Research Methods in Toxicology and Insecticide Resistance ...

1. Use of an appropriate synergist, for example, piperonyl butoxide, DEM, and
S,S,S-tributyl phosphotrithioate, to increase the effectiveness of an insecticide
without increasing the dosage of the insecticide in use. Nonetheless, it must
be remembered that the constant or frequent use of an insecticide over time
will encourage resistance development.
2. Overcoming metabolic resistance using insecticide composed of two or more
isomers of the active insecticidal ingredient.
3. In N. cincticeps, a mixture of N-propyl and N-methyl carbamates—the former
inhibits altered ACh-esterase in the resistant strain, while the latter inhibits
the enzyme in the susceptible strain.
4. A change to using a different class of insecticides with different modes of action.
This is one of the obvious methods to delay resistance built up for any one class
of insecticide. Rotation of two or more appropriate classes of insecticides with
entirely different modes of action will go a long way to delaying resistance to
any one of the insecticides used. However, it should be cautioned that getting
involved in the “pesticide treadmill” should be discouraged. This is because
the best way to avoid resistance is to avoid the use or total dependence on
insecticides for insect pest control.
5. Avoid intensive spraying or reduce/avoid the use of insecticides and practice a
good area-wide IPM program. This practice of implementing sound area-wide
IPM should be the pillar of support for ecofriendly insect pest management
through the judicious use (only when it is absolutely necessary) of an effective
insecticide within the context of a reliable “economic threshold.”
Conclusions
Frequently, among pest control agencies or farmers, there is a belief or assumption
that the discovery and/or marketing of new insecticides will always be way ahead
of resistance development. Nonetheless, the ever-increasing cost of research and
development for a new insecticide and, more importantly, the number of insect pest
species or strains resistant to even recently introduced insecticide—such as imidacloprid
and buprofezin against the BPH—demand the implementation of pest control
strategies within a proper IPM (integrated pest management) program to delay or
avoid resistance.
The development of insecticide resistance is an inevitable event when an insecticide
is used over a period of time with frequent and indiscriminate or extensive and
intensive applications. With the understanding of the mode of action as well as the
mechanism of resistance to insecticides, management of insecticide resistance in the
control of insect pests can be better planned, developed, and implemented, thereby
enhancing the involvement of insect toxicology in the proper management of insecticide
resistance within a well-planned and well-executed insect pest management
program. It is also important to note that the main defense against the development
of insecticide resistance is tight and regular surveillance, without any slipshod approach,
of the susceptibility of insecticide(s) in use within the targeted fi eld area so
as to enhance an insect pest management program.
Research methods in toxicology and insecticide resistance monitoring of rice planthoppers 35