Potency of emulsifiable concentrate and nanoemulsion formulations as green insecticides against two insects, Aphis craccivora and Liriomyza trifolii

Abstract

The current research aims to develop emulsifiable concentrates (EC) and nanoemulsions derived from the plant essential oils of Salvia officinalis (L.) and Melissa officinalis (L.) at a concentration of 5%. The toxicity of the prepared formulations was evaluated against two insect species, the cowpea aphid, Aphis craccivora (Koch), and the broad bean leafminer, Liriomyza trifolii (Burgess). EC preparations were formed by mixing the essential oils with Tween 80, vegetable, and mineral oils. The nanoemulsions were manufactured by mixing different ratios of the essential oils and the surfactant (Tween 80) into an aqueous solution, followed by an ultrasonic emulsification process. The results showed that both EC and nanoemulsions with a ratio of essential oil to Tween 80 of 1:2 after 10 min of sonication passed the physical characteristics. The particle droplet size, zeta potential, and transmission electron microscopy (TEM) were measured for the successful nanoemulsion formulations. The ultrasonication and stirring procedures lowered the amounts of essential oils during preparations of S. officinalis and M. officinalis nanoemulsions to 17% and 20%, respectively. The laboratory trials elucidated that EC formulations were more potent than nanoemulsions for two insect species after a short period of time. While the field experiments showed that nano-formulations were more efficient than EC formulations with time elapsing. The results suggested that the prepared nanoemulsions can be used as eco-friendly alternatives to synthetic insecticides for controlling A. craccivora and L. trifolii infestations.