Development and evaluation of clove and cinnamon oil-based nanoemulsions against adult fleas ( Xenopsylla cheopis )

Adult fleas is one of the important vector borne insects which transmitting many diseases to mammals (cats, dogs, rodents, and humans) and birds worldwide. Because of the impact of climatic changes, the distribution of transmitted vector-borne pathogens may change, as well as the host ranges and the spread of diseases. Rat flea, Xenopsylla cheopis, can transmit Plague, a dangerous infectious disease caused by the bacterium Yersinia pestis. As the widespread use of synthetic insecticides to control fleas for a long time led to the development of insect resistance, and adverse health effects on humans, animals, and the ecosystem. This is the first work for formulating and evaluating clove and cinnamon oil nanoemulsions and studying their effect on adult flea. Clove and cinnamon nanoformulations were prepared and subjected to physicochemical and stability studies. Results showed that the small droplet size of nanoformulations was 158.4 nm and 282.5 nm of clove and cinnamon oils at a ratio of 1:2 of oil: tween 80 with 15 min as the sonication time. Cinnamon nanoemulsions have high insecticidal activity against flea compared to clove nanoemulsions. The LC 50 account for 14.50 μg/ml and 26.42 μg/ml with a 39.90% increase in cinnamon nanoemulsion activity compared to clove nanoemulsion, respectively. Cinnamon nanoformulation is solvent-free and did not have any toxic effects on experimental animals and EC 50 more than 100 mg/l (EC 50  > 100 mg/l) on Vibrio fischeri bacteria. Therefore, it considers an eco-friendly green nano-insecticide for controlling Xenopsylla cheopis flea.