Effect Of Uv-Light, Sun-Light And Field Conditions On The Stability Of Neem Seed Oil Extract

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Ahmed, Aymen El Misbah Babiker
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Although, neem extracts were believed to be effective and safe botanical insecticides, but their active ingredients appear to be unstable under environmental factors. The experiments conducted under this study aim to verify the effect of ultra violet-light (UV-light), sun light and field conditions on the stability of neem seed oil extract (N.S.O.E.). The mortality rate of khapra beetle larvae T. granarium(Everts), caused by neem seed oil extract N.S.O.E. treatment after being exposed to the factors under study was taken for assessment. The neem seed oil was extracted by means of Hexane. Wheat seeds were then treated inside glass Petri-dishes with the concentrations 1%, 2% and 3% neem seed oil extract (N.S.O.E). Third instar larvae were fed on the seeds, to find out the efficacy of these concentrations. The same 400 wheat seeds was treated with the same concentrations inside Petri-dishes and covered with muslin cloth before being exposed to 254 nm UV-light for 15, 30 and 45 minutes. Another 400 wheat seeds, already treated with the same concentrations, was exposed to 1, 2 and 3 hours of sun light. The same number was tested under field conditions for 1, 3, 5, 7 and 14 days. The three concentrations of N.S.O.E. were tested also on the same 400 wheat seeds without exposing to the factors under test, as standard fresh neem seed oil extract (N.S.O.E). The test larvae were then transferred softly to the standard and the treated exposed Petri-dishes. Mortality rates for the insects were recorded for 7 days (period of the experiment). The statistical analysis confirmed that, the neem seed oil extract N.S.O.E. has an insecticidal effect on the test insects as follows: 3%>2%>1%. However, the results reveal a decrease in the stability and potency of the neem seed oil extract N.S.O.E. when exposed to more than 15 min. UV-light and more than 1 hour to sun light. The result also confirmed that the stability of neem seed oil extract N.S.O.E. decreases in more than one day under field conditions, and no effect was noticed after exposure to more than 7 days under field conditions.
University of khartoum