The use of a pollen substitute in the Spring is recommended for packages, nucleus colonies, and splits for increased production of bees and honey.
Honey bee colonies depend on a cache of honey and pollen that is collected before overwintering to survive the long cold winters in northern temperate zones (Mattila and Otis 2006a). Stored pollen is consumed by workers when they resume brood rearing in early spring after the mostly broodless period that colonies enter during winter (Nolan 1925; Seeley and Visscher 1985). The nutrients that workers derive from consuming pollen provide all of the proteins, lipids, vitamins and minerals that are required for rearing larvae (DeGroot 1953; Haydak 1970; Manning 2001). Colonies require large Winter pollen reserves because brood rearing recommences within the protective warmth of the cluster long before ambient conditions favor foraging for additional food resources (Nolan 1925; Seeley and Visscher 1985; Farrar 1993). Because of the timing of the brood rearing schedule in the early Spring, colonies may deplete their pollen stores before additional pollen inputs are available from the environment. If this happens, brood rearing will suffer once workers have catabolized the nutritional reserves held in their bodies (Crailsheim 1990). Spring cold snaps have been correlated with interruptions in flight activity, reduced pollen intake, and increased brood cannibalism, resulting in smaller populations of nurses that must carry heavier nursing loads (Dustmann and von der Ohe 1988). Brood rearing may be suspended altogether when pollen reserves are exhausted (Imdorf et al. 1998). In northern temperate climates, early Spring remains the period during which pollen shortages occur most frequently. The supply of pollen available to a colony has the greatest influence over the number of workers that are reared by colonies (Allen and Jeffree 1956; Doull 1973; Hellmich and Rothenbuhler 1986) and Winter pollen reserves determine the size of the bee population the next Spring.
The protein obtained from pollen plays a major role in colony reproduction and the life of honey bees. A shortage of pollen or stores of poor quality pollen results in stunted growth and weight gain of young bees, reduced longevity and incomplete development of hypopharyngeal glands. This leads to insufficient royal jelly production to support normal growth and development of larvae or egg production by the adult queen (Standifer et al. 1977a; Zahra and Talal 2008). Colonies that lack access to pollen have a reduced capacity to rear brood, quickly decline in population, and may eventually die. Protein deficiency also affects the ability of honey bees to resist diseases (Matilla and Otis 2006b). As pollen is not always available, an alternative protein source is sometimes necessary to ensure bee health and continued colony development, as well as to maintain colony strength for pollination, overwintering and honey production (Standifer et al. 1980). For these reasons, beekeepers often find it advantageous to supplement the pollen diet of colonies in the Spring with additional pollen supplements/substitutes (Matilla and Otis 2006a). This is done not only to avoid some of the pitfalls associated with pollen deficits but also to improve the performance of colonies beyond that supported by natural reserves of pollen (Farrar 1993).
The protein supplemental foods fed to honey bees are usually divided into two classes: 1) pollen supplements (artificial high-protein diets containing five to 25 percent pollen) and 2) pollen substitutes (artificial high-protein diets containing no pollen). None of the protein supplemental foods fed to honey bees is a complete replacement for natural pollen, nor can they be regarded as more than adequate supplements for natural pollens (Standifer et al. 1977b).
A good protein supplement food for bees is one that they will readily consume and has the quality and quantity of proteins, lipids, vitamins, and minerals required for growth and development of individuals and reproduction of the colony. Several brewer’s yeast products, Wheast, and soybean flour, fed singly or in combination, are palatable and contain the essential nutrients. The brewer’s yeast products and soybean flour used in bee diet formulations can be supplied to bees as a dry mix inside or outside the hive or as a moist cake inside of the hive.
Soybean flour should be expeller processed (44-percent protein) to remove excess fat and improve biological availability of the protein (Standifer et al. 1977b).
Two field experiments with a commercial pollen supplement provided information on possible relationships between pollen, brood rearing and consumption of the supplement (Doull 1973). When colonies were provided with the supplement continuously for one year, the results showed that brood rearing was initiated and maintained by pollen and that consumption of the supplement varied in direct relationship to the rate of brood rearing. In a second experiment with colonies on a nectar flow, but virtually devoid of pollen, they did not consume the pollen supplement and reared larvae from less than 20% of eggs laid. When an extract of pollen was added to the supplement, the bees consumed it readily, and eventually reared larvae from 91% of eggs laid. The extract of pollen induced the bees to eat the supplement and Doull (1973) concluded that this caused their hypopharyngeal glands to become active so that they could feed more newly emerged larvae. The author also suggested the presence of a chemical or chemicals in pollen, which may serve as a trigger to activate the hypopharyngeal glands and that bees secreting larval food, would then feed on supplements that do not contain the primary phagostimulants that are contained in pollen.
The effects of changes in Spring pollen diet on the development of honey bee colonies were examined in a three-year study (2002-2004) (Mattila and Otis 2006a). Pollen supplemented and pollen-limited conditions were created in colonies every spring, and brood rearing and honey yields were subsequently monitored throughout the Summer. In all three years, colonies that were supplemented with pollen or a pollen substitute in the spring started rearing brood earlier than colonies in other treatment groups and produced the most workers by late April or early May. In 2002, these initial differences were reflected by a two-fold increase in annual honey yields by September for colonies that were pollen-supplemented during the Spring compared with pollen-limited colonies. In 2003 and 2004, differences between treatment groups in the cumulative number of workers produced by colonies disappeared by midsummer, and all colonies had similar annual honey yields (exception: in one year, productivity was low for colonies supplemented with pollen before wintering). Discrepancies between years coincided with differences in Spring weather conditions. Colonies supplemented with pollen or a substitute during the Spring performed similarly in all respects. These results indicate that an investment in supplementing the pollen diet of colonies would be returned for situations in which large Spring populations are important, but long-term improvement in honey yields may only result when Spring foraging is severely reduced by inclement weather.
Package colonies of bees fed pollen substitute upon installation in the Spring were more productive than package colonies that were not fed a pollen substitute. Treated colonies produced more drawn comb, more brood and more honey by the end of the honey flow (Nabors 2000). The pollen substitute did not induce swarming. All colonies were fed enough sucrose syrup to draw out foundation in the brood area before the honey flow began. The use of a pollen substitute in the Spring is recommended for packages, nucleus colonies, and splits for incrased production of bees and honey.
Commercially available pollen substitute diets for honey bees were evaluated for consumption and colony growth (brood and adult populations) and compared with pollen cake and high fructose corn syrup (HFCS) (DeGrandi-Hoffman et al. 2008). Two trials were conducted; the first for 12 weeks during the Fall and Winter in southern California and a second for two months in the Summer in southern Arizona. The diets tested were FeedBee, Bee-Pro®, and MegaBee® (liquid and patty form) in Trial one and Bee-Pro® and MegaBee® in Trial two.
In both trials, Bee-Pro® and MegaBee® patties were consumed at rates that were comparable to pollen cakes. Colonies consumed significantly less FeedBee than the other diets. There was a significant relationship between the amount of diet consumed and the change in brood area and adult population size in both trials. Colonies fed MegaBee® patty produced significantly more brood than those fed pollen cake or any other diet in Trial one. The lowest brood production occurred in colonies fed FeedBee or HFCS. Adult populations in colonies fed MegaBee® liquid or patty did not differ from those fed pollen cake, and were significantly larger than colonies fed Bee-Pro® or FeedBee. In Trial two, when some pollen was being collected by colonies Bee-Pro® and MegaBee® did not differ from pollen cake in brood or adult population growth.
Pollen substitute palatability tests were done in commercial apiaries in early Spring 2004 (Saffari et al. 2010). In this trial, three different feeds, FeedBee, TLS Bee Feed and Bee-Pro® were fed to 153 colonies in 12 bee yards for six weeks (March 25th- May 6th) in southern Ontario. Two methods of feeding were used: 1) No-choice feeding, where each yard received only one of the three feeds, and 2) Choice feeding, where each yard received all three experimental feeds. The mean feed intake (g/colony/six weeks) of FeedBee was 960 g and 883 g for the first and second feeding methods, respectively. These amounts were significantly greater than for the other two feeds. The amount of Bee-Pro® consumed (g/colony/six weeks) in the two feeding methods was 224 g and 106 g and for the TLS Bee Feed, 115 g and 52 g, respectively. These results indicate that FeedBee in powder/dry form is highly palatable to honey bees. The results show that it is well accepted by bees during the shortage or absence of natural pollen.
Adequate substitutes for pollen are necessary for maintaining healthy colonies during periods of pollen dearth. DeJong et al. (2009) compared two commercial diets with bee collected pollen and acacia pod flour (used by beekeepers is some parts of Brazil) by measuring their effect on hemolymph (blood) protein contents of young bees exclusively fed on these diets. The commercial diets included a non-soy based substitute diet named FeedBee and a soy-based diet, named Bee-Pro®. The diets were each given in patty form to groups of 100 Africanized honey bees in hoarding cages, maintained and fed from emergence until six days of age. Sucrose, in the form of sugar syrup, was used as a protein free control. FeedBee, Bee-Pro®, pollen and acacia pod flour diets increased protein titers in the hemolymph by factors of 2.65, 2.51, 1.76 and 1.69, respectively over protein titers in bees fed only sucrose solution. The bees fed FeedBee and Bee-Pro® had their hemolymph significantly enriched in protein compared to the controls and those fed acacia pod flour had titers slightly higher than those fed pollen. All four proteinaceous diets were significantly superior to sucrose alone.
Morais et al. (2013) compared two artificial protein diets formulated from locally-available ingredients in Brazil with bee bread and a non-protein sucrose diet. Groups of 100 newly-emerged, adult workers of Africanized honey bees and European honey bees were confined in small cages and fed on one of four diets for seven days. The artificial diets included a high protein diet made of soy milk powder and albumin (D1), and a lower protein level diet consisting of soy milk powder, brewer’s yeast and rice bran (D2). The initial protein levels in newly emerged bees were approximately 18-21 µg/µL hemolymph. After feeding on the diets for seven days, the protein levels in the hemolymph were similar among the protein diet groups (~37-49 µg/µL after seven days), although Africanized bees acquired higher protein levels, increasing 145 and 100% on diets D1 and D2, respectively, versus 83 and 60% in the European bees. All the protein diets resulted in significantly higher levels of protein than sucrose solution alone. In the field, the two pollen substitute diets were tested during periods of low pollen availability in the field in two regions of Brazil. Food consumption, population development, colony weight, and honey production were evaluated to determine the impact of the diets on colony strength parameters.
The colonies fed artificial diets had a significant improvement in all parameters, while control colonies dwindled during the dearth period. They concluded that these two artificial protein diets have good potential as pollen substitutes during dearth periods and that Africanized bees more efficiently utilize artificial protein diets than do European honey bees.
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~Clarence Collison is an Emeritus Professor of Entomology and Department Head Emeritus of Entomology and Plant Pathology at Mississippi State University, Mississippi State, MS.