Abstract:
Global trends in malaria incidence and mortality has declined in many malaria endemic countries
due to the massive scale-up of indoor based malaria control interventions. However, the impact
of these interventions has been restricted due to insecticide resistance, the animal and outdoor
biting behaviors of malaria vectors. Hence, approaches to target insecticide resistant and
zoophilic vectors are urgent. This study was designed to evaluate the effect of treating cattle
ivermectin on mortality, fecundity and survivorship of laboratory reared Anopheles arabiensis.
Three calves were randomly selected to receive a subcutaneous injection of ivermectin at the
therapeutic dose of 0.2 mg/kg of body weight, while the other two calves received no treatment
and used as control. Five tents were constructed for the trial. The calves were introduced into the
tents (one per tent) and then, 30 starved An. arabiensis were released into each tent. Only fully
engorged females were collected from each tent. Later, their mortality, survivorship and
fecundity were recorded. Data analysis was done using SPSS version 16. Over all, ivermectin
had significant effect on the mortality, survivorship and fecundity of An. arabiensis. The mean
mortality rate of An. arabiensis was 81.6% at day one after treatment. The survivorship of An.
arabiensis was significantly reduced after feeding on ivermectin treated compared to those fed
on control calves (F= 110.7, DF = 1, P < 0.001). The effect was significantly affected by the
interaction of treatment and day after injection (F = 15.13, DF = 4, P < 0.001). Those mosquitoes
fed on calves treated with ivermectin produced significantly lower number of eggs compared to
control groups (F = 435.3, DF = 4, P < 0.001). In conclusion, ivermectin had impact on
mortality, fecundity and survivorship of laboratory reared An. arabiensis. However, further study
could be recommended on the impact of treatment of cattle with ivermectin on wild vector
population, and combining the use of existing indoor based interventions with mass ivermectin
administration for domestic animals.
