POLLINATION: BREAKING THE EITHER/OR PARADIGM
A recent issue of The Beekeepers Quarterly (No. 64, February 2001), published by my good friend Jeremy Burbidge in the United Kingdom, the Owner of Northern Bee Books, features an article billed as a “pollination debate”: Osmia rufa (the red mason bee) vs Apis mellifera (the honey bee). Contributors Bill Clarke, Geoff Hopkinson and Chris O’Toole weigh in on the topic with some zest.
Mr. Clarke says that O. rufa is certainly an interesting and useful bee, but surely not as good as “our honey bees.” He is concerned about the mathematics of it all. Conservatively he judges that simple division using conservative numbers reveals that one red mason bee must do the work of 180 honey bees. He is also “unhappy” about the comparison between the two bees. “It is all very well to note how quickly the two types of bee gather their pollen or nectar, perhaps both simultaneously, in a race with each other, but it is what happens between that time that counts. Whilst she is building her pellet of nectar and pollen, Osmia will return at about 15-minute intervals, some three to four times. One bee nesting in my door lock took around a fortnight (two weeks) to make fourteen cells, that is some 68 visits to the field to pollinate, add another two or three visits each day to top up her energy supply, then she has made over a hundred pollination trips. In the meantime, the honey bee has dumped her load with her sisters and returned time after time — if the hive is in an orchard then she would easily make a hundred excursions in three to four days.”
Mr. O’Toole ripostes that the data supporting the fact that Osmia spp. are more efficient pollinators of orchard crops is in the public domain and backed up by a wealth of observations. He too uses arithmetic. “The female part of any apple flower comprises 5 stigmas borne in a subdivided style, 5 carpels with 2 ovules per carpel. Thus, a fully cross-pollinated apple flower requires the transfer of at least 2 pollen grains from flower of a pollinizer cultivar to EACH of the 5 stigmatic surfaces of the pollinated flower during the short period of stigma receptivity. All this boils down to the number of pollen grains delivered per bee visit. For anatomical and behavioural reasons, Osmia bees deliver more pollen per stigmatic surface than honey bees: their pollen is carried in dense, dry masses on the underside of the abdomen and, unlike honey bees, they always land directly on anthers and stigmas and actively scrabble for pollen in a violent manner. By contrast honey bees at apple flowers often make side-visits only, which result in little or no pollination. Pollination results with Apis which are considered adequate depend on the ease of ensuring blanket coverage to offset the low efficiency of individual workers.”
Mr. Hopkinson says Mr. Clarke’s concerns regarding the mathematics of hive population are well presented, and follow a line of thought fundamental to any essay on the dynamics of fruit population. A possibly contentious statement, he says, is that “any flower visited by the honey bee will be adequately pollinated.” Pollination is not the same as fertilization, according to Mr. Hopkinson who concludes, “the aim is surely to supplement existing pollination agencies, at a time when the Apis mellifera populations are in the decline.” Mr. O’Toole adds: “Because of their differing flower-handling behaviours and resource needs, Osmia spp. and Apis mellifera do not threaten each other competitively and I would advocate that Osmia spp. be used to complement rather than entirely replace Apis.”
In reality, comparison of the two kinds of bees, one a solitary, few-crop specialist and the other a social, cosmopolitan pollinator of a wide variety of plants, is a futile exercise. It very much is in line with the classic statistical statement, “one cannot compare apples and oranges.” Thus, the either/or paradigm in pollination probably should be replaced with a more bee-friendly complementary message. This is also the approach taken by others, including The Solitary Bee Web, which uses the phrase: “Solitary Bees: An Addition to Honey Bees. Dr. Joseph Wilson, Utah State University, looks at wild (native, Non-Apis) bees with a wider lens. He discusses buzz pollination in the following video, along with other topics like bee mimics, native bees (most species), while the honey bee is only one of thousands of bees. Most Basic needs for bees are food and nesting sites. How can we “save the bees” if we don’t know and can’t identify bonafide bees, 8 minutes, 40 seconds.
Some may have heard of the successful program begun out west called “The Forgotten Pollinators.” Although this targets the insects involved, the pollination process is also important, especially within the context of modern agriculture.
I have modified “forgotten pollinators” to read “Pollination, the Forgotten Agricultural Input.” I gave a paper with this title at the Florida Agriculture Conference and Trade Show (FACTS) in Lakeland. It concluded: “Much is known about the panoply of other agricultural inputs, but pollination has often been sidestepped in the process. Only when growers and commercial pollinators get a better picture of the key relationship between certain plants and their pollinators will they be able to take advantage of this forgotten agricultural input.”
Perhaps the most influential publication on pollination is Insect Pollination of Cultivated Crop Plants, A section called the Economics of Plant Pollination discusses a broad range of issues. Contributor David MacFawn and collaborators have produced a more focused economic analysis of cotton pollination.
WIDENING THE POLLINATION PERSPECTIVE
Dr. Keith Delaplane at the recent Beekeepers Institute at Young Harris, Georgia discussed a variety of non-Apis bees that are potential pollinators. He urged those present to become actively involved in helping to conserve these so-called “pollen bees.” Allowing fields to fallow and fence rows to grow up in wild plants, Dr. Delaplane said, will help conserve the vegetation all insect pollinators, including honey bees, need for forage. In addition, these practices will help preserve the soil nesting sites required by many solitary bees. This message should be spread by beekeepers, Dr. Delaplane concluded, because few others are knowledgeable enough to do the job adequately.
For rabid honey beephiles, some of Dr. Delaplane’s remarks might have raised a few eyebrows. Historically, many are concerned only with the welfare of Apis. Other bees have often been relegated to the sidelines because they produce no honey. However, it is becoming clear that concentrating on honey bees as either the only pollinators in the environment or the most efficient is no longer tenable. In fact in some quarters there is discussion of the honey bee as an invasive and harmful species.That said, Apis mellifera still remains the principal manageable resource agriculturalists can use to increase yields and crop quality.
And there is mounting evidence that growers are finally receiving the message beekeepers have been trying to communicate for many years. Simply put, pollination is just as important an input as irrigation, fertilization and pesticide application. Pollination is difficult to measure, however, and honey bee colony performance may not always be up to par. According to Dr. Eric Mussen, writing in his May/June 1995 From the UC Apiaries, the latter is likely to be a contentious topic. Growers, he says, want to rent highly populous colonies that cannot fail to provide 100 percent pollination.
Few farmers or average citizens are aware, Dr. Mussen says, that darkness, rain, heavy fog and winds more than 12 miles an hour (conditions prevalent during a series of winter storms in California) not only kept honey bees inside their hives, but also caused pollen degradation and the spread of plant diseases. These conditions resulted in production losses, according to Dr. Mussen, practically ignored until California cherries became priced four times higher than normal this shipping season. In spite of efforts to communicate a different message, however, the simple perception spread by The Wall Street Journal and other media sources prevailed, according to Dr. Mussen. The honey bees, and by extension the beekeeper, didn’t get the job done.
Thus, it’s up to the beekeeper, Dr. Mussen concludes, to inform growers and others about the problems associated with keeping honey bees and using them as pollinators. Many do not realize how much expense is involved in managing colonies, nor what other factors might affect pollination success, including environmental conditions and the role of alternative pollinators.
Both Drs. Delaplane and Mussen seem to agree. The beekeeper is in the best position to consult with growers not just about honey bee rental, but pollination problems in general. Thus, the day may have finally dawned for pollination to become the growth industry many predicted. In order to remain credible, however, apiculturalists must widen their pollination perspective. Instead of simply focusing on the management of honey bee populations, they should become experts in all facets of the pollination process, including the role played by other pollinators.
POLLINATION INFORMATION RESOURCES
A Guide to Managing Bees for Crop Pollination by the Canadian Association of Professional Apiculturists (CAPA) is out of print, but can still be viewed. Although concentrating on honey bees, this publication also contains information on other factors affecting pollination. The 34-page booklet contains seven chapters: Pollination, Pollinating Agents, Primary Insect Pollinator – The Honey Bee, Management of Bee Colonies for Pollination, Management of Alternative Bee Pollinators, Pollination Requirements of Specific Crops, Pesticide Hazards and Bee Pollinators.
Two sections are of particular interest. One discusses other insect pollinators and another focuses on pollination aids. According to the publication, although honey bees are the most important pollinator, alternatives do exist. However, the management of these pollinators is as varied as the insects themselves. The technology to rear the leafcutting bee, Megachile rotundata, is well defined, as is that for the orchard bee (Osmia), cultivated in Japan for apple pollination.
The bumble bee (Bombus) is an important pollinator of native plants because it has a long tongue, forages during cold temperatures and buzz-pollinates (sonicates the anthers, causing pollen discharge). However, the rearing practices for bumble bees are not easily undertaken by the novice. The best advice, according to the publication, is to provide nesting habitat and a wide variety of food plants these insects need to complete their reproduction.
In his remarks at Young Harris College, Dr. Delaplane recounted some of what he has learned about rearing bumble bees. Calling them, the “hamsters of the bee world,” he has designed a nest box and is trying to get these insects to complete their life cycle under controlled conditions. Most bumble bee rearing currently depends on capturing wild queens in early spring, letting the colony grow and abandoning it to its natural senescence in the fall. Because these rearing practices are time-consuming and complex, each insect in a bumble bee nest pollinating tomatoes in greenhouses may be worth as much as $1.25!
As a pollinating aid, the publication describes the concept of using a pollenizer, a plant variety providing a source of compatible pollen for cross-pollination. The use of pollen inserts that automatically apply pollen to bees a the hive’s entrance is also explained, as are techniques that reduce competition from other plants that may be blooming at the same time. Finally, there is the possibility of directing or luring bees to crops.
The latter is controversial and requires a good deal more study. According to the publication, directing bees to target crops is difficult if the flowering plants have little or no pollen or nectar available, or if the crops provide less reward than nearby forage. The best attraction occurs when the target crop’s odor is incorporated into the colony’s food supply. Although spraying sugar syrup on plants may increase the number of visiting bees, the publication concludes, this seldom results in more yield. More research is needed to prove that pollen odors from extracts attract bees to plants requiring pollination.
Of the substances used to lure honey bees to plants, only those based on bee pheromones appear to hold much promise, according to the publication. The queen produces a five-component Queen Mandibular Pheromone (QMP) that has been synthesized and is sold under the name FruitBoost(R) in Canada. The publication states, “QMP is mixed with water and sprayed on crops slightly preceding peak bloom. Research on apples, pears, cherries, cranberries and blueberries indicate that QMP is effective in increasing the number of honey bees foraging on these crops under a wide range of environmental conditions, orchard management systems and geographical locations.”
The honey bee vs southeastern blueberry bee and other pollinators is an interesting contrast. The honey bee is not the most efficient pollinator of blueberries, especially some varieties adapted to the South, but often makes for this by delivering huge numbers of potential pollinators. An article entitled: “Honeybees are Poor Pollinators – Why? (Plant Systematics and Evolution, Vol. 177:7175) by Christian Westerkamp discusses some of the biological reasons that honey bees are not always the best pollinators.
The principle thesis of the paper is that honey bees, because of the colony’s perennial life over many generations, cannot afford to adapt to the needs of one or a few plant species. These insects must take advantage of as many plants as possible and thus remain generalists. This is good for bees as well as beekeepers, for it guarantees productivity in a great many geographic locations. However, it also means that few if any honey bee adapted flowers exist and so pollination by these insects is a hit and miss affair. The paper’s conclusion: “Considering the high number of flower and pollinator species and the multitude of their respective interrelations it is obvious that a single species cannot take over all pollinatory tasks…Honeybee monocultures thus must be avoided or overcome and a manifoldness of pollinators must be fostered instead by all means.”
In spite of evidence that honey bees are not perfect pollinators in all situations, fans of these insects don’t need to despair. The fact that honey bees are generalists means they can be used as pollinators for a wide variety of crops. And in most circumstances, they are the insect of choice when it comes to employing practical pollination practices.
Due to pubic and beekeeper anxiety about honey bee and general pollinator health, an initiative by the Obama administration was developed in 2014. Subsequent information was published in 2016 on this effort.