Open Agriculture. 2019; 4: 676-683. by Maria C.-Y. Leung*, Jessica R.K. Forrest
Everyone who has ever grown haskaps (honeyberries) knows that they attract bumble bees. In Fairbanks, they bloom so early, and air temperatures can be cool, that honeybees can be insufficient for good berry production. Researchers Maria Leung and Jessica Forrest showed that bumble bees rule the day. The authors also reported that commercial berry production Yukon doubled from 2011 and 2016, and the most prevalent berry crop is haskap.
Haskaps are self incompatible and require two compatible cultivars for pollination. and they attract a variety of insects including bee flies, syrphid flies, honeybees, butterflies and bumblebees. The researchers counted and identified insect visitors in commercial fields between 11 am and 5 pm on cool, sunny days near Whitehorse, Yukon Territory. Bumble bee visitors ranged from 96% to 32% of all insect visitors. Despite the flower architecture which is trumpet shaped and would hint at butterflies, they were the least common insect visitors. Native insect are very important to pollination in the North. The authors contrasted their results with Saskatchewan where honey bees outnumbered bumble bees as insect visitors on hasps. Anyone who gardens in the North should promote nesting sites for native bumble bees.
Abstract: Recently, the Yukon has seen a large growth in agricultural activity. Crops of commercial interest for local consumption and the export market include domestic berries, especially haskap (Lonicera caerulea L.). However, information on the pollination of these crops in our northern climate is lacking. To begin addressing this knowledge gap, we characterized foraging habits of on-farm bees in southwest Yukon by: 1) identifying pollen collected by bees occupying solitary bee houses; and 2) identifying and counting insect visitors to haskap flowers. Results show that cavity-nesting bees collect a wide variety of pollen including pollen from haskap, and that bumble bees (Bombus spp.) were much more common on haskap flowers than domestic honey bees (Apis mellifera L.), other bee species, syrphid flies, and butterflies. The number of bumble bees per haskap flower was also higher than reported elsewhere in Canada. The ability of bumble bees to be active in cool temperatures and the proximity of the study farms to natural ecosystems likely explain the prevalence of bumble bees in this study. In Yukon, it is still possible to support insect pollinators by maintaining natural areas among agricultural lands. Such undeveloped lands are, at present, typical of agricultural landscapes in subarctic Canada.
Two Prolonged Bee Visits Suffice to Maximize Drupelet Set for Red Raspberry by Corey J. Andrikopoulos and James H. Cane, Utah State University, Logan, HORTSCIENCE 53(10):1404–1406. 2018. https://doi.org/10.21273/HORTSCI13124-18
Everyone knows that insect pollination is critical for fruit set in many commercial berry species. The red raspberry is no exception. It produces an aggregate fruit composed of individual drupelet fruits. If the weather is bad, the insects are not flying, or something else interrupts pollination, you can easily get misshapen fruit and lower yields. Researchers at Utah State found that it only takes two prolonged visits of 1 minute or more to get great fruit set. You don’t need hundreds of bees visiting the flowers. Here are a few tidbits about red raspberries from this article:
- Red raspberries are mostly self fertile but because the pollen bearing anthers are not located directly adjacent to the female stigmas, self pollination can be spotty.
- A single flower bears 60 – 90 stamens with ample pollen, but bees and other insects are needed to move the pollen to the central region of female stigmas. Each individual stigma needs to be pollinated to get a good fruit.
- Previously scientists estimated that up to 68 visits per flower were necessary to get adequate fruit set, but these authors showed that 2 visits were great.
- For two visits to be adequate, the bee must really work the flower for a prolonged period of time (up to a minute or more). Bees often spend long times on a newly opened flower first thing in the morning because that’s when nectar flow is at its peak after a night time of storing up nectar in the flower’s nectar pool.
- Individual flowers remain receptive for about 2 days, and every morning the nectar pool is recharged. Nectar release is temperature dependent.
- By individually covering flowers as they bloomed and comparing them to uncovered controls, the researchers showed that bee visits increased drupelet formation by 2 to 4 times. If a flower was visited first thing in the day for a prolonged period, two such visits would be sufficient to have great fruit formation.
- There is also a condition of over visitation where bees actually damage the female stigmas if there are too many of them working the flowers.
Adding honey bee hives to a raspberry garden is a good idea for most commercial businesses. However, Alaska temperatures, especially in the a.m. can be cold – too cold for honey bees to be very active. Since nectar flow is greatest first thing in the morning, wild bumble bees become even more critical for great fruit set in northern gardens.
This is a summary of Rehanon Pampel’s thesis documenting bumble bees in agricultural areas of the Interior. It documents species as well as seasonal occurrence. You think bumbles are doing their thing all summer, but there is a definite seasonal pattern to their work.
Here is a link to a journal article comparing native and non-native pollinators of Haskap. They concluded that native bumble bees (compared to orchard bees and honey bees) have the highest pollen deposition per visit, visited the most flowers in a given period of time and could fly at the coldest temperatures, making them the most suited for successful pollination at least in cooler springs. Another interesting thing to note is Figure 1c in the paper. It shows a fruit in which the bracteoles have not fused around the two ovaries of the paired flowers. I find this interesting because I observed several fruits shaped like this and wondered what caused it. Understanding the biology of the flower, the formation makes more sense! KD Fairbanks
Frier, S.D, C.M. Somers and C.S. Sheffield. 2016. Comparing the performance of native and managed pollinators of Haskap (Lonicera caerulea: Caprifoliaceae), an emerging fruit crop. Agriculture, Ecosystems and Environment 219:42-48.
It was all over the internet recently, bumble bees were put on the endangered species list. Research into this decision told me that the “rust-patched” bumblebee (Bombus affinis) was the pollinator. According to the U.S. Fish and Wildlife Service, the bee can be found in the eastern portion of the United States and in some parts of Canada. The Alaskan Department of Fish and Game cites Bombus polaris, the Arctic bumblebee, in this article describing the life of a bumble bee in Alaska. Because they are important pollinators, this is of horticultural interest. The article can be found here:
Sutton, A. n.d. A brief busy life of the arctic bumblebee. Available online: Bumble bees
U.S> Fish and Wildlife Service. 2016. Rusty Patched Bumble Bee. Available online: Rusty patched
. Accessed 5 Oct, 2016
The Leonard Lab at The University of Nevada Reno has been conducting some neat experiments on pollination. Here is a link to a write up of one study showing bumble bee recognition of flower color in association with pollen rewards. They are such smart creatures! Bumble bee learning
If you’re a gardener, berry lover, or if you eat food, it wouldn’t hurt to spend a little more time appreciating our pollinators. One of my favorite authors, Rowan Jacobsen, wrote an enlightening book on the topic of pollination–Fruitless Fall (see below), in particular, on colony collapse disorder in honeybees. It’s frightening to think about the fragility of our current system of pollination. Luckily, wild berries in Alaska do not depend on managed hives for pollination. On my reading list since I read Fruitless Fall is Forgotten pollinators. We should probably all spend a little more time appreciating these flying wonders. I enjoyed watching the beautiful video of buzz pollination(see below) And while we’re on the topic, check out the Xerces society. They have a plethora of great resources on protecting and appreciating our sometimes forgotten and under-appreciated invertebrates. HR Fairbanks
Buchman, S. L. 1997. Forgotten pollinators. Island Press.
Jacobsen, R. 2010. Fruitless Fall: The Collapse of the Honey Bee and the Coming Agricultural Crisis. Bloomsbury, USA.
Xerces Society for Invertebrate Conservation (Home Page). 2016. Available at: http://www.xerces.org.
14 Sept, 2016.
Pollination is the process that leads to the production of the fruits we eat and the seeds we need to grow more plants. It is the process of transferring pollen from flowers to flowers to aide fertilization and encourages new propagation. Natural pollinators are highly effective and although man can mimic the pollination process done by many species, no amount of mimicry can compare to the efficiency of the many different bee species. Of the large variety of bee species, I find the bumble bee to be the easiest to identify as well as the easiest to actually see the pollination process.
There are over 250 bumble bee species worldwide with 49 of them being native to North American (Inouye). Scientifically they can be identified by dividing them into three groups based on the length of their proboscis or tongue (long, medium and short), but the best way to identify a bumble bee is by its fairly large round shape, super fuzzy body and the amplified buzzing sound emitted by their wings. The bumble bees tend to build nests in old hollowed out logs, abandoned rodent holes and other locations down on the ground. The queen will borrow into the ground and hibernate throughout the winter while the rest of the colony will die off in fall. During the spring the new queens come out of their borrow, find a suitable place for a nest and begin to collect pollen and nectar to help feed the first generation of worker bees to hatch. The bumble bee queens will rear a few generations of worker bees which are all non-fertile females to help collect pollen and nectar to help feed the final generation, next year’s queens and fertile males (NPS).
The bumble bee is a hugely important pollinator because of the efficient techniques in which these bees can collect and transfer pollen. The bumble bee will bite the flower in its jaws and use its flight muscles to microscopically and violently vibrate the pollen grains off the flowers anthers this is called buzz pollination or sonication (Inouye). The pollen will stick to the fuzzy body of the bumble bee as well as sticking to what is referred to as pollen baskets or sacs on the back legs. As the bumble bee flies from flower to flower each time carrying away a little pollen as well as transplanting pollen from flower to flower and possibly fertilizing hundreds. “The average mass of pollen and nectar carried by bumblebees returning to the nest is around 25% of their body weight. However some bumblebees fly back carrying as much as 75% or more of their body weight!” (Nature mapping).
Humans are deeply invested in the health status of bee populations because of the environmental services they provide and because of it many species are being commercially developed and shipped all over the globe, even in places they don’t naturally occur. Another hot topic is that bees are of conservation concerns. Human activities including habitat degradation, pesticides, diseases and floral resource depletion can have detrimental effects to bee populations (Inouye). Bees are of major importance to the Earth’s ecosystem functionality and are worth giving a second thought before smashing them out of fear of being stung. Next time you got a big bumble headed your way, think about the significant job that bee performs before reacting with fear. LH Fairbanks
“Bumblebee.” Nature Mapping Foundation. N.p., n.d. Web. 22 Sept. 2016.
Inouye, David. “Bumblebees (Bombus Spp.).” United States Department of Agriculture Forest Service. University of Maryland, n.d. Web. 22 Sept. 2016.
“Pollinators – Bumble Bee.” National Park Services. U.S. Department of the Interior, n.d. Web. 21 Sept. 2016.
Here is a link to an article by Canadian Researchers who are interested in following the growth, flowering and fruiting of two of the most important wild berries, cloudberry and lingonberry. They followed phenological sequences of flowering and fruiting and documented potential pollinators in their region. It is interesting to compare their cycles with Alaska. It was published in:
Canadian. Journal. of Plant Science. 96: 329–338 (2016)
Cloudberry and Lingon phenology
Abstract: Plant habitat, growth, fruit yield and occurrence of pollinators in cloudberry and lingonberry fields/bogs were monitored and analyzed at three locations in southern Labrador: Lanse’au Clair (51°41’ N, 57°08’ W), Red Bay (51°43’ N, 56°26’ W), and Cartwright (53°42’ N, 57°0’ W) over the two growing seasons, 2011 and 2012. The length of the growing seasons was 100–120 d (DFRA 2014) with 600–700 growing degree days (GDD) (AAFC 2014). The 2012 season was warmer than 2011. The plants recorded in belt transects belong to six families: Rosaceae, Ericaceae, Pottiaceae, Juncaeae, Equisetaceae, and Sphagnaceae. In the Ericaeae family, Vaccinium vitis-idaea, Arctostaphylos alpina, Empetrum nigrum, and Vaccinium angustifolium were found. In both seasons, the cloudberry was the first to bloom, followed by wild blueberry, lingonberry, and Labrador tea. The fruit yields of cloudberry and partridgeberry in southern Labrador were higher than those recorded in Finland, Norway, and in the USA. Pollinators were present in large numbers. Most of the specimens were from three orders: Hymenoptera, Diptera, and Lepidoptera. Temperature, precipitation, wind, and sunlight affected plant growth and the occurrence of pollinators. To our knowledge this is the most comprehensive study of plant growth, yield, and pollinators’ activity in cloudberry/partridgeberry fields conducted in Southern Labrador, Canada.
This research showed that bumble bees, Bombus terrestris were the most important pollinators of Lonicera cerulea, honey berry/haskap. Honey bees are good as a supplement but they don’t work in cold temperatures, and their efficiency is far less that the B.B.
Here is a link to a book just published on all Alaska butterflies. Senior author is the late Ken Philip, an amazing man who loved butterflies and tromping around the state looking for them. He was a wonderful resource for all things butterflies. His collections now reside at the UAF museum and the Smithsonian.
Explosive Flowering of the Bunch Berry
NPR’s All Things Considered covers the discovery of the Bunch Berry as the worlds fastest flower. The audio recording on NPR’s website (link below) includes an interview with the student, Sarah Klionsky, who made the initial discovery and her Biology professor, Joan Edwards, who facilitated the subsequent research. The story drives home how important discoveries can still be made of what is often overlooked. Exploding Bunchberries. More about the research that was done and how it was performed is available on Williams College website: Student Research
This week, I listened to a brief 2012 KYUK radio piece on the threat of invasive white sweetclover (Melilotis alba) to Y-K Delta berry patches. It was suggested that the weed, which at publishing had yet to be noticed off the road system, had the potential to invade wild blueberry and cranberry stands in the Interior and lure pollinators away. If blueberries and cranberries received less pollinator visitation or the incorrect pollen, fruit set could be affected.
Research conducted by UAF on 20 test plots near the Steese, Elliot and Dalton Highways found that flowering sweetclover actually encouraged pollinator visitation to berries. Cranberries and blueberries saw at least 3 times the pollinator activity they normally would and cranberries actually had improved fruit set when flowering sweetclover was present. However, researchers couldn’t quite link the results solely to the sweetclover.
Another study was done in a more controlled setting (sweetclover was introduced to test plots around UAF):
“During a rainy June in the first year, conditions seemed to draw pollinators away from native berry plants that were a moderate distance away. During a sunny June in 2012, conditions were good enough that all the plants seemed to benefit.”
More research is necessary, but it was suggested that certain geographic areas might be more susceptible to sweetclover competition (especially those where the sweetclover and berries have highly overlapping flowering periods). Competition for space, however, might be the real issue for native berries:
“Mulder said white sweetclover towers over berry plants and adds nitrogen to the soil, which are factors that could cause it to slowly crowd native plants out of their turf.”
This website is for Honeyberry USA, which is a berry farm that sells cultivated berry bushes. They are located in Minnesota, so most of their berry bushes are cold-hardy. They mostly sell honeyberry bushes, but also have gooseberries, currants, and juneberries. Another item they sell is a mechanical pollinator for berry bushes. Honeyberry Source
Bumblebees and buzz pollination make the NY times. This article reviews work scientists are doing to understand buzz pollination and how it and the flowers that rely on it evolved. It provides a good description of what buzz pollination is explaining that “Bees experience forces 30 times greater than gravity as they buzz for pollen — near the limit of human endurance.” Buzz Pollination
This presentation on pollination effectively illustrates the relationship between flowers and their pollinators. It contains striking photos of pollinating insects and birds and is told from the perspective of an entomologist. The photos of pollinating bees and bats are particularly dramatic. Plants and Pollinators
Haskaps (AKA honeyberries) are hardy plants with delicious fruit – all Alaskan’s should be growing these plants in their garden!
Most haskap varieties are considered self-incompatible, meaning more than one plant is necessary to get substantial fruit set. But it is not just a simple math equation. Certain varieties are too similar genetically and will not be able to pollinate one another. And certain varieties bloom early or late, so one must consider bloom time of specific varieties.
So how many do you need? According to the University of Saskatchewan, leaders in haskap breeding for commercial and garden applications, one pollinating plant is needed for every five plants. Other sources claim planting a pollinator plant for every 2-4 plants is adequate, while others advocate planting 2 or more varieties in the same plot. As you can see, there is some disagreement in this area, but the common thread is that more than one variety is necessary to get productive fruit set! This is a true case of more is better, and isn’t it nice to be able to justify those extra berry shrubs in your cart? And of course, insects are necessary in this process to get pollen between plants.
Learn more about haskap pollination here:
University of Saskatchewan haskap page-see the table at the bottom of the page with variety compatibility information
Being able to identify common insects in your berry stand will help you understand the relationships between plants and insects to help you become a better manager. A majority of the insects encountered in wild and cultivated berry stands play a beneficial role, such as pollinators or predators of potential pests, but some may be pests that decrease yields. Below are some resources that growers can consult as a starting point to learning more about insects in Alaska.
Insects of South-central Alaska by Dominique Collet. Although the title professes a focus on south-central Alaska, most species described can be found throughout the state. Excellent photos and descriptions make this a useful guide for the amateur through professional.
Cooperative Extension Service – Integrated Pest Management program. Have you collected an insect that you suspect is a pest? You can contact your local IPM technician for assistance identifying the insect and to provide you with management information. If you live in an area without a local Cooperative Extension Office and are good with a camera you can submit photos and information through the digital portal and be connected with the nearest IPM technician. Through the Extension IPM website you can also search available publications, such as Beneficial Insects and Spiders of Alaska.
US Forest Service – Forest Health Protection Program. Their website has resources about forest pests, some of which cross-over to berry plants.
UAF Museum of the North – Entomology Collection. Learn more about the variety of insects that have been documented in Alaska. This website, and the searchable ARCTOS database, is most useful if you already know a bit about the insect in question and you are just checking to confirm its existence in Alaska. You can also look through all the insect records in ARCTOS that have pictures in the record.
Alaska Entomological Society – Are you REALLY interested in Alaska’s insects? You may want to consider joining this society to support further investigation and awareness of Alaska’s insects.
Berries Northwest – Although not Alaska specific, this site could be an excellent first step to diagnosing an insect or pest problem. You can search by crop or pest, then look through descriptions and management options.
The Forest Service has an easy to navigate site on all of the different types of animal pollinators Animal Pollinators
This research is on cloudberry pollinators (Rubus Chamaemorus).Cloudberry pollinators