Acaricidal properties of piperazine and its derivatives against house‐dust and stored‐food mites

BACKGROUND: Piperazine derivatives possess pharmacological properties, yet the acaricidal activity of these compounds has not been investigated. This study was conducted to evaluate the colour alteration and acaricidal activity of piperazine derivatives against Dermatophagoides spp. and Tyrophagus putrescentiae (Schrank) using filter paper and fumigant methods. RESULTS: In a fumigant bioassay, 1-phenylpiperazine (7.83 microg cm(-2)) against D. farinae (Hughes) was found to be 4.7 times more toxic than DEET (36.84 microg cm(-2)), followed by benzyl benzoate (9.72 microg cm(-2)), piperazine (11.41 microg cm(-2)), 1-ethoxycarbonylpiperazine (20.14 microg cm(-2)) and 1-(2-methoxyphenyl)piperazine (22.14 microg cm(-2)). In a filter paper bioassay, 1-(2-methoxyphenyl)piperazine (3.65 microg cm(-2)) was 5.7 times more toxic than DEET (20.64 microg cm(-2)), followed by 1-ethoxycarbonylpiperazine (4.02 microg cm(-2)), 1-phenylpiperazine (4.75 microg cm(-2)), benzyl benzoate (7.83 microg cm(-2)) and piperazine (10.59 microg cm(-2)). Similar results have been exhibited with piperazine derivatives against D. pteronyssinus (Troussart). However, no activity against T. putrescentiae was observed for piperazine derivatives, except for piperazine. CONCLUSIONS: These results indicate that piperazine derivatives may be suitable as vapour-phase acaricide fumigants owing to their high volatility, acaricidal activity and safety. 1-Phenylpiperazine was found to be an excellent mite indicator based on the colour change it induced. Taken together, these findings indicate that piperazine derivatives may be used to replace existing problematical acaricides owing to their activity and ability to act as a mite indicator.