Hydrolysis of sex pheromone by antennal esterases of the cabbage looper, Trichoplusia ni

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Abstract
Esterases were isolated from chemosensory sensilla on the antennae of Trichoplusia ni (Hübner). The disc gel electrophoretic patterns of these esterases from males and females were similar; however, more bands were observed in the antennae than in 8 other tissues examined. Most of the esterases detected in the 100,000 g supernatant of the antennal preparation could be dissociated from the 100,000 g membrane pellet. Esterases from both male and female antennae hydrolyzed the sex attractant, (Z)-7-dodecen-l-ol acetate, more rapidly than did the legs, fat body or Malpighian tubules. The enzymes primarily responsible for pheromone catabolism were less sensitive to paraoxon, eserine and p-(hydroxymercuri)benzoate than those hydrolyzing 1-napthyl acetate. This suggested that a major portion of the observed pheromone-hydrolytic activity was due to acetylesterases. Measurement of pheromone hyrolysis in sections of disc gels that contained separated antennal or abdominal body wall esterases revealed 2 peaks of activity with both tissues; however, the rate of pheromone hydrolysis by the abdominal esterases was slower than that of the antennae. The significance of these findings is discussed in relation to the possibility of antennal esterases having a functional role in the olfactory process of males of T. ni.

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