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At least 685 records · Page 38Linked to original sources
PubMed1998

Spatial distribution of insecticide resistance in Caribbean populations of Aedes aegypti and its significance.

To monitor resistance to insecticides, bioassays were performed on 102 strains of the dengue vector Aedes aegypti (L.) from 16 countries ranging from Suriname in South America and through the chain of Caribbean Islands to the Bahamas, where the larvicide temephos and the adulticide malathion have been in use for 15 to 30 years. There was wide variation in the sensitivity to the larvicide in mosquito populations within and among countries. Mosquito strains in some countries such as Antigua, St. Lucia, and Tortola had consistently high resistance ratios (RR) to temephos, ranging from 5.3 to 17.7. In another group of countries--e.g., Anguilla and Curaçao--mosquitoes had mixed levels of resistance to temephos (RR = 2.5-10.6), and in a third group of countries, including St. Kitts, Barbados, Jamaica, and Suriname, mosquitoes had consistently low levels of resistance to temephos (RR = 1-4.6) (P < 0.05). On occasion significantly different levels of resistance were recorded from neighboring A. aegypti communities, which suggests there is little genetic exchange among populations. The impact of larval resistance expressed itself as reduced efficacy of temephos to kill mosquitoes when strains were treated in the laboratory or in the field in large container environments with recommended dosages. Although a sensitive strain continued to be completely controlled for up to 7 weeks, the most resistant strains had 24% survival after the first week. By week 6, 60% to 75% of all resistant strains of larvae were surviving the larval period. Responses to malathion in adult A. aegypti varied from a sensitive population in Suriname (RR = 1.3) to resistant strains in St. Vincent (RR = 4.4), Dominica (RR = 4.2), and Trinidad (RR = 4.0); however, resistance was generally not on the scale of that observed to temephos in the larval stages and had increased only slightly when compared to the levels that existed 3 to 4 years ago. Suggestions are made for a pesticide usage policy for the Caribbean region, with modifications for individual countries. This would be formulated based on each country's insecticide-resistance profile. Use of physical and biological control strategies would play a more critical role than the use of insecticides.

Aedes↗
PubMed2000

Correlated insecticide cross-resistance in azinphosmethyl resistant codling moth (Lepidoptera: Tortricidae).

Resistance to several classes of insecticides was correlated with azinphosmethyl resistance in codling moth, Cydia pomonella (L.), in California. In tests of laboratory and field populations, cross-resistance was positively correlated with azinphosmethyl and two organophosphates (diazinon, phosmet), a carbamate (carbaryl), a chlorinated hydrocarbon (DDT), and two pyrethroids (esfenvalerate and fenpropathrin). Additionally, negatively correlated cross-resistance was identified between azinphosmethyl and two other organophosphates, chlorpyrifos and methyl parathion. Patterns of resistance observed in laboratory colonies were confirmed with field bioassays. In bioassays of field populations, azinphosmethyl resistance was observed to increase from 1991 to 1993, although levels of resistance remained < 13-fold. Because orchards with azinphosmethyl resistance have had difficulties with suppression of codling moth, and cross-resistance was found for all tested classes of insecticides, strategies for managing resistance will need to be developed so as to protect current and future control tactics. The two insecticides with negatively correlated cross-resistance are discussed as potential tools for resistance management.

Animals↗
PubMed2000

Assessment of insecticide resistance in five insect pests attacking field and vegetable crops in Nicaragua.

Field populations of Hypothenemus hampei (Ferrari), Plutella xylostella (L.), Spodoptera exigua (Hübner), Helicoverpa zea (Boddie) and Bemisia tabaci (Gennadius) were tested for resistance to several insecticides commonly used in Nicariagua. Assays were conducted to estimate the LD50s or LC50s and the corresponding resistance ratios. A diagnostic concentration was used to discriminate between susceptible and resistant strains of H. hampei. The tests with >6,000 H. hampei adults collected from six different sites indicate the absence of resistance to endosulfan. Resistance to cypermethrin, deltamethrin, chlorfluazuron, thiocyclam, and methamidophos was documented in six field populations of P. xylostella. High levels of resistance to cypermethrin and deltamethrin, but moderate levels of resistance to chlorpyriphos and methomyl, were also documented in two field populations of S. exigua. Moderate levels of resistance to cypermethrin, deltamethrin and chlorpyriphos were also documented in three field populations of H. zea. Moderate to high levels of resistance to bifenthrin, methamidophos and endosulfan were documented in four field populations of B. tabaci. The presence of significant correlations between LD50s or LC50s suggests the occurrence of cross-resistance or simultaneous selection for resistance by different insecticides with different modes of action. Our data could not differentiate between these two possibilities. Because insecticides will continue being used in Nicaragua, a resistance management program is urgently needed. The implementation of integrated pest management tactics must be accompanied by specific regulations for pesticide registration. In the future, pesticide registration regulations in Nicaragua should include periodic resistance monitoring. The mechanisms to cover the costs of resistance monitoring and resistance management should also be established.

Animals↗
PubMed2002

In-season changes in resistance to insecticides in Helicoverpa armigera (Lepidoptera: Noctuidae) in India.

Discriminating doses of fenvalerate, cypermethrin, quinalphos, and endosulfan were determined with an insecticide-susceptible Helicoverpa armigera (Hübner) strain. In-season changes in insecticide resistance were monitored with discriminating dose assays at weekly intervals throughout the cropping season for 6 yr from 1993 to 1999 in central India. Resistance to pyrethroids was high throughout all seasons. Resistance to 0.75 microg of quinalphos was consistent, with seasonal averages ranging from 23 to 27% survival over the 6 yr. Resistance to 10.0 microg of endosulfan was moderately high at an average of 40-47% survival during 1993-1994 and in 1997-1998. It was lower in 1996-1997 at 27%, and in 1998-1999 at 33%. The weekly monitoring data for all seasons were pooled and the consolidated 6-yr seasonal average profile indicated that resistance to quinalphos and endosulfan was low during September at 21 and 27% survival, respectively, but increased to 28 and 37% by the end of November. Resistance levels to organophosphates and endosulfan increased during the season, depending on the use of these compounds. At almost all monitoring sites, the within-season changes in quinalphos resistance for all seasons through the study period followed a trend similar to that of endosulfan. The results suggest the possibility of cross-resistance between these compounds. Based on this study and the existing information on cotton pest management, we have developed a "window strategy" for cotton pest management with specific emphasis on the management of insecticides for effective control of H. armigera. This strategy has contributed to improved control at reduced costs in extensive trials.

Animals↗
PubMed2002

Resistance and cross-resistance to four insecticides in populations of obliquebanded leafroller (Lepidoptera: Tortricidae).

Populations of obliquebanded leafroller, Choristoneura rosaceana (Harris), were collected from organic and conventionally managed orchards located in the Okanagan and Similkameen Valleys of British Columbia Neonate F1 progeny were assayed for resistance to azinphosmethyl, tebufenozide, methoxyfenozide, and indoxacarb using a leaf disk bioassay. Significant differences in resistance levels among populations were observed for all four insecticides. Insects collected from organic sites were more susceptible to all insecticides than were insects collected from conventional sites. Resistance to the benzoylhydrazine insect growth regulators tebufenozide and methoxyfenozide was highly correlated with resistance to azinphosmethyl across populations, indicating cross-resistance between these compounds. The highest levels of resistance were observed with indoxacarb, but resistance levels to indoxacarb did not correlate with those for azinphosmethyl. Dose-response regression lines for tebufenozide were parallel across populations, suggesting that the resistance mechanism(s) were quantitatively, but not qualitatively, different. Cross-resistance between azinphosmethyl and benzoylhydrazine insecticides indicates that a resistance management strategy for obliquebanded leafroller involving the rotation of these materials is not likely to be successful.

Animals↗
PubMed2002

Effect of tolerance to insecticides on substrate penetration by Formosan subterranean termites (Isoptera: Rhinotermitidae).

Seven selected insecticides were applied to three substrates and bioassayed for barrier efficacy and toxicity against the Formosan subterranean termite, Coptotermes formosanus Shiraki, originating from colonies that differed in their tolerance to the insecticides. A profound substrate effect was seen with all insecticides tested. Sand was the most difficult substrate to penetrate and caused faster and greater mortality of C. formosanus. Increased tolerance in C. formosanus was accompanied by a decrease in penetration of treated substrata with chlordane, methoxychlor, chlorpyrifos, and deltamethrin. The opposite was true in the case of permethrin and bendiocarb. More tolerance C. formosanus displayed decreased mortality in the presence of chlorpyrifos, deltamethrin, bendiocarb, and fipronil. The opposite was true for permethrin.

Animals↗
PubMed2005

Toxicity of insecticides in a glass-vial bioassay to adult brown, green, and southern green stink bugs (Heteroptera: Pentatomidae).

Adult brown, Euschistus servus (Say); green, Acrosternum hilare (Say); and southern green, Nezara viridula (L.), stink bugs were collected from soybean, Glycine max (L.) Merr., in fall 2001 and 2002 near Stoneville, MS, and Eudora, AR. A glass-vial bioassay was used to determine LC50 values for the three species of stink bugs for the pyrethroids bifenthrin, cypermethrin, cyfluthrin, lambda-cyhalothrin, and permethrin, and the organophosphates acephate, dicrotophos, malathion, and methyl parathion. Results confirmed findings of other researchers that the brown stink bug was less susceptible to pyrethroid and organophosphate insecticides than were green and southern green stink bugs. The susceptibility of all three stink bug species to the insecticides tested was very similar at both test locations. The study established baseline insecticide mortality data from two locations in the mid-South for three stink bug species that are pests of soybean and cotton, Gossypium spp. Data from the tests are valuable for future use in studies on resistance and in resistance monitoring programs.

Animals↗
PubMed2003

Evidence for selection of insecticide resistance due to insensitive acetylcholinesterase by carbamate-treated nets in Anopheles gambiae s.s. (Diptera: Culicidae) from Côte d'Ivoire.

Pyrethroid-treated nets are an efficient tool for reducing malaria transmission and morbidity. The recent evolution of pyrethroid resistance in several Anopheles species represents a major threat for the future success of roll back malaria in Africa. The possible use of nonpyrethroid insecticides, such as carbamates, on nets is a promising alternative solution because these insecticides are effective against susceptible and pyrethroid-resistant populations of Anopheles and Culex mosquitoes. Unfortunately, carbamate resistance as a result of insensitive acetylcholinesterase has recently been detected in Anopheles gambiae s.s. populations from Côte d'Ivoire. Using biochemical assays on surviving Anopheles mosquitoes from an experimental hut trial, we showed evidence for selection for an insensitive acetylcholinesterase mechanism by carbamate impregnated bednets. However, no such selection has been found with nets treated with pyrethroid alone or pyrethroid/carbamate "two-in-one" -treated nets. Because pyrethroid-impregnated nets were suspected to select for the Kdr mutation in An. gambiae, we propose that use of two-in-one nets could be a promising alternative strategy for the management of insecticide resistance in malaria vectors.

Acetylcholinesterase↗
PubMedDate not supplied

Insecticide resistance and vector control.

Insecticide resistance has been a problem in all insect groups that serve as vectors of emerging diseases. Although mechanisms by which insecticides become less effective are similar across all vector taxa, each resistance problem is potentially unique and may involve a complex pattern of resistance foci. The main defense against resistance is close surveillance of the susceptibility of vector populations. We describe the mechanisms of insecticide resistance, as well as specific instances of resistance emergence worldwide, and discuss prospects for resistance management and priorities for detection and surveillance.

Animals↗
PubMed2002

The role of agricultural use of insecticides in resistance to pyrethroids in Anopheles gambiae s.l. in Burkina Faso.

Agricultural use of insecticides is involved in the selection of resistance to these compounds in field populations of mosquitoes in Burkina Faso. Anopheles gambiae s.l. was resistant to permethrin and DDT in cotton-growing and urban areas, but susceptible in areas with limited insecticide selection pressure (rice fields and control areas). Nevertheless, resistance to these insecticides was observed in a village on the outskirts of the rice fields at the end of the rainy season, suggesting that the latter population of mosquitoes had migrated from the surrounding cotton villages into the rice fields. A seasonal variation of resistance observed in the cotton-growing area is related to the distribution of the molecular M and S forms of An. gambiae, since resistance to pyrethroids has so far only been reported in the S form. Pyrethroid resistance in west African An. gambiae was conferred by target site insensitivity through a knockdown resistance (kdr)-like mutation, which was present at high frequencies in mosquitoes in the cotton-growing and urban areas.

Animals↗
PubMed2024

Omics approaches to unravel insecticide resistance mechanism in Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae).

Bemisia tabaci (Gennadius) whitefly (BtWf) is an invasive pest that has already spread worldwide and caused major crop losses. Numerous strategies have been implemented to control their infestation, including the use of insecticides. However, prolonged insecticide exposures have evolved BtWf to resist these chemicals. Such resistance mechanism is known to be regulated at the molecular level and systems biology omics approaches could shed some light on understanding this regulation wholistically. In this review, we discuss the use of various omics techniques (genomics, transcriptomics, proteomics, and metabolomics) to unravel the mechanism of insecticide resistance in BtWf. We summarize key genes, enzymes, and metabolic regulation that are associated with the resistance mechanism and review their impact on BtWf resistance. Evidently, key enzymes involved in the detoxification system such as cytochrome P450 (CYP), glutathione S-transferases (GST), carboxylesterases (COE), UDP-glucuronosyltransferases (UGT), and ATP binding cassette transporters (ABC) family played key roles in the resistance. These genes/proteins can then serve as the foundation for other targeted techniques, such as gene silencing techniques using RNA interference and CRISPR. In the future, such techniques will be useful to knock down detoxifying genes and crucial neutralizing enzymes involved in the resistance mechanism, which could lead to solutions for coping against BtWf infestation.

Hemiptera↗
PubMedDate not supplied

[Resistance to insecticides in Blattella germanica species strains from Santiago de Cuba].

A study was conducted on the level of resistance to seven insecticides, namely, 3 organophosphate compounds (malathion, chlorpyrifos and pirimiphos-methyl), one carbamate (propoxur) and 1 pyrethroid (cypermethrin, deltamethrin and lambdacialotrine) of three field-collected strains of Blattella germanica (Linnaeus, 1767) from Santiago de Cuba. These strains showed high resistance levels to malathion, cypermethrin, deltamethrin and lambdacialotrine and low resistance to pirimiphos-methyl, and also they were susceptible to chlorpyrifos and propoxur. The levels of resistance to tested organophosphate insecticides such as malathion and pirimiphos-methyl and to pyrethroid compounds like cypermethrin, deltamethrin and lambdacialotrine may be related to the increased production of esterases as a mechanism of resistance. The value of frequency of the resistant genes for enzyme acetylcholinesterase was very low, therefore, the modified acetylcholinesterase is not involved in resistance to insecticides tested in the studied strains from Santiago de Cuba.

Animals↗
PubMed2001

Studies on the present status of insecticides resistance on mosquitoes using the diagnostic dosages in El-Fayium Governorate, a spot area of malaria in Egypt.

Insecticides susceptibility tests were conducted using the World Health Organization diagnostic doses on the adult and larvae of Anopheles pharoensis and Culex pipiens mosquitoes from Fayium Governorate in Egypt. Insecticides used were malathion, fenitrothion, temephos, diazinon, bromophos and fenthion from organophosphorous group and deltamethrin, permethrin and cypermethrin from synthetic pyrethroid group while propoxur was from carbamate group. Larvae of A. pharoensis were resistant to fenitrothion and susceptible to other insecticides used, while the adults were susceptible to malathion, deltamethrin, fenitrothion and premethrin. Larvae of C. pipiens were resistant to temephos, fenitrothion, bromophos and fenthion and susceptible to malathion, permethrin and diazinon, while the adults were resistant to fenitrothion, permethrin and propoxur and susceptible to deltamethrin, cypermethrin and malathion. These results are important for the success of the control programmes and monitoring the susceptibility status of vectors.

Animals↗
PubMed2002

[An experimental tool essential for the evaluation of insecticides: the testing huts].

The following study analyses the potentialities of the experimental huts built in M'be Valley (Côte d'Ivoire) where the evaluations of the insecticide products have been carried out for many years in line with the WHOPES protocol on the methodology of stage 2 assays. Starting a testing station first requires a good knowledge of the sensitivity of Anopheles gambiae to the main insecticide families. Then thanks to the experimental huts the efficacy of the various means of treatment can be compared with the one in untreated huts; this study focuses on house spraying using 100 mg a.i./m2 and bednets impregnated with lambda-cyhalothrin at a dose of 15 mg a.i./m2. The fipronil used in house spraying doesn't show any repellent effect, however it does have an irritating effect that increases the natural exophily of An. gambiae females entering the testing huts. The blood-feeding rate recorded in the treated huts was reduced to 24% and to 38% mortality rate consisting mainly of a 24 hours delayed mortality. The bednets treated with lambda-cyhalothrin have greatly reduced the contact between man and vector since the entry rate of An. gambiae females was cut down by 68% compared to the control. The exophily of this anopheles was twofold greater with the impregnated bednets and the blood-feeding rate reduced to 47%. Finally the global mortality rate, two thirds of immediate mortality, one third of delayed mortality, reached 35%. The experimental huts in the M'be Valley therefore provide essential information regarding the selection of the most efficacious insecticides against An. gambiae. This experimental method must be extended to other sites in order to finalize ever more selective and appropriate means of control against nuisance and disease-vector mosquitoes.

Animals↗
PubMed2002

Assessment of Helicoverpa Armigera resistance to pyrethroid insecticides in northern Cameroon.

In Central Africa savannas, the noctuid Helicoverpa armigera (Hübner) is a major pest of cotton and vegetable crops (including tomato and okra) which directly affects production by attacking fruit-bearing organs. In order to prevent and anticipate problems, the national cotton company (SODECOTON), with the help of the agricultural research (IRAD-PRASAC), implemented in 1999 a monitoring network for the early detection of resistance of target insects to the main recommended insecticides. Over the last three years, from 1999 up to 2001, assessment of H. armigera susceptibility to pyrethroid insecticides was carried out through both vial tests and topical bioassays. Revealed in southern and western Africa, pyrethroid resistance now seems to affect Central Africa also. Although control failure due to resistance has not yet been reported from the field, these results indicate the presence of resistant genes within H. armigera populations in Northern Cameron. Further laboratory studies confirmed the loss of susceptibility to cypermethrin in wild populations. Priority actions to be developed must focus on the rational and concerted management of pesticide use and the implementation of a regional monitoring network for the early detection of the loss of sensibility of target insects to the main recommended insecticides. At the same time, more fundamental research should be undertaken on the epidemiological profile of resistance in order to define practical ways of reducing the selection pressure.

Abelmoschus↗
PubMed2002

Evidence for negative cross resistance to insecticides in field collected Spodoptera littoralis (Boisd.) from Lebanon in laboratory bioassays.

A sample of Spodoptera littoralis pupae were field collected from in Lebanon in November 1999. Approximately 50 healthy pupae were used to initiate a laboratory colony (stain code LEB). As a benchmark for sensitivity to insecticides the susceptible laboratory strain (LET) was used for comparison. The LET stain has been held in laboratory culture for over 10 years and originated from Israel. Three test chemicals were investigated; Spinosad (Tracer, 480 g/L SC), chlorpyrifos (Dursban 480 g/L EC) and cypermethrin (Ambush C 100 g/L EC) representing a range of different modes of actions. To estimate the sensitivity of the LEB strain relative to the LET stain laboratory bioassays, conducted on second instar larvae exposed treated tomato leaves for two days. The method used was based on IRAC (Insecticide Resistance Action Committee) insecticide susceptibly test number 7. Larvae from the LEB strain were tested in both the F1 and F2 laboratory generations. LC50 values were calculated using a Log-Probit model allowing the susceptibly of each strain to each test item to be compared. The LEB (field) strain were approximately twice as sensitive to spinosad compared with the LET (laboratory) strain. The LEB strain was 6-10 times less sensitive to chlorpyrifos which was within the range expected. However the LEB stain was 250-360 times less sensitive to cypermethrin compared with the LET strain, indicating a high level of resistance to pyrethroids in the field population. This kind of relationship gave a strong indication for negative cross resistance between spinosad and cypermethrin. It was concluded that spinosad had potential as a resistance management tool due to its novel mode of action and negative cross resistance with pyrethroids.

Animals↗
PubMed1953

A simple and effective device for housefly control with insecticides.

A simple, portable frame tied with string soaked in insecticide has been devised by the authors to give a much greater chance for houseflies to contact the insecticide residue. Shell Dieldrex 15 was tested on the frame both in the laboratory and in the field with excellent results. The residual effect seems to last at least up to two-and-a-half months. No ill-effect resulting from the handling of dieldrin-treated frames has been observed. As the frame method is cheap and effective for housefly control, it can be introduced into any community which has unsatisfactory sanitation and where the housefly is still susceptible to insecticide.

Animals↗
PubMed1957

Effectiveness of organo-phosphorus insecticides against houseflies and mosquitos.

The paper describes the research being undertaken on organo-phosphorus insecticides for the control of houseflies and mosquitos. The information obtained from laboratory and field tests indicates that these insecticides are at present effective substitutes for DDT and other chlorinated-hydrocarbon insecticides for use against resistant houseflies and culicine mosquitos, but the residual applications are not as long lasting as those of DDT and therefore will probably not be as efficient in anopheline control.

Animals↗