Sunday, March 11, 2012

Answer to Case 199

Identification: Leptoglossus occidentalis - Western Conifer Seed Bug (in the Family Coreidae or Leaf-footed Bugs)

Check out this BugGuide entry for more details.


My special thanks to B.A.M. from DPDx for providing the specific identification in this case.


Most of you noticed that this arthropod has a clear resemblance to the "Kissing"bugs (Reduviidae family, Triatominae subfamily) that transmit the human pathogen Trypanosoma cruzi. Indeed, this is clearly what the submitting laboratory thought as well, since they included a web link to this bug along with their submission.


So herein lies the dilemma. Clinical Parasitology laboratories commonly receive both free-living and human ectoparasites for identification, and the challenge is to distinguish the two so that patients are not inappropriately treated or subjected to unnecessary eradication efforts (e.g. house fumigation, etc). Therefore, even if the clinical laboratory does not have the expertise to fully identify the non-human ectoparasites, it is important to be able to say with confidence that the object in question is NOT a human ectoparasite. The best option is to have an entomologist available for consultation. Again, DPDx is an excellent resource.


However, there are also some features that allow quick differentiation of this specimen from a kissing bug:

First, the wing venation is more numerous on this specimen (below, left) than would be seen for a kissing bug (below, right):


Second, many of the
coreids (Leaf-footed Bugs), although not all, have tibial expansions that can appear leaf-like. These can clearly be seen in this specimen and provide a quick way to exclude a kissing bug in this case.


Again, check out the BugGuide for more information.

Finally, I should point out that not all kissing bugs look alike. The subfamily Triatominae consists of 3 genera (12 species) that can transmit Trypanosoma cruzi to humans: Rhodnius, Panstrongylus, and Triatoma. These genera can be differentiated by multiple features, including placement of their antennae in relation to their eyes:

4 comments:

Verity Sandahl said...

I appreciate this article. I found the bug on the left in our kids' playroom today and was very confused and worried!

It seemed odd for MN, but I had to make sure!

Thank you for the comparison.

Bobbi Pritt said...

I'm glad you found it to be helpful!

Anonymous said...

Thanks, this information just turned a moment of panic into a "whew, OK, go back to bed" event...and, right on the heels of all the headlines about the kissing bug and Chagas disease. Thanks for what you've done here.

Bobbi Pritt said...

You're welcome!