2.4 Formulation of the test extracts
The test extracts were formulated using melted Vaseline Pure
Petroleum Jelly® by volumentarily diluting with melted jelly
in water bath at 80 °C to the desired concentrations.
Different combinations that consisted of Neem oil and Sweet
basil oil, Lemon Eucalyptus oil and Neem oil and Lemon
Eucalyptus oil, Neem oil and Sweet basil oil in the ratio 1:1:1
were then prepared.
Crude oleoresin extract of pyrethrum was synergised with
PBO in a ratio of PBO to pyrethrum as 4:1 (v:v) and the
resultant stock solution was serially diluted to the desired
concentration.