فهرست نشریات علمی دسترسی آزاد ایران

Botanical biopesticides are recognized for their efficacy in combating a variety of crop pests. They are characterized by their biodegradability and affordability. The application of nanotechnology is viewed as a promising avenue for advancing pest control methods. This study revealed a detrimental impact associated with the conversion of neem oil into its nano form using high-energy sonication. Transmission Electron Microscopy (TEM) analysis indicated that prepared nano particles were spherical and smooth with mean particle size ranged from 90 to 120 nm. The effects of both bulk neem oil and its nano-emulsion were evaluated against the fifth instar nymphs of Schistocerca gregaria under semi-field conditions. Topical applications of both formulations, at doses of 5 and 2.5 ppm, resulted in a significant increase in mortality rates, as well as nymphal malformations and failed molting, in comparison to the control group. However, the crude form of neem oil demonstrated greater effectiveness than the nano formulation. The chitinase activity and total protein were influenced by both formulations. Notably, the nano emulsion resulted in a significant extension of duration period in the survived nymphs. Gas chromatography/mass spectrometry (GC/MS) analysis indicated the absence of linoleic acid in the nano sample, which may account for the superior efficacy of the bulk sample over the nano formulation. The prolonged ultrasonic treatment during preparation of neem oil nano-emulsion adversely affected the active biocompounds presented in neem oil, leading to a reduction in its bioactivity against the fifth instar nymphs of S. gregaria compared to its crude form.