Surface contact toxicity and synergism of several insecticides against different stages of the tropical bed bug, Cimex hemipterus (Hemiptera: Cimicidae)

BACKGROUND: Five formulated insecticides (lambda‐cyhalothrin at 10 mg m −2 , bifenthrin at 50 mg m −2 , fipronil at 10 mg m −2 , fenitrothion at 50 mg m −2 , imidacloprid at 5 mg m −2 ) and one active ingredient (DDT at 500 mg m −2 ) were evaluated using a surface contact method against early and late instars and adults of two strains of the tropical bed bug, Cimex hemipterus (F.). Synergism of lambda‐cyhalothrin and fipronil using piperonyl butoxide (PBO) was also assessed. RESULTS: The order of susceptibility of different stages of bed bugs was as follows: early stage − lambda‐cyhalothrin > bifenthrin = imidacloprid > fipronil > fenitrothion > DDT; late stage—lambda‐cyhalothrin > bifenthrin > fenitrothion > imidacloprid > fipronil > DDT; adult—lambda‐cyhalothrin > imidacloprid > bifenthrin > fenitrothion > fipronil > DDT. The late instars exhibited significantly higher LT 50 among the life stages. The addition of PBO to fipronil increased the susceptibility of the insects. CONCLUSIONS: Lambda‐cyhalothrin, bifenthrin, fenitrothion and fipronil at the recommended application rates were effective against C. hemipterus . Although imidacloprid demonstrated good initial response against C. hemipterus , the insects showed substantial recovery 72 h post‐treatment. The late instars (fourth and fifth instars) should be used as the model for toxicological evaluation. Copyright © 2011 Society of Chemical Industry