Cynthia Downs
Cynthia Downs

The editors of the Journal of Experimental Biology (JEB) have chosen Assistant Professor of Biology Cynthia Downs’ paper, “Flea fitness is reduced by high fractional concentrations of CO2 that simulate levels found in their hosts’ burrows,” as the Editors’ Choice for its December issue. The paper is featured in the Inside JEB section of the publication, titled “Fleas Don’t Cope in Burrowing Host’s Stale Air.” According to the journal, “Inside JEB highlights the key developments in Journal of Experimental Biology. Written by science journalists, the short reports give the inside view of the science in JEB.”

As explained in JEB, Downs, the paper’s lead author, wondered how parasitic hitchhikers may be affected by the stale subterranean air produced by their hosts. “I wanted to determine how concentrations of CO2 that mimic those found in some burrows where fleas reside affected how fleas interacted with their hosts,” said Downs. “I was interested in how environmental conditions affect host–parasite interactions.” What she and her co-authors discovered was that death rates increased by 27% in the stale air and reproduction rates decreased.

Downs interest in this research began while working in Berry Pinshow’s lab in Ben-Gurion University of the Negev, Israel with rodents known as jirds. “The jirds are fairly docile and very easy to work with,” recalled Downs, but she admitted that she had to overcome her natural squeamishness about plunging her hand into a box of Xenopsylla ramesis fleas before transferring them to the rodents – even though the fleas do not bite humans, according to the JEB article.

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