How much pollen does a colony need?

In Flemming V’s blog of last week, 35 kg pollen was mentioned as the amount a colony collects. Is this realistic, too much or too few? Rortais et al. (2005), reviewed the bee’s pollen consumption literature comprehensively and noted 10 up to 55 kg collected annually per colony. Crailsheim et al., calculated the annual pollen consumption in two colonies to be 13.4 and 17.8 kg respectively in colonies of about 25 000 bees in June-August. Wille et al., recorded 10 to 26 kg pollen per year. It obviously depends on the colony size, colony development, environment and pollen type. For example, pollen of maize is consumed in about the double amount compared to mixed pollen, due to its relative low percentage of nutrients of the whole pollen grain. The percentage protein of the dry weight is comparable to mixed pollen (Höcherl et al, 12012). Obviously, there is no fixed amount a colony could or should collect to grow, maintain and function. Nevertheless there good studies available to assess the annual pollen need for a colony. Based on the aforementioned Rortais et al. (2005) article, a nurse bee consumes on average 65 mg pollen and a worker-larvae 5.40 mg. Consequently, a bee consumes in her life minimally 70.4 mg. This is the average estimation, double amounts have been reported as well. In the aforementioned Crailsheim et al study the pollen consumption per day was 3.4 to 4.3 mg. In a 30-days life span of the summer honeybee this is approximately 115 mg in her lifespan. Another approach to assess pollen consumption is presented in the review article of Keller et al., (2005a). It is the assessment of pollen consumption based on nitrogen (N) in brood and bees. Pollen is the solely N source in the bee’s diet. To convert N to pollen, it is assumed that the pollen protein contains 16% nitrogen, that pollen contains 20% protein and that the digestive efficiency is 80%. So, for 10 mg N, it takes 62.5 mg protein; for 62.5 mg protein it takes 312.5 mg pollen and by the efficacy of the alimentary process it takes 390.6 mg pollen consumed by the bee. Taking all this into account it takes 125 mg pollen to raise a bee. The N in the bees after emergence, increases by 0.86 mg. The 0.86 mg N correspond to 39 mg pollen. So in total each bees required minimally 125 + 39 = 164 mg pollen as N loss by defecation is not taken into account. Counting the bee’s active and reproducing period on 200 days and the average life span of a bee of 35 days (Steen et al, 2012), it takes 200/35 = 6 generations. To maintain a colony of on average 15000 bees, 15000 x 6 = 90000 bees are raised. The number of bees raised annually and the calculated amount of pollen required are summarised in table 1.

The 35 kg mentioned in the beginning is the amount required for a big colony and is an optimal estimation. Amounts varying between 15 and 25 looks more realistic. Again, it all depends on pollen type, environment, colony development and yes/no pollen trap. Depriving colonies from pollen stimulated pollen collection. It is up to the beekeeper to maintain an adequate pollen flow. To check whether the pollen stores are sufficient it simply takes a rough estimation of the surface/ number of beebread cells in a colony. A healthy normally sized colony needs / consumes per day about 0.5 to 2 dm2 (200 – 800 half-full beebread cells). Another simple estimation is weighing the harvest of the pollen trap. It must be taken into account that the efficacy of the pollen trap varies between 10 and 50% (Keller et al., 2005b).

Crailsheim, K., Schneider, L. H. W., Hrassnigg, N., Bühlmann, G., Brosch, U., Gmeinbauer, R., & Schöffmann, B. (1992). Pollen consumption and utilization in worker honeybees (Apis mellifera carnica): dependence on individual age and function. Journal of insect Physiology, 38(6), 409-419.

Höcherl, N., Siede, R., Illies, I., Gätschenberger, H., & Tautz, J. (2012). Evaluation of the nutritive value of maize for honey bees. Journal of insect physiology, 58(2), 278-285.

Keller, I., Fluri, P., & Imdorf, A. (2005a). Pollen nutrition and colony development in honey bees: part 1. Bee world, 86(1), 3-10.

Keller, I., Fluri, P., & Imdorf, A. (2005b). Pollen nutrition and colony development in honey bees—Part II. Bee World, 86(2), 27-34.

Rortais, A., Arnold, G., Halm, M. P., & Touffet-Briens, F. (2005). Modes of honeybees exposure to systemic insecticides: estimated amounts of contaminated pollen and nectar consumed by different categories of bees. Apidologie, 36(1), 71-83.

Steen, van der, J. J.M., Cornelissen, B., Donders, J., Blacquière, T., & van Dooremalen, C. (2012). How honey bees of successive age classes are distributed over a one storey, ten frames hive. Journal of Apicultural Research, 51(2), 174-178.

Wille, H., Wille, M., Kilchenmann, V., Imdorf, A. & Bühlmann, G. (1982). Pollenernte und Massenwechsel von drei Apis mellifera-Völkern auf demselben Bienenstand in zwei aufeinanderfolgenden Jahren. Revue Suisse de Zoologie(4), 897-914



Sjef van der Steen

Colony strength assessment

The amounts of substances, detectable in a colony, depends on how much is bio-sampled outside. This is directly linked tot he number of foragers. Therefore part of recordings done in the Insignia project is colony strength assessment with Image J. To do so the number of hive entering bees is counted with beecounters during about one week and in this week all frames with bees are photographed. The number of bees per photograph = one frame side is calculated by recording the surface covered with bees. One cm2 is covered by 1.25 bees (Delaplane, Guzman-Novoa, Steen, 2013).

These recordings are done in Rome by Marco and will be done next year in Denmark by Flemming, by Valters in Latvia and by Ivo and myself in the Netherlands. However want to join, please join.

With the colony strength data and number of hive entering bees, we study the linkage between these two parameters in order to have a simple citizen science tool that the colony strength can be assessed by counting the beelanes between frames of specific sizes. That is why the question of frame sizes and occupied bee lanes is added to the lime survey.

Keith S Delaplane, Jozef van der Steen & Ernesto Guzman-Novoa (2013) Standard methods for estimating strength parameters of Apismellifera colonies, Journal of Apicultural Research, 52:1, 1-12

Sjef van der Steen

The first eight months of the Insignia pilot study

A mail, drawing my attention to an EU bio-monitoring call caught my attention. Wow! This is an ultimate chance to demonstrate the honeybee colony’s bio-sample feature as a tool for environmental monitoring. More colleagues had this idea and we found each other in this shared interest. Obviously, this resulted in the start of a consortium which expanded like a swan glue game, resulting in the final Insignia consortium with experts of all required scientific disciplines. Many telemeetings later, with launching, discussing and evaluating ideas, we had a clear interpretation of the call and routes to achieve this. Our focus should be on developing and testing a scientifically substantiated citizen science protocol and the application of passive samplers to meet both the non-invasive and innovative requirements in the call and applying the common matrices trapped pollen and beebread as benchmarks.

Writing the final submission, waiting for the selection and the selection itself sounds simple but was stressful, hectic and required skills for all of us as there were science, statistics, grammar, flow charts, budgeting, summarizing, planning, financial recordings, (very) frequent communicating and reporting, use of social media, etc. etc..

Now we are eight months ahead and we already do have an impressive palmarès thanks to all particip[ants involvement and energy. Passive samplers were developed, testing schemes were  made, discussed and implemented,  picture/ instruction manual written, test apiaries selected, five samplings done, first analyses done, progress in molecular detection of pollen made, social study conducted, a lime survey running, the first data for evaluation of the Corine database collected, an active social media life and several practical issues addressed, solved or parked.

Still, five samplings to go in year 1 and the plenary discussions in January 2020 on best practices both scientifically, practically and citizen-scientifically. It feels good to  cooperate in the consortium and, I am looking forward to the coming exciting 20 months.

The enigma of sample coding

Communication in itself is simply a matter of sending and receiving a message. This implies on one hand, a clear message. On the other hand, every receiver interprets the message within his/her own reference frame. This makes communication a difficult issue anyway. In Insignia, this shows in interpreting the coding of the Insignia samples. This coding is clearly explained and communicated in the picture manual.   On the other hand, other lay-outs are suggested in the conviction that his/ her interpretation is better. Remember that there is a chain of “receivers” and the coding is six-dimensional: country, apiary, colony, date, material and replicates in time. Miscoding will for sure results in potential misinterpretations and certainly in time and energy loss in sorting out the samples. The solution is simple. Stick to the appointments and don’t make labeling

20919709 – human head silhouette with question mark concept

an enigma. 

The 5th sampling in Denmark by Flemming and Ole and assistance of Valters and Sjef

The best way to learn all the ins and outs of Insignia sampling is simply doing it. Flemming and Ole were so kind as to invite me and Valters to assist in the 5th sampling. Due to mine and Valters agenda, the 5th sampling in Denmark was brought forward to Thursday and Friday 4 and 5 July. It was an interesting learning experience for myself and Valters to prepare package and coding,  to do the pollen collection,  taking out and inserting respectively the old and new APIStrips and Beehold tubes, collecting beebread and emptying the pollen trap, to have an indication of the time and energy spent on the labour before and after the field work. I learned/ was confirmed that coding/ sample preparation requires a consequent and accurate effort, beebread picking takes time in two ways, looking for the best frame and the picking itself, the facility of the APIStrip and Beehold tube change and the every time wonderful view of the diversity of pollen in the trap.  All samples are stored in the freezer.

Just a reminder for sending the samples latest half July as described in the picture manual except alcohol on trapped pollen for PCR (and not for pesticide analyses).

Pollen identification
– trapped pollen for pollen identification are sent to Alice in alcohol 96%,
– Beehold tubes and beebread straws are sent, wrapped together with frozen icepacks in an insulating package of e.g. plastic foil with air bubbles or styrofoam box.

Pesticide residues
– APIStrips, Beehold tubes, trapped pollen and bee bread  are sent to the labs wrapped together with frozen icepacks from the freezer in an insulating package of e.g. plastic foil with air bubbles or styrofoam box.
– The division, where to send the samples for pesticide residue analyses will be announced in time.

The second stage

The second stage; from year 1 sampling to the evaluation of the results.

We depart for the second stage. Most of the preliminary studies planned in stage 1, from kick-off to sampling commencement, are done, coming to an end in the months to come or will start soon. Surely new questions will raise and are to be addressed in the project course. Within six months after the attribution of the Grant Agreement in the last week of October 2018, the sampling begins this weekend of 28 April 2019. After the preparations as there were  telemeetings, study set-up discussions, and agreements on numbers of colonies, number of apiaries, number of samplings, matrices replications and combinations, development of the APIStrip, local organization of the beekeeper citizen scientists, picture manual, tutorials and other instruction tools, questionnaire, preliminary pollen- and pesticide residue binding- and deterioration tests, practical lab and field work, initiation of the sociological study, the dissemination structure and a lot of everyday issues, the field work starts. This is exciting because we are doing pioneering work with the non-invasive sampling, with the non-biological matrices APIStrip and Beehold tubes, the new beebread collection tool, the familiar pollen trap, apiculturist citizen scientist for pesticide monitoring and the first sociological evaluation of apiculturist citizen scientists. We will encounter a lot of practical issues like swarming, drought, heavy rainfall, supersedure, and issues we can not imagine now. It is up to the Insignia team to find answers and solutions. It will be as challenging as stage 2 and the Insignia team is aware of this and accepts.