Fluorescence-Labeled Abamectin Nanopesticide for Comprehensive Control of Pinewood Nematode and <i>Monochamus alternatus</i> Hope

Abstract

Pine wilt disease is a major forestry quarantine disease caused by pinewood nematode and spread by the vector insect Monochamus alternatus (MA), which has brought destructive harm to pine trees. Avermectin (AVM) is a broad-spectrum fungicide, insecticide, and nematicide. However, AVM easily degrades under ultraviolet light and is almost insoluble in water, which seriously affect its control effect on the pine wilt disease. In this study, an original nanopesticide was designed to improve the bioactivity and utilization of AVMactive ingredients, with antiphotolysis and slow release properties especially. Bovine serum albumin (BSA) was dissolved in water, taking advantage of the oleophobic properties of the protein to wrap AVM in an oil phase by self-assembly. The obtained AVM BSA nanoparticles (AVM@BSA·NPs) had preferable sustained-release performance, the cumulative release reached 90.2%, the nanoparticles could be released continuously for about 20 days, the particle size of the AVM@BSA·NPs was about 65 nm, and the loading efficiency reached 78%. The nanodelivery system could effectively protect AVM from photolysis, and the retention of AVM@BSA·NPs was close to 80 and 75% after 48 and 72 h under ultraviolet light, respectively. In addition, the nanopesticides were prepared by labeling AVM@BSA·NPs with fluorescein isothiocyanate (FITC) to research the mechanism of contact and stomach toxicity of AVM using the probe function of FITC. Compared with AVM original, the stomach toxicity and contact toxicity of AVM@BSA·NPs increased by 35.3 and 19.6%, respectively. There are broad application prospects of AVM@BSA·NPs for the prevention and control of forest diseases and other pests.