CLOFENTEZINE TOXICITY AND FATE IN THE BULB MITE RHIZOGLYPHUS-ECHINOPUS (ACARI, ACARIDAE)

Clofentezine was toxic to bulb mite, Rhizoglyphus echinopus (Fumouze a nd Robin), eggs and larvae; however, it was not toxic to adults alone or in the presence of piperonyl butoxide. When adults were exposed to radioactive clofentezine, the acaricide was absorbed, metabolized and excreted. After 48 h exposure, 49.8% of the recovered radiocarbon was parent compound with 37.1, 9.1 and 3.6% detected in the container rins e, mite rinse and internal fraction, respectively. Homogenates of adul ts extensively metabolized clofentezine. The most active fraction was the 12 000 g supernatant plus glutathione followed in decreasing order by the supernatant, supernatant plus NADPH and the whole homogenate, each of which metabolized at least 16% of the acaricide. In the presen ce of piperonyl butoxide, in vitro metabolism of clofentezine by each of these active fractions was increased approximately 10%. Although it is possible that rapid metabolism could have contributed to the lack of toxicity of clofentezine to bulb mite adults, it is more likely tha t another major mechanism was involved. Perhaps adult bulb mites lack the sensitive target found in immature mites.