Efficacy of Mentha spicata and Mentha pulegium essential oil nanoformulation on mortality and physiology of Tribolium castaneum (Col.: Tenebrionidae)

Recently, the methods that improve essential oils (EOs) properties and make them appropriate to be applied as biorational pesticides have been regarded more precisely. The essential oils nanoformulation (EONF) is a promising strategy to develop and facilitate the applicability of the EOs in stored pest management. In this study, the toxicity, antifeedant and physiological effects of Mentha spicata L. and Mentha pulegium L. EOs and their NFs was investigated on the red flour beetle, Tribolium castaneum (Herbst). Characterization of nanocapsules using dynamic light scattering (DLS) and transmission electron microscopy (TEM) showed that the nanocapsules were spherical in shape with the average sizes of 56.91 and 98.99 nm for M. spicata and M. pulegium EONF, respectively. The encapsulation efficiency obtained was 95.47 and 86.03% for M. spicata and M. pulegium EONF, respectively. After 72 h, the LC50 values of the EOs and NF of M. spicata were 18.422 and 9.279 µl/ml and 7.939 and 6.793 µl/ml for M. pulegium, respectively. The results confirmed that the feeding indices of T. castaneum were affected by the EOs and their NFs. In addition, both the EOs and EONF decreased the relative growth rate (RGR) and relative consumption rate (RCR) and had a moderate feeding deterrent activity on the adults of T. castaneum. The EOs and their NFs decreased the general esterase, acetylcholine esterase, α-amylase and general protease and increased the glutathione S-transferases activity of T. castaneum. The overall findings of this research suggest that the NF of the EOs (especially M. pulegium) can be used for an efficient control of T. castaneum.