Pollen Harvest by Sonoran Native Bees and Flowering
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Pollen Harvest by Sonoran Desert Honey Bees: Conservation Implications for Native Bees and Flowering Plants Item Type Article Authors Buchmann, Steven L.; Shipman, Charles W. Publisher University of Arizona (Tucson, AZ) Journal Desert Plants Rights Copyright © Arizona Board of Regents. The University of Arizona. Download date 08/10/2021 03:05:24 Link to Item http://hdl.handle.net/10150/554244 Pollen HarvestBuchmann and Shipman 3 on its host plants, it would have been available for transport by co- adapted insect, bird and bat pollinators which are of- ten better at depositing viable pollen, effecting subsequent fertilization, fruit and seed set on native flowering plants. Sonoran Desert bees are predominantly specialist feeders Pollen Harvest by Sonoran and depend upon certain plants more than honey bees which can switch hosts at will and have a highly mixed diet. Thus, Desert Honey Bees: in direct competition with these alien social bees living in Conservation Implications forlarge colonies, native desert bees are often at a disadvantage in acquiring pollen and producing replacement offspring. Native Bees and FloweringDesert flowering plants, especially rare, threatened and en- Plants dangered species are also adversely affected since honey bees remove most of the pollen and often are responsible for setting fewer seeds or dispersing pollen at different distances than their original pollinators once did. Introduction Honey bees (Apis mellifera L.) live in eusocial matriarchal colonies usually founded and headed by one long -lived queen. Because of their ability to produce a new queen from Stephen L. Buchmann a young fertilized egg of the previous queen, the process USDA -ARS Carl Hayden Bee Research Center known as reproductive swarming, colonies may persist for 2000 East Allen Road many years. A single colony, living in deciduous forests in Tucson, Arizona 85719 New York state, has been estimated to have an average lon- gevity of 5.6 years (Seeley, 1986). Mature colonies are com- Charles W. Shipman prised of 20,000 to 60,000 individuals, of which at any time Arizona -Sonora Desert Museum there may be a few thousand drone bees (males) present. 2021 North Kinney Road The collective biomass of the adult bees in such a hypotheti- Tucson, Arizona 85743 -8918 cal colony may be from one to six kg. In one year, during 10 to 15 brood -rearing cycles, the colony may produce a total of 150,000 to 250,000 individuals. The food consumed by the "superorganism" colony in one year's time is staggering. A colony may easily collect and collectively ingest as much as 20 to 50 kg of pollen (the floral equivalent of tens of millions Abstract of flowers), 40 -60 kg of stored honey and perhaps 0.1 kg of Managed and feral honey bee colonies (Apis mellifera) har-plant resins, saps and gums, known to beekeepers and herbal vest immense quantities of nectar and pollen within kilome- medicine practicioners as propolis. To amass such floral re- ters of their nests whether they live in relatively undisturbed sources the bees may have made as many as 1.3 to 2.0 million or agricultural habitats. Within the Sonoran Desert of south-trips for pollen and perhaps three million foraging sorties in ern Arizona, pollen collection by European honey bee colo-search of nectar (Seeley, 1986; Buchmann, unpubl.). During nies was monitored by the use of apicultural pollen traps.its first year of life a new bee colony will produce approxi- Managed colonies near Tucson, Arizona routinely collectedmately 9,900 cm' of comb area containing about 4,100 double - from 20 to 50 kg of pollen each year. Flowering pulses (phe-sided hexagonal cells in which to raise their larvae along nology) in the local flora was closely tracked by the colonies,with storing pollen and floral nectar, processed into honey. and pollen influx into their nests usually occurred as three to four distinct seasonal peaks, although some pollen was ac-Only four resources - pollen, nectar, water and plant resins tively harvested during 48 or more weeks every year. The - are required by the honey bee colony to support all life range of flowers visited for pollen by the honey bee is likelyfunctions. Floral and extrafloral- derived nectar contains sug- the most diverse for any social or solitary bee yet studied, ars (mainly sucrose, glucose and fructose) which are the en- largely due to their massive food requirements, efficient scout-ergy -rich nutrients necessary for individual metabolism, part ing and recruitment to ephemeral flower patches, and persis- of the larval diet, a thermoregulatory and flight "fuel ", and tence of their colonies as perennial units for many years. Atthe material hoarded, as honey, in capped combs to support most Sonoran Desert sites, honey bee colonies took pollenlife during periods of extranidal nectar dearths or over the from at least 12 and as many as 40 -50 dominant angiospermlong cold confinement during winter. Pollen, the collective taxa. Additionally, pollen diet breadth of feral honey bee colo- term for the individual sperm cell- containing male gameto- nies was determined microscopically from blackened below - phytes of angiospermous plants provides the major dietary nest refuse deposits known as bee middens. One such de-source of proteins, amino acids, lipids, minerals, vitamins posit from the Arizona -Mexico borderlands is thought to rep- and other essential nutrients for larval growth and adult resent more than a half century of accumulated materials.physiological maintenance. Honey bees are dominant invertebrate herbivores in desert regions taking pollen and nectar in massive amounts from atA honey bee colony can thus be visualized as a highly spe- least 25 percent of the local flora. Had this pollen remained cialized foraging "machine" able to locate through the initia- 4 Desert Plants1996 tive of scout bees and their recruits, the richest floral patches delimited by using palynological methods (O'Rourke and for pollen and nectar, and rapidly and efficiently communi- Buchmann, 1991) to assess residual pollen in old brood cate these discoveries. These resources are exploited usingcombs, honey, propolis, or debris middens below feral colo- olfactory and the so- called "dance language" communica-nies. Honey bee colonies are ideally suited to this type of tion. Individual foragers are essentially constant to one plant"forensic palynology" since their nests are virtual "sinks" species during a foraging trip, but over time are directed, or for ingested pollen grains which can be sampled quantita- locate on their own, better or newly available flowers. Thistively. Probably the best single source of multiyear pollen shifting of bees from poorer floral resources to better floralplant dietary records are several year old, darkened brood patches has been termed the "information- center foragingcombs. These contain a representative subsample of all the strategy" (Seeley, 1995). pollen grains found in the larval feces (meconia). These ma- terials become "fossilized" in strata within the cell bases of Mature colonies, with 40,000 adult workers for example, mayold brood comb as the colony ages. Further, pollen contribu- have from 10,000 to 20,000 or more foragers actively engagedtions from nectar- producing plants can be separated from in daily flights to collect pollen, nectar, water and resin. Flightpollen plant records through the use of melissopalynology distances by honey bee workers in natural ecosystems havewhereby pollen grains left in stored honey reveal which an- been little studied, but indications for Apis mellifera colo-giosperm species were visited for nectar. nies living in New York forests are that 99 percent of all flights are to flowers less than eight km from the nest, with almost 90During the mid 1980's the author made a surprising discov- percent of the colony's foraging effort taking place withinery in shallow mountain caves within the Organ Pipe Cactus four km (Visscher and Seeley, 1982). National Monument on the Arizona/Mexico border. Large deposits of blackened asphalt -like waxy materials were found Calculations of the effective total area foraged, averaged overbelow extant and old dead feral honey bee colonies. Upon a season or during one year and estimated as concentricexamination, these deposits were found to contain honey circular foraging bands, indicate an immense floral landscape bee corpses, beeswax, corbicular pollen loads, cocoons, bee controlled by even one honey bee colony. Roubik (1989)parts and larval feces along with unidentified materials. I've estimated that a single Africanized honey bee (Apis mellifera called these "debris middens" and they hold great poten- scutellata) colony may forage from an area of 100 or evential-as palynological samples- to infer the vegetation of 300 km2 in Panamanian rainforests. In the Sonoran Desert ofthe surrounding area along with information on honey bee Arizona, colonies appear to forage within an area estimatedpollen diet breadth. Unlike packrat middens (indurated de- to be 80 -100 km2 in extent (Southwick and Buchmann, unpubl; posits from white -throated packrats and other species in the Southwick and Buchmann, 1995). area), the honey bees travel great distances from their nests giving a more regional vegetative reconstruction than pos- Honey Bee Colonies as Biological and Chemical Monitoring Units sible with the rodent middens. If such middens are present in With their remarkable foraging abilities, it is surprising toAfrica in dry caves, produced belowApis mellifera scutellata learn that honey bees have been underutilized as "biological colonies, they may hold invaluable information for future monitoring agents" for the study (on an hourly, daily, sea-paleocologists who find and exploit their pollen -rich infor- sonal, annual and multiyear basis) of events occurring within mation. environments found inside their immense foraging domains. It is common for beekeepers to be aware of honey yields perBy using such palynological sampling and analysis tech- hive when apiaries are established in different plant commu-niques, it is possible to reconstruct major and minor bloom- nities.