Abstract:
Insects that survive lethal concentrations have impacted a sub lethal effect which might not
produce immediate mortality but have a prolonged effect on the biology and elevation of
oxidative enzymes. Laboratory analyses was carried out with LD10, LD20 and LD30 of
cypermetrin at temperature of 27-29° C, relative humidity of 70-85% with water and acetone
as chemical control. The percentage of adult emergence from the 4th instar larval of the
mosquito were significantly different for all the sublethal concentrations and control (F(3, 19)
= 167.568, p = 0.000). Mean rate of oviposition decreases, in the control = (107.20±3.02),
LD10= (104.40±2.82), LD20= (93.67±2.69) and LD30= (87.00±2.19). The mean life span bythe
adult female decreases from 12.44+0.193 in the control to 7.20+0.109 at LD20 and the
decrease were significantly different (F (3, 19) = 226.149, p = 0.000). The content of tissues
protein in both the larvae (Sig= 0.02) and adult (Sig= 0.001) significantly reduced with
respect to the control. Similarly, tissue carbohydrate content were significantly different
within the sub lethal concentration tested and the control in the larvae (p= 0.004) and the adult
(P= 0.001). The activation of GSTs in both larvae (Sig= 0.0021) and adult (Sig= 0.001)
significantly increase with increase in sub lethal concentration. A significant increase was
observed in the activation of Acetylcholinesterase (AChE) in both the larvae and adult. There
is a need to constantly review the lethal and sub lethal effects of many insecticides as this will
help in the prioritization and determination of effective dosage for mosquito control.
