Insecticide resistance status of Aedes aegypti and Aedes albopictus in Malaysia(2010 to 2022):A review

This review aimed to determine the prevalence of the insecticide resistance status of the field-collected Aedes(Ae.)aegypti and Ae.albopictus in Malaysia from 2010 to 2022 towards carbamates,organochlorines,organophosphates and pyrethroids.Biological and environmental controls were summarized with an emphasis on the mosquito vector control strategies in Malaysia.The information in this review was extracted from several databases such as PubMed(MEDLINE),Science Direct and Scopus by using keywords including“insecticide resistance”,“carbamate resistance”,“organochlorine resistance”,“organophosphate resistance”,“pyrethroid resistance”,“Aedes”and“Malaysia”,between January 2022 and December 2022.Distribution of resistant Ae.aegypti and Ae.albopictus in Malaysia was mapped using QGIS software.Insecticide resistance in both Ae.aegypti and Ae.albopictus is widespread in Malaysia,although the rates vary by states.The most notable was the steep increase in permethrin resistance of Ae.aegypti in Selangor,Malaysia,over the past decade.Ae.albopictus also displayed moderate resistance to permethrin,though not as widespread as Ae.aegypti in Selangor,but showed sign of resistance in Sarawak,East Malaysia.Resistance towards four main classes of insecticides have been widely documented in Malaysia.The extensive resistance towards permethrin in Malaysia which is one of the current insecticides used in Malaysia suggested that policies supporting the widespread use of permethrin fogging needs further evaluation.

Insensitive Acetylcholine Receptor Conferring Resistance of Plutella xylostella to Nereistoxin Insecticides

The combinative rate measurement of （3-[I125] iodotyrosyl） α-bungarotoxin was applied in the analysis of the relation between nerve acetylcholine receptor and three types of insecticide resistance in diamondback moth, Plutella xylostella （L.）. In the dimehypo-resistant strain and in the cartap-resistant strain, the nerve acetylcholine receptor showed the remarkable insensitivity to dimehypo and cartap, of which the binding rate to ligand was approximately 66 and 60%, respectively, of the susceptible strain. The sensitivity to deltamethrin in the deltamethrin-resistant strain did not show visible change. These results indicated that the decline in the sensitivity of nerve acetylcholine receptor to insecticide might be a potential mechanism to nereistoxin insecticides resistance in the diamondback moth.

Characterization of carboxylesterase PxαE8 and its role in multi-insecticide resistance in Plutella xylostella(L.)

Carboxylesterase(CarE)was considered as important phase-I detoxifying enzymes which participated in detoxification of different types of insecticides.Up-regulation of CarE genes has been proved playing a major role in insecticide resistance in many pest insects,but its involvement in resistance to insecticides in Plutella xylostella has been rarely reported.In this study,a CarE cDNA named PxαE8 was identified in P.xylostella,which has an open reading frame of 1599 nucleotides and putatively encodes 532 amino acids.The investigation of spatial expression profiles of PxαE8 revealed that it was expressed in all developmental stages,especially in larvae and adults.The body part/tissue-specific expression profiles showed that the PxαE8 mainly expressed in fat body,malpighian tubule and hemolymph of larvae.Further,the relative expression of PxαE8 in two multi-resistant field populations,Hainan(HN)and Guangdong(GD)populations,was found 24.4-and 15.5-fold higher than that in susceptible population,respectively.Knockdown of PxαE8 by RNA interference dramatically increased the mortalities of larvae of HN population treated with LC_(50) of beta-cypermethrin and phoxim by 25.3 and 18.3%,respectively.These results suggested that up-regulation of PxαE8 was involved in resistance to both beta-cypermethrin and phoxim in P.xylostella,which shed light on further understanding of molecular mechanisms of multi-insecticide-resistance in P.xylostella and other pest insects.

Insecticide resistance status and biochemical mechanisms involved in Aedes mosquitoes: A scoping review

Mosquitoes belonging to the genus Aedes pose a significant threat to human health on a global scenario due to their role in transmission of dengue,chikungunya,zika,and yellow fever.In absence of specific medications and vaccines against these diseases,disease prevention relies on vector control.However,in today’s world,vector control is facing major challenges due to the onset of insecticide resistance in mosquitoes.There are four main mechanisms of insecticide resistance,namely,behavioral resistance,reduced penetration/cuticular resistance,metabolic detoxification,and target site resistance;however,the latter two mechanisms have been studied widely in Aedes mosquitoes.Insecticide resistance in Aedes mosquitoes is widespread throughout the world.This review compiles the degree of insecticide resistance/susceptibility prevailing among different field populations of Aedes mosquitoes worldwide.In addition,the review has detailed the mechanisms providing the resistance phenomenon observed in nature in Aedes mosquitoes.

The Relationship Between Resistance to Controlled Atmosphere and Insecticides of Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae)

The cross resistance of four resistant strains of Liposcelis bostrychophila Badonnel, an important stored-product insect pest, was investigated. These four strains included the HCO2-R (hypercarbia-resistant strain), HCLO-R (hypoxia and hypercarbia resistant strain), DDVP-R (DDVP-resistant strain) and PH3-R (PH3-resistant strain). The results indicated that there were cross-resistances between CA and insecticides, and the quantities of the cross-resistance were different. The cross-resistance factor (RF) of HCO2-R to hypoxia and hypercarbia was 3.2458, whilst, that of HCLO-R to hypercarbia was 1.8280. The RF of DDVP-R to PH3 was 3.9614, whilst, that of PH3-R to DDVP was 2.7852. The RF values of DDVP- R and PH3-R to hypercarbia were 1.3550 and 1.1816, respectively. However, the RF of HCO2- R to DDVP was 2.1372. There also was a low cross-resistance between DDVP-R and HCO2-R. The RF of HCO2-R to PH3 was 3.3698. This suggested that the insects resistant to high CO2 concentration atmosphere would develop significant resistance to PH3. However, the insects resistant to PH3 remain sensitive to hypercarbia atmosphere. Both DDVP-R and PH3- R developed resistance to high CO2 treatment. There was a low cross-resistance between DDVP-R and HCLO-R. The insects resistant to hypoxia and hypercarbia were very sensitive to DDVP. There also was cross-resistance between HCLO-R and PH3-R, but the resistance of PH3-R to hypoxia and hypercarbia was lower than that of HCLO-R to PH3. The difference of the overlapping and separate values indicated that there were differences in the intercross-resistance of four resistant strains.

Modeling Insecticide Resistance in Endemic Regions of Kenya

In this study, we develop an SIS model for two types of mosquitoes, a traditional one and one that is resistant to IRS and ITNs. The resistant mosquito develops behavioral adaptation to control measures put in place to reduce their biting rate. They also bite early before dusk and later after dark when people are outside the houses and nets. We determine the effect of the two types of mosquitoes on malaria transmission in Kenya. The basic reproduction number R 0 is established as a sharp threshold that determines whether the disease dies out or persists in the population. Precisely, if R 0 ≤ 1, the disease-free equilibrium is globally asymptotically stable and the disease always dies out and if R 0 > 1, there exists a unique endemic equilibrium which is globally stable and the disease persists. The contribution of the two types of mosquitoes to the basic reproduction number and to the level of the endemic equilibrium is analyzed.

The insecticide resistance in stripped stem borer,Chilo suppressalis(Walker)

The stripped stem borer (SSB),Chilo suppressalis (Walker) is one ofthe major insect pests of rice in Chi-na. Chemical control has been acommon practice in SSB managementsince 1950s. Insecticides used in-cluded BHC before 1983; organophos-

The insecticide resistance in two planthoppers from three areas to three insecticides

Migrating insects brown planthopper(BPH),Nilaparvata lugens St(?)l andwhite-backed planthopper(WBPH),Sogatella furcifera Horvath are both mostharmful insects on rice in China.Chemical control is thought to be the best wayto manage them,but it may cause insecticide resistance.Methamidophos,buprofezin,and imidacloprid were the three insecticides often used.In 2000and 2001,resistance of the field populations collected from three areas,i.e.Dongtai,Jiangsu Province,Anqing,Anhui Province,and Guilin,GuangxiAutonomous Region,to the three insecticides was monitored.The toxicities ofthe three insecticides were determined with the female adult(3-5 d after e-mergence)and by the topical application method with the hand microapplicator.

Comparison of Insecticide Resistance and Its Enzyme Mechanisms among Aedes aegypti Collected with Three Methods in a Dengue-Endemic City in Southern Mexico

Background: Despite the physical and chemical effort to control Aedes aegypti, the arboviruses transmission in the south of Mexico remains latent. Trying to improve the methods of entomological surveillance routinely used, whether the estimation of resistance to insecticides used for its control, as well as their enzyme mechanisms, were influenced by the phase in which the mosquitoes were collected through three different collection methods was investigated. Materials and Methods: Mosquito collections from the “5 de Febrero” neighborhood in Tapachula, Mexico were obtained by ovitraps, larvitraps, and a CDC backpack aspirator. Insecticide resistance of F1 females was determined by WHO diagnostic doses and resistance ratios (RR50), furthermore, levels of insecticide metabolism enzymes were determined by biochemical assays. Results: Overall, in mosquitoes collected by ovitraps, larvitraps, and CDC backpack aspirator respectively, the low mortalities obtained with the discriminant dose to Malathion (27.57%, 26.97%, and 26.91%), and to Bendiocarb (50.5%, 45.36%, and 54.97%) suggest resistance. However, LC50 for Malathion (0.922, 0.934, and 0.915) and for Bendiocarb (0.112, 0.109, and 0.107);and the low resistance ratios (RR50) for Malathion (3.34, 3.29, and 3.27) and for Bendiocarb (2.15, 2.1, and 2.06) does not suggest resistance. Although a slight numerical variation is observed between the three LC50 values, the overlap observed between their confidence intervals allows us to assume that there were no differences between the three methods. In general, esterases (determined with three substrates), glutathion S-transferases (GST) and cytochromes P450 were statistically higher than those of the susceptible strain;and the three enzyme levels were statistically different among the three collection methods (P Conclusion: Although using a CDC backpack aspirator demonstrated being the best collection method determining a specific resistance mechanism (as elevation at the enzyme level) in the mosquito adult phase, any collection method is reliable to determine whether a field mosquito population is resistant or susceptible to an insecticide.

Field resistance to spinosad in western flower thrips Frankliniella occidentalis(Thysanoptera:Thripidae)

The western flower thrips, Frankliniella occidentalis, is one of the most destructive sucking pests of vegetables, fruits and ornamental crops in China. Spinosad is one of the most commonly used insecticides to manage thrips. To assess the incidence of spinosad resistance in F. occidentalis field populations in eastern China, survival rates for 24 different populations were compared with those of a susceptible laboratory strain. All populations showed significantly higher resistance to spinosad compared with the control as determined by comparing median lethal concentrations. Two populations from Shouguang and Liaocheng in Shandong Province were classified as having moderate and high levels of resistance to spinosad with a mean resistance ratio of 17.0 and 89.2, respectively. Our research indicates a widespread reduction in spinosad efficacy for controlling F. occidentalis field populations, and that resistance management strategies should be implemented as soon as practicable, to reduce the potential of progressive resistance development and loss of efficacy.

Genetics and fitness costs of resistance to flupyradifurone in Bemisia tabaci from China

Flupyradifurone is a promising new insecticide used for controlling Bemisia tabaci during vegetable production.In this study,we assessed the fitness costs and mode of inheritance associated with resistance to flupyradifurone in B.tabaci by comparing the susceptible strain(MED-S)to one field-evolved flupyradifurone-resistant strain(WH-R,with 199-fold resistance)and one laboratory-selected flupyradifurone-resistant strain(FLU-SEL,with 124-fold resistance).Progenies of reciprocal crosses between WH-R and MED-S(F_(1A),F_(1B),and pooled F_(1)),and between FLU-SEL and MED-S(F_(1C),F_(1D),and pooled F_(1)’),showed varying degrees of dominance,indicating that resistance to flupyradifurone in WH-R was autosomal and incompletely dominant,yet in FLU-SEL it was autosomal and incompletely recessive.Furthermore,the development of resistance to flupyradifurone occurred at the expense of fitness costs for the resistant populations.Compared to the MED-S strain,WH-R showed a relative fitness of 0.50 with significantly prolonged developmental durations and reduced survival rates of the nymphal and pseudopupal stages,as well as decreased fecundity and hatchability.Similarly,FLU-SEL showed a relative fitness of 0.65 and also demonstrated prolonged developmental durations and reduced survival rates of nymphs and pseudopupae,as well as decreased hatchability in comparison with the MED-S strain.However,no significant differences in fecundity were observed between MED-S and FLU-SEL.The present study provides useful knowledge for formulating pest management strategies in the field,which will allow growers to slow the development of resistance to flupyradifurone and to sustainably control B.tabaci.

Susceptibility to Insecticides and Ecological Fitness in Resistant Rice Varieties of Field Nilaparvata lugens Stl Population Free from Insecticides in Laboratory

A population of rice brown planthopper （BPH） Nilaparvata lugens collected from a paddy field in Hangzhou was successively reared on susceptible rice Taichung Native 1 （TN1） in a laboratory free from insecticides for more than 14 generations. The changes in susceptibility to insecticides and ecological fitness on different resistant rice varieties were monitored in each generation. The resistance ratio to imidacloprid sharply declined with the succession of rearing generations without insecticides from 359.94-fold at F1 to 6.50-fold at F14 compared with the susceptible strain, and the resistance ratio to chlorpyrifos was from 9.90-fold at F1 to 5.94-fold at F14. Nymphal duration and weights of newly hatched female adults were significantly affected by rice variety, generation and their interactions, but nymphal survival was significantly affected by the generation only. The ratio of brachypterous adults in males was affected by the generation and generation × variety interaction, whereas no difference was found in females. Nymphal duration extended with increasing generations, and the female nymphal duration was shorter in the susceptible variety TN1 than those in the resistant varieties IR26 and IR36. In addition, the female adult weight in TN1 was higher than those in IR26 and IR36. These results indicated that the resistance of field BPH population to insecticides was reversed after several generations of no-exposure to insecticides, and the ecological fitness in TN1 was higher than those in IR26 and IR36. These findings suggested the rational and reduced use of insecticides in combination with the manipulation of resistant rice varieties would be effective for BPH management.

Relationship Between the Development of Methamidophos Resistance and the Activities of Three Detoxifying Enzymes in Brown Planthopper, Nilaparvata lugens

Methamidophos resistance of brown planthopper(BPH), Nilaparvata lugens was selected in laboratory for 19 generations (F1 to F19). The resistance development in BPH was approximatively shaped as the letter 'S' : resistance change was small before the fifth generation and after the fifteenth generation, and the changing pattern was sharp between the fifth and the fifteenth generation. Esterase might play an important role in the resistance development, because the esterase activity and the number of individuals with high activities increased along with the resistance development. The esterase activities of insecticide-sensitive population S, field population F0, its selective generations F5, F10 and F15 were highly correlated with the resistance ratios of these generations, and the coefficient was 0.9899. Mixed-function oxidases and glutathione S-transferase also might play some roles in the resistance development, but the big change in the activities of the two detoxifying enzymes both took place before the tenth generation.

Research Overview on Occurrence and Control of Tetranychus urticae Koch in China

Tetranychus urticae Koch;Insecticide resistance;Chemical control This paper elaborates the occurrence factors and damage characteristics of Tetranychus urticae Koch in China,and emphatically summarizes three main control strategies of T.urticae,namely agricultural control,chemical control and biological control,as well as research progress in its resistance mechanisms.The problems existing in controlling T.urticae and its resistance management strategies are put forward,to provide a theoretical basis for the resistance management and comprehensive control of T.urticae.

Feeding behavior and hormoligosis associated with imidacloprid resistance in Asian citrus psyllid,Diaphorina citri

Imidacloprid is a neonicotinoid insecticide used for managing the Asian citrus psyllid,Diaphorina citri Kuwayama,which serves as vector of phytopathogens causing citrus greening.However,development of resistance to neonicotinoids among populations of D.citri has coincided with occasional control failures in the field.The objectives of this research were to(1)survey current levels of imidacloprid resistance in Florida citrus;(2)compare feeding behavior between imidacloprid-resistant and susceptible D.citri using electrical penetration graph recordings,and(3)investigate the possible amplification of insecticide hormoligosis associated with resistance.Field surveys confirmed that the susceptibility of D.citri populations to imidacloprid has decreased in commercial Florida citrus groves compared with a laboratory-susceptible population.Following 12 generations of selection,resistance to imidacloprid increased by 438 fold compared with the susceptible strain.Imidacloprid-susceptible D.citri feeding on citrus exhibited significantly more bouts associated with intercellular pathway(C),phloem penetration(D),phloem salivation(E1),and nonprobing(Np)activities than imidacloprid-resistant counterparts.However,there were no differences observed in the frequency or duration of phloem ingestion or xylem feeding between susceptible and resistant D.citri.There was no statistical difference in fecundity between resistant and susceptible strains.However,the fecundity of imidacloprid-susceptible female D.citri treated with a sublethal concentration of imidacloprid(LC_(25))increased significantly compared with controls,while such hormoligosis was less pronounced among imidacloprid-resistant psyllids.Our results suggest that imidacloprid-resistant psyllids may cease feeding sooner than susceptible counterparts following sublethal exposure to this insecticide,indicative of a behavioral resistance mechanism.

Whole-genome sequencing to detect mutations associated with resistance to insecticides and Bt proteins in Spodoptera frugiperda

The fall armyworm(FAW),Spodoptera frugiperda,is a major pest native to the Americas that has recently invaded the Old World.Point mutations in the target-site proteins acetylcholinesterase-1(ace-1),voltage-gated sodium channel(VGSC)and ryanodine receptor(RyR)have been identified in S.frugiperda as major resistance mechanisms to organophosphate,pyrethroid and diamide insecticides respectively.Mutations in the adenosine triphosphate-binding cassette transporter C2 gene(ABCC2)have also been identified to confer resistance to Cry IF protein.In this study,we applied a whole-genome sequencing(WGS)approach to identify point mutations in the target-site genes in 150 FAW individuals collected from China,Malawi,Uganda and Brazil.This approach revealed three amino acid substitutions(A201S,G227A and F290V)of S.frugiperda ace-1,which are known to be associated with organophosphate resistance.The Brazilian population had all three ace-1 point mutations and the 227A allele(mean frequency=0.54)was the most common.Populations from China,Malawi and Uganda harbored two of the three ace-1 point mutations(A201S and F290V)with the 290V allele(0.47-0.58)as the dominant allele.Point mutations in VGSC(T929I,L932F and L1014F)and RyR(I4790M and G4946E)were not detected in any of the 150 individuals.A novel 12-bp insertion mutation in exon 15 of the ABCC2 gene was identified in some of the Brazilian individuals but absent in the invasive populations.Our results not only demonstrate robustness of the WGS-based genomic approach for detection of resistance mutations,but also provide insights for improvement of resistance management tactics in S.frugiperda.

Establishing the role of detoxifying enzymes in field-evolved resistance to various insecticides in the brown planthopper （Nilaparvata lugens） in South India

The brown planthopper （BPH）, Nilaparvata lugens （Stal）, is one of the major pests of rice throughout Asia. Extensive use of insecticides for suppressing N. lugens has resulted in the development of insecticide resistance leading to frequent control failures in the field. The aim of the present study was to evaluate resistance in the field populations of N. lugens from major rice growing states of South India to various insecticides. We also determined the activity of detoxifying enzymes （esterases [ESTs], glutathione S- transferases [GSTs], and mixed-fimction oxidases [MFOs]）. Moderate levels of resistance were detected in the field populations to acephate, thiamethoxam and buprofezin （resistance factors 1.05-20.92 fold, 4.52-14.99 fold, and 1.00-18.09 fold, respectively） as compared with susceptible strain while there were low levels of resistance to imidacloprid （resistance factor 1.23-6.70 fold） and complete sensitivity to etofenoprox （resistance factor 1.05- 1.66 fold）. EST activities in the field populations were 1.06 to 3.09 times higher than the susceptible strain while for GST and MFO the ratios varied from 1.29 to 3.41 and 1.03 to 1.76, respectively. The EST activity was found to be correlated to acephate resistance （r = 0.999, P ≥ 0.001）. The high selection pressure of organophosphate, neonicotinoid, and insect growth regulator （IGR） in the field is likely to be contributing for resistance in BPH to multiple insecticides, leading to control failures. The results obtained will be beneficial to IPM recommendations for the use of effective insecticides against BPH.

Evidence of insecticide resistance selection in wildmosquitoes due to agricultural pesticide use

Background:The wetlands used for some agricultural activities constitute productive breeding sites for many mosquito species.Thus,the agricultural use of insecticide targeting other pests may select for insecticide resistance in malaria mosquitoes.The purpose of this study is to clarify some knowledge gaps on the role of agrochemicals in the development of insecticide resistance in malaria vectors is of utmost importance for vector control.Methods:Using the CDC bottle test and the log-probit analysis,we investigated for the first time the resistance levels ofAnopheles coluzzii mosquitoes to neonicotinoids,insecticides used exclusively for crop protection in C?te d’Ivoire.The study was conducted in two agricultural regions(Tiassale and Gagnoa)and one non-agricultural region(Vitre)between June and August 2017 using clothianidin,acetamiprid and imidacloprid.Results:Mosquito populations from Tiassale and Gagnoa(agricultural settings)were determined to be resistant to acetamiprid with mortality rates being<85%at 24 h post-exposure.In Vitre(non-agricultural area)however,the mosquito population was susceptible to acetamiprid.In all three localities,mosquito populations were resistant to imidacloprid(mortality rates were 60%in Vitre,37%in Tiassale,and 13%in Gagnoa)and completely susceptible to clothianidin(100%mortality).An.coluzzii represented 100%of mosquito collected in Gagnoa,86%in Tiassale and 96%in Vitre.Conclusions:This study provides strong evidence that agricultural use of insecticides can cause insecticide resistance in malaria vector populations.Insecticide resistance driven by agrochemical usage should be considered when vector control strategies are developed.

Levels of insecticide resistance to deltamethrin,malathion,and temephos,and associated mechanisms in Aedes aegypti mosquitoes from the Guadeloupe and Saint Martin islands(French West Indies)

Background:In the Guadeloupe and Saint Martin islands,Aedes aegypti mosquitoes are the only recognized vectors of dengue,chikungunya,and Zika viruses.For around 40 years,malathion was used as a mosquito adulticide and temephos as a larvicide.Since the European Union banned the use of these two insecticide molecules in the first decade of the 21st century,deltamethrin and Bacillus thuringiensis var.israelensis are the remaining adulticide and larvicide,respectively,used in Guadeloupe.In order to improve the management of vector control activities in Guadeloupe and Saint Martin,we investigated Ae.aegypti resistance to and mechanisms associated with deltamethrin,malathion,and temephos.Methods:Ae.aegypti mosquitoes were collected from six different localities of Guadeloupe and Saint Martin.Larvae were used for malathion and temephos bioassays,and adult mosquitoes for deltamethrin bioassays,following World Health Organization recommendations.Knockdown resistance(Kdr)genotyping for V1016I and F1534C mutations,and expression levels of eight enzymes involved in detoxification mechanisms were examined in comparison with the susceptible reference Bora Bora strain.Results:Resistance ratios(RR50)calculated for Ae.aegypti larvae showed high resistance levels to temephos(from 8.9 to 33.1-fold)and low resistance levels to malathion(from 1.7 to 4.4-fold).Adult females displayed moderate resistance levels to deltamethrin regarding the time necessary to affect 50%of individuals,varying from 8.0 to 28.1-fold.Molecular investigations on adult mosquitoes showed high resistant allele frequencies for V1016I and F1534C(from 85 to 96%and from 90 to 98%,respectively),as well as an overexpression of the glutathione S-transferase gene,GSTe2,the carboxylesterase CCEae3a,and the cytochrome genes 014614,CYP6BB2,CYP6M11,and CYP9J23.Conclusions:Ae.aegypti populations from Guadeloupe and Saint Martin exhibit multiple resistance to organophosphates(temephos and malathion),and pyrethroids(deltamethrin).The mechanisms associated with these resistance patterns show strong frequencies of F1534C and V1016I Kdr mutations,and an over-expression of CCEae3a,GSTe2,and four cytochrome P450 genes(014614,CYP9J23,CYP6M11,CYP6BB2).These results will form the baseline for a deeper understanding of the insecticide resistance levels and associated mechanisms of Ae.aegypti populations and will be used to improve vector control strategies in Guadeloupe and Saint Martin.