Resistance Mechanism for Resistance and Resistance Potential

Pimprikar and Georghiou (1979) were the first to report very high levels of resistance (> 1,000-fold) to diflubenzuron in a housefly population stressed with the compound. Since then, several research groups in different parts of the world have reported resistance to CSIs in Lepidoptera, Diptera, and whiteflies. In Southeast Asia, selection of diamondback moth, Plutella xylostella, from Thailand during six generations with chlorfluazuron and teflubenzuron resulted in resistance levels of...

Site of Action

Pyrethroids are recognized for their rapid knockdown action on insects but are generally poor at killing them, a fact not fully appreciated for many years. Measurements of LD50 are usually made 24 and 48 h after treatment, at which times paralyzed insects are regarded as dead. However, insects often recover fully, even at higher doses (e.g., 5 x LD50) (Bloomquist and Miller, 1985), over the following few days. In practice, such long-term recovery does not limit pyrethroid efficacy in the field,...

Symptoms of SCBI Poisoning in Insects Pseudoparalysis

Pyrazolines and indoxacarb produce identical acute neurotoxic symptoms in the American cockroach Periplaneta americana, progressing through initial incoordination 5-20 min after 1-10 mg injection , then tremors and prostration, and finally a distinctive pseudoparalysis, so named because the apparently paralyzed insects produce violent convulsions when disturbed. This pseudoparalysis was maintained for 3-4 days, after which the ability to move when disturbed waned. By 4-6 days, the insects could...

References

Abdelaal, Y.A.I., Soderlund, D.M., 1980. Pyrethroid-hydrolyzing esterases in southern armyworm larvae -tissue distribution, kinetic properties, and selective inhibition. Pestici. Biochem. Physiol. 14, 282-289. AbdElghafar, S.F., Knowles, C.O., 1996. Pharmacokinetics of fenvalerate in laboratory and field strains of Helicoverpa zea Lepidoptera Noctuidae . J. Econ. Entomol. 89, 590-593. Ahmad, M., McCaffery, A.R., 1999. Penetration and metabolism of trans-cypermethrin in a susceptible and a...

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Figure 7 Schematic diagram showing a yeast cell transformed with plasmids carrying cDNAs encoding ecdysone receptor, RXR-g, co-activator glucocorticoid receptor interaction protein GRIP , and b-galactosidase b-Gal reporter gene fused to 6 heat shock protein 27 hsp27 ecdysone response elements in a reconstituted and ecdysteroid muristerone A inducible high throughput screening system for discovery of new nonsteroidal ecdysone agonists. Figure 7 Schematic diagram showing a yeast cell transformed...

Resistance Mechanisms

Metabolism of pyrethroids in insects The principal metabolic pathways by which pyre-throids are degraded in insects were mostly evaluated prior to 1985 and are summarized in Roberts and Hutson 1999 . Metabolism is conveniently divided into two phases the initial biotransformation of a pesticide is referred to as Phase I metabolism, comprising mainly oxidative, reductive, and hydrolytic processes Phase II metabolism is biotransformation, in which the pesticide or Phase I metabolite...

Catabolism of Indoxacarb and Other Na Channel Blocker Insecticides

Relatively little is known about the metabolic breakdown of indoxacarb or other SCBIs in insects. On balance, it is clear that bioactivation is occurring much more rapidly than degradation after field application, when satisfactory insect control is observed. However, like any other novel insecticide, resistance management will be a key to maintaining the agricultural utility of this insecticide class. Indeed, several field populations of North American oblique-banded leafroller Choristoneura...

Development of Commercial Pyrethroids

Pyrethroids Structure

There are several reviews Elliott, 1977, 1995, 1996 Davies, 1985 Henrick, 1995 Pap et al., 1996a Matsuo and Miyamoto, 1997 Pachlatko, 1998 Bryant, 1999 Katsuda, 1999 Khambay, 2002 Soderlund et al., 2002 covering aspects of structure-activity relationships in pyrethroids. To appraise the advances made since 1985, it is useful to recollect the systematic approaches adopted earlier, in particular by Elliott, in the discovery of synthetic pyrethroids see Figure 1 for structures . The key to his...