Leaf-Dip Bioassay for Chlorantraniliprole Toxicity

Bioassays were conducted using a leaf-dip method based on methods of He et al. (2012) and Zhang et al. (2022) (link) with minor modifications. 95% chlorantraniliprole (DuPont) was dissolved in acetone solution, and then diluted into five to six concentrations with distilled water containing .05% Triton X-100 at a triple gradient dose. The .05% Triton X-100 solution was used as blank control. The fresh leek cultured in the laboratory measuring 5 cm × .5 cm were immersed in the prepared various concentrations of chlorantraniliprole for 15 s, and taken out in ventilated cupboard to air dry and then placed into a Petri dish lined with filter paper. Twenty healthy 2-day third instar larvae were placed into each Petri dish with six pieces of leek leaves with four replications for toxicity assessment bioassays. Mortality was assessed after 48 h of exposure, larvae that did not move when gently pushed with a fine hair brush were considered dead. The control groups was below 5%, mortality was corrected using Abbott’s formula (Abbott, 1925 (link)). The LC₅₀ value and slope were calculated by regression probit analysis conducted with the POLO-Plus software (2002) .