About Pollination 

​Plants and pollinators have developed very intimate associations over time-- so much that insects are a necessary part of the reproductive success of many plants. Pollination is the process by which pollen is transferred to the female reproductive organs of a plant, thereby enabling fertilization to take place. Without this step, there may be no seed, no nut, no fruit, no vegetable!​
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Most plants require assistance of animal (insects, birds, bats) or wind to be pollinated. 1 in 3 bites of food relies on insect pollination! ​Like all living organisms, plants have a single major goal: to pass their genetic information on to the next generation.  Successful pollination means that a pollen grain produced by the anther, the male part of a flower, is successfully transferred to a stigma, the female part of the flower of a plant of the same species, where a seed will then be produced​. Pollinating insects have many special adaptations- such as pollen-attractive ​hairs on their​ bodies- to ensure that this happens. ​
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Why are honey bees the best pollinators in the business?  Honey bees are good at the transfer of pollen from the anther to the stigma​, they are easily transported​ in their colonies, the size of their nest can be manipulated and may contain up to 60,000 individuals, they adapt to find forage quickly in new settings​ and ​they can travel great distances. 

Current Pollination Research

Please click on titles for more information about research projects
Comparison of US honey bee genetic lines for queen production and pollination efficiency under field conditions
Principal Investiagtor:  Steve Sheppard, Washington State University, 2016
There is evidence that honey bee subspecies that have evolved in mountainous/temperate regions fly at lower temperatures than subspecies originating from warmer regions.  A majority of the US commercial breeding stock is derived from Apis mellifera ligustica, a subspecies native to the Italian peninsula.  The subspecies evolved in a generally warm “Mediterranean” climate.  Previous importations of a number of other subspecies are reported in the literature, but most fell out of favor with US beekeepers or were lost due to founder effects.  There remains a small percentage of queens in the US sold as “carniolian queens” originally derived from A. m. carnica, a subspecies endemic to the Alps Mountains. With genetic material imported by WSU over the past 8 years, coupled with the ability to backcross progeny using cryopreserved semen, we have been able to largely reconstruct several subspecies here in the US.   Two of these, A. m. caucasica and A. m. carnica, have been made available recently to commercial queen producers and are beginning to be more widely distributed to beekeeper customers.  As a result, we now have an opportunity to directly compare among subspecies for traits such as mating flight success and foraging behavior during inclement temperatures.
 
Coincident with this new opportunity to directly compare subspecies and unique US breeding lines we now have the capacity to delineate differences that could have significant impacts on crops that depend on honey bees as the main source of pollination.  There are a number of crops in the US that can suffer reduced yields due to poor pollination that results from decreased bee flight time during cold or inclement weather through bloom.  This project will, for the first time, provide empirical data to test the long-held hypothesis that honey bee subspecies from mountainous regions fly/pollinate at lower temperatures than subspecies from warm/arid climates.  At the other end of the spectrum there are high value seed crops that bloom during the heat of the summer that can also show reduced yields caused by a lack of pollination, because at a certain temperature honey bees divert the foraging force from pollen collection to water collection when temperatures are too hot.  It would be logical to hypothesize that honey bees adapted for hot/arid climates might be better pollinators in those conditions than bees derived from mountainous areas.
 
A better understanding of the characteristics of the available breeding stock in the US is essential as we face unknown climatic shifts that have major impacts in our agricultural system.  Findings from research described above have the potential to change pollination strategies and demands for specific honey bee “types”.  It might be, that for increased pollination security/insurance there is value in stocking orchards/fields with a mix of distinct honey bee genotypes to improve crop yields in years of abnormal weather.
Specific Objectives: 
1.Compare 2 Old World subspecies and 3 commercial lines for mating success in early season (temperate/inclement weather) queen production.
2.Compare 2 Old World subspecies and 3 commercial lines for pollination efficiency under various weather conditions (cold weather fruit and nut pollination and hot weather seed crop pollination)
3.Compare 2 Old World subspecies and 3 commercial lines for overwintering survival, productivity/vigor and Varroa tolerance.

Completed Pollination Research

Please click on titles for more information about subjects and research projects
​The Effect of Colony Size and Composition on Almond Pollen Collection
Principal Investigator:  Dr. Frank Eischen, USDA, 2007
​Dr. Frank Eischen and colleagues from the Honey Bee Research Unit, USDA-ARS, Weslaco, TX, monitored US and Australian honey bee pollen collection of various colony sizes on a large almond orchard near Shafter, CA. After 20 days of continuous pollen collection, 11 colonies were evaluated for strength, broodnest size and stored pollen.

​Click here to view Dr. Eischen’s 2006 WAS PowerPoint Presentation.
Click here to view Dr. Eischen’s 2007 CSBA PowerPoint Presentation.

The list of treatments in ascending order of pollen collected was:
US 4-frame; US 6-frame; AUS colony established Dec 06 from 4-lb pkg; US 4-frame + 4 lb AUS pkg; US 8-frame; US 4-frame + US 4-frame (2 united 4-frames); US 10-frame; and US 14-frame.

Dr. Eischen’s conclusions are as follows:
-Colonies should have been fed protein supplement prior to bloom.
-Colonies increased pollen collection as their size increased to about 12 frames.
-The addition of an Australian package improved pollen collection by 4-fame colonies.
-The addition of the AUS package greatly improved brood rearing.
-When two US 4-frame colonies were united they collected more pollen than two separate 4-frame colonies.
-Large colonies begin foraging earlier than small colonies.
-Colonies facing east begin foraging earlier than those face west.
-The addition of brood decreased pollen collection.
-Australian colonies collected more pollen than their size would indicate, but the researchers suspect this was due to their behavior in handling pollen traps differently.
The Effect of a Synthetic Brood Pheromone (Superboost, Pherotech) on Almond Pollen Collection by Honey Bees
Principal Investigator:  Dr. Frank Eischen, USDA-ARS, Weslaco, TX, 2008
​Dr. Frank Eischen, USDA-ARS, Weslaco, TX monitored almond pollen collection by colonies treated with Superboost, a synthetic brood pheromone.
Small overwintered colonies (US 4-frame) that were pollen trapped and treated with Superboost collected about 35% more pollen than untreated and trapped colonies. Larger colonies (US 8-frame) showed no increase in pollen collection when treated and trapped. Newly established Australian package colonies, which were pollen trapped, did not respond to treatment with Superboost. In a parallel series of treatments, free-flying colonies matched for origin and size with the trapped groups exhibited no increase in pollen foraging when treated with Superboost.
Crops with scant pollen flows, (eg. blueberries and cucurbits) may be appropriate crops for treating colonies with Superboost as bees are unlikely to harvest enough pollen from the crops alone.
Quantifying the Exposure and Effect of Farmer Applied Pesticides on East Coast Migratory Operations Destined for Almond Pollination
Principal Investigator:  Dennis VanEngelsdorp, Penn State University, 2008
​Along with PAm, the USDA/CSREES, the National Honey Board and the Florida Department of Agriculture contributed to funding this project performed in cooperation with USDA-ARS Beltsville. The purpose of this study was twofold: 1) to analyze pesticide exposure in bees and pesticide residues in pollen of samples taken in the initial national CCD study, and 2) to establish a centralized cost-sharing pesticide screening program at Penn State as a service to beekeepers. One aspect of this project focused on the importance of East Coast migratory operations servicing Western pollinated crops. Of colony samples analyzed during this time period, coumaphos and fluvalinate, two compounds used by beekeepers themselves, were highly prevalent. More pesticide analysis was conducted in other funded research studies
Residues of Neonicotinoid Insecticides in Flowers, Pollen and Nectar of Treated Blueberries, Cranberries and Squash
Principal Investigator:  Dr. Kimberly Stoner, COnneticut Agricultural Experiment Station, 2008
The published paper, “Movement of Soil-Applied Imidacloprid and Thiamethoxam into Nectar and Pollen of Squash (Cucurbita pepo),” (PLoS ONE June 2012) has been cited 101 times, considered by the scientific community as a wide influence for this research.
Click here to view research publication
PAm sponsored researcher Dr. Kimberly Stoner, Connecticut Agricultural Experiment Station, to measure the levels of neonicotinoid pesticides bees are exposed to when contacting flowers and collecting nectar and pollen in the field. The goal of the research project was to quantify movement of neonicotinoid insecticides into the pollen and nectar of plants when applied directly to the soil, either by direct spray to the soil just before seeding or through drip irrigation.
These insecticides are some of the most widely used pesticides in the U.S. and are thought to move from the seeds and root system into other areas of the plant. The U.S. EPA has not yet analyzed sublethal effects of neonicotinoids on honey bees.
Residues of the insecticides were found in the whole plants, pollen and nectar. The concentrations found in nectar are higher than previously documented concentrations of neonicotinoids in nectar of plants grown from treated seed (corn, canola, sunflowers). The concentrations in pollen are at the high end of the previously documented range. These concentrations fall into the range being investigated for sublethal effects on honey bees and other beneficial insects.

The research findings in Maine wild blueberry indirectly benefited both migratory and local Maine beekeepers. Wild blueberry is the major bee pollinated crop in Maine. Our Project Apism. funded research provided the data that formed the basis of Cooperative Extension recommendations regarding the neonicotinoid insecticides, imidacloprid and acetamiprid. Oral presentations at blueberry grower field days and written recommendations posted on the Wild Blueberry Website, and at the University of Main Cooperative Extention, resulted in advisories against using imidacloprid pre-bloom or bloom for defoliating insect pests and only for blueberry maggot fly twenty-two months prior to bloom. Our data shows that applications of imidacloprid made 22 months prior to bloom does not result in residues and honey bee exposure risk during bloom. This has been a very SUCCESSFUL program as pollen trapping, wax and worker assessment for residues has resulted in almost no evidence of exposure to neonicotinoid insecticides in Maine wild blueberry during bloom.
            In addition, the research findings on acetamiprid formed the basis of another funded research project (funded on USDA/SCRI block grants) to investigate possible synergy effects on honey bees and bumble bees with simultaneous exposure to acetamiprid and the fungicide ​
Honey Bees and Colony Evaluation - An Online Learning Program
Principal Investigator:  Shannon Mueller, UC Cooperative Extension, 2011
Dr. Shannon Mueller, University of CA Cooperative Extension, has created a new Online learning program for honey bee colony evaluation.  The information includes basic honey bee biology, recommended colony strength evaluation practices, and recognition of important diseases, pests, and parasites that impact honey bee health. This large amount of information, organized by specific topics, can be accessed at any time with the click of a web link!

View the online learning program 
Honey Bee Colony Density and Almond Nut Set 
Principal Investigator:  Frank Eischen, USDA, 2011
​Dr. Frank Eischen, Honey Bee Research Unit, USDA-ARS, and a team of researchers, examined the impact of honey bee colony density on almond pollination on ranches near Bakersfield, CA. Both early and late varieties were tested on each of the four ranches. Flower counts and video recordings of bee activity aided in interpreting pollination rates.
Early varieties:  With the exception of Sonora, all early varieties in orchards with higher colony densities had significantly higher pollination rates.   Differences in percent pollination between low and high bee densities ranged from 1.5 to 18.4% for varieties Nonpareil, Fritz, Monterey, Sonora, and Aldrich. Significant increases in pollination occurred in 92% of the paired early variety blocks.
Late varieties:  With the exception of one, all orchards stocked with the higher colony density had significantly higher levels of pollination.  Differences in percent pollination between low and high bee densities ranged from 5.7 to 18.4% for varieties Butte, Padre, and Mission.
Video recordings of bee activity on flowers found that foragers in high bee density blocks remained on a flowering branch longer than foragers in low density blocks. This increased time spent on a branch helps to explain why a doubling of honey bee colonies generally did not result in a doubling of the pollination rate for pairs of orchards. That is, pollination is more likely to occur when pollinators move from branch to branch.
​Effects of a Fungicide and Spray Adjuvant on Queen Rearing Success in Honey Bees
Principal Investigator:  Reed Johnson, Ohio State University, 2011
Click Here to view research publication
​Reed Johnson and Eric Percel, The Ohio State University, studied the effects of queen bee health when exposed to applications of the fungicide Pristine (boscalid and pyraclostrobin) and spray adjuvants (used to increase the efficacy of the active ingredients).  Their research was of particular interest as it analyzed compounds that are not regarded as highly toxic to adult honey bees but have less know effects on immature bees.  The study conclusions have been published in the Journal of Economic Entomology Research in Dec, 2012.  To test the effect of these compounds on queen development a new test was developed in which queens were reared in closed swarm boxes for four days, until capping, with nurse bees fed exclusively on artificially contaminated pollen.  Pollen was treated with several concentrations of Pristine, a spray adjuvant (Break-Thru), the combination of Pristine and spray adjuvant, and the insect growth regulator insecticide diflubenzuron (known for having a toxic effect on immature bees).   Analysis confirmed that diflubenzuron, in conjunction with Pristine or a spray adjuvant, led to substantial reduction in survival of immature queens.  The potential for diflubenzuron toxicity to change in the presence of fungicides and pesticide adjuvants needs further research.
Effects of “Bee-Safe” Insecticides and Common Insecticide-Fungicide Combinations on Queen and Worker Larval Development
Principal Investigator:   Reed Johnson, Ohio State University, 2013
Reed Johnson, The Ohio State University, will continue his research to further the information gleaned by his previous study on the effects of insecticides applied to almonds during bloom to developing honey bees. As insecticide use continues to grow, more research is needed to assess the effects of insecticides on colony health. The research study will focus a majority of the effort on diflubenzuron (Dimilin 2L), as this insecticide is the most widely used during almond bloom and has documented potential to harm bee development. The team will also research the effects of high concentrations of methoxyfenozide (Intrepid 2F) and chlorantraniliprole (Altacor), to determine their potential to affect the development of bees. Tests will be conducted on these insecticides and combinations on queen larval rearing and worker larval rearing success.
Watch related video:  Chemtura discusses BMPs for Dimilin Use
Petal Fall
Principal Investigator: Frank Eischen, USDA, 2014
Evaluation of Accuracy and Cost-Benefits of Using Infra-Red Imaging of Honey Bee Colonies as an Augmentation to Visual Grading to Determine Colony Population Size
Principal Investigator:  Robert A. Seccomb, Bee Alert Technology, Inc., 2014
Visual grading of colony strength is a major contribution to the cost of bringing Honey Bee colonies in for almond pollination. Visual estimation of bee population size is most accurate during the early morning at low air temperatures, and it is least accurate on warm, sunny periods when the cluster expands and the majority of the forager bees are in the field. The latter conditions may lead to significant under-estimates of colony size. In addition, counting frames of bees does not provide a reliable means of determining whether a laying queen or brood is present, critical factors that govern whether a colony gathers pollen, and which require laborious inspection of each colony.
As an augmentation to visual counts of frames covered by bees, Infra-Red (IR) imaging offers the possibility of reducing the labor needed to grade large numbers of colonies. This is done through enabling a single person to rapidly assess relative colony strength of a large number of hives. Imaging with IR can be used to detect colonies that are weak or borderline. Then those colonies selected for visual grading can be isolated and ideally the number of visual inspections will be reduced. While the number of visual inspections would go down, the number of total colonies given a strength assessment should go up. Additionally, a visual record (both IR and visible spectrum) of the population size of each colony is acquired and archived. Since IR imaging is conducted at night or early in the morning, all of the bees are in each colony at the time of the assessment of colony strength, which should improve overall accuracy.
Objectives: The primary objective of this proposal is to determine the utility of our IR imaging systems to identify colonies that need additional inspection and reach a target benchmark of within ±1 frame equivalency of visual grading. Doing so will provide a labor reduction tool for growers and beekeepers.Through this we can develop a toolset that can benefit growers and beekeepers and still provide a reasonable return on investment. 
The Impact of Blueberry Pollination on Colony Health
Principal Investigator:  Dennis Van Engelsdorp, University of Maryland, 2015
Blueberry shrubs require pollination to produce high, uniform yields, so a viable and healthy supply of bees is essential. The Bee Informed Partnership has received numerous reports of large beekeeper losses during and shortly following blueberry pollination, which may be driving up pollination prices as beekeepers build compensation into their rates against potential pesticide losses. Emergency Response Kits evaluated on behalf of commercial beekeepers demonstrate elevated fungicide exposure during blueberry pollination in some samples. 
While fungicides are currently deemed safe for honey bees, increasing evidence suggests these fungicides may be detrimental to honey bee larvae and colony health. We propose to follow hives from three commercial operations before, during and after blueberry pollination to evaluate the impacts on colony growth, colony survival and pollen pesticide contamination. 
Specific Objectives: Determine the risk blueberry pollination has on colony health by:
measuring impacts (if any) of blueberry pollination has on colony size, and measuring and comparing pesticide residues in bee bread before, during, and after blueberry pollination.

Research Quicklinks: