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Hylaeus and Chelone

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  • Joel Gardner
    Yesterday I was out collecting bees and noticed some behavior that may be of interest to this group. I found a large patch of *Chelone glabra* (white
    Message 1 of 3 , Aug 28, 2014
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      Yesterday I was out collecting bees and noticed some behavior that may be of interest to this group.

      I found a large patch of Chelone glabra (white turtlehead) full of the sound of bumble bees buzz pollinating.  There were a couple bumble bees flying around but not nearly enough to account for all the noise.  So I pried open some flowers, thinking they must all be inside, but found no bumble bees.  Instead, there were tiny Hylaeus inside.  I could hardly believe those little bees were responsible for such loud buzzing--just like a bumble bee, only in quick (~1 second), regular bursts.  The Hylaeus stayed in the flowers for minutes at a time, intermittently buzzing.  Bumble bees also visited the flowers, but spent much less time inside and did not noticeably buzz.  They seemed to be primarily interested in the nectar.

      Could this be an example of pollination by Hylaeus?  I know this topic has come up in this group before and I recall that we didn't know a whole lot about Hylaeus pollination.  I did find a reference (Williams 1998) stating that Senna acclinis, an Australian shrub, is buzz-pollinated by Hylaeus, but the Hylaeus may not actually carry the pollen themselves.  Instead they may release pollen onto the lower petals by buzzing, which is then picked up by other bees.  Perhaps something similar is happening here with Chelone.

      I collected a few specimens and they appear to be Hylaeus modestus or something else in that species group.  This was in Minnesota, near the Minneapolis area.

      Joel Gardner
    • Leif Richardson
      Hi Joel, Cool observations! I have seen the same thing on turtlehead in northern Vermont. I work on the plant in lots of sites and while bumble bees,
      Message 2 of 3 , Aug 29, 2014
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        Hi Joel,
        Cool observations! I have seen the same thing on turtlehead in northern Vermont. I work on the plant in lots of sites and while bumble bees, especially Bombus vagans, are the most common flower visitors and the most effective pollinators, Hylaeus is invariably present. All of the specimens I have taken are (I think) H. annulatus. The females enter the flower and spend long periods of time there, intermittently sonicating the anthers, walking around and possibly consuming nectar. I can hear the buzz without amplification but it's easy enough to miss. Do they pollinate? I have not been able to get enough single-visit data to say, but they are small enough to be able to avoid contact with the stigma while they work on the anthers, and don't appear to passively transport much pollen on the outside of their bodies. I think they are usually pollen robbers.

        I am working on the effects of turtlehead nectar chemistry on bee foraging behavior. The nectar and pollen contain the same iridoid glycoside compounds present in other tissues, and I have found that bumble bees spend longer at flowers and donate more pollen to conspecific stigmas when nectar iridoid concentrations are high. For some measures, this effect is dependent on whether the bee is parasitized, and we also have found that consumption of these compounds reduces bee parasitism. I have wondered about how Hylaeus consumption of turtlehead pollen fits into this picture!
        Leif

        --
        Leif Richardson
        Doctoral Candidate
        Biological Sciences, Dartmouth College
        78 College Street, Hanover, NH 03755
        (802) 793-6449
        Bumble Bees of North America: an Identification Guide
      • Peter Bernhardt
        Dear Joel: That is very interesting. Steve Buchmann is our resident authority on buzz-pollination so let s see what he says. Small bees do pollinate some big,
        Message 3 of 3 , Aug 29, 2014
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          Dear Joel:

          That is very interesting.  Steve Buchmann is our resident authority on buzz-pollination so let's see what he says.

          Small bees do pollinate some big, snap-dragon type flowers when they cling to one of the two anthers that is fused to the ceiling of the flower.   The next time they visit a flower for pollen they may contact the receptive stigma wedged between the anthers.  My former PhD student, the late Richard Clinebell, noted this option in his study of Penstemon.

          Clinebell, R. & Bernhardt, P.  1998.  The pollination ecology of five species of Penstemon (Scrophulariaceae) in the tallgrass prairie.  Annals of the Missouri Botanical Garden. 85: 126-136.


          Hylaeus receives a bad reputation because they swallow pollen and don't have pollen collecting hairs on their hind legs or abdomens.  However, years ago I placed some Australian species under the SEM and found they carried polyads of acacias on their bodies.  Entomologists forget that the pollen grains of most animal-pollinated flowers wear an oil-based glue (pollenkitt).  Likewise, Brian Dykstra may have something to say about the role of the native Hylaeus species and the pollination of the surviving Hawaiian flora.  I think there have been a couple of recent reports or papers on this by other students in recent years.  In Australia, some Hylaeus species can be found on flowers that lack nectar and are probably responsible, in part, for the pollination of guinea flowers (Hibbertia; Dilleniaceae).  The related genus, Hylaeoides is physically larger than most Hylaeus species s.s. and I have unpublished (PhD thesis)  data on their pollination of Amyema preisii (Loranthaceae).


          Peter



          On Thu, Aug 28, 2014 at 4:48 PM, Joel Gardner gard0228@... [beemonitoring] <beemonitoring-noreply@yahoogroups.com> wrote:
           

          Yesterday I was out collecting bees and noticed some behavior that may be of interest to this group.

          I found a large patch of Chelone glabra (white turtlehead) full of the sound of bumble bees buzz pollinating.  There were a couple bumble bees flying around but not nearly enough to account for all the noise.  So I pried open some flowers, thinking they must all be inside, but found no bumble bees.  Instead, there were tiny Hylaeus inside.  I could hardly believe those little bees were responsible for such loud buzzing--just like a bumble bee, only in quick (~1 second), regular bursts.  The Hylaeus stayed in the flowers for minutes at a time, intermittently buzzing.  Bumble bees also visited the flowers, but spent much less time inside and did not noticeably buzz.  They seemed to be primarily interested in the nectar.

          Could this be an example of pollination by Hylaeus?  I know this topic has come up in this group before and I recall that we didn't know a whole lot about Hylaeus pollination.  I did find a reference (Williams 1998) stating that Senna acclinis, an Australian shrub, is buzz-pollinated by Hylaeus, but the Hylaeus may not actually carry the pollen themselves.  Instead they may release pollen onto the lower petals by buzzing, which is then picked up by other bees.  Perhaps something similar is happening here with Chelone.

          I collected a few specimens and they appear to be Hylaeus modestus or something else in that species group.  This was in Minnesota, near the Minneapolis area.

          Joel Gardner


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