21 June 2013

Bug Grooming

Welcome back. Yes, I’m writing about bugs again, as if giant African millipedes weren’t enough. If you read my post on Cyborg Insects from last September, you’ll know I’ve got this thing about cockroaches. I want to annihilate them. There’s new research that might help. (Can you see me grinning diabolically?) 
American cockroach enjoying a cracker.
 (from www.pestid.msu.edu)


If you did see the Cyborg Insects post, you’ll likely recall the photos of the cute stuffed animal that I used to spare you from viewing photos of actual cockroaches. Today, I’ve got to go with the real thing. That’s a cockroach over there in the photo; the thing on the cracker.

Why the Reality Show? So you’ll see the bug’s antennae. Cockroaches go nuts keeping their antennae clean. Well, they don’t actually go nuts, they just spend lots of time grooming them. The new research found that the poor things don’t function well if their antennae aren’t spotless.

The Bug Study

The study was conducted by researchers at North Carolina State University with a collaborator from the Russian Academy of Sciences. Observing the incessant cleaning, the researchers sought to determine what the cockroaches were removing from their antennae, its source and its affect on the antennae and the bug.

Working first with American cockroaches (Periplaneta americana), which are a tad bigger than other cockroaches, the researchers compared antennae that they prevented from being cleaned with antennae that they allowed to be cleaned normally.

They found that unclean antennae collected significantly more environmental contaminants from surface and air as well as 3 to 4 times more fatty, wax-like material that roaches produce themselves to reduce water loss.

The researchers also found that the grooming process cleaned microscopic pores on the antennae that allow sensory chemicals to reach the bugs’ olfactory nerves. When the pores of the unclean antennae were plugged (sort of like a stuffed up nose), the cockroaches did not do as well at smelling (i.e., detecting) chemical signals that would be important to them. This was demonstrated by exposing cockroaches to chemicals associated with mating and other, I’ll guess less stimulating odors.

That would have been enough for me, but the investigators then subjected German cockroaches, carpenter ants and houseflies to many of the same tests. The results were similar even though cockroaches lick their antennae clean, while flies and ants appear to rub away the dirt with their legs.

Wrap Up

Allow me to jump to pest control implications. We’re probably not going to be able to convince the bugs to stay unkempt and thus less aware of their environment (i.e., not smell it coming). The researchers do suggest, however, that perhaps we could use the findings to improve the method of insecticide delivery.

For example, a mist or dust that lands directly on the antennae will be lapped up quickly by cockroaches and be much more effective than any residual insecticide. Since some of the more finicky cockroaches are demanding that a sweetener other than glucose be offered in roach motels, I think we’d better get on this immediately. Thanks for stopping by.

P.S.

- Paper in Proceedings of National Academy of Sciences:
http://www.pnas.org/content/early/2013/01/29/1212466110.full.pdf
- News release from North Carolina State University: http://news.ncsu.edu/releases/mkschalgroom/
- LiveScience article on the study:
http://www.livescience.com/26829-cockroaches-grooming-behavior-explained.html
- Science Magazine report on cockroach aversion to glucose:
http://www.sciencemag.org/content/340/613
deadline Monday, 1 July5/972

P.P.S.

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-Writing: Describe your Personal Best, deadline Monday, 1 July,
link: Personal Best Writing Contest
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link: Personal Best Photo Contest

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