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RE: [beemonitoring] Defending the Professional Honor of Male Bees

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  • Vincent Tepedino
    It seems to me that this is a far more complicated question than we presently have the data to resolve and that we ought to be up front about it. I believe
    Message 1 of 8 , Jun 24 3:59 PM
      It seems to me that this is a far more complicated question than we presently have the data to resolve and that we ought to be up front about it. I believe that male bees, in general, certainly accomplish some pollinations, but I doubt that one male is equivalent to one female. Why? Because, while the males of many species patrol flowers, they do not VISIT nearly as many flowers per unit time as do females, at least not when I'm watching them. So, if you want to equate males and females, pollination-wise, then you have to make the argument that males make up for fewer flower contacts per unit time by spending a lot more total time patrolling, and occasionally visiting, flowers. While that may be true, I doubt it translates to more total flower visits over a day.

      As others have pointed out, females probably pick up more pollen per flower visit than do males, and are therefore more likely to have something to transfer. On the other hand, females are also far more likely to make many within-plant visits and to transfer pollen within plants; conversely, a far greater proportion of male visits are likely to be to different genets; so males may make a disproportionate number of cross-pollinating visits. This might be especially important for self-incompatible plant species. Males may also contribute to female cross-pollination effectiveness by forcing them to move more frequently between plants by harassing them when on the flowers.

      And then there's the question of how much of the pollen that's picked up by males actually stays on the body as they zip around from plant to plant. Conversely, females may be more likely to groom pollen off many contact areas, but then many males land on rocks, twigs, etc., where they also seem to be grooming. I know of no data that compares pollen on randomly captured male and female bodies.

      Anyway, it seems to me that the safest thing to say, until the data are at hand, is that males undoubtedly make some contribution to pollination, but at present it's unclear how much that contribution might be. I'd guess the importance of males as pollinators has a wide range and is greatly dependent on what plant group we might be considering.

      By the way, I think Jim Cane was trying to put together some lit data on this and he may have something more definite to say when he returns.

      Vince

      Vincent J. Tepedino
      USDA ARS (retired)
      Bee Biology & Systematics Lab
      Dept of Biology
      Utah State University
      Logan UT 84322-5310

      vince.tepedino@...
      435-797-2559
      435-797-0461 (FAX)

      -----Original Message-----
      From: beemonitoring@yahoogroups.com [mailto:beemonitoring@yahoogroups.com] On Behalf Of Richardson, Leif
      Sent: Monday, June 21, 2010 6:33 AM
      To: beemonitoring@yahoogroups.com
      Subject: Re: [beemonitoring] Defending the Professional Honor of Male Bees

      Hello,
      I have been interested in this topic too. A few other thoughts. Male bumblebees do not sonicate Vaccinium, Rosa, Cassia, Geum, Solanum, etc. They remove far less pollen from these plants than buzzing females (if they visit them at all), but on the other hand, any pollen they pick up incidentally is not going back to the colony, and may end up on the stigmas of another flower. It would be interesting to know how males and workers compare in pollination of something they both like to forage on-goldenrods and asters for instance.

      I'm also curious about the effect of male bee territoriality on pollination... do aggressive male Anthidium keep pollinating flower visitors away from the plants they patrol?

      Leif



      Leif Richardson
      Ecologist
      Vermont Fish and Wildlife Department
      5 Perry Street, Suite 40
      Barre, VT 05641
      (802) 476-0128
      (802) 279-5320 (c)

      www.vtfishandwildlife.com/wildlife_nongame.cfm

      ------------------------------------

      Yahoo! Groups Links
    • Doug Yanega
      ... We could probably be safe in saying that the situations in which males might be *superior* to females are rare, even allowing for specialized cases such as
      Message 2 of 8 , Jun 24 4:22 PM
        Vince Tepedino wrote:

        >Anyway, it seems to me that the safest thing to say, until the data
        >are at hand, is that males undoubtedly make some contribution to
        >pollination, but at present it's unclear how much that contribution
        >might be. I'd guess the importance of males as pollinators has a
        >wide range and is greatly dependent on what plant group we might be
        >considering.

        We could probably be safe in saying that the situations in which
        males might be *superior* to females are rare, even allowing for
        specialized cases such as orchids and other flowers using
        pseudo-copulation. And just as certainly as we can state that certain
        bee taxa are going to be better pollen vectors than others (e.g.,
        Hylaeines are about as bad as they get), we can state that
        differential within-taxon dimorphism is also going to mean more of a
        discrepancy between males and females in some taxa than in others,
        and never in the males' favor. All in all, I wouldn't be confident
        with any overall estimate of male bee pollination contribution more
        ambitious than "minor with rare exceptions", and can't imagine that
        we'd ever gather data sufficient to do much more than quantify just
        how minor.

        Peace,
        --

        Doug Yanega Dept. of Entomology Entomology Research Museum
        Univ. of California, Riverside, CA 92521-0314 skype: dyanega
        phone: (951) 827-4315 (standard disclaimer: opinions are mine, not UCR's)
        http://cache.ucr.edu/~heraty/yanega.html
        "There are some enterprises in which a careful disorderliness
        is the true method" - Herman Melville, Moby Dick, Chap. 82
      • Peter Bernhardt
        Dear Vince and Doug: This is interesting but the whole point of my original message was that it s time for us to help the public understand that the honeybee
        Message 3 of 8 , Jun 25 7:10 AM
          Dear Vince and Doug:

          This is interesting but the whole point of my original message was that it's time for us to help the public understand that the honeybee drone's life is rather "atypical" when one considers the biology of over 20,000 bee species.  Unfortunately, the honeybee's "glamorous and bizarre" cycle is the only one the general public knows... vaguely.  We can change their impressions with hard facts and some humor.

          1) Fact, male bees of many species are commonly found taking nectar and other resources (see 3) from flowers.  Honeybee drones are not paying members of the much larger flower-visiting club.

          2) Fact, many flowers fail to offer edible pollen.  Bees don't go to most orchids, milkweeds and a wide number of flowers with long, tubular floral throats (see Goldblatt's work on pollination of African Iridaceae) for pollen.  Pollen "collection" by bees at such flowers is passive so males may be just as efficient as females.  In fact, Drs Meier, Arduser and I are now in the position to compare and contrast milkweed pollinaria loads attached to legs of male vs. female Anthophora abrupta and Xylocopa virginica.  We stumbled onto this and I want to expand the collection of data over the following two years.

          3) Fact, male bees don't always visit flowers looking for edible rewards.  Yes, we know males camp out at flowers to hunt incoming females but also consider the perfume flowers of Neotropical orchids, aroids and at least one nightshade tree pollinated by male euglossines exclusively,  Also, consider the male bees that pollinate orchids that look like female bees (Ophrys) or the flower offers the males a place to sleep at night (Serapias and "black" Iris spp. in section Oncocyclus).  Isn't it interesting that no one has found an orchid yet pollinated by male honeybees within the natural distribution of A. mellifera?

          4)  Fact, male bees probably carry less granular pollen than females but is that so important?
               a) What if the flower's ovary contains only one ovule?  One viable grain on the stigma works as well as a dozen.  Please note that Dr. Weston and I counted pollen loads of male bees on Australian persoonias.  Most males carried less than 100 grains but consider the many flowers pollinated by flies the same size.  It would be good to do a pollen count of male bees and syrphids at the same plant species.  

          Peter

               



          On Thu, Jun 24, 2010 at 6:22 PM, Doug Yanega <dyanega@...> wrote:
           

          Vince Tepedino wrote:

          >Anyway, it seems to me that the safest thing to say, until the data
          >are at hand, is that males undoubtedly make some contribution to
          >pollination, but at present it's unclear how much that contribution
          >might be. I'd guess the importance of males as pollinators has a
          >wide range and is greatly dependent on what plant group we might be
          >considering.

          We could probably be safe in saying that the situations in which
          males might be *superior* to females are rare, even allowing for
          specialized cases such as orchids and other flowers using
          pseudo-copulation. And just as certainly as we can state that certain
          bee taxa are going to be better pollen vectors than others (e.g.,
          Hylaeines are about as bad as they get), we can state that
          differential within-taxon dimorphism is also going to mean more of a
          discrepancy between males and females in some taxa than in others,
          and never in the males' favor. All in all, I wouldn't be confident
          with any overall estimate of male bee pollination contribution more
          ambitious than "minor with rare exceptions", and can't imagine that
          we'd ever gather data sufficient to do much more than quantify just
          how minor.

          Peace,
          --

          Doug Yanega Dept. of Entomology Entomology Research Museum
          Univ. of California, Riverside, CA 92521-0314 skype: dyanega
          phone: (951) 827-4315 (standard disclaimer: opinions are mine, not UCR's)
          http://cache.ucr.edu/~heraty/yanega.html
          "There are some enterprises in which a careful disorderliness
          is the true method" - Herman Melville, Moby Dick, Chap. 82


        • Cane, Jim
          Folks- I can add some to the discussion, although Vince covered the factors admirably. From my own data and an unpublished literature survey, males are
          Message 4 of 8 , Jun 28 3:10 PM

            Folks- I can add some to the discussion, although Vince covered the factors admirably.  From my own data and an unpublished literature survey, males are inferior to females in their pollination efficacies at individual flowers, but they do deliver are some substantial fraction of it.  Thus, for instance, male Megachile rotundata and Nomia melanderi are about 2/3 as likely to trip an alfalfa flower as a conspecific female ( I can send the reprint pdf).  Contrast that with a honey bee, which is about 4%, as I recollect.  Having stated that, of course, exceptions will be found.  I am working out the energetics of flight for male Nomia to estimate their daily nectar needs, and so visits to alfalfa flowers for nectar.  It appears that they contribute no more than 10% to the full yield of cultivated alfalfa (but then that is close to the grower’s profit margin), mostly because they only need nectar to fuel their flight, as Vince points out, so they don’t visit that many flowers in a day.  Blair Sampson and I have a paper in revision that shows that male Peponapis can contribute substantially to fruit production at Cucurbita, but then, that is where they hunt for females as well as forage.  The whole topic warrants more study.  And then there are no doubt indirect effects, like male bee attentions driving females to other individual plants (or on alfalfa, it seems, to entirely different more distant fields!).  It is nothing to proud of, but it is a straw to grasp at least!

             

            Yours,

             

            jim

             

            ===============================

            James H. Cane

            USDA-ARS Bee Biology and Systematics Lab

            Utah State University, Logan, UT 84322 USA

            tel: 435-797-3879   FAX: 435-797-0461

            email: Jim.Cane@... 

            http://www.ars.usda.gov/npa/logan/beelab

            http://www.biology.usu.edu/people/facultyinfo.asp?username=jcane

            Gardening for Native Bees: http://extension.usu.edu/files/publications/factsheet/plants-pollinators09.pdf

             

            "The obscure takes time to see,

            but the obvious takes longer"
            Edward R. Murrow

             

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