Insecticidal effect of controlled release formulations of etofenprox based on nano-bio technique

The characteristics and the bioassay of controlled release formulations (CRFs) of etofenprox which has been used for pest control using a nano-sized chitosan carrier to control the released amount of the active ingredients were evaluated. The CRF was prepared in three types, ENCl (M.W 3000, 0.3%), ENC2 (M.W 30,000, 0.1%) and ENC3 (M.W. 30,000, 0.3%), according to a difference in release patterns by adjusting the molecular weight and concentration of chitosan. After the release properties of the active ingredients and biological activities of the 3 formulations were evaluated, the ENC2 type was selected. A shape of the ENC2 type was taken by a scanning electron microscope (SEM), and it was confirmed that the ENC2 type had a polygonal shape and ENC2 particles with various sizes of 800 nm or less were mixed. The release of the ENC2 type in a CRF began after it reacted with a solvent, and the ENC2 became smaller, and the shape of ENC2 nanoparticle was changed. However, in the ENC2 type formulation, de-encapsulated active ingredients of etofenprox exhibited initial insecticidal effects, and thus the ENC2 type was modified to be prepared as an ENC2A formulation in which all the active ingredients of etofenprox were encapsulated. The ENC2A formulation exhibited the properties of CRF in the release properties of the active ingredients and the effective activity against Spodoptera litura. These results suggest that such CRF is considered to be used as a method of preventing loss of active ingredients of chemicals and increasing the activity of the chemicals against a target pest, thereby decreasing the use of the chemicals.