Labaratory Study For The Effect of Neem Oil (Azadirachta indica) Against Mosquito Larvae of (Culiseta longiareolata) in Wasit Governorate/Iraq.

Abstract

The study was undertaken to investigate the effect of neem oil that extracted from Azadirachta indica tree against the larvae of Culiseta longiareolata (Macquarrt) mosquito in all larval instars.The larvae were exposed to different concentrations of neem oil (0.001%,0.01%,0.1%,0.5% and 1%) for 24h and 48h under laboratory conditions.Neem oil was more toxic against 1st.larval instar and reached 90% mortality at concentration of 1% for 48h while the responds of 2nd.,3rd. and 4th. Larval instars were(86.66%,46.66% and 43.33%), respectively. The statistical results of LC50% value have been shown of the larvae: 1st.,2nd.,3rd. and 4th.instars were (0.713%, 0.748%, 1.588% and 1.797%), respectively. While the LC90% were (1.120%,1.169%,7.599% and 9.516%) , respectively with confidance limits (95%) within 24h . The lethal concentration was increased with larval stage. In the same period the LC50% of the 4th. larval instar is 2.52 times the LC50% of the 1st.larval instar, also the LC 90% is equivalent 8.49 times the LC90% of the 1st.larval instar. In 48 h, the LC50% of the 4th. larval instar is 2.61 times the LC50% of the 1st.larval instar, also the LC 90% is equivalent 7.53 times the LC90% of the 1st.larval instar.The results of the statistical analysis(Gretl) showed a significant positive correlation with both levels (0.05 and 0.01) from significant between the mortality ratios of the larval stages and the concentrations used ,the peak was in the larvae of the first instar when the P-value = 0.0001.