Abstract: The Mediterranean (MED) cryptic species of  Bemisia tabaci (Gennadius) is a major pest in agricultural production. Abamectin is widely used as a key chemical agent for controlling B. tabaci. To clarify the ecological safety of abamectin to Nesidiocoris tenuis (Reuter), a key natural enemy of B. tabaci, we comprehensively assessed its toxicity to different developmental stages of these two species using the leaf-dipping method, agar moisture method, as well as a combination of contact toxicity and food chain transfer method. The safety of abamectin to N. tenuis was evaluated using safety factor and the benefit-harm toxicity ratio. The results showed that the toxicity of abamectin decreased with increasing insect age. The first instar nymphs of B. tabaci were the most sensitive (LC₅₀=0.53 mg·L^-1), while the female adults were the least sensitive (LC₅₀=6.05 mg·L^-1). Compared to B. tabaci, N. tenuis was less sensitive to abamectin, with an LC₅₀ of 55.25 mg·L^-1 for female adults, indicating that abamectin has low toxicity against female adults of N. tenuis. Under the recommended concentration, the female adults of N. tenuis held the highest safety factor (41.44-55.25) in the field, and the benefit-to-harm toxicity ratio reached 9.13, which was much higher than that of the nymphs. Therefore, abamectin demonstrates a high level of safety toward adult N. tenuis, making it a preferred chemical agent for integrated pest management that combines N. tenuis with chemical pesticides against B. tabaci.

Key words: Bemisia tabaci, Nesidiocoris tenuis, abamectin, safety evaluation, selective toxicity, green prevention and control