Why do I ask for full dates? In a recent post I commented that full dates are actually useful to the recording scheme. BUT, I then thought - well Id better provide some evidence as to why? I therefore thought that the attached phenology graph might help to show why full data are useful. This graph shows the separate phenology of male and female Volucella zonaria from photographic records. What we see in this graph is not only the difference in representation of males and females in the dataset, but also the respective difference in phenology with males emerging slightly earlier and dying off much earlier than the tail of the female population. Several questions arise from this graph: Firstly, where do male V. zonaria go? I cannot believe that females so greatly outnumber males - it seems more likely that males are just not seen. This disparity is not apparent in other Volucella. Secondly, what is the longevity of female V. zonaria? We know that V. pellucens may live for as much as 30-40 days, and that Hammerschmidtia ferruginea can live for as many as 50 days. Finally, if the disparity between males and females is so great, are females partially parthenogenetic? This is perhaps a long shot, but the whole issue raises a huge number of questions about the reproductive biology of Volucella zonaria. V. zonaria is eminently suited to mark-release-recapture so anybody living in southern England and wanting an interesting project might consider making such a study if there is a good local population.
Posted on: Sat, 24 Jan 2015 10:31:45 +0000
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