Lena Brattsten - Academia.edu (original) (raw)
Papers by Lena Brattsten
Herbivores: Their Interactions with Secondary Plant Metabolites, 1992
Journal of Medical Entomology, 2014
An NADPH-cytochrome P450 reductase (CPR) gene was identiÞed in Aedes sollicitans Walker (Diptera:... more An NADPH-cytochrome P450 reductase (CPR) gene was identiÞed in Aedes sollicitans Walker (Diptera: Culicidae). The open reading frame is 2,040 bp long, encoding a 679-residue polypeptide. Amino acid sequence analysis indicates that the Ae. sollicitans CPR carries conserved ligand-binding domains and belongs to the same phylogenetic group as CPRs in other mosquitoes. The cDNA of the CPR gene was cloned, and the recombinant protein was expressed in Escherichia coli. Cytochrome c reductase activity was detected in the bacterial cytosolic and membrane fractions and in larval microsomes from two New Jersey Ae. sollicitans populations, indicating that the Ae. sollicitans CPR is enzymatically functional and closely related to that in other dipterans.
Journal of Economic Entomology, 1970
... Sylvester, ES 1954. ... tetrophthalmus (Forster) (red milkweed beetle) Clirculionidae, SCYPho... more ... Sylvester, ES 1954. ... tetrophthalmus (Forster) (red milkweed beetle) Clirculionidae, SCYPhoPhorus yuccae Hom Anthonomus eugenii Cano (pepper weevil) Rhynchites aeneus Boheman HYMOPTERA Ichneumonidae, CampoPlex haywardi Blanchard Braconidae, Orgilus ...
Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1973
An inhibitor of microsomal oxidation was isolated and partially purified from the soluble fractio... more An inhibitor of microsomal oxidation was isolated and partially purified from the soluble fraction of house cricket (Acheta domesticus) gut contents. 2. Inhibitory activity was greater towards armyworm gut microsomal enzymes than those from rat liver. 3. The material was characterized as a proteolytic enzyme with a molecular weight of approximately 16,500. 4. Proteolytic and inhibitory activity were blocked by Soy trypsin inhibitor and phenylmethanesulfonyl fluoride but not by p-chloromercuribenzoate or reduced glutathione. 5. Inhibition apparently results from solubilization of NADPH cytochrome e reductase from the microsomal membrane.
Journal of Economic Entomology, 1973
Molecular Aspects of Insect-Plant Associations, 1986
There has been a dramatic evolutionary shift in the polysaccharide composition of cell walls in t... more There has been a dramatic evolutionary shift in the polysaccharide composition of cell walls in the grasses, with increases in arabinoxylans and (1,3;1,4)-β-glucans and decreases in pectic polysaccharides, mannans, and xyloglucans, compared with other angiosperms. Several enzymes are involved in the biosynthesis of arabinoxylans, but the overall process is not yet defined and whether their increased abundance in grasses results from active or reactive evolutionary forces is not clear. Phylogenetic analyses reveal that multiple independent evolution of genes encoding (1,3;1,4)-β-glucan synthases has probably occurred within the large cellulose synthase/cellulose synthase-like (CesA/Csl) gene family of angiosperms. The (1,3;1,4)-β-glucan synthases appear to be capable of inserting both (1,3)-and (1,4)-β-linkages in the elongating polysaccharide chain, although the precise mechanism through which this is achieved remains unclear. Nevertheless, these enzymes probably evolved from synthases that originally synthesized only (1,4)-β-linkages. Initially, (1,3;1,4)-β-glucans could be turned over through preexisting cellulases, but as the need for specific hydrolysis was required, the grasses evolved specific (1,3;1,4)-β-glucan endohydrolases. The corresponding genes evolved from genes for the more widely distributed (1,3)-β-glucan endohydrolases. Why the subgroups of CesA/Csl genes that mediate the synthesis of (1,3;1,4)-β-glucans have been retained by the highly successful grasses but by few other angiosperms or lower plants represents an intriguing biological question. In this review, we address this important aspect of cell wall polysaccharide evolution in the grasses, with a particular focus on the enzymes involved in noncellulosic polysaccharide biosynthesis, hydrolysis, and modification.
Biochemical Journal, 1975
1. Activity of 5-aminolaevulinate synthetase was measured in the midgut and other tissues of the ... more 1. Activity of 5-aminolaevulinate synthetase was measured in the midgut and other tissues of the last larval instar of the southern armyworm (Spodoptera eridania Cramer, formerly Prodenia eridania Cramer). 2. Optimum conditions for measuring the activity were established with respect to all variables involved and considerable differences from those reported for mammalian enzyme preparations were found. 3. Maximum activity (20 nmol/h per mg of protein) occurs 18-24 h after the fifth moult and thereafter decreases to trace amounts as the larvae age and approach pupation. 4. Synthetase activity was rapidly induced by oral administration (in the diet) of pentamethylbenzene, phenobarbital, diethyl 1,4-dihydro-2,4,6-trimethylpyridine-3, 5-dicarboxylate, and 2-allyl-2-isopropylacetamide. 5. Puromycin inhibited the induction of synthetase by pentamethylbenzene. 6. Induction of 5-aminolaevulinate synthetase correlated well with the induction of microsomal N-demethylation of p-chloro-N-methyl...
Plant Resistance to Insects, 1983
The cytochrome P-450-dependent microsomal mono--oxygenase system is important in several ways in ... more The cytochrome P-450-dependent microsomal mono--oxygenase system is important in several ways in insect herbivores that feed on terpene-containing plants. Cytochrome P-450 metabolises many terpenes to polar products that can be excreted, often after further conjugation ...
Comparative Biochemistry and Physiology Part C: Comparative Pharmacology, 1984
Carrot foliage monoterpenes induce cytochrome P-450 up to 2.9-fold, NADPH cytochrome c (P-450) re... more Carrot foliage monoterpenes induce cytochrome P-450 up to 2.9-fold, NADPH cytochrome c (P-450) reductase up to 1.6-fold, NADPH-oxidation up to 3.8-fold, aldrin cpoxidation up to 1.5-fold in southern armyworm larval midgut tissues when incorporated in their diet at 0.2~/o for 3 days. 2. Stigmasterol and ergosterol did not substantially induce microsomal oxidase activities and significantly inhibited GSH S-aryltransferase activity and sulfotransferase activity. 3. Coumarin did not substantially affect microsomal oxidase and sulfotransferase activity but is the most potent inducer of GSH S-aryltransferase activity, increasing this activity 7-fold. 4. None of the chemicals is acutely toxic to the sixth instar larvae or affect the larval weight gain except coumarin which significantly depressed the maximal body weight attained.
The Quarterly Review of Biology, 1988
Science, 1977
Several commercial solvent mixtures commonly used as insecticide carriers in spray formulations i... more Several commercial solvent mixtures commonly used as insecticide carriers in spray formulations increase by more than threefold the microsomal N-demethylation of p-chloro N-methylaniline in midgut preparations of southern army-worm (Spodoptera eridania) larvae exposed orally to the test solvents. Under laboratory conditions, the same solvent mixtures exhibit a protective action against the in vivo toxicity of the insecticide carbaryl to the larvae. The data are discussed with respect to possible solvent-insecticide interactions occurring under field conditions and, more broadly, to potential toxicological hazards of these solvents to humans.
Pesticide Biochemistry and Physiology, 1986
ABSTRACT The mint monoterpene pulegone and one of its oxidation products, menthofuran, are 3.5–4 ... more ABSTRACT The mint monoterpene pulegone and one of its oxidation products, menthofuran, are 3.5–4 times more toxic, acutely, to southern armyworm, Spodoptera eridania (Cramer) than to fall armyworm, S. frugiperda (J. E. Smith) larvae. When the insects are exposed to these compounds in the diet, over an extended period of time, the reverse is true. The southern armyworm larvae have higher cytochrome P-450 content and activities in midgut and fatbody tissues than the fall armyworm larvae. Glutathione transferase activities are comparable in midgut tissues of the two species, but higher in fatbodies of the fall armyworm than of the southern. Pulegone induces cytochrome P-450 activities in both species including its own oxidation as indicated by pulegone-dependent NADPH oxidation. When the insects are stressed with pulegone or menthofuran as in the present study, the observed differences in metabolic activities in the two species may be factors influencing the observed acute and chronic toxicities in each case.
Pesticide Biochemistry and Physiology, 1986
ABSTRACT Larvae of the southern armyworm, Spodoptera eridania (Cramer), grew well in the 15–30°C ... more ABSTRACT Larvae of the southern armyworm, Spodoptera eridania (Cramer), grew well in the 15–30°C temperature range. Pupae survived poorly at 15°C but moths emerged from 85% of the pupae at 30°C. The time for development was prolonged at 15°C and larvae grew significantly bigger than at 30°C. Cytochrome P-450 content, cytochrome P-450 reductase, p-chloro N-methylaniline N-demethylation, methoxyresorufin 0-demethylation, and aldrin epoxidation activities were higher at 15°C than at 30°C. All cytochrome P-450 activities were more inducible by dietary pentamethylbenzene at 30°C than at 15°C. High cytochrome P-450-catalyzed activities were associated with increases in microsomal protein rather than with changes in membrane lipid or phospholipid content. Phosphatidylcholine was the major midgut membrane phospholipid. There was only a tendency towards increased unsaturation of the phospholipid fatty acyl moieties and lowered membrane phase transition temperature in cold-adapted larvae. Acute oral carbaryl toxicity was generally inversely correlated with cytochrome P-450 catalyzed activities. Carbaryl toxicity was decreased about 10-fold by pentamethylbenzene induction and about 3-fold by the lower acclimatization temperature.
Pesticide Biochemistry and Physiology, 1973
Abstract Levels of microsomal epoxidation, N-demethylation, and cytochrome P-450 in the gut tissu... more Abstract Levels of microsomal epoxidation, N-demethylation, and cytochrome P-450 in the gut tissues of sixth instar southern armyworm larvae were considerably enhanced following oral in vivo treatment with a series of methylbenzenes. Induction increased with increasing methyl substitution and was maximal with pentamethylbenzene. The increase in microsomal activity occurred rapidly after initiation of treatment and the final levels of induction achieved were dependent on the concentration of the inducer in the diet and the time of exposure. Microsomal enzyme activity returned to control levels following termination of exposure and induction was blocked by puromycin and cycloheximide but not by actinomycin D. The in vivo tolerance of induced worms to orally administered carbaryl was increased in a manner reflecting the enhanced microsomal enzyme activity.
Pesticide Biochemistry and Physiology, 2001
Cytochrome P450 monooxygenase (P450)-mediated metabolism is an important mechanism by which insec... more Cytochrome P450 monooxygenase (P450)-mediated metabolism is an important mechanism by which insects detoxify insecticides. In this report, a major contribution of P450s as a mechanism of insecticide detoxification was demonstrated by the effect of herbicides and fungicides and the synergist piperonyl butoxide on carbaryl toxicity and P450 activities in the mosquito Aedes albopictus. Mosquito larvae preexposed to technical and analytical grade pentachlorophenol (PCP T , PCP A) showed significant increases of survival from carbaryl toxicity. This phenomenon was reversed when piperonyl butoxide was also applied. Microsomes from PCP T-and PCP A-treated larvae showed higher levels of N-demethylation of p-chloro-N-methylaniline than those from control larvae. Microsomes from larvae treated with PCP T also yielded a very high level of O-demethylation of methoxyresorufin. However, peroxidation of tetramethylbenzidine was decreased in both treated groups. This suggests that PCP may induce certain P450 isozymes but suppress others. SDS-PAGE bands corresponding to the molecular weights of 61 and 63 kDa presented strong intensity in the treated microsomes; these may represent P450s induced by PCP. P450s in the mosquito larvae are active, inducible, and capable of detoxifying the insecticide carbaryl.
Pest Management Science, 2001
In vivo toxicity assays have shown that organophosphate insecticides are less toxic to male than ... more In vivo toxicity assays have shown that organophosphate insecticides are less toxic to male than to female Oriental fruit moths Grapholita molesta. While male moths have higher levels of acetylcholinesterase and general esterase activities, female moth acetylcholinesterase enzymes are less sensitive to aromatic and aliphatic organophosphates than male enzymes. Elevated esterase and acetylcholinesterase activities in male moths explain their greater tolerance to aromatic and aliphatic organophosphates. Male and female acetylcholinesterase enzymes are equally tolerant to heteroaromatic organophosphates, the most widely used of this class of insecticides in G molesta control. This observation, in contrast to the greater sensitivity of male acetylcholinesterases to aromatic and aliphatic organophosphates, shows the potential for the evolution of insensitive target sites in male moths, which would increase male G molesta tolerance to these insecticides. Significant sex-linked differences in insecticide tolerance have not been reported previously in lepidopterans. The practical implications of the observed differences in tolerance in male and female G molesta question the practice of using pheromone traps to monitor populations of these moths in orchards.
Pesticide Science, 1989
This introductory paper to the Rutgers Symposium outlines the background of the development of re... more This introductory paper to the Rutgers Symposium outlines the background of the development of resistance to insecticides and discusses various aspects of the problem in the context of modern agrochemical practice. Resistance can only be countered by properly mounted management programmes, but the successful design and implementation of these requires a thorough understanding of the fundamental processes involved, and the importance of continuing research into these is stressed.
Herbivores: Their Interactions with Secondary Plant Metabolites, 1992
Journal of Medical Entomology, 2014
An NADPH-cytochrome P450 reductase (CPR) gene was identiÞed in Aedes sollicitans Walker (Diptera:... more An NADPH-cytochrome P450 reductase (CPR) gene was identiÞed in Aedes sollicitans Walker (Diptera: Culicidae). The open reading frame is 2,040 bp long, encoding a 679-residue polypeptide. Amino acid sequence analysis indicates that the Ae. sollicitans CPR carries conserved ligand-binding domains and belongs to the same phylogenetic group as CPRs in other mosquitoes. The cDNA of the CPR gene was cloned, and the recombinant protein was expressed in Escherichia coli. Cytochrome c reductase activity was detected in the bacterial cytosolic and membrane fractions and in larval microsomes from two New Jersey Ae. sollicitans populations, indicating that the Ae. sollicitans CPR is enzymatically functional and closely related to that in other dipterans.
Journal of Economic Entomology, 1970
... Sylvester, ES 1954. ... tetrophthalmus (Forster) (red milkweed beetle) Clirculionidae, SCYPho... more ... Sylvester, ES 1954. ... tetrophthalmus (Forster) (red milkweed beetle) Clirculionidae, SCYPhoPhorus yuccae Hom Anthonomus eugenii Cano (pepper weevil) Rhynchites aeneus Boheman HYMOPTERA Ichneumonidae, CampoPlex haywardi Blanchard Braconidae, Orgilus ...
Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1973
An inhibitor of microsomal oxidation was isolated and partially purified from the soluble fractio... more An inhibitor of microsomal oxidation was isolated and partially purified from the soluble fraction of house cricket (Acheta domesticus) gut contents. 2. Inhibitory activity was greater towards armyworm gut microsomal enzymes than those from rat liver. 3. The material was characterized as a proteolytic enzyme with a molecular weight of approximately 16,500. 4. Proteolytic and inhibitory activity were blocked by Soy trypsin inhibitor and phenylmethanesulfonyl fluoride but not by p-chloromercuribenzoate or reduced glutathione. 5. Inhibition apparently results from solubilization of NADPH cytochrome e reductase from the microsomal membrane.
Journal of Economic Entomology, 1973
Molecular Aspects of Insect-Plant Associations, 1986
There has been a dramatic evolutionary shift in the polysaccharide composition of cell walls in t... more There has been a dramatic evolutionary shift in the polysaccharide composition of cell walls in the grasses, with increases in arabinoxylans and (1,3;1,4)-β-glucans and decreases in pectic polysaccharides, mannans, and xyloglucans, compared with other angiosperms. Several enzymes are involved in the biosynthesis of arabinoxylans, but the overall process is not yet defined and whether their increased abundance in grasses results from active or reactive evolutionary forces is not clear. Phylogenetic analyses reveal that multiple independent evolution of genes encoding (1,3;1,4)-β-glucan synthases has probably occurred within the large cellulose synthase/cellulose synthase-like (CesA/Csl) gene family of angiosperms. The (1,3;1,4)-β-glucan synthases appear to be capable of inserting both (1,3)-and (1,4)-β-linkages in the elongating polysaccharide chain, although the precise mechanism through which this is achieved remains unclear. Nevertheless, these enzymes probably evolved from synthases that originally synthesized only (1,4)-β-linkages. Initially, (1,3;1,4)-β-glucans could be turned over through preexisting cellulases, but as the need for specific hydrolysis was required, the grasses evolved specific (1,3;1,4)-β-glucan endohydrolases. The corresponding genes evolved from genes for the more widely distributed (1,3)-β-glucan endohydrolases. Why the subgroups of CesA/Csl genes that mediate the synthesis of (1,3;1,4)-β-glucans have been retained by the highly successful grasses but by few other angiosperms or lower plants represents an intriguing biological question. In this review, we address this important aspect of cell wall polysaccharide evolution in the grasses, with a particular focus on the enzymes involved in noncellulosic polysaccharide biosynthesis, hydrolysis, and modification.
Biochemical Journal, 1975
1. Activity of 5-aminolaevulinate synthetase was measured in the midgut and other tissues of the ... more 1. Activity of 5-aminolaevulinate synthetase was measured in the midgut and other tissues of the last larval instar of the southern armyworm (Spodoptera eridania Cramer, formerly Prodenia eridania Cramer). 2. Optimum conditions for measuring the activity were established with respect to all variables involved and considerable differences from those reported for mammalian enzyme preparations were found. 3. Maximum activity (20 nmol/h per mg of protein) occurs 18-24 h after the fifth moult and thereafter decreases to trace amounts as the larvae age and approach pupation. 4. Synthetase activity was rapidly induced by oral administration (in the diet) of pentamethylbenzene, phenobarbital, diethyl 1,4-dihydro-2,4,6-trimethylpyridine-3, 5-dicarboxylate, and 2-allyl-2-isopropylacetamide. 5. Puromycin inhibited the induction of synthetase by pentamethylbenzene. 6. Induction of 5-aminolaevulinate synthetase correlated well with the induction of microsomal N-demethylation of p-chloro-N-methyl...
Plant Resistance to Insects, 1983
The cytochrome P-450-dependent microsomal mono--oxygenase system is important in several ways in ... more The cytochrome P-450-dependent microsomal mono--oxygenase system is important in several ways in insect herbivores that feed on terpene-containing plants. Cytochrome P-450 metabolises many terpenes to polar products that can be excreted, often after further conjugation ...
Comparative Biochemistry and Physiology Part C: Comparative Pharmacology, 1984
Carrot foliage monoterpenes induce cytochrome P-450 up to 2.9-fold, NADPH cytochrome c (P-450) re... more Carrot foliage monoterpenes induce cytochrome P-450 up to 2.9-fold, NADPH cytochrome c (P-450) reductase up to 1.6-fold, NADPH-oxidation up to 3.8-fold, aldrin cpoxidation up to 1.5-fold in southern armyworm larval midgut tissues when incorporated in their diet at 0.2~/o for 3 days. 2. Stigmasterol and ergosterol did not substantially induce microsomal oxidase activities and significantly inhibited GSH S-aryltransferase activity and sulfotransferase activity. 3. Coumarin did not substantially affect microsomal oxidase and sulfotransferase activity but is the most potent inducer of GSH S-aryltransferase activity, increasing this activity 7-fold. 4. None of the chemicals is acutely toxic to the sixth instar larvae or affect the larval weight gain except coumarin which significantly depressed the maximal body weight attained.
The Quarterly Review of Biology, 1988
Science, 1977
Several commercial solvent mixtures commonly used as insecticide carriers in spray formulations i... more Several commercial solvent mixtures commonly used as insecticide carriers in spray formulations increase by more than threefold the microsomal N-demethylation of p-chloro N-methylaniline in midgut preparations of southern army-worm (Spodoptera eridania) larvae exposed orally to the test solvents. Under laboratory conditions, the same solvent mixtures exhibit a protective action against the in vivo toxicity of the insecticide carbaryl to the larvae. The data are discussed with respect to possible solvent-insecticide interactions occurring under field conditions and, more broadly, to potential toxicological hazards of these solvents to humans.
Pesticide Biochemistry and Physiology, 1986
ABSTRACT The mint monoterpene pulegone and one of its oxidation products, menthofuran, are 3.5–4 ... more ABSTRACT The mint monoterpene pulegone and one of its oxidation products, menthofuran, are 3.5–4 times more toxic, acutely, to southern armyworm, Spodoptera eridania (Cramer) than to fall armyworm, S. frugiperda (J. E. Smith) larvae. When the insects are exposed to these compounds in the diet, over an extended period of time, the reverse is true. The southern armyworm larvae have higher cytochrome P-450 content and activities in midgut and fatbody tissues than the fall armyworm larvae. Glutathione transferase activities are comparable in midgut tissues of the two species, but higher in fatbodies of the fall armyworm than of the southern. Pulegone induces cytochrome P-450 activities in both species including its own oxidation as indicated by pulegone-dependent NADPH oxidation. When the insects are stressed with pulegone or menthofuran as in the present study, the observed differences in metabolic activities in the two species may be factors influencing the observed acute and chronic toxicities in each case.
Pesticide Biochemistry and Physiology, 1986
ABSTRACT Larvae of the southern armyworm, Spodoptera eridania (Cramer), grew well in the 15–30°C ... more ABSTRACT Larvae of the southern armyworm, Spodoptera eridania (Cramer), grew well in the 15–30°C temperature range. Pupae survived poorly at 15°C but moths emerged from 85% of the pupae at 30°C. The time for development was prolonged at 15°C and larvae grew significantly bigger than at 30°C. Cytochrome P-450 content, cytochrome P-450 reductase, p-chloro N-methylaniline N-demethylation, methoxyresorufin 0-demethylation, and aldrin epoxidation activities were higher at 15°C than at 30°C. All cytochrome P-450 activities were more inducible by dietary pentamethylbenzene at 30°C than at 15°C. High cytochrome P-450-catalyzed activities were associated with increases in microsomal protein rather than with changes in membrane lipid or phospholipid content. Phosphatidylcholine was the major midgut membrane phospholipid. There was only a tendency towards increased unsaturation of the phospholipid fatty acyl moieties and lowered membrane phase transition temperature in cold-adapted larvae. Acute oral carbaryl toxicity was generally inversely correlated with cytochrome P-450 catalyzed activities. Carbaryl toxicity was decreased about 10-fold by pentamethylbenzene induction and about 3-fold by the lower acclimatization temperature.
Pesticide Biochemistry and Physiology, 1973
Abstract Levels of microsomal epoxidation, N-demethylation, and cytochrome P-450 in the gut tissu... more Abstract Levels of microsomal epoxidation, N-demethylation, and cytochrome P-450 in the gut tissues of sixth instar southern armyworm larvae were considerably enhanced following oral in vivo treatment with a series of methylbenzenes. Induction increased with increasing methyl substitution and was maximal with pentamethylbenzene. The increase in microsomal activity occurred rapidly after initiation of treatment and the final levels of induction achieved were dependent on the concentration of the inducer in the diet and the time of exposure. Microsomal enzyme activity returned to control levels following termination of exposure and induction was blocked by puromycin and cycloheximide but not by actinomycin D. The in vivo tolerance of induced worms to orally administered carbaryl was increased in a manner reflecting the enhanced microsomal enzyme activity.
Pesticide Biochemistry and Physiology, 2001
Cytochrome P450 monooxygenase (P450)-mediated metabolism is an important mechanism by which insec... more Cytochrome P450 monooxygenase (P450)-mediated metabolism is an important mechanism by which insects detoxify insecticides. In this report, a major contribution of P450s as a mechanism of insecticide detoxification was demonstrated by the effect of herbicides and fungicides and the synergist piperonyl butoxide on carbaryl toxicity and P450 activities in the mosquito Aedes albopictus. Mosquito larvae preexposed to technical and analytical grade pentachlorophenol (PCP T , PCP A) showed significant increases of survival from carbaryl toxicity. This phenomenon was reversed when piperonyl butoxide was also applied. Microsomes from PCP T-and PCP A-treated larvae showed higher levels of N-demethylation of p-chloro-N-methylaniline than those from control larvae. Microsomes from larvae treated with PCP T also yielded a very high level of O-demethylation of methoxyresorufin. However, peroxidation of tetramethylbenzidine was decreased in both treated groups. This suggests that PCP may induce certain P450 isozymes but suppress others. SDS-PAGE bands corresponding to the molecular weights of 61 and 63 kDa presented strong intensity in the treated microsomes; these may represent P450s induced by PCP. P450s in the mosquito larvae are active, inducible, and capable of detoxifying the insecticide carbaryl.
Pest Management Science, 2001
In vivo toxicity assays have shown that organophosphate insecticides are less toxic to male than ... more In vivo toxicity assays have shown that organophosphate insecticides are less toxic to male than to female Oriental fruit moths Grapholita molesta. While male moths have higher levels of acetylcholinesterase and general esterase activities, female moth acetylcholinesterase enzymes are less sensitive to aromatic and aliphatic organophosphates than male enzymes. Elevated esterase and acetylcholinesterase activities in male moths explain their greater tolerance to aromatic and aliphatic organophosphates. Male and female acetylcholinesterase enzymes are equally tolerant to heteroaromatic organophosphates, the most widely used of this class of insecticides in G molesta control. This observation, in contrast to the greater sensitivity of male acetylcholinesterases to aromatic and aliphatic organophosphates, shows the potential for the evolution of insensitive target sites in male moths, which would increase male G molesta tolerance to these insecticides. Significant sex-linked differences in insecticide tolerance have not been reported previously in lepidopterans. The practical implications of the observed differences in tolerance in male and female G molesta question the practice of using pheromone traps to monitor populations of these moths in orchards.
Pesticide Science, 1989
This introductory paper to the Rutgers Symposium outlines the background of the development of re... more This introductory paper to the Rutgers Symposium outlines the background of the development of resistance to insecticides and discusses various aspects of the problem in the context of modern agrochemical practice. Resistance can only be countered by properly mounted management programmes, but the successful design and implementation of these requires a thorough understanding of the fundamental processes involved, and the importance of continuing research into these is stressed.