Comparison between in vivo and in vitro cutaneous penetration of fenvalerate in tobacco budworm (Lepidoptera: Noctuidae).

In vivo and in vitro penetration of fenvalerate were compared in the 3-d-old fifth-instar tobacco budworm, Heliothis virescens (F). In the in vitro studies, a piece of cuticle was excised and mounted on a diffusion cell, and the amount of radioactivity present in the cuticle and medium was determined at various time intervals. At 24 h, approximately 7.4% of the dose was located in the cuticle, whereas only 1.6% actually penetrated. In the in vivo studies, approximately 7.4% of the radioactivity was recovered from the body after cuticular wash.