Induction of detoxification enzymes in phytophagous insects: Role of insecticide synergists, larval age, and species

Abstract

Five insecticide synergists, all of which were either methylenedioxyphenyl compounds or analogs, were compared as to their effect on cytochrome P450 monooxygenase induction caused by an allelochemical in fall armyworm larvae. Feeding the synergists (piperonyl butoxide, safrole, isosafrole, MCK 264, and myristicin) individually to the larvae caused decreases in the microsomal aldrin epoxidase activities ranging from 38% to 74% when compared with controls. Feeding indole-3-carbinol resulted in a 4-fold increase in the rnicrosomal epoxidase activity. However, cotreatment of any of the synergists and the inducer completely eliminated the induction. Sixth instar larvae were more inducible than second instar larvae with respect to microsomal epoxidase and glutathione transferase in the fall armyworm. Enzyme inducibility varied widely among the seven phytophagous Lepidoptera examined. When indole-3-carbinol was used as an inducer of microsomal epoxidase, the extent of inducibility of the enzyme was fall armyworm > velvetbean caterpillar > corn earworm > beet armyworm > tobacco budworm > cabbage looper > diamondback moth. When indole-3-acetonitrile was used as an inducer, the inducibility of glutathione transferase was fall armyworm > beet armyworm > corn earworm > cabbage looper > velvetbean caterpillar > tobacco budworm > diamondback moth. lnducibilityoffive microsomal oxidase systems also varied considerably in the corn earworm, indicating the multiplicity of cytochrome P450 in this species. Microsomal epoxidase and glutathione transferase were induced by cruciferous host plants such as cabbage and their allelochemicals in diamondback moth larvae. o 1993 WiIey-Liss, Inr

Phytochemical Study and Bioinsecticidal Effect of the Crude Ethonolic Extract of the Algerian Plant Artemisia Judaica L. (Asteraceae) Against the Black Bean Aphid, Aphis Fabae Scop.

“…GST play a pivotal role in detoxification and antioxidant defense of insects against natural and synthetic exogenous xenobiotics including insecticides, allelochemicals and endogenously activated compounds (Papadopoulos et al, 2004). GSTs catalyse the addition of a tripeptide glutathione to a wide variety of electrophilic substrates including host plant secondary compounds (Yu and Hsu, 1993). In our study, the GST activity in A. fabae was significantly stimulated by the low dose of the crude ethanolic extract of A. judaica.…”

Induction of Glutathione S-transferase Activity in Triatoma infestans

“…The high GST activity found in insecticide resistance in insects was associated with increased level of specific mRNA (Yu 1996). The microsomal epoxidase and GST in Lepidoptera (Diamondblack moth larvae) were induced by cruciferous host plants such as cabbage and their allelochemicals (Yu 1993). Furthermore, three Lepidoptera species were able to metabolize benzylthiocyanate (allelochemical) using larvae midgut soluble fraction as the enzyme source of GST and this enzyme activity was inducible by dietary indole 3-carbinol (I-3-C) (found in cruciferous vegetables), indole-3-acetonitrile (I-3-A), flavone and xanthotoxin (Wadleigh 1988).…”

“…In insects GST have been induced and is becoming recognized for their importance in the metabolic detoxication of insecticides (Yu 1996), of allelochemicals from host plants (Yu 1993, Wadleigh 1988, in protecting insects from the toxic effects of active oxygen species (Ahmad & Pardini 1990, Parkes et al 1993, Zaman et al 1994, Hodnick et al 1996 and for the practical role of GST induction in turning on the detoxifying enzymes enhancing the defense machinery, speeding the development of resistance and causing cross-tolerance to other pesticides (Anspauch et al 1994, Hinkle et al 1995, Carlini et al 1995.…”

How do herbivorous insects cope with noxious secondary plant compounds in their diet?

“…Herbivorous insects can override their aversive response to toxic plant secondary compounds through the induction of detoxication enzymes in their midgut (Brattsten et al, 1977;Yu & Hsu, 1993;Zangerl & Berenbaum, 1993;Glendinning & Slansky, 1995). For example, nicotine is an abundant secondary plant compound in tobacco (Nicotiana spp.…”