Development Of Insecticide Resistance Research Articles

The southern house mosquito Culex quinquefasciatus in Abu Dhabi, UAE, is developing resistance to deltamethrin insecticide

Culex quinquefasciatus is a widely spread mosquito species that poses a significant public health threat in many countries. This insect vector is present in the United Arab Emirates (UAE), yet no studies have been conducted on its resistance to any insecticide group. Research shows that controlling mosquitoes is crucial to eliminating mosquito-borne diseases, but when these vectors develop insecticide resistance, the situation can escalate dangerously out of control. This study aimed to identify a knockdown resistance (kdr) mutation L1014F using molecular tools. Additionally, it aimed to assess deltamethrin resistance using the Centers for Disease Control and Prevention (CDC) bottle bioassay. We screened Cx. quinquefasciatus adults (N = 174) for the presence of the mutation using allele-specific PCR (AS-PCR) and DNA sequencing. We detected the mutation and found the kdr allele in all the sampled locations. Furthermore, the CDC bottle bioassay revealed deltamethrin resistance from only one sampling location. To our knowledge, this is the first report of insecticide resistance in Cx. quinquefasciatus in the UAE. Our findings show the need for continued insecticide resistance monitoring for effective mosquito control in the UAE.

Enhancement of thiodicarb efficacy using synergists and role of carboxylesterase in potentiation of synergistic activity in brinjal fruit and shoot borer (Leucinodes orbonalis Guenee)

The primary cause of low productivity in brinjal is the infestation by the fruit and shoot borer and field control failure is due to the evolution of insecticide resistance. In the current study, an investigation has been carried out in bimonthly intervals from Nov-2021 to Sept-2022 to assess the efficacy of some selected synergists with a carbamate, thiodicarb and the role of carboxylesterase enzyme in imparting insecticide resistance in Brinjal fruit and shoot borer from two locations of Odisha, Bhubaneswar and Bargarh. Out of all the synergists tested in the topical bioassay method, propargyl-oxy-phthalimide (PP) being a member of esterase hydrolase inhibitor group provided remarkable SR ratio (10.78) during May- 2022 in the Bhubaneswar population while that of Bargarh population indicated comparatively higher value (12.68) indicating efficacy of the synergist lowering the dose of thiodicarb to 1.464 µg/µl compared to 18.564 µg/µl when thiodicarb alone is used. This can be related to enhanced levels of detoxifying enzyme, Carboxylesterase in Bhubaneswar during May 2022 (4.52-fold) and Bargarh (5.36-fold) population compared to laboratory-reared susceptible population revealing the role of carboxylesterase enzyme in detoxification mechanism behind the efficacy of the synergists. This study highlights the importance of synergists like PP and Triphenyl phosphate (TPP) and suggests their inclusion in the existing pest management strategies of L. orbonalis in a wider agricultural area they reduce doses of insecticides and hence reduce impact on the environment which can lead to sustainable agriculture.

Field Evolved Insecticide Resistance in Legume Pod Borer, Maruca vitrata F. (Lepidoptera: Crambidae)

Background: Maruca vitrata, commonly known as the legume pod borer, is a significant pest affecting leguminous crops like cowpea, pigeon pea, lab lab, beans, mung bean and others across tropical and subtropical regions. It severely reduces yields by boring into flowers, pods and seeds, causing significant damage. Field control failures with insecticides have been experienced by farmers due to development of insecticide resistance upon over reliance on insecticides. Hence, the present study attempted to quantify the levels of insecticide resistance and their detoxification routes in field collected populations of M. vitrata from intensive legume growing regions of India. Methods: In this study, a survey was conducted in intensive legume-growing regions of India to collect field populations of M. vitrata in 2024. Dose mortality bioassays were conducted against five commonly used insecticides (quinolphos, chlorantraniliprole, chlorpyrifos, flubendimide, indoxacarb) and resistance ratios were determined by comparing the LC50 values of field populations with the susceptible laboratory population. Enzyme assays were performed to evaluate the role of detoxifying enzymes like cytochrome p 450s, glutathione S-transferases and carboxylesterases in conferring resistance. Result: The resistance ratios varied from 56.48 to 311-fold for quinolphos, 3.84 to 97-fold for chlorantriniliprole, 15.76 to 92.088-fold for chlorpyrifos, 30.86 to 75.26-fold for flubendimide and 33.21 to 82.95-fold for indoxacarb. The activities of detoxification enzymes were significantly higher in the midgut of field collected M. vitrata larvae. The data suggests rational use of various insecticides in rotation so as to delay the further development of resistance in M. vitrata.

Long-Term Exposure to Lambda-Cyhalothrin Reveals Novel Genes Potentially Involved in Aedes aegypti Insecticide Resistance

Insecticide resistance in Aedes aegypti populations hinders vector control programs. Many studies have focused on the classical mechanisms, kdr mutations, and metabolic enzymes to understand the development of insecticide resistance. In this study, we subjected a strain of Ae. aegypti to selective pressure for 13 consecutive generations to understand the development and extent of insecticide resistance. We delved into the transcriptomics of this pressured strain to gain insights into the molecular changes underlying insecticide resistance in Ae. aegypti. Our data suggest mosquito resistance is influenced by additional mechanisms that are difficult to explain using only classical mechanisms. The response by mosquitoes varies depending on the exposure time. Initially, when mosquitoes are in contact with insecticides, they modulate the expression of metabolic enzymes and gain some point mutations in the sodium channel genes. After long-term exposure, the mosquitoes respond to insecticides by expressing different proteins involved in the cuticle, energetic metabolism, and synthesis of proteases. We propose a model that includes these novel mechanisms found after prolonged insecticide exposure, which work in conjunction with established mechanisms (kdr and metabolic resistance) but have a different timeline in terms of expression and appearance.

Consequences of insecticide overuse in Hungary: assessment of pyrethroid resistance in Culex pipiens and Aedes albopictus mosquitoes

BackgroundMosquitoes, as vectors of various pathogens, have been a public health risk for centuries. Human activities such as international travel and trade, along with climate change, have facilitated the spread of invasive mosquitoes and novel pathogens across Europe, increasing the risk of mosquito-borne disease introduction and their spread. Despite this threat, mosquito control in Hungary still relies predominantly on chemical treatments, which poses the risk of developing insecticide resistance in local populations. While pyrethroid resistance has been documented in several countries, there is no information on this issue from Hungary. This study aims to investigate the presence of resistance in Hungarian mosquito populations by analyzing a native, already known disease vector and a recently established invasive species with public health significance.MethodsWe assessed the presence of knockdown resistance (kdr) mutations L1014F in Culex pipiens and V1016G and F1534C in Aedes albopictus mosquitoes, which are responsible for pyrethroid resistance. Mosquito specimens were investigated retrospectively, collected from previous years within the framework of local monitoring programs run in urban areas representing five regions of Hungary. The mutations in mosquitoes were detected individually by allele-specific polymerase chain reaction (PCR) and gel electrophoresis, following generally used protocols.ResultsIn Cx. pipiens, the kdr mutation was detected across all five collection sites, with resistance allele frequencies ranging from 18.1% to 36.3%. Resistance alleles were identified in homozygosity and heterozygosity with the susceptible allele, resulting in 53% of the investigated mosquitoes showing resistance to pyrethroids in the Hungarian populations. In contrast, for Ae. albopictus, the analyzed individuals were found to carry only the susceptible alleles, indicating a homozygous susceptible genotype across the investigated populations on the basis of V1016G and F1534C genes.ConclusionsOur work highlights the consequences of the unilateral and long-term use of chemical treatments on mosquitoes. This indicates an urgent need for a change of concept in mosquito control strategy in Hungary, as well as in countries where mosquito control still relies dominantly on insecticides. The restricted use of chemical treatment is highly recommended to prevent the development of pyrethroid resistance in recently established populations of the invasive Ae. albopictus, and to decrease the public health risk of vector-borne diseases.Graphical

Target site mutations and metabolic detoxification of insecticides in continental populations of Cimex lectularius and Cimex hemipterus (Hemiptera: Cimicidae).

In recent decades, the common and the tropical bed bugs have experienced a resurgence in many parts of the world. The evolution of insecticide resistance in bed bug populations is considered a significant factor contributing to this resurgence. We analyzed samples of Cimex lectularius L. and Cimex hemipterus (F.) from Europe (Spain 41, Switzerland 2, the Czech Republic 1), Asia (Hong Kong 34), North America (USA 14, Mexico 3), and South America (Colombia 3) to assess the prevalence and mechanisms of insecticide resistance. We identified specimens morphologically and barcoded them by sequencing the mitochondrial Cytochrome c oxidase subunit I (COI) and the 16S ribosomal RNA (16S rRNA) genes. Additionally, we screened segments of the voltage-gated sodium channel (VGSC) and the nicotinic acetylcholine receptor (nAChR) genes for point mutations associated with insecticide resistance and measured the activity of detoxifying enzymes. All samples from North America and Europe were identified as C. lectularius, whereas specimens from Hong Kong were C. hemipterus. Out of 64 C. lectularius samples tested for knockdown resistance (kdr) mutations, 90.6% contained at least 1 known mutation. All 35 C. hemipterus samples exhibited kdr mutations. A new mutation was identified in the pyrethroid target site in both common (F1524C) and tropical (F1450C) bed bugs. No resistance-associated mutations in the nAChR gene were found. Several populations that exhibited kdr mutations also showed elevated activity of detoxifying enzymes. The high frequency of kdr-associated mutations in bed bug populations from Spain and Hong Kong limits the efficacy of pyrethroids for their control.

Comparing simulated aerial and chemigation insecticide applications to manage western bean cutworm (Lepidoptera: Noctuidae) in corn.

The efficacy of aerial application and chemigation of insecticides is not well explored for western bean cutworm, Striacosta albicosta (Smith), management in corn. In the short term, inadequate application of insecticides can lead to control failures when insect pests are not effectively targeted. In the longer term, exposure to sublethal insecticide concentrations can contribute to the evolution of insecticide resistance. The goal of this study was to compare aerial application and chemigation under simulated conditions to determine the most effective insecticide application method for managing S. albicosta. Three larval stages were exposed to the highest and lowest label rates of commercial formulations of bifenthrin (36.8 and 112.1g a.i. ha-1) and chlorantraniliprole (52.7 and 75.1g a.i. ha-1). Experiments were conducted in spray chambers, utilizing a carrier volume of 18.7L ha-1 for aerial application and 1.57cm ha-1 for chemigation. Mortality was recorded at 16, 24, and 41h after infestation. The simulated aerial application was more effective than simulated chemigation in controlling S. albicosta, resulting in 100% mortality 24h after infestation. Within the chemigation applications, chlorantraniliprole treatments were effective at both rates for all instars, while the high rate of bifenthrin exhibited greater efficacy than the lower rate. In conclusion, it was evidenced that the same insecticide active ingredients do not yield equivalent efficacy when applied via aerial application compared to chemigation. The present study highlights the importance of selecting appropriate insecticide application methods in controlling S. albicosta larvae.

Comparative Proteomics of Resistant and Susceptible Strains of Frankliniella occidentalis to Abamectin.

Western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae) is an invasive agricultural pest with developed resistance to abamectin in some strains due to frequent treatment with the pesticide. In this study, we examined differentially expressed proteins (DEPs) between abamectin-resistant (AbaR; under abamectin selective pressure) and susceptible strains (AbaS; without abamectin selective pressure) of F. occidentalis. Proteins were isolated from second instar larvae of both strains and separated via two-dimensional polyacrylamide gel electrophoresis. Nano-flow liquid chromatography-tandem mass spectrometry identified selected protein spot features. From 70 DEPs, 43 spot features were identified: A total of 23 showed an increase in abundance, and 20 were down-regulated in response to abamectin pressure. The enzymatic and structural proteins were classified into the functional groups of macromolecular metabolisms, signaling and cellular processes, immune system, genetic information processing, and exoskeleton-related proteins. The up-regulation of exoskeleton-related proteins may contribute to forming a thicker cuticle, potentially hindering abamectin penetration, which is an interesting finding that needs further investigation. Two novel proteins, triacylglycerol lipase and cuticle protein CPF 2, were only expressed in AbaR. This work provides insights into abamectin resistance mechanisms in F. occidentalis, which will provide important information for developing insecticide resistance management approaches for this pest.

First detection of the S989P+V1016G+D1763Y haplotype and expansion of voltage-gated sodium channel mutations in Aedes aegypti in Taiwan in 2016-2023.

Aedes aegypti transmits various arthropod-borne diseases such as dengue, posing a significant burden to public health in tropical and subtropical regions. Pyrethroid-based control strategies are effective in managing this vector; however, the development of insecticide resistance has hindered these efforts. Hence, long-term monitoring of insecticide resistance in mosquito populations is crucial for effective vector and disease control. In this study, we identified insecticide resistance due to a voltage-gated sodium channel (vgsc) mutation in Ae. aegypti in Taiwan between 2016 and 2023. In total, 1,761 field-caught Ae. aegypti samples from Tainan, Kaohsiung, and Pingtung were genotyped. The frequencies of S989P, V1016G, T1520I, F1534C, and D1763Y amino acid variants increased over the surveillance period. A T1520I mutation was detected for the first time and has since rapidly spread throughout Taiwan. The triple-mutant haplotype PGTFY was first documented in Ae. aegypti. Moreover, the unmutated haplotype vanished in Taiwan, suggesting that the vgsc mutations were fixed in local populations of Ae. aegypti. Five resistance-associated genotypes, SVTCD/SVTCD, SGTFY/PGTFD, SVTCD/SGTFY, PGTFD/PGTFD, and SVTCD/PGTFD, exhibited an increased frequency and accounted for 76% of the total field population. We also detected the resistant genotype SVICD/PGTFD, and its frequency increased 13-fold in the field between 2016 and 2023. Moreover, we also observed that mutations differed geographically, with S989P mainly found in Kaohsiung and V1016G in Kaohsiung and Pingtung. The frequency of T1520I was noticeably higher in Kaohsiung, and D1763Y occurred mainly in Tainan. The emergence and expansion of mutations along with the disappearance of wild-type mosquitoes in Taiwan underscores the threat of resistance and difficulty of mosquito control in Taiwan as well as globally. This study determined the insecticide resistance status of Ae. aegypti in Taiwan, and the findings will be helpful for resistance monitoring in areas where pyrethroids are used to control Ae. aegypti.

Fitness costs associated with laboratory induced resistance to chlorpyrifos in Spodoptera litura

Spodoptera litura (Fabricius) is a major polyphagous pest of global relevance due to the damage it causes to various crops. Chlorpyrifos (CPF) is generally used by farmers to manage S. litura, however, its widespread use has resulted in the development of insecticide resistance. Therefore, in the present study, a population of S. litura was exposed to CPF for eight generations under laboratory conditions, resulting in a 2.81-fold resistance ratio compared with that of the unselected laboratory population (Unsel-Lab). The exposure of Unsel-Lab and CPF-Sel populations to their respective lethal and sublethal concentrations reduced larval survival, adult emergence, and prolonged development period, and induced morphological deformities in adults. The reproductive and demographic parameters were also significantly lowered in the treated larvae of both populations at higher concentrations. Moreover, hormetic effects on fecundity, next-generation larvae, the net reproductive rate (R0), and relative fitness (Rf) were observed at lower sublethal concentrations of CPF, specifically at the LC5 of Unsel-Lab and the LC10 of the CPF-Sel population. Sublethal exposure to CPF negatively affected the biological and demographic parameters in both populations, although the impact was more prominent in the CPF-Sel population. The relative fitness of the CPF-Sel was also greatly reduced at the LC50 (0.28) compared to that of the Unsel-Lab population. However, only a marginal trade-off of insecticide resistance evolution was observed in the CPF-Sel population in the absence of insecticide selection pressure. These results provide useful information for devising improved pest management strategies for CPF resistance in S. litura.

Impact of field evolved resistance on biological parameters of non-targeted Aedes aegypti populations.

The yellow fever mosquito, Aedes aegypti L., known for transmitting viruses causing yellow fever, dengue, chikungunya, and Zika fever, presents a substantial risk to global human health. The development of insecticide resistance in disease vectors has become a significant problem in Ae. aegypti. Monitoring insecticide resistance is essential for resistance management in Ae. aegypti. This study involved the collection of Ae. aegypti populations from four important cotton-growing regions in southern Punjab, Pakistan, for resistance monitoring over a two-year period (2021-2022). This study also assessed the impact of insecticide resistance on biological parameters of Ae. aegypti. Moderate-to-high levels of resistance were observed against all the tested insecticides viz., chlorpyrifos, chlorfenapyr, deltamethrin, flonicamid, spirotetramat, and spinetoram. However, compared to the Lab-susceptible population, higher levels of resistance to buprofezin (59.03-84.40) and imidacloprid (68.49-100.01) were found in all populations. This high resistance can be attributed to increased use of these two insecticides in cotton fields, as compared to other insecticides. In the lab-susceptible population, higher values for the intrinsic rate of increase (r) and the net reproductive rate (R0) i.e., 0.20 per day and 23.24 offspring/female were observed, respectively. This was also validated by population projection data where more than 2.5-fold adults (1,020,361.80 individuals) were calculated in the Lab-susceptible population as compared to the most resistant populations. Sublethal exposure to insecticides may induce physiological or biochemical changes in organisms, subsequently influencing the biological traits. Resistance monitoring provides essential guidance before launching a successful chemical-based vector management program.

Evolutionary consequences of long-distance dispersal in mosquitoes.

Long-distance dispersal (LDD) provides a means for mosquitoes to invade new regions and spread adaptive alleles, including those conferring insecticide resistance. Most LDD takes place on human transport vessels and will typically be rarer and more directionally constrained than active flight but can connect populations and regions that are otherwise mutually inaccessible. These features make LDD worthy of specific consideration in mosquito research. This paper reviews recent evolutionary research on LDD and its consequences for mosquito populations and mosquito control. LDD is the main source of mosquito range expansions, and genomic methods can now trace the origins of new invasions to specific towns or cities. Genomic methods can also give a rough indication of the number of invaders, which if very small may lead to the stochastic loss of advantageous alleles during invasion bottlenecks. Once invasions are established, LDD spreads adaptive alleles between populations. Emerging insights into insecticide resistance evolution indicate that LDD has repeatedly spread resistance mutations across global species ranges, but these broad patterns are convoluted by two other evolutionary processes: parallel adaptation at the same gene or gene cluster and polygenic adaptation at different genes in different populations. Together, these processes have produced patterns of similarity and dissimilarity at resistance genes that are decoupled from geographical distance. LDD within cities is less well studied but is important for planning and evaluating local control efforts. Urban investigations of LDD may help identify areas experiencing weaker selection pressures from insecticides and isolated areas to target for control.

The role of evolving niche choice in herbivore adaptation to host plants.

Individuals living in heterogeneous environments often choose microenvironments that provide benefits to their fitness. Theory predicts that such niche choice can promote rapid adaptation to novel environments and help maintain genetic diversity. An open question of large applied importance is how niche choice and niche choice evolution affect the evolution of insecticide resistance in phytophagous insects. We, therefore, developed an individual-based model based on phytophagous insects to examine the evolution of insecticide resistance and niche choice via oviposition preferences. To find biologically realistic parameter ranges, we performed an empirical literature survey on insecticide resistance in major agricultural pests and also conducted a density-dependent survival experiment using potato beetles. We find that, in comparison to a scenario where individuals randomly oviposit eggs on toxic or non-toxic plants, the evolution of niche choice generally leads to slower evolution of resistance and facilitates the coexistence of different phenotypes. Our simulations also reveal that recombination rate and dominance effects can influence the evolution of both niche choice and resistance. Thus, this study provides new insights into the effects of niche choice on resistance evolution and highlights the need for more studies on the genetic basis of resistance and choice.

Development and application of species ID and insecticide resistance assays, for monitoring sand fly Leishmania vectors in the Mediterranean basin and in the Middle East.

Development of insecticide resistance (IR) in sand fly populations is an issue of public health concern, threatening leishmaniasis mitigation efforts by insecticide-based vector control. There is a major knowledge gap in the IR status of wild populations worldwide, possibly attributed to the unavailability of specialized tools, such as bioassay protocols, species baseline susceptibility to insecticides and molecular markers, to monitor such phenomena in sand flies. Sand fly populations from (semi-)rural regions of Greece, Turkey and Iran were sampled and identified to species, showing populations' structure in accordance with previously reported data. Genotyping of known pyrethroid resistance-associated loci revealed the occurrence of voltage-gated sodium channel (vgsc) mutations in all surveyed countries. Knock-down resistance (kdr) mutation L1014F was prevalent in Turkish regions and L1014F and L1014S were recorded for the first time in Iran, and in Turkey and Greece, respectively, yet in low frequencies. Moreover, CDC bottle bioassays against pyrethroids in mixed species populations from Greece indicated full susceptibility, using though the mosquito discriminating doses. In parallel, we established a novel individual bioassay protocol and applied it comparatively among distinct Phlebotomus species' populations, to detect any possible divergent species-specific response to insecticides. Indeed, a significantly different knock-down rate between P. simici and P. perfiliewi was observed upon exposure to deltamethrin. IR in sand flies is increasingly reported in leishmaniasis endemic regions, highlighting the necessity to generate additional monitoring tools, that could be implemented in relevant eco-epidemiological settings, in the context of IR management. Our molecular and phenotypic data add to the IR map in an area with otherwise limited data coverage.

Three years of insecticide resistance evolution and associated mechanisms in Aedes aegypti populations of Ouagadougou, Burkina Faso.

Resistance to insecticides is spreading among populations of Aedes aegypti, the primary vector of important human arboviruses. The escalating insecticide resistance poses a significant threat to dengue vector control, with an expanding number of countries affected by the disease. To gain a deeper insight into the evolution of insecticide resistance, it is essential to have longitudinal surveillance results, which are currently lacking, particularly from African Ae. aegypti populations. Here we report on three-years of surveillance of Ae. aegypti susceptibility to insecticide resistance phenotypes and associated kdr mutations in Burkina Faso, a country with regular dengue outbreaks. Ae. aegypti susceptibility to insecticides and the V410L, V1016I, and F1534C kdr target site mutations linked to pyrethroid insecticide resistance were monitored in Ouagadougou from 2016 to 2018. Larvae were collected from artificial containers at two sites and reared to adulthood in an insectary. Bioassays were conducted on female adults, along with a laboratory-susceptible strain, following standard WHO protocols. Allele-specific PCR genotyping assays were utilized to identify the V410L, V1016I, and F1534C kdr pyrethroid target site mutations. Bioassays revealed a high level of resistance to permethrin and deltamethrin that progressively increased over the three-year period in both localities. The 1534C mutation was nearly fixed throughout the three years at each locality, and while the closely-related 410L and 1016I mutations did not vary between localities, their frequency notably increased from 2016 to 2018. Interestingly, Ae. aegypti populations in both areas remained susceptible to bendiocarb, fenitrothion, and malathion. Modelling the mortality data further confirmed the escalating resistance trend over the years and emphasized the significant role played by the three kdr mutations in conferring resistance to pyrethroids. Mortality rates indicate that Ae. aegypti populations from Ouagadougou are becoming increasingly resistant to pyrethroid insecticides, likely due to an increase in the frequencies of the 410L and 1016I kdr mutations. Organophosphate insecticides are likely to be better alternative options for control.

Physiological and Molecular Mechanisms of Lepidopteran Insects: Genomic Insights and Applications of Genome Editing for Future Research.

Lepidopteran insects are a major threat to global agriculture, causing significant crop losses and economic damage. Traditional pest control methods are becoming less effective due to the rapid evolution of insecticide resistance. This study explores the current status and genomic characteristics of 1315 Lepidopteran records, alongside an overview of relevant research, utilizing advanced functional genomics techniques, including RNA-seq and CRISPR/Cas9 gene-editing technologies to uncover the molecular mechanisms underlying insecticide resistance. Our genomic analysis revealed significant variability in genome size, assembly quality, and chromosome number, which may influence species' biology and resistance mechanisms. We identified key resistance-associated genes and pathways, including detoxification and metabolic pathways, which help these insects evade chemical control. By employing CRISPR/Cas9 gene-editing techniques, we directly manipulated resistance-associated genes to confirm their roles in resistance, demonstrating their potential for targeted interventions in pest management. These findings emphasize the value of integrating genomic data into the development of effective and sustainable pest control strategies, reducing reliance on chemical insecticides and promoting environmentally friendly integrated pest management (IPM) approaches. Our study highlights the critical role of functional genomics in IPM and its potential to provide long-term solutions to the growing challenge of Lepidopteran resistance.

Influence of Inert Minerals and Botanicals on Adult Emergence of Pulse Beetle, Callosobruchus maculatus (Fabricius), in Stored Blackgram

Background: Pulses hold significant global importance as a food source, with the pulse beetle, Callosobruchus maculatus, being a major pest affecting them. As consumer preferences shift towards insecticide residue-free food, pest management strategies are adapting. Inert minerals and botanicals offer a promising solution to address concerns about insecticide safety, resistance development, and regulatory standards. Hence, this study seeks to assess how these substances impact the emergence of C. maculatus adults. Methods: One kilogram of blackgram was taken in three replications and treated with inert minerals and botanicals. In each container, ten pairs of newly emerged adult beetles were introduced. A subsample of 50 g was taken in small plastic jars to record, the day when the first adult beetle emerged, the daily count of adult beetles, and the overall count of emerged adult beetles. Result: The research showed no significant difference between treatments and untreated control w.r.t day of first adult emergence of C. maculatus. The percentage of adult emergence of C. maculatus in blackgram seeds treated with diatomaceous earth was 21.06% which was significantly the lowest value when compared to untreated control (86.03%). The total count of emerged adult beetles from the main sample was less in diatomaceous earth (135.33 adults) against untreated control (751.67 adults). Among all the treatments tested, diatomaceous earth performed better in controlling the adult emergence of C. maculatus.

Toxicity and residual activity of insecticides to Grapholita molesta (Lepidoptera: Tortricidae) in apple orchards: implications for insecticide resistance management.

Organophosphate (OP) insecticides have been used to control Grapholita molesta (Busck, 1916) in Brazil since 1990. However, the evolution of pest insecticide resistance and toxicological reassessments has led to the replacement of OPs with other chemical groups. This study evaluated the toxicity of the insecticides abamectin + cyantraniliprole (1.1 + 3.7g a.i./100L-1), acetamiprid + etofenproxi (9.1 + 16.5g a.i./100L-1), emamectin benzoate (0.5g a.i./100L-1), Sophora flavescens (Fabales: Fabaceae) (22.8g a.i./100L-1), phosmet (87.5g a.i./100L-1), and indoxacarb (11.2g a.i./100L-1) to eggs, larvae, and adults of G. molesta. Additionally, the residual activity of these insecticides in apple orchards was assessed, and the diagnostic concentration for resistance monitoring was estimated using LC99 values (Lethal Concentration that causes 99% mortality in a susceptible population). In larval studies, all insecticides resulted in mortality rates of more than 90%. The insecticide acetamiprid + etofenproxi reduced larval hatching by 99%. This insecticide with phosmet and Sophora flavescens caused over 80% adult mortality and had a 14-day residual activity in apple orchards. The estimated LC99 (μg.ml-1) for resistance monitoring were 1.75 (indoxacarb), 6.45 (metaflumizone), 9.10 (acetamiprid + etofenproxi), 9.67 (Sophora flavescens), 36.13 (phosmet), and 45.61 (abamectin + cyantraniliprole). The insecticides evaluated have high toxicity for G. molesta, being new tools for integrated pest management and for insecticide resistance management in apple orchards.

Control efficacy of eight insecticides on Myzus persicae (Hemiptera: Aphididae) and insecticide resistance development of aphid populations collected from kimchi cabbage in South Korea

Insecticide control efficacy was investigated with Myzus persicae (Hemiptera: Aphididae) populations collected on kimchi cabbage across South Korea, and their insecticide resistance levels were evaluated. Using a standard leaf-dip bioassay, the lethality at recommended active ingredient rate and lethal concentration 50 (LC50) were acquired. Then, the resistance ratio was calculated as ratio between LC50 of field population and LC50 of laboratory population. Finally, regression analysis was conducted between the log-scaled resistance ratio and the lethality to address associations between the two estimators. Overall, sulfoxaflor and spirotetramat were the most effective insecticides, where > 80 % lethality was observed from almost all local populations. Nevertheless, five out of 12 local populations showed the resistance ratio > 5 to sulfoxaflor, suggesting resistance development to the insecticide. Imidacloprid and pyrifluquinazon also offered effective means to control M. persicae. However, large variations in the lethality, as well as the resistance ratio, were observed in imidacloprid. Deltamethrin was the least effective at recommended active ingredient rate yielding 20.2 to 63.2 % lethality, despite its low resistance ratio values. Finally, regression analysis revealed that there was in general significant negative correlation between the resistance level and the insecticide control efficacy in the insecticides evaluated. Moreover, the insecticide control efficacy declined with substantially varying rates among the insecticides with flonicamid, thiacloprid, and deltamethrin showing steeper slopes. These results indicate that both the current control efficacy and its projected decline regarding the resistance development should be taken into account together to formulate effective and sustainable management programs against M. persicae.

Toxicity and Sublethal Effect of Chlorantraniliprole on Multiple Generations of Aedes aegypti L. (Diptera: Culicidae).

Due to the quick development of insecticide resistance, it is crucial to optimize management programs by understanding the sublethal effects of effective insecticides like chlorantraniliprole on Aedes aegypti L. populations. Using age-stage and two-sex life tables, we investigated the sublethal impacts of chlorantraniliprole on Ae. aegypti. Larval duration in the progeny of exposed parents was reduced by 0.33-0.42 days, whereas, the longevity of male and female adults was decreased by 1.43-3.05 days. Similarly, the egg-laying capacity of F1 and F2 progeny of the exposed parents was significantly reduced from 27.3% to 41.2%. The mean generation time (T) increased up to 11.8% in exposed populations, and the net reproduction rate (Ro) decreased by 51.50-55.60%. After 24 h of chlorantraniliprole treatment, there was a significant increase in cytochrome P450 activity. Contrarily, the activity of glutathione S-transferase (GST) initially declined but started increasing after 48 h of treatment. This research highlights the importance of chlorantraniliprole in mosquito management, as well as the importance of considering sublethal effects when developing strategies to handle them. Having a thorough understanding of the harmful effects of insecticides on mosquito populations can greatly enhance the effectiveness of insecticide-based interventions, while also minimizing the risk of pest resurgence.