Insect Control With Growth Regulators Interfering With the Endocrine System

Abstract

Out of a field of many thousands of amdogs of the insect juvenile hormones (JHA). only a few have found practical utility in the control of a variety of insect species. Their mode of action and the lack of foliar stability in all but the must rcccntlv discovered juvcnoids have st) far precluded their use against pests of field crops. A possible more efficacious mode of action is present in anti-juvenile hormone agents (AJH). which can induce premature metamorphosis, but of which none of the present prototypes has yet been. developed into a cost cflective control agent. These AJH prototypes represent a number of vcrv different action mechanisms and degrees of selectivity lk)r different insect taxa. In an even more contemporary approach, the interference with ncurohormonal pathways presents significant perspectives for insect control.

Juvenile hormone activity of optically active ethyl 4-(2-benzylalkyloxy)benzoates inducing precocious metamorphosis

“…KF-13 was designed by modifying the structure of ethyl 4-[2-(tert-butylcarbonyloxy)butyloxy]benzoate (ETB), which is the only compound that is reported to act as a partial JH antagonist in the larval epidermis of Manduca sexta in vitro. 2) KF-13 and its analogs (1)(2)(3) showed stronger precocious metamorphosis-inducing activity than ETB (Fig. 1).…”

“…1). 1) ETB is known to show JH activity as well as anti-JH activity for M. sexta 3) and B. mori, 4) depending on the dose applied; low doses of ETB induced precocious metamorphosis, but at higher doses precocious metamorphosis-inducing activity disappeared and instead, JH activity was observed. ETB as a JH agonist counteracted the effect of allatectomy, i.e., induction of precocious metamorphosis, in a dose-dependent manner.…”

Synthesis and anti-juvenile hormone activity of ethyl 4-(2-benzylalkyloxy)benzoates and their enantiomers

“…The reaction mixture was quenched with 5 ml of saturated NH 4 Cl solution at 0°C. The product was extracted with ethyl acetate and the organic layer was washed with brine and dried over Na 2 SO 4 .…”

“…The mixture was stirred for 1 hr at Ϫ78°C and the reaction was quenched by the addition of 10 ml of saturated NH 4 Cl solution. The product was extracted with ethyl acetate.…”

“…2) Although several anti-JH agents such as precocenes, fluoromevalonate, dichloroallyl hexanoate, ethyl 4-[2-(tert-butylcarbonyloxy)butoxy]benzoate (ETB), 1,5-disubstituted imidazoles, and brevioxime 3) have so far been reported, none of the compounds has been developed for practical use in pest control as yet. Among them, ETB has been found to have both JH-like action and anti-JH action for the tobacco hornworm, Manduca sexta 4) and the silkworm, Bombyx mori, 5) depending on the dose applied; low doses of ETB induced precocious metamorphosis, a clear sign of JH deficiency, but at higher doses the precocious metamorphosis-inducing activity disappeared and instead, JH-like activity was observed. Riddiford et al have reported that ETB acts as a partial JH antagonist at the target tissue of the larval epidermis.…”