BIOASSAY OF ANTI JUVENILE HORMONE COMPOUNDS: AN ALTERNATIVE APPROACH.

During the last larval stadium of the cabbage looper, Trichoplusia ni, Hubner, the prepupal burst of juvenile hormone (JH) stimulates the appearance of juvenile hormone esterase (JHE) which, in turn, degrades the JH. Disruption of this prepupal burst of JH by anti-juvenile hormones (AJHs) such as fluoromevalonolactone, result in a variety of teratogenic effects including delayed tanning and/or pupation, malformed larvae and reduced JHE activity. Although general toxicants and esterase inhibitors may also cause malformed larvae, there is usually no delay in tanning and/or pupation. These observations provide the basis for a simple, rapid AJH bioassay using an economically important pest insect (T. ni). A simple 'key' was devised to help facilitate the use of this bioassay.