Indoxacarb-loaded fluorescent mesoporous silica nanoparticles for effective control of Plutella xylostella L. with decreased detoxification enzymes activities

BACKGROUND Plutella xylostella L. is a cosmopolitan lepidopteron insect pest for numerous vegetables and crops. The extensive use of insecticides has resulted in the emergence of resistance in P. xylostella. Thus, development of innovative strategies to overcome the insecticide resistance and control P. xylostella effectively is highly desirable. Inspired by the concept and breakthrough of nanomedical strategies to treat multidrug resistance, nanotechnology may find potential application in overcoming or delaying insecticide resistance. RESULTS Carbon dots-embedded fluorescent mesoporous silica nanoparticles (FL-SiO2 NPs) were successfully developed. Indoxacarb-loaded nanoparticles (IN@FL-SiO2 NPs) were facilely prepared with loading content of 24%. The release of indoxacarb from IN@FL-SiO2 NPs was pH sensitive. IN@FL-SiO2 NPs exhibited better insecticidal activity against P. xylostella than indoxacarb technical under the same doses of active ingredient applied. Moreover, the activities of detoxification enzymes including GST, CarE, and P450 of P. xylostella were suppressed by treatment with IN@FL-SiO2 NPs. Furthermore, the entry of FL-SiO2 NPs into the midgut of P. xylostella was confirmed by CLSM observation. CONCLUSIONS Although there is no absolute correlation between the enzyme activity and resistance, the change in corresponding enzyme activity can afford valuable information on the resistance situation. IN@FL-SiO2 NPs treated P. xylostella displayed higher mortality, along with decreased enzymes activities, which indicates that nano-based delivery system of insecticide could be potentially applied in insecticide resistance management.