Tuesday, November 20, 2012

Distractions of field work

Polybia species?
Now that I have a working lab protocol to measure cyanide, and have at least a rough idea of which species produce cyanide and which don't, I want to turn more attention to observing the flea beetles.  To accomplish this I have been hiking over to the successional plots, five experimental areas that are deliberately chopped to the ground on a five-year rotation, and allowed to recover naturally.  This repeated treatment provides good habitat for passionflower vines near ground level, and is one area where I can usually find flea beetles.  But, it can take a while to get there.
Lirometopum coronatum katydid on Passiflora auriculata
Ptocadica bifasciata on Passiflora auriculata
 The first photo shows the kind of distractions that happen every time I step out the door.  It shows a wasp colony (genus Polybia?) with 1-200 members, I expect with the queen (queens?) in the huddles.  A few workers seem busy building  new nest carton.  When I checked back a couple of hours later the carton was much more enclosed.  You can click on the photo to enlarge and see the wasps in detail.

The second photo shows a very bizarre katydid-like insect (Orthoptera: Tettigoniidae), with a rounded green cricket-like body, long antennae, and a strangely flattened head.  It took me a while to figure out what I was looking at.  The flat face is covered with light colored nodules and the jaws are black, giving the appearance of a crinkled, folded leaf with holes in it!  Only when it moved did I see what it was.  Apparently this species is carnivorous.

Monomacra violacea on Passiflora auriculata
When I finally arrived at the successional plots I did find some flea beetles to observe.  In fact I found one leaf of P. auriculata with three genera on it!  To the right is Ptocadica bifasciata, one of the larger species about 3 mm long.  I also saw Monomacra violacea, the shiny blue flea beetle, and Parchicola d.f. 2, the yellow-legged yellow flea beetle (not shown here).

I also saw 2 tiny orange flea beetles with black legs sitting on Passiflora vitifolia.  At first I thought it might be another species to add to my study, but after looking I couldn't find any sign that the beetles were feeding.  I suspect they were just sitting on the plant.  Later another large flea beetle landed near a P. auriculata, but it too showed no signs of feeding on Passiflora.  So far, in all my work here at La Selva, I have consistently found the same set of flea beetles.  The only exception is I haven't recently seen the "fat yellow" Ptocadica species nor the Dysonycha decemlineata species.  But no new species have cropped up.

unknown flea beetle (Coleoptera: Chrysomelidae: Alticini)

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