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Thursday, November 14, 2013

On Sarracenia, drugs and Lepidoptera…

flava fly

Saracenia flava with soon-to-be dinner.

Way back in 1976, a group of researchers extracted coniine, a narcotic drug, from the nectar of Sarracenia flava. Using the fire ants (Solenopsis invicta) as test subjects, they demonstrated that the amount of coniine in the nectar was sufficient to paralyse the ants. While I can’t access the original study online, I have often wondered what effect the coniine has on prey capture? (NB – the amount of coniine secreted by Sarracenia is not anywhere near enough to affect humans!).

BDQyIJ8CEAEoaAu.jpg large

Over the past couple of seasons, I have made some interesting observations with butterflies and moths coming to my Sarracenia. Last season, I watched a number of adults of the dayflying grapevine moth (Phalaenoides glycinae, Noctuidae sensu stricta: Agaristinae) drink the nectar of Saracenia leucophylla x psittacina pitchers (see photo above).

I was bemused that these moths would be attracted to Sarracenia, but became more intrigued when I found them alive but very intoxicated on the surface of the Sarracenia pots. When I picked them up, they barely but up a struggle, strange for such a strong flying (and often hard to catch) moth. However, they were never trapped by the Sarracenia hybrid they drank from, as the opening is too constricted for the moth to get inside. It was always this hybrid they were feeding at too – I never saw them at any other Sarracenia.

Now, fast forward to this season.

Heteronympha merope_M_R_sml

Over the past few days, we have had Common Brown butterflies (Heteronympha merope merope, Nymphalidae: Satyrinae) make their first appearance in Canberra. The above photo shows a male specimen, which are more conspicuous than females at this time of year.

Here is where I found one today (plant is an S. leucophylla ‘Tarnok’):

merope in pitcher_sml

What is impressive here is the relative sizes of the common brown butterfly…

Heteronympha merope 50c_b

and the pitcher that caught it…

tarnok 50c

As you can see, males of the common brown have a wingspan nearly twice the size of the mouth of this S. leucophylla pitcher. In fact, the specimen I photographed (from Tenterfield, NSW), is a little smaller (and paler) than the ones I often see here in Canberra.

merope in pitcher_2

And yet, this leucophylla managed to snag one. Sure, with its wings folded above its back, the butterfly could fall in, but the feeding behaviour of these butterflies is such that they usually settle head up, on top of the flower they are feeding on, and rhythmically open and close their wings while they feed. Once inside the pitcher, I think the butterfly’s struggling would suck it further down the pitcher, but I really wonder whether it would fall in on its own.

Perhaps the leucophylla had a little help from some coniine?

I will keep watching what goes on with insets around my Sarracenia over the summer and see if I can photograph some interesting encounters.

2 comments:

  1. That's interesting, I wonder if my alumni card can get me access to that study if it's a paid only version. Do you remember the title or author(s)? I've noticed a few hawk moths like my pitchers, but I think they're a bit too big to fall in even wings folded (like hummingbird size). It's amazing to me how little we still understand about these, but research is where the money is unfortunately.

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    Replies
    1. Hi Melody,

      The study is at: http://link.springer.com/article/10.1007%2FBF02003710

      Given the age of this article, and how well covered your alma mater is journal wise, you might just swing it. I couldn't access it via subscriptions available to me, but it would be great to read it. There is much research to be done yet - please email me and we'll talk further...

      Best wishes,

      John.

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