**6. Conclusion**

The levels of resistance in the two strains of Gaborone and Molepolole for both esterases B1 and A2–B2 are yet to be elucidated by carrying out bioassays against the susceptible strains. This approach will help to determine whether there is any correlation between esterase levels and insecticide resistance in these strains. This will also give an indication to the kind of resistance mechanism that may be conferred in these strains. It is at the DNA level that we can be able to trace the origin and the migration path of these esterases into Botswana.

The continuous use of DDT and pyrethroids on ITNs and IRS has shown that *A. arabiensis* is susceptible to both insecticides. However, there have been reports of DDT resistance in South Africa (ANVR, 2005). Monitoring of the current susceptibility status of the malaria vector *Anopheles arabiensis* using other insecticides should be encouraged as Botswana continues with the campaign to eradicate malaria.

Despite the extensive use of insecticides in the agricultural sector in Botswana, it is encouraging that research is focussing on using alternative insecticides that would not pose any threat to the environment and humans in any way. This way the agriculture and health sectors can be able to manage the evolution of insecticide resistance in insect pests of crops and insect vectors of diseases, respectively.
