Abstract:

Toxicity of 27 insecticides belonging to nine different types against the 3rd-instar and 5th-instar larvae of Hyphantria cunea was investigated by the leaf dipping method. The results showed that the 3rd-instar and 5th -instar larvae of H.cunea were sensitive to pyrethroids and molting hormones insecticides (LC₅₀ values were between 0.11 mg·L^-1 and 18.81 mg·L^-1). The toxicity of organochlorus and carbonates insecticides was related to the types of insecticides. Phoxim, Chlorpyrifos, Profenofos, Ethoprophos and Methomyl had higher toxicity to both 3rd-instar and 5th-instar larvae of H. cunea (LC₅₀ values were between 1.62 mg·L^-1 and 42.74 mg·L^-1). The 3 rd -instar larvae of H. cunea were sensitive to the benzoyl phenyl urea, phenylpyrazole, macrocyclic lactone and organochlorines insecticides (LC₅₀ values were between 3.13 mg·L^-1 and 30.86 mg·L^-1). However the 5th-instar larvae of H. cunea were less sensitive (LC₅₀ values were higher than 51.75 mg·L^-1).

Key words: Hyphantria cunea, insecticides, relative toxicity, leaf dipping