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Re: [beemonitoring] Andrena commoda mystery

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  • Doug Yanega
    ... I can suggest one possible explanation. Many ground-nesting bees aggregate their nests, and will mass-emerge at a single overwintering site; when the
    Message 1 of 4 , Mar 28, 2013
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      On 3/28/13 11:41 AM, Laura Russo wrote:
       

      I sampled for bees in an agroecosystem for two summers, sampling every other week with pan traps at 30 locations (spatially separated) around the fields.  The pan traps were yellow and large.  There is one day that stands out because, in one pan at one site on June 25, 2010, we captured 54 individual specimens of Andrena commoda.  (The identification was confirmed by an expert.)

      In two years of sampling, we only ever caught 5 other individuals of that species.

      Does anyone have any intuition as to why we would catch so many in just one pan on just one day?  What caused them to commit mass suicide in the pan, and where did they all come from?  Why June 25th, and why not anywhere else, or in the other year?

      Any insights you might have would be greatly appreciated.

      I can suggest one possible explanation. Many ground-nesting bees aggregate their nests, and will mass-emerge at a single overwintering site; when the trigger for emergence is specific enough, the nesting conditions are uniform enough, and the bees are hard-wired enough, you can have basically the entire overwintering population pop out of the ground all at once. Admittedly, 54 bees caught at a single pan trap seems a bit excessive, but you don't say how far it was from that to the next nearest trap. Having 54 bees emerge in an area of approximately 5-10 square meters would not be that hard to imagine, but having none of them show up in any other traps is harder to grasp unless the traps were very widely spaced, and the bees only vulnerable to being trapped right after they emerge. In effect, you wouldn't be able to replicate it unless you just happened to plop a trap down exactly in the middle of another nest aggregation (and aggregations can and do "relocate" - it certainly has some adaptive potential).

      Peace,
      -- 
      Doug Yanega      Dept. of Entomology       Entomology Research Museum
      Univ. of California, Riverside, CA 92521-0314     skype: dyanega
      phone: (951) 827-4315 (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
    • Anita M. Collins
      Hi Laura, I ve the same experience. Sampling at Lehigh Gap Nature Center in Slatington, PA, we had 150 Lassioglossum of primarily 3 species in about 4 bowls of
      Message 2 of 4 , Mar 31, 2013
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        Hi Laura,
         
        I've the same experience.  Sampling at Lehigh Gap Nature Center in Slatington, PA, we had 150 Lassioglossum of primarily 3 species in about 4 bowls of a 12 bowl transect, on one date.  I planned to resamples in the same area the following year, but it got upset by a major building project for the Center.  My explaination was that there were a lot of nests in that area, a rocky/gravely section of hillside.  If you want the exact species, I'll dig it out of the data set.  What a pain to pin all those tiny bees and separate them by abdominal hair distribution, expecially as I was really new at this.  But I did it. 
         
        Anita Collins
         
         
         
        If we knew what we were doing, it wouldn't be called research.
        Albert Einstein
         
        On 03/28/13, Laura Russo<lar322@...> wrote:
         
         

        Dear listserve,

        I have a bit of a bee mystery that I thought someone might have insight into. 

        I sampled for bees in an agroecosystem for two summers, sampling every other week with pan traps at 30 locations (spatially separated) around the fields.  The pan traps were yellow and large.  There is one day that stands out because, in one pan at one site on June 25, 2010, we captured 54 individual specimens of Andrena commoda.  (The identification was confirmed by an expert.)

        In two years of sampling, we only ever caught 5 other individuals of that species.

        Does anyone have any intuition as to why we would catch so many in just one pan on just one day?  What caused them to commit mass suicide in the pan, and where did they all come from?  Why June 25th, and why not anywhere else, or in the other year?

        Any insights you might have would be greatly appreciated.

        Best,
        Laura

        --
        PhD Candidate
        Intercollege Graduate Degree Program in Ecology
        Biology Department
        Pennsylvania State University
        University Park, PA 16802

        office: 415 Mueller Lab
        phone: 814-865-7912

      • Kuhn,Bernadette
        Dear Listserve- I am looking for any tips on sampling nesting density of ground nesting bees in native grasslands. I have read the methods described by Kim et
        Message 3 of 4 , Mar 31, 2013
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          Dear Listserve-

           

          I am looking for any tips on sampling nesting density of ground nesting bees in native grasslands. I have read the methods described by Kim et al. 2006* which describe using floating rowcover. The authors covered patches of ground with rowcover at night and captured bees that emerged from nests in the morning. I am considering using similar methods, maybe paired with pan traps beneath the rowcover. Has anyone tried rowcover with or without pan traps to measure nesting density? Perhaps there are other methods I have not stumbled across?  Any input is appreciated.

           

          *Reference: Kim, J., N. Williams, C. Kremen. 2006. Effects of Cultivation and Proximity to Natural Habitat on Ground-Nesting Native Bees in California Sunflower Fields. Journal of the Kansas Entomological Society, 79 (4): 309-320.

           

          Thanks,

          Bernadette Kuhn

           

          Botanist

          Colorado Natural Heritage Program

          259 General Services Building

          1475 Campus Delivery

          Fort Collins, CO 80523-1474

          phone (office): 970 491 1416

          phone (cell): 785 764 2948

          email: bernadette.kuhn@...

           

           

           

          From: beemonitoring@yahoogroups.com [mailto:beemonitoring@yahoogroups.com] On Behalf Of Anita M. Collins
          Sent: Sunday, March 31, 2013 6:59 PM
          To: lar322@...; beemonitoring@yahoogroups.com
          Subject: Re: [beemonitoring] Andrena commoda mystery

           

           

          Hi Laura,

           

          I've the same experience.  Sampling at Lehigh Gap Nature Center in Slatington, PA, we had 150 Lassioglossum of primarily 3 species in about 4 bowls of a 12 bowl transect, on one date.  I planned to resamples in the same area the following year, but it got upset by a major building project for the Center.  My explaination was that there were a lot of nests in that area, a rocky/gravely section of hillside.  If you want the exact species, I'll dig it out of the data set.  What a pain to pin all those tiny bees and separate them by abdominal hair distribution, expecially as I was really new at this.  But I did it. 

           

          Anita Collins

           

           

           

          If we knew what we were doing,! it wouldn't be called research.
          Albert Einstein

           

          On 03/28/13, Laura Russo<lar322@...> wrote:

           

           

          Dear listserve,

          I have a bit of a bee mystery that I thought someone might have insight into. 

          I sampled for bees in an agroecosystem for two summers, sampling every other week with pan traps at 30 locations (spatially separated) around the fields.  The pan traps were yellow and large.  There is one day that stands out because, in one pan at one site on June 25, 2010, we captured 54 individual specimens of Andrena commoda.  (The identification was confirmed by an expert.)

          In two years of sampling, we! only ever caught 5 other individuals of that species.

          Does any one have any intuition as to why we would catch so many in just one pan on just one day?  What caused them to commit mass suicide in the pan, and where did they all come from?  Why June 25th, and why not anywhere else, or in the other year?

          Any insights you might have would be greatly appreciated.

          Best,
          Laura

          --
          PhD Candidate
          Intercollege Graduate Degree Program in Ecology
          Biology Department
          Pennsylvania State University
          University Park, PA 16802

          office: 415 Mueller Lab
          phone: 814-865-7912

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