and Integrated Pest Management - part - usaid

PESTICIDE RESISTANCE
PROBLEMS
N. Sinchaisri
Department of Entomology
Kasetsart University, Bangkhen
Bangkok 10900, Thailand
IN THAILAND
The circumstances under which pesticide resistance may develop in any
are immensely variable, usually highly complex
and, in our present state of knowledge, only partially understood. Resistance is
insect (arthropod) population
A range of other organisms including
not limited to sects and insecticides.
and rodents develop resistance to chemicals intended to control
fungi, wC iecs,
number of species of arthropods resistant to insecticides has increased
them. Th
n 1928, 14 in 1948, 76 in 1957, 224 in
almost linearly, from I in 1908 to 5
1967, 364 in 1975 and 432 in 198g0 (Georghiiou & Taylor 1977, Georghiou &
It is estimated that approximately 500 species of arthropods
1ellon31983) rssac is not From an almost isolateda
o several g,--- oups 'crta of toxic chemicals.
shllon show resistance 13). to t one or severl,,
a is is
century of experience, it would also appear that resistance
species showing enough variability
but rather that, when a
exposed to intensive treatments, it will most likely adapt to the toxicants.
phenomenon
Pesticide resistance in a pest Commonly manifests itself when field
applicationis fail to give the desired level of control, thus presenting a problem to
the fairmcr. Resistance to pesticides is not just found among insects since it has
also been reported for spider mites to acariCides nematodes to nematicides,
bacteria to antibiotics, fungi to fungicides, and rodents to rodenticides. it must
a beneficial aspect when it
be mentioned that sometimes, resistance may have
concerns beneficial organisms such as an egg parasite Trichogramlla, or fungus
or entomopathogenic bacteria on agricultural crops.
Bcarse of serious problems associated with tle development of resistance
to pathogens, the chcmical industry, under the auspices of GIFAP (Groupement
de Fabricants de Pesticides, or
International des Ass;ociations Nationlales
Pesticide vlanufacturers' Associations),
International Group of National
This subsequently led to
the topic in Brussels in 1981.
a seminar on Committee (FRAC).
organized Action
of Fungicide Resistance as a practical problem. The
tle phy~the creation generally recognize resistance
most prominent cases of field resistance have occurred against dicarboximides and against i
foliar o ycetes
acylalanins in certain
otrytis, against
onc the
•in Fusarium and more recently inPseud
Very serious cases of fungicide resistance appear to be based on alteration of
target site of action of the fungicide whereas insecticide resistance benzimidaz.i
commonly
results from increased metabolic detoxication.
It is well-known that the diamondback moth (DBM) Pluitellaxylostella is a
Between 1978 and 1980, DBM was
cosmopolitan pest of cruciferous crops.
found to be resistant to 15 insecticides from all groups (Sinchaisri et al. 1980,