ACS 2007 Chicago: The rotten stink of ladybirds(bugs)
“Ladybird, ladybird, fly away home, your house is on fire and your children are gone…”
Always one of my favourite nursery rhymes, possibly for the gruesome reason that I thought it suggested that all the baby bugs were dead. (And before I delve deeper into this subject of ladybirds I might have to clarify for non-brits that the ladybird is more commonly known in North America as the ladybug, and I will switch to that definition for the rest of this post).
Did you know that the cutest red and black spotted bug is the enemy of another of my favourite things – wine? “Ladybug taint” is responsible for a stench in wine that makes it unmarketable. Bad news, then.
A researcher at the University of Iowa, Lingshuang Cai, has looked at live asian ladybugs and taken precise mass spectrometry measurements of the stuff to come out of their heads. She and her team simultaneously sniffed the bugs as they were mass spec-ed.
This combination of sophisticated machinery/human discernment led Cai to identify 38 different smells. Impressive. And four of these were new ones in a class of stinky compounds called methoxypyrazines (MPs). The main culprit for ladybug taint is the catchy IPMP (2-isopropyl-3-methoxypyrazine), which was present in the ladybug headspace at a concentration of 0.1626 nanograms/L.
No suggestions given for how to combat any impending ladybug attack, but nice to know what it is that’s causing a stink, I suppose.
(the work was published recently in the Journal of Chromatogrphy A - but you'll need a password to read the whole thing)