Big Fleas Have Little Fleas: How Discoveries of Invertebrate Diseases are Advancing Modern Science

  • Elizabeth W. Davidson
University of Arizona Press: 2006. 208 pp. $35 (hbk); $17.95 (pbk) 0816526125 | ISBN: 0-816-52612-5

Insects get sick too, and the curious invertebrate pathologists who have delved into this diseased world have revealed some compelling insights into nature, illness and scientific practice. That is the basic premise of Big Fleas Have Little Fleas by Elizabeth Davidson, a book based on tales about the diverse organisms that plague not just insects, but crustaceans and horseshoe crabs too. The author draws on these pathologies to open the door on biological complexity and the splendour of scientific enquiry.

Davidson takes us through stories of infestations and plagues, uncovering how scientists have methodically unravelled both basic principles and potential control measures by studying parasites and diseases of invertebrates. European investigations into rotting silkworms in the nineteenth century found maladies caused by fungi and protozoans, and inspired Pasteur to establish the field of epidemiology. Elegant research into cholera found the causative bacteria Vibrio cholerae hitchhiking globally on copepods, and led US scientist Rita Colwell to suggest filtering drinking water in India through old sari cloth, a simple control measure that cut infection rates in half. Infestations of gypsy moths today are partly controlled by an arsenal of pathogens whose biology and utility have emerged from more than a hundred years of research.

Much of the work described in the book occurred during the founding era of invertebrate pathology, before the availability of technologies such as gas chromatography, electron microscopy and gene sequencing. Davidson's book reminds us that intuition, rigorous thinking and thorough probing were the most important scientific tools for these early researchers.

Unfortunately, Davidson does not use a similar rigour to probe the relevant policy issues, such as why biological control remains a minuscule sideshow compared with chemical pesticides. Viral, fungal, protozoan, nematode and bacterial agents can provide a solution but are dwarfed by the almost 2 million tonnes of chemicals used globally each year.

Even Bacillus thuringiensis, the most widespread biological control agent, is usually used by incorporating its toxins into genetically modified crops, rather than through more ecologically compatible whole-organism field sprays. Rampant antibiotic resistance among human diseases and today's rapidly evolving pandemic agents that afflict or threaten humans, plants and animals are other serious concerns that receive insufficient attention from Davidson.

Big Fleas Have Little Fleas is a book in search of a voice: it is not detailed enough for academic specialists, and not sufficiently well written for a general audience. Chapters start with interesting tidbits, but the writing quality is not sustained. It is a frustrating tease, with occasional elegant moments linked by formulaic descriptions of how this scientist did this, then the next one did that, with each piece of research contributing in a tiny way to larger scientific principles. Yes, science is a slow, methodical and painstaking process, but it's the rare moments of brilliance and the great investigative stories that thrill readers — elements that are too sparsely described here to make the book a compelling read.

Still, Davidson's book reminds us of one fundamental point: there is still much to learn from contemplating creatures smaller than ourselves, and we have barely begun to unravel the vast biological complexity on which we humans rely.