Insect Control: Biological and Synthetic Agents - Index of

door for a more rational approach to developing
target specific control agents.
4.3.3. Pest Management with JHAs
The idea that insects would be unable to develop
resistance against JH if it was used as a control agent
was one of the driving principles behind the impetus
to develop this hormone as an insecticide (Williams,
1967). The difficulty and cost of synthesizing such a
complex molecule with a labile epoxide moiety and
susceptibility to degradation delayed the realization
of this concept. However, it soon became apparent
that several synthetic analogs of JH, many of
them several fold more active than the native hormone,
could be used as control agents. The discovery
that some synthetic synergists of insecticides
have intense JH activity (Bowers, 1968) was the
Figure 19 Some synthetic and naturally occurring JHAs.
4: Insect Growth- and Development-Disrupting Insecticides 149
harbinger for the development of various new analogs
with diverse chemical structures. Consequently,
the modes of action of these analogs may not necessarily
be similar.
Over the years, numerous JHAs have been synthesized
and their relative potencies, structure–activity
relationships, and differential effects on various species
have been studied (Slama et al., 1974;
Romanuk, 1981). Many naturally occurring JHAs,
also called juvenoids, have been isolated from plants
such as the ‘‘paper factor’’ from the balsam fir tree
(Abies balsamea), and juvocimenes from the sweet
basil plant (Ocimum basilicum) (Bowers and
Nishida, 1980). During coevolution, the plants
probably developed these JHAs to defend themselves
against insects. Some representative examples
of these compounds are shown in Figure 19.