Ecological Basis for Low-Toxicity Integrated Pest Management 189been successful in increasing owl populations to control rats in rice and planta-
tion crops.
The Golden apple snail, Pomacea canaliculata, was originally introduced to
rice growing areas as an income generating activity for a caviar look-alike given its
brightly pink coloured egg clusters. It has since become widespread from Japan to
Indonesia and is now one of the most damaging pests of rice. It was introduced
without appropriate tests in any country even though it was on the quarantine lists
of several countries. The snail feeds on vegetation in aquatic environments, includ-
ing newly transplanted rice seedlings up to about 25 days old when the stems
become too hard. With no natural enemies and having highly mobile early stages
that flow with irrigation water, the golden snail spreads rapidly. Pesticides are often
used before transplanting or direct seeding, mainly highly toxic products such as
endosulfan, organo-tin products and metaldehyde. These products have serious
health implications and also cause the death of potential fish predators and natural
enemies early in the season (Halwart, 1994). The use of bamboo screens as inlets
to fields to inhibit snail movement is reported as the first line of snail defence.
Draining fields that have several shallow ditches where the snails will congregate
allows for faster collection or eases the herding of ducks into fields to eat the snails.
In Vietnam, snails are reported to be collected, chopped, cooked and used as fish
food to such an extent that they are now a declining problem.
Birds can be very damaging especially when occurring in large flocks. The
Red-billed Quelea, Quelea quelea, in sub-Saharan Africa and various species in Asia
are known as consistent problems in rice ecosystems. In most Asian countries and
in Chad, netting is used to trap large numbers of birds for sale as food. Mass nest
destruction is also possible for some species. In Asia, these methods have effectively
reduced pest bird populations to very low numbers. In Africa, the capture method
may bring benefits to local people in terms of income or a good protein addition
to the diet, but the impact on pest bird populations has been small. During the
ripening period in North-East Asia, some fields are protected by being covered
with bird nets. Reflective ribbons or used video or cassette tape are widely used to
scare birds in Asia. Sound cannons and owl or hawk look-alikes are also used in
many countries, though some birds become quickly habituated to mechanical
devices. Use of poisoned baits and the destruction of bird nesting habitat are dis-
couraged both because they are seldom effective and also because of the potential
negative effect on non-target species in adjacent aquatic environments.
Does IPM Work for Rice Farmers?
Although there is a large amount of grey literature (see http://www.communityipm.org))
related to rice IPM impact among farmers, there is little peer-reviewed published
data. This is in part a reflection of the financial and technical difficulty of conduct-
ing these studies. Longitudinal studies in agriculture are notoriously difficult due