Study on insecticidal properties of nanoemulsion Mentha longifolia L. (Lamiaceae) essential oil against Callosobruchus maculatus (Fabricius) (Coleoptera: Chrysomelidae)

Abstract

Nowadays, nanoemulsions are considered by many researchers because of their unique physiochemical properties such as small particle size, long-term physical stability and transparency. In this research, fumigant toxicity of Mentha longifolia L. essential oil and its nanoemulsion against Callosobruchus maculatus (Fabricius) has been studied. The experiments were conducted at laboratory conditions at 27±2°C temperature, 65±5% relative humidity and darkness. Essential oil of M. longifolia had higher fumigant toxicity than nanoemulsion, during early hours after treatment. The LC50 values of oil and nanoemulsion for the adults of the pest were 10.1 and 16.1 µl/l, respectively. The values of LC50 were 4.9 and 9.4 µl/l for oil and nanoemulsion during incubation period, respectively. In concentration of 25 µl/l, LT50 of M. longifolia essential oil and nanoemulsion were 2.2 and 11.1 days, respectively. In concentration of 10.1 µl/l, essential oil did not have durability, but this parameter of nanoemulsion is good (LT50= 9.04 days). At 9 µl/l of essential oil, the average time for the mortality of 50% eggs was 4.7 days. The LT50 of nanoemulsion at this concentration was 17.09 days. At 4.9 µl/l of nanoemulsion, the LT50 was 12.8 days, while essential oil did not have durability. The average diameter of nanoemulsion particles has been estimated about 10-36 nm by using transmission electron microscope (TEM). By using laser light scattering (SEMATech), this value was 234 nm. Considering obtained results, using nanoemulsion form of M. longifolia essential oil increase its fumigant toxicity and durability.

Keywords

• callosobruchus maculatus
• essential oil
• insecticidal
• mentha longifolia
• nanoemulsion