Eugenol nanoemulsion as bio‑fumigant: enhanced insecticidal activity against the rice weevil, Sitophilus oryzae adults.

Nanoemulsion is a promising delivery system for
delivering the plant bioactive molecules against insect pests.
In this study, we aimed to prepare eugenol based nanoe�mulsions (EL-NE) by ultrasonication method to investigate
its fumigant toxicity against Sitophilus oryzae adults and
to analyse the residual characteristics of eugenol bioactive
on the treated grains and beetles. In EL-NE preparations,
1:1 ratio of eugenol: Tween 80 combination with 5 min of
ultrasonication at frequency of 10 kHz and 12 W power
output was determined as optimal. In the optimized nanoe�mulsions, 19.21 to 42.82 d.nm range of mean droplet size,
0.50 to 0.77 range of polydispersity index and −21.80 to
−29.83 mV range of zeta potential values were observed
with respect to 2.5 to 10.0% of eugenol concentrations. After
72 h of fumigation, enhanced fumigant toxicities (3.5–11.2
fold) were observed against S. oryzae adults for the opti�mized EL-NEs compared to eugenol alone. Fumigant toxic�ity results revealed 14.40 µl/L air of least LC50 value for the
10.0% EL-NE. Persistence of eugenol was more (12.46%)
in EL-NE treated wheat grains compared to eugenol alone
treatments based on Gas Chromatography–Mass Spectros�copy analysis, which indicates the improved fumigation.
This study results suggests EL-NEs as promising nano�biofumigant against the S. oryzae adults for eco-friendly
Integrated Pest Management (IPM).