Structural characterization of chitosan nanoparticle loaded with Piper nigrum essential oil for biological efficacy against the stored grain pest control.

In this study, Piper nigrum essential oil (PNO) has been encapsulated in chitosan nanoparticle (CS NPs) via ionic gelation method with sodium tripolyphosphate (TPP). The successfully loaded Piper nigrum EO was confirmed by UV-Vis spectrophotometry and X-ray diffraction (XRD) techniques. The average particle size of P. nigrum essential oil loaded chitosan nanoparticle (CS/PNO NPs) showed 527.5 nm with spherical shape morphology. Zeta potential values of the particles were found to be negative -5.34 mV. Encapsulation efficiency and loading efficiency was in the range of 35% to 40% and 4.85% to 7.04% respectively. CS/PNO NPs exhibited strong insecticidal activity against Sitophilus oryzae and Tribolium castaneum. In addition, CS/PNO NPs enhanced the fumigant toxicity and altered the neurotransmitter, acetylcholine in both the stored grain pests. Overall results of nanoformulation indicated that these novel design systems could be promoted in integrated pest management schedule for T. castaneum and S. oryzae.

Toxicity, antifeedant and biochemical efficacy of Mentha piperita L. essential oil and their major constituents against stored grain pest.

The efficiency of chemically characterized Mentha piperita L. essential oil (EO), a plant based insecticide was tested for acetylcholinesterase activity (AChE) and antioxidant enzyme system (SOD, CAT, GSH and GSSH) in Sitophilus oryzae (L.) and Tribolium castaneum (Herbst.). GC-MS results evidenced for menthone and menthol as the major compounds of EO. As a fumigant, EO and its major component showed 100% mortality at 75.0 µL/L air and 100.0 µL/L air against S. oryzae and T. castaneum at 24 h of exposure. Antifeedant activity exhibited 100% lethal activity against pests in comparison to sub lethal doses. In vivo percent inhibition of AChE activity ranged between S. oryzae (29.68%, 18.81% and 14.34%) and T. castaneum (20.67%, 13.73% and 9.19%). Significant changes in antioxidant defense system studied for SOD, CAT, GSH and GSSH were noticed. Results revealed the toxicity of EO associations with the inhibition of AChE activity accompanied by oxidative imbalance. Therefore, M. piperita EO has a noteworthy role in insecticidal properties and could be recommended as an eco-friendly alternative to synthetic insecticides.