Time-dose-mortality of formic acid and amitraz on western honeybee, Apis mellifera ligustica

In order to investigate the lethal effects of formic acid and amitraz on honeybee workers, Apis mellifera ligustica, the toxicity of formic acid and amitraz against western honeybee were measured using the bioassay method of insecticide stomach poisoning activity under laboratory condition. And they were also tested by time-does-mortality (TDM) model to confirm the dynamics and does-mortality of the lethal effects. Those data would provide theoretically guide in practical application in the field. The results showed that, by the Hosmer-Lemeshow test, the sensitivities of adult workers to the concentration change of the acaricides were formic acid > amitraz. The apex mortality rates of formic acid and amitraz to honeybee workers was determined at 60 h and 42 h respectively. The median lethal time (LT₅₀) of formic acid and amitraz under the concentration of 1 μg/mL was 4.8 h and 4.2 h, respectively. And that under 10 μg/mL was 1.5 h and 1.4 h, respectively. The values of LD₅₀ and LD₉₀ at 60 h after the treatment was 7.40×10^–2 μg/mL, 2.99×10^–2 μg/mL and 4.21×10^–2 μg/mL, 2.60×10^–2 μg/mL, respectively. High concentration of the formic acid and amitraz has stronger lethal effect for honeybee workers and time-does-mortality model accurately reflected the process of insecticides for western honeybees.