To the FWGNA group:
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.
http://www.philrice.gov.ph//index.php?option=com_content&task=view&id=104&Itemid=139
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Keep in touch,
Rob
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