee (Anthidium)

About 70% of the global human population is expected to reside in cities by the year 2050, further increasing our urban footprint and reducing wildlife resources. Green infrastructure incorporates natural elements into city spaces often heavily laden by concrete and can provide ecosystem resources for declining insects.  Pollinators, in particular, benefit from greater access to foraging rewards and nest sites. In this study, we surveyed two contiguous urban gardens which sit adjacent to substantial amounts of impervious surfaces, two active railroad tracks, and the Kanawha Canal in Richmond, Virginia (U.S.A). These gardens were planted with a preference toward Virginia-state native plants, and contain 70 unique species made up of flowering trees, shrubs and herbaceous perennials.

Our aim was to identify insects using the urban gardens for floral resources, like pollen and nectar. We surveyed floral visitor interactions on 19 plant species at Great Shiplock Park and the Low Line Gardens from June to August in 2023. Flower visiting insects were visually-identified in the field or via photography/specimen collection. Overall, 110 distinct floral visitors were observed over the ten weeks and categorized as a bee (25% of all observations), wasp (18%), butterfly/moth (16%), fly (15%), beetle, or true bug. We found that insect visitation varied by category across the surveyed plant species, and the two gardens hosted a broad range of both generalists and specialists. For example, the common eastern bumblebee (Bombus impatiens) was identified on all nineteen plant species. Meanwhile, many of the observed taxa were seen on four or fewer of the monitored plant species. Of the 11 bee species observed on four or fewer flowers were two rare bumblebee species, the golden northern bumblebee (Bombus fervidus) and southern plains bumblebee (Bombus fraternus), which were both recently recommended for federal protection.

The results of this survey provide a regional and seasonal perspective on urban green space ecosystem dynamics, and a reference that new green infrastructure projects can utilize. Our observations, especially for bees, were similar to another assessment recently conducted in the region. Furthermore, the outcome of this inventory can be used to assess impacts of urbanization on plant-pollinator interactions with response to pressures like climate change.

 

Read the scientific publication in JPE