Global Advances in Ecology and Management of Golden Apple Snails. R. C. Joshi & L. S. Sebastian (editors). Philippine Rice Research Institute (2006) 600 pp, hardbound. US$ 102.
The large ampullariid "golden apple snail" (Pomacea) has, in the last 25 years, become a significant pest of rice and other lowland crops throughout Asia and the Pacific. A native of South America, the snail was initially spread by Asian peoples who, at least occasionally, include large freshwater gastropods in their diet. Here in the United States, apple snails have been introduced into Florida, south Georgia, and Texas, and have significantly damaged taro crops in Hawaii.
The new volume on golden apple snails under review here is a collection of 46 chapters by approximately 100 authors. Most chapters do not report primary research, but rather are themselves reviews of even larger bodies of regional or specialized literature, often from sources unfamiliar here in the West. Without question, anybody whose research involves Pomacea will want a copy of this reference on his shelf. But might those of us who do not encounter an apple snail on a normal business day also find some value in this volume? The quick answer is yes..
Section 1 (History, Taxonomy and Impacts) includes the eight chapters of most general interest. Members of the FWGNA group will appreciate the contribution on taxonomy by Cowie and colleagues as well as that of Baoanan & Pagulayan. The chapter by Bob Howells and his four colleagues is an excellent review of the ampullariid situation in North America, with ecological notes. The paper by N. J. Cazzaniga entitled "Pomacea canaliculata, harmless and useless in its natural realm (Argentina)" is also packed with good biological information.
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Section 2 (Country Reports) includes 17 chapters focusing on apple snail invasions and their consequences throughout Asia. Reports are filed from 13 countries, with a nice chapter on the situation in Hawaii contributed by Levin and colleagues. This is the heart of the book. Clearly the environments, habitats, and culture practices to which apple snails have become adapted are extremely diverse. One would expect the variation in their behavior, life history, and other dimensions of their ecophenotypic response to be profound. Thus where the researchers from the diverse countries overlap in the biological data they report, important generalizations begin to emerge.
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Section 3 (Management Methods) contains seven chapters reporting approaches to apple snail control. I found the contribution by Halwart and colleagues modeling Pomacea population ecology in rice fields to be particularly valuable. Section 4 (Utilization) includes four chapters focusing on apple snails for food, fertilizer, or weed control.
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Perhaps the most unexpected section was #5 (Electronic Databases), a pair of chapters describing the "Crop Protection Compendium" and the "Asian-Pacific Alien Species Database." Apparently there are so many efforts ongoing throughout the world to electronically catalogue the growing apple snail literature that we need a database of databases.
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Section 6 (Notes) is an odd lot of eight chapters, apparently bundled together because each is ten pages or less. There are three chapters I would have preferred to see in the section on country reports, two chapters that would have fit in the section on databases, two chapters dealing with utilization, and one chapter on management.
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So how useful will this 600 page collection be to a general audience of ecologists and evolutionary biologists interested in freshwater gastropods, such as ourselves? I devised an analytical test to answer this question.
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I picked the single most important life history variable expressed by populations, age or size of maturation, and searched the electronic version of the book on my desktop for instances of "adult" or the two-syllable fragment "matur." I got several hundred hits, which upon direct examination yielded 14 estimates distributed through 11 chapters as follows: 20-80 d, 25-40 d, 59-90 d, 60-85 d, 60-90 d, 60-90 d (25 mm), 60-95 d (30-35 mm), 90 d, 90 d, 90 - 120 d, 107 d (25-40 mm), 20-30 mm, 25 mm, and 35-40 mm.
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None of these records turned out to be primary - most cited a published source, but some did not. Rather frustratingly, I found the index not to include any entry under the headings adulthood or maturation, and only a single entry under life cycle. The six entries under "reproduction" caught but 5 of the 14 data. Nevertheless, a large amount of information clearly exists regarding the age or size of maturity in Pomacea populations, and the work presently under review can provide a wedge into it.
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Wow - 25 mm of snail in 20 days, are you kidding me? Even the slower estimates of 60 - 90 days to maturity are impressive for such a large gastropod. Those of us who have spent our professional lives in the higher latitudes may have a hard time wrapping our minds around some of the most fundamental aspects of Pomacea biology.
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The only caveat I feel compelled to offer has to do with general problems of organization. Shortcomings regarding the chapter arrangement and index have already been touched upon. The work is rather repetitive in spots, featuring two chapters on Taiwan, two on Vietnam, and three on China, as well as two forewords and a preface. Clearly the editors could have boiled this book down and tightened it up into much, much less than 600 pages. But readers with patience and stamina will be rewarded.
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In summary, it must be a point of great regret to all of us that freshwater gastropod populations have become such terrible pests in the rice and taro fields of Asia and the Pacific. But the experience of science has been that pest species (rats, mice, fruit flies) can prove to be especially useful as model organisms for research into questions of great generality and importance. This volume leads me to expect important advances from the community of Pomacea researchers for many years to come.
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Keep in touch,
Rob
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