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At least 667 records · Page 37Linked to original sources
PubMed2003

Incidence of insecticide resistance alleles in sexually-reproducing populations of the peach-potato aphid Myzus persicae (Hemiptera: Aphididae) from southern France.

Intensive chemical treatments have led to the development of a number of insecticide resistance mechanisms in the peach-potato aphid Myzus persicae (Sulzer). Some of these mechanisms are known to be associated with negative pleiotropic effects (resistance costs). Molecular and biochemical methods were used to determine the genotypes or phenotypes associated with four insecticide resistance mechanisms in single aphids from sexually-reproducing populations in southern France. The mechanisms considered were E4 and FE4 carboxylesterase overproduction, modified acetycholinesterase, and kdr and rdl resistance-associated mutations. A new method for determining individual kdr genotypes is presented. Almost all resistant individuals overproduced FE4 carboxylesterase, whereas modified acetylcholinesterase was rare. Both the kdr and rdl resistance mutations were present at high frequencies in French sexually-reproducing populations. The frequencies of insecticide resistance genes were compared before and after sexual reproduction in one peach orchard at Avignon to evaluate the potential impact of selection on the persistence of resistance alleles in the over-wintering phase. The frequencies of the kdr and rdl mutations varied significantly between autumn and spring sampling periods. The frequency of the kdr mutation increased, probably due to pyrethroid treatments at the end of the winter. Conversely, the frequency of the rdl mutation decreased significantly during winter, probably because of a fitness cost associated with this mutation.

Acetylcholinesterase↗
PubMed2005

Molecular and biochemical characterization of a sand fly population from Sri Lanka: evidence for insecticide resistance due to altered esterases and insensitive acetylcholinesterase.

With an increasing incidence of cutaneous leishmaniasis in Sri Lanka, particularly in northern provinces, insecticide-mediated vector control is under consideration. Optimizing such a strategy requires the characterization of sand fly populations in target areas with regard to species composition and extant resistance, among other parameters. Sand flies were collected by human bait and cattle-baited net traps on Delft Island, used as an illegal transit location by many refugees returning to the north of Sri Lanka from southern India where leishmaniasis is endemic. For species identification, genomic DNA was extracted and a fragment of the ribosomal 18S gene amplified. The sequence from all flies analysed matched that of Phlebotomus argentipes Annandale & Brunetti, the primary vector in India and the most likely vector in Sri Lanka. Independent morphological analysis also identified P. argentipes. To establish the current susceptibility status of vector species, data were obtained at the biochemical level, from which potential cross-resistance to alternative insecticides can be predicted. The Delft Island collection was assayed for the activities of four enzyme systems involved in insecticide resistance (acetylcholinesterase, non-specific carboxylesterases, glutathione-S-transferases and cytochrome p450 monooxygenases), establishing baselines against which subsequent collections can be evaluated. There was preliminary evidence for elevated esterases and altered acetylcholinesterase in this population, the first report of these resistance mechanisms in sand flies to our knowledge, which probably arose from the malathion-based spraying regimes of the Anti-Malarial Campaign.

Acetylcholinesterase↗
PubMed2005

The attack of the clones: tracking the movement of insecticide-resistant peach-potato aphids Myzus persicae (Hemiptera: Aphididae).

Myzus persicae (Sulzer) collected in Scotland were characterized for four microsatellite loci, intergenic spacer fingerprints and the resistance mechanisms modified acetylcholinesterase (MACE), overproduced carboxylesterase and knockdown resistance (kdr). Microsatellite polymorphisms were used to define a limited number of clones that were either fully susceptible to insecticides or possessed characteristic combinations of resistance mechanisms. Within these clones, intergenic spacer fingerprints could either be very consistent or variable, with the latter indicating ongoing evolution within lineages, most likely derived from the same zygote. Two clones (termed A and B) possessed all three resistance mechanisms and predominated at sites treated with insecticides. Their appearance on seed potatoes and oilseed rape in Scotland in 2001 coincided with extensive insecticide use and severe control failures. Clones C, I and J, with no or fewer resistance mechanisms, were found in samples from 1995 and were dominant at untreated sites in 2001. A comparison of Scottish collections with those from other UK and non-UK sites provides insight into the likely origins, distribution and dynamics of M. persicae clones in a region where asexual (anholocyclic) reproduction predominates, but is vulnerable to migration by novel genotypes from areas of Europe where sexual (holocyclic) reproduction occurs.

Animals↗
PubMed2005

Insecticide resistance in German cockroaches (Blattella germanica) from hospitals and households in Taiwan.

Since a high percentage of cockroach infestation has been determined in hospitals in Kaohsiung, South Taiwan, insecticide resistances may have developed in the cockroach populations. To determine the resistances in cohorts of German cockroach (Blattella germanica) from hospitals and households to organophosphates, carbamates and pyrethroids, cockroaches were trapped from 30 hospitals and 30 households in this area. Bioassays by topical application were then carried out on the first generation bred in the laboratory. Resistance ratio (RR) was determined by comparing the LD50 of the collected cohorts with that of a susceptible cohort. RR ranges of chlorpyrifos, propoxur and cypermethrin in the hospitals were 2.04 - 28.80, 2.86 - 30.86 and 1.95 - 14.05 and those in the household were 1.92 - 17.72, 6.93 - 62.50 and 2.80 - 27.35 respectively. Significant correlations among the RRs of the three insecticides were separately found in the hospitals and households, indicating the existence of cross resistance among the three groups of insecticides. The patterns of propoxur > chlorpyrifos > cypermethrin in hospitals and propoxur > cypermethrin > chlorpyrifos in households reflect that chlorpyrifos is more frequently used in hospitals than in households. In contrast, cypermethrin is used more frequently in households.

Animals↗
PubMed1991

Studies on the resistance to various insecticides of a house fly strain (Diptera: Muscidae) selected with azamethiphos.

A colony of azamethiphos-resistant house flies, Musca domestica (L.), was obtained from Denmark and further selected in the laboratory with azamethiphos for four generations. LD50s for various insecticides were determined and compared with those of a susceptible house fly strain. The selected flies showed cross-resistance to all insecticides evaluated. The flies were highly resistant to most organophosphorus, carbamate, and chlorinated hydrocarbon insecticides except prothiophos, p,p'-DDT, and the pyrethroids. We conclude that the main mechanisms responsible for resistance are presumed to be factors other than acetylcholinesterase sensitivity and nerve sensitivity due to knockdown resistance.

Animals↗
PubMed1993

Relationship between insecticide resistance and performance in choice tests of field-collected German cockroaches (Dictyoptera: Blattellidae).

Topical application (LD) and time-mortality response (LT) methods were used to determine resistance levels of field-collected strains of the German cockroach, Blattella germanica (L.). LD50s for chlorpyrifos were determined for seven strains. LT50s and LT90s with eight insecticides were determined for another three strains. Resistance ratios (RR) of > 10 to chlorpyrifos (LD50) were directly related to a significant decrease in activity in Ebeling choice-box tests. Using the LT method, the three field-collected strains were shown to possess zero to moderate resistance at the RR50 level (0.9-5.3) to organophosphates, moderate to high resistance to (1.4->21.0) to carbamates, moderate to high resistance (4.3-20) to cypermethrin, and high resistance (>17->35) to synergized pyrethrins. When the three field-collected strains were tested in choice boxes, RR50S of 1.2-2.2 for chlorpyrifos and 2.5-5.3 for diazinon directly related to significantly lower efficacy. Low-level propoxur resistance (RR50 of 1.4-2.3) also reduced choice-box efficacy, but an RR50 of 0.9-1.3 for acephate did not reduce its performance. Cypermethrin deposits used in choice tests killed cockroaches exhibiting RR50s as high as 20 in the lethal time test, perhaps because resistance mechanisms could not detoxify the exceptional activity of the active ingredient formulated as a wettable powder. Because they were repellent, residual deposits of pyrethrins resulted in poor efficacy in choice tests with either susceptible or field-collected strains. Strains with low-level physiological resistance as measured by the time-mortality response method survived insecticide exposure in choice-box tests to certain organophosphate and carbamate insecticides, indicating that these compounds would not be effective in the field.

Animals↗
PubMed2000

Development of diagnostic concentrations for insecticide resistance monitoring in soybean looper (Lepidoptera: Noctuidae) larvae using an artificial diet overlay bioassay.

Diagnostic concentrations for several standard and experimental insecticides were determined for a laboratory reference strain of soybean looper, Pseudoplusia includens (Walker), using an insecticide diet overlay bioassay to evaluate the relative susceptibility of field (P) and F1 generations of four field-collected strains of third-, fourth-, and fifth-instar soybean loopers in 1996 and 1997. Diagnostic concentrations were defined as concentrations that killed 90-95% of the susceptible individuals and were 5 ppm for permethrin, 1,300 ppm for thiodicarb, 60 ppm for chlorfenapyr, 5 ppm for emamectin benzoate, and 60 ppm for spinosad. Field strains exhibited significantly greater percentage survival than the laboratory reference strain in the permethrin bioassays in 1996 and 1997 in both the P and F1 generation bioassays and in the thiodicarb bioassays in 1997. Larvae exposed to diagnostic concentrations of the experimental insecticides chlorfenapyr, emamectin benzoate, and spinosad usually did not exhibit significantly higher percentage survival than the reference strain.

Animals↗
PubMed2002

Genetic basis of cross-resistance to three organophosphate insecticides in Drosophila melanogaster (Diptera: Drosophilidae).

To investigate the genetic basis of cross-resistance to insecticides, we conducted genetic analyses of resistance to three organophosphate insecticides, malathion, prothiophos, and fenitrothion. After isofemale lines resistant and susceptible to all of the three organophosphates had been screened from natural populations of Drosophila melanogaster (Meigen), chromosomal analyses were performed by using chromosome-substituted lines between the resistant and the susceptible lines. The chromosomal analyses revealed that both the second and the third chromosomes contributed to resistance to the organophosphates, suggesting that this resistant line possessed at least two factors for organophosphate resistance. However, the relative contribution of each chromosome was different in resistance to different organophosphates. We further carried out genetic mapping of a resistance factor for each organophosphate on each of the two chromosomes. Each resistance factor was mapped to the position of each chromosome, about II-62 and III-50. Results of the chromosomal analyses and the genetic mapping revealed that at least two resistance factors exhibiting different patterns of cross-resistance to the organophosphates existed within a natural population of D. melanogaster. Based on this research, genetic variation in insecticide resistance within natural populations and complex as well as simple aspects of the mechanism of cross-resistance are discussed.

Animals↗
PubMed2003

Residual susceptibility of the red imported fire ant (Hymenoptera: Formicidae) to four agricultural insecticides.

The red imported fire ant, Solenopsis invicta Buren, is an abundant predator in cropping systems throughout its range. It has been documented to be an important predator of numerous crop pests, as well as being an agricultural pest itself. Information on the impact of insecticides on natural enemies such as fire ants is necessary for the integration of biological and chemical control tactics in an effective pest management program. Therefore, a residual vial bioassay was developed to determine the concentration-mortality responses of S. invicta workers to four commonly used insecticides: acephate, chlorpyrifos, methomyl and lambda-cyhalothrin. Fire ant workers showed a mortality response to serial dilutions to all four chemicals. Methomyl (LC50 0.04 microg/vial, fiducial limits 0.03-0.06) was the most toxic, followed by chlorpyrifos (LC50 0.11 microg/vial, fiducial limits 0.07-0.17) and acephate (LC50 0.76 microg/vial, fiducial limits 0.50-1.04). Of the chemicals assayed, it took a much higher concentration of lambda-cyhalothrin (LC50 2.30 microg/vial, fiducial limits 1.57-3.59) to kill 50% of the workers compared with the other three chemicals. The results of this study demonstrate the wide range in responses of fire ants to four insecticides that are labeled and commonly used on numerous agricultural crops throughout the United States. These results further suggest the possibility of using a discriminating dose of lambda-cyhalothrin to control the target pest species while conserving fire ants in the agricultural systems in which their predatory behavior is beneficial to the integrated pest management program.

Animals↗
PubMed2005

Local variation in susceptibility of Colorado potato beetle (Coleoptera: Chrysomelidae) to insecticide.

The susceptibility status of Colorado potato beetle, Leptinotarsa decemlineata (Say), adults to phosalone was determined by dip and glass jar assay techniques. Bioassay results indicated a narrow variation in Colorado potato beetle insecticide susceptibility among sample sites. LC50 values were generally highest from specimens collected in field that received frequent phosalone applications for seven consecutive growing seasons. In five populations tested, LC50 values ranged from 503.72 to 827.95 ppm in dip test method. In glass jar technique, resistance ratio value of 1.72 for LC50 was obtained. A significant linear relationship between LC50 values of individual populations across test methods was detected. Both bioassay techniques were suitable for monitoring resistance to insecticide in Colorado potato beetle adult populations. Glass jar technique, however, exhibited less variability in LC50 estimates and showed a higher degree of sensitivity than the dip method. Filter paper and leaf disk techniques for larvae were two bioassay methods used to determine phosalone susceptibility in L. decemlineata populations. Both bioassay techniques exhibited a similar level of susceptibility of the larvae to phosalone; however, the fiducial limit values from filter paper method were narrow than the leaf disk assay technique. A significant direct relationship between LC50 values of individual population across test methods was observed. Differences in LC50 ranking among fields between adults and larvae indicated a differential susceptibility to insecticide between life stages. Low LC50 values obtained from Colorado potato beetle in sample sites indicated that phosalone resistance was not severe in these fields. The glass jar and filter paper testing methods are simple and sensitive test techniques for measuring susceptibility of Colorado potato beetle adults and larvae to phosalone, respectively.

Animals↗
PubMed2005

Comparative susceptibility of western corn rootworm (Coleoptera: Chrysomelidae) adults to selected insecticides in Kansas.

Susceptibility of adult populations of the western corn rootworm, Diabrotica virgifera virgifera LeConte, to several insecticides was evaluated in seven Kansas counties, including Dickinson, Ford, Finney, Pottawatomie, Republic, Riley, and Stevens, between 1996 and 2002. All populations surveyed were highly susceptible to methyl parathion with the largest difference in susceptibility of only three-fold based on 16 complete bioassays for the populations from six counties over a 5-yr period. Noticeable decreases in carbaryl susceptibility were found in populations collected from Republic County between 1997 and 2001 when the cucurbitacin-carbaryl-based bait SLAM was widely used as an areawide management approach for adult corn rootworm control. However, the lowered carbaryl susceptibility returned to previous levels 1 yr after the use of SLAM was halted in the managed (treated) cornfields. This change implies possible dispersal of insects into the relatively small managed area from surrounding untreated cornfields and / or some fitness cost associated with carbaryl resistance within the population. Relative susceptibility of western corn rootworm adults also was evaluated for seven commonly used insecticides, including bifenthrin, carbaryl, chlorpyrifos, cypermethrin, fipronil, malathion, and methyl parathion. They were tested with corn rootworm adults collected from a single cornfield. Methyl parathion and bifenthrin were highly toxic to corn rootworm adults, and cypermethrin, chlorpyrifos, carbaryl, and malathion were only slightly less toxic. Although fipronil was highly toxic to adult rootworms, its activity was much slower than that of other insecticides. Thus, bifenthrin and methyl parathion were among the most effective in killing corn rootworm adults.

Animals↗
PubMed2002

A novel acetylcholinesterase gene in mosquitoes codes for the insecticide target and is non-homologous to the ace gene in Drosophila.

Acetylcholinesterase (AChE) is the target of two major insecticide families, organophosphates (OPs) and carbamates. AChE insensitivity is a frequent resistance mechanism in insects and responsible mutations in the ace gene were identified in two Diptera, Drosophila melanogaster and Musca domestica. However, for other insects, the ace gene cloned by homology with Drosophila does not code for the insensitive AChE in resistant individuals, indicating the existence of a second ace locus. We identified two AChE loci in the genome of Anopheles gambiae, one (ace-1) being a new locus and the other (ace-2) being homologous to the gene previously described in Drosophila. The gene ace-1 has no obvious homologue in the Drosophila genome and was found in 15 mosquito species investigated. In An. gambiae, ace-1 and ace-2 display 53% similarity at the amino acid level and an overall phylogeny indicates that they probably diverged before the differentiation of insects. Thus, both genes are likely to be present in the majority of insects and the absence of ace-1 in Drosophila is probably due to a secondary loss. In one mosquito (Culex pipiens), ace-1 was found to be tightly linked with insecticide resistance and probably encodes the AChE OP target. These results have important implications for the design of new insecticides, as the target AChE is thus encoded by distinct genes in different insect groups, even within the Diptera: ace-2 in at least the Drosophilidae and Muscidae and ace-1 in at least the Culicidae. Evolutionary scenarios leading to such a peculiar situation are discussed.

Acetylcholinesterase↗
PubMed1987

Laboratory evaluation of cyromazine against insecticide-resistant field strains of Musca domestica.

A screening programme was undertaken to examine the possibility of cross resistance occurring between cyromazine and conventional insecticides. The responses of nine strains of Musca domestica to treatment with cyromazine, trichlorphon, methomyl and pyrethrins with piperonyl butoxide were measured. No tolerance to cyromazine was found, neither was there a direct correlation between larval responses to cyromazine and adult responses to other insecticides. Cyromazine is a potent larvicide against M. domestica and the results of these tests show that it has good potential for the control of houseflies with high levels of resistance to other insecticides.

Animals↗
PubMed2000

Insecticide resistance studies on Blattella germanica (Dictyoptera:Blattellidae) from Cuba.

We studied the levels of resistance to seven insecticides: malathion, chlorpyrifos, pirimiphos-methyl, propoxur, cypermethrin, deltamethrin, and lambda-cyhalothrin in nine strains of Blattella germanica (Linnaeus, 1717) collected from sites in Santiago de Cuba and Havana City. The strains from Santiago de Cuba, generally had high levels of resistance to malathion, cypermethrin, deltamethrin, and lambda-cyhalothrin, but only low levels of resistance to pirimiphos-methyl, chlorpyrifos, and propoxur. In the strains from Havana City we found a moderate resistance to the organophosphate insecticides, resistance to the pyrethroids (except for three strains that showed susceptibility to lambda-cyhalothrin), and susceptibility to the carbamate insecticide (propoxur).

Animals↗
PubMed2006

Stimulatory effect of insecticides on partially purified P-glycoprotein ATPase from the resistant pest Helicoverpa armigera.

A P-glycoprotein-like protein (Ha-Pgp) was detected in a membrane preparation from the insecticide-resistant pest Helicoverpa armigera (Lepidoptera: Noctüidae) using C219 antibodies that are directed towards an epitope in the nucleotide-binding domains. This protein was partially purified and found to be a glycoprotein displaying ATPase activity. SDS-PAGE confirmed that a high molecular mass glycoprotein (150 kDa) was overexpressed in resistant pests, but was not detected in susceptible pests. The partially purified Ha-Pgp ATPase was reconstituted into proteoliposomes and it was found that some insecticides, namely, monocrotophos, endosulfan, cypermethrin, fenvalerate, and methylparathion, stimulated the ATPase activity. The effect of various inhibitors on partially purified Ha-Pgp showed that orthovanadate is a potent inhibitor of its ATPase activity, inhibiting it by 90% at a concentration of 2 mmol/L. Other inhibitors, such as EDTA, sodium azide, and molybdate resulted in only a 20% decrease in activity. Details of the structure and function of Ha-Pgp will be important in the development of strategies to overcome insecticide resistance in this pest.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1998

Golden age of insecticide research: past, present, or future?

Insecticide research led to the first "complete" victories in combatting pests almost 50 years ago with the chlorinated hydrocarbons followed quickly by the organophosphates, methylcarbamates, and pyrethroids--all neuroactive chemicals. This Golden Age of Discovery was the source of most of our current insecticides. The challenge then became health and the environment, a Golden Age met with selective and degradable compounds. Next the focus shifted to resistance, novel biochemical targets, and new chemical approaches for pest control. The current Golden Age of Genetic Engineering has curtailed, but is unlikely to eliminate, chemical use on major crops. Insecticide research, having passed through several Golden Ages, is now in a renaissance of integrating chemicals and biologicals for sustainable pest control with human safety.

Animals↗
PubMed1999

Differences of susceptibility of five triatomine species to pyrethroid insecticides - implications for Chagas disease vector control.

As pyrethroids are presently the favored group of insecticides to control triatomines, we performed a series of bioassays to determine the intrinsic activity of some of the main compounds used in the control campaigns, against five of the main species of triatomines to be controlled. Comparing the insecticides it can be seen that lambdacyhalothrin is more effective than the other three pyrethroids, both considering the LD50 and 99 for all the three species with comparable results. On Triatoma infestans the LD50 of lambdacyhalothrin was followed by that of alfacypermethrin, cyfluthrin and deltamethrin. On Rhodnius prolixus the sequence, in decreasing order of activity, was lambdacyhalothrin, alfacypermethrin, deltamethrin and cyfluthrin. Some modifications can be seen when we compare the LD99, that has more to see to what happens in the field. T. brasiliensis showed to be as sensible to lambdacyhalothrin as T. infestans, the most susceptible for this product. By the other side T. sordida is the least susceptible considering the LD99 of this insecticide.

Animals↗
PubMed2003

Resistance of Aedes aegypti from the state of São Paulo, Brazil, to organophosphates insecticides.

Since the reintroduction of Aedes aegypti in the state of S o Paulo, in the middle of the 1980-decade, organophosphate insecticides are being used to control the dengue vector. In 1996, an annual program for monitoring the susceptibility of Ae. aegypti to the insecticides was implemented. Some of the results of this monitoring program are presented. Ae. aegypti populations from ten localities have been submitted to bioassays with the diagnostic dose of temephos and fenitrothion. Only two (Mar lia and Presidente Prudente) remain susceptible to both insecticides and one (Santos) exhibits true resistance. Ae. aegypti from the remaining localities showed an incipient altered susceptibility. Resistance ratios varied from 1.2 to 2.9 for temephos and from 1.5 to 3.2 to fenitrothion, indicating moderate levels of resistance. Biochemical assays did not detect alterations in the enzyme acetilcholinesterase, but indicated that resistance is associated with esterases.

Aedes↗