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2232Re: [beemonitoring] Lasioglossum (Dialictus) nests

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  • Doug Yanega
    Jul 2, 2012
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      Re: [beemonitoring] Lasioglossum (Dialictus) nests
      I recently was walking around a farm field and stumbled across a large Dialictus colony (I believe they are Lasioglossum versatum).  The nest density was incredibly high in some areas - the colony covered about 15X30 m with up to 200-250 nest holes per square meter.  There were thousands of males hovering around the nest holes and they were pouncing on females and each other.  So I have a few questions - Are Dialictus colonies regularly this large?  Do they tend to use the same areas in multiple years?  Are the males out earlier than usual (everything is about 4-5 weeks advanced this year in Indiana)?  Often I dont start seeing male Dialictus until August or September.  Any other info on good literature on Dialictus nesting would also be appreciated.  Many thanks,

      Many of the primitively eusocial halictines are capable of forming large, dense aggregations, but it requires a fairly special and stable set of conditions persisting - as you suggest - for many years. From work that I and others have done, halictines tend to be *extremely* philopatric, initiating their nests within a meter of where they were born [Yanega, D. 1990. Philopatry and nest founding in a primitively social bee, Halictus rubicundus. Behav. Ecol. Sociobiol. 27: 37-42]. As long as the soil and foraging conditions remain favorable for years, populations can build up for a long time - and crash rather abruptly. John Wenzel did some genetic work on Dialictus aggregations (in river banks in Kansas) that were only about 10 meters apart and found significant genetic differentiation even on that spatial scale, indicating that rather little movement occurs between aggregations. I've also published work showing that higher temperatures increase the proportion of male eggs being laid, and the more males there are appearing early in the season, the fewer workers are recruited per nest within the aggregation (it appears that if a female mates immediately after emerging, she becomes an early-season gyne and goes into diapause rather than becoming a worker - and the more males, the more likely it is that females are to get mated immediately). Male production also appears to follow photoperiod, with the highest proportion of male eggs being laid near the summer solstice - so in about 1 or 2 more weeks, the emerging brood should be almost exclusively males, and then gradually the proportion of females should increase again, as the late-season gynes emerge. [Yanega, D. 1993. Environmental effects on male production and social structure in Halictus rubicundus (Hymenoptera: Halictidae). Insectes Sociaux 40: 169-180, and Yanega, D. 1997. Demography and sociality in halictine bees (Hymenoptera: Halictidae). pp. 293-315 in Choe, J.C. & Crespi, B.J. (eds.) Social Competition and Cooperation in Insects and Arachnids: Vol. II. Evolution of Sociality. Princeton Univ. Press, Princeton - I have no copies available of either work].


      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)
        "There are some enterprises in which a careful disorderliness
              is the true method" - Herman Melville, Moby Dick, Chap. 82
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