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The termicidal effects of Chlorpyrifos 48 EC, Endosulfan 35
EC, Dichlorvos 1000 EC and Diazinon 600 EC against termites
in South-West Nigeria
E. U. Asogwa*, F. A. Okelana, T. C. N. Ndubuaku and
I.
U.
Mokwunye
Crop Protection Division,
Cocoa Research Institute of Nigeria,
Ibadan,
Nigeria.
*Corresponding author.
E-mail:
ucheasogwa1@yahoo.com.
Accepted 3 November, 2008 |
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Studies were carried out at
the Cocoa Research Institute of Nigeria, Ibadan to determine
the efficacy of four insecticides (Chlorpyrifos 48 EC,
Endosulfan 35 EC, Dichlorvos 1000 EC and Diazinon 600 EC) on
termites (workers and soldier castes). The results showed
that for both topical and residual action tests, worker
caste mortality rates ranging from 70 to 100% were recorded
for Chlorpyrifos, Endosulfan, Dichlorvos and Diazinon at
0.063, 0.125, 0.25 and 0.5% treatment levels within 120 min
after exposure (MAE). For the soldier caste, the mortality
rate was between 10 and 70% at the same treatment levels
within the same time interval. However, the insecticide
concentrations had very low fumigant action against the
termites (workers and soldiers) when exposed to different
concentrations of their fumes. There was no mortality
recorded in any of the control petridishes. A higher
mortality of the soldier caste was recorded for the topical
application (10 to 70%) than the residual application, which
gave a better kill of the workers caste (90 to 100%) 120
MAE. The high death rate of the workers might be due to the
fact that they were generally more active during foraging
and thus more susceptible to the effects of the insecticide
either by contact or systemic actions. The fact that the
workers have a lower surface area and body weight than the
soldiers might have also contributed to their higher
vulnerability to the insecticides. The application of these
insecticides at 0.25% active ingredient is adjudged the best
due to the high mortality rate achieved. Also the
application at 0.25% will help to maintain cost
effectiveness of these insecticides and minimize
environmental pollution, toxicity and phytotoxicity problems
associated with pesticides.
Key words:
Worker caste, soldier caste, mortality, topical, residual
and fumigant. |
