Current Resistance Status Research Articles

Current profile of phenotypic pyrethroid resistance in Rhipicephalus microplus (Acari: Ixodidae) populations sampled from Marathwada region of Maharashtra state, India.

This study examined the pattern of resistance to widely applied synthetic pyrethroids, i.e., cypermethrin and deltamethrin, against larvae of Rhipicephalus microplus ticks sampled from Marathwada region in Maharashtra, India. The study also examined the role of α- and β-esterases and glutathione-S-transferase (GST) in resistance development. All eight R. microplus isolates tested were resistant to deltamethrin (RL IV), having RR50 values from 6.88 to 131.26. LPT analysis exhibited the resistance level II deltamethrin resistance in Beed and Hingoli, III in Dharashiv, and IV in Sambhajinagar, Parbhani, Latur, Jalna, and Nanded isolates. The LIT analysis showed that Dharashiv field isolates had the lowest LC50 value of 229.09ppm against cypermethrin, while Sambhajinagar field isolates had the highest at 489.78ppm. The RR50 ranged from 1145.45 to 2448.9. Seven isolates were level I resistant to cypermethrin while the Jalna isolate was level II resistant. In larvae treated with deltamethrin and cypermethrin, the activity of α- and β-esterase enzymes increased significantly compared to control groups. The enzyme ratios in treated larvae ranged from 0.7533 to 1.7023 for α-esterase and 0.7434 to 3.2054 for β-esterase. The Hingoli isolate treated with cypermethrin exhibited the highest α-esterase activity (903.261), whereas Sambhajinagar isolate had the highest GST enzyme ratio (2.8224) after deltamethrin exposure. When exposed to cypermethrin, the Hingoli isolate showed the highest GST enzyme ratio, 2.0832. The present study provides the current resistance status in tick populations from Marathwada region indicating deltamethrin and cypermethrin to be ineffective for tick control. The results also suggest that SP compounds should be regulated in this region and alternative control strategies should be introduced.

Recent insights into pesticide resistance mechanisms in Plutella xylostella and possible management strategies.

Insects are incredibly successful and diverse organisms, but they also pose a significant threat to agricultural crops, causing potential losses of up to US$470 billion. Among these pests, Plutella xylostella (Linnaeus), a devastating insect that attacks cruciferous vegetables, alone results in monetary losses of around US$4-5 billion worldwide. While insecticides have effectively protected plants under field conditions, their use comes with various environmental and mammalian hazards. Additionally, insects are developing resistance to commonly used insecticides, rendering management strategies less effective. Arthropods employ a range of behavioral and biochemical mechanisms to cope with harmful chemicals, which contribute to the development of resistance. Understanding these mechanisms is crucial for addressing the issue of resistance. It is imperative to integrate strategies that can delay the development of resistance and enhance the efficiency of insecticides. Therefore, we present an overview of insecticide resistance in insects, focusing on P. xylostella, to provide insights into the current resistance status of this pest and propose tactics that can improve the effectiveness of insecticides.

Resistance monitoring in field populations of Chilo suppressalis (Lepidoptera: Crambidae) in Hubei Province to four insecticides in 2019–2022

AbstractChilo suppressalis is a highly destructive insect pest of rice crops. Chemical insecticides have been used as an effective method for controlling this pest. In this study, we evaluated the susceptibility of seven field populations of C. suppressalis from three regions in Hubei Province, China, to four different insecticides over a period of 4 years (2019–2022). Our results showed that the populations of C. suppressalis in these areas have evolved low to high levels of resistance to abamectin (Resistant Ratio, RR = 8.5–413.4). Furthermore, the field populations were susceptible to high levels of resistance to chlorantraniliprole (RR = 2.0–401.6) and showed moderate levels of resistance to triazophos (RR = 56.9–78.7) and chlorpyrifos (RR = 10.6–54.5). Correlation analysis indicated significant positive correlations between the susceptibility of abamectin and chlorantraniliprole and chlorpyrifos, as well as chlorpyrifos and chlorantraniliprole, and triazophos. This study provides valuable information on the current resistance status of field populations of C. suppressalis, which can aid in the judicious use of these insecticides and serve as an important reference for effective resistance management strategies.

Field Resistance to Cyantraniliprole in <I>Plutella Xylostella</I>

Cyantraniliprole belongs to new chemical class of diamides and used Plutella xylostella one of the highly devastating lepidopteran insect pests of cole crops has been found to develop resistance to cyantraniliprole worldwide including India . However their mechanism of resistance is not examined in Indian scenario. Hence a survey was conducted to analyse the current resistance status of field population of P. xylostella to cyantraniliprole. The maximum lethal concentration expressed by field population in Tamil Nadu was 19.81 ppm which had higher ratio (2828.57) of resistance to that of susceptible population. The enzyme analysis revealed the over expression of GST up to at 24 hr after exposure (HAE) and MFO up to 48 hr upon exposure. Further the synergistic study stated that PBO and DEM could increase the toxicity of cyantraniliprole to some extent.

Current Status of Insecticide Susceptibility in the Principal Malaria Vector, Anopheles gambiae in Three Northern States of Nigeria.

Background:Malaria is a major public health problem in Nigeria with 97% of its population with high morbidity and mortality. Mosquitoes play an important role in the transmission of malaria parasites. This study was conducted to evaluate the current resistance status of Anopheles gambiae to insecticides.Methods:Larvae of An. gambiae was collected from three zones; A, B and C differentiated on the basis of variation in agricultural ecosystems between August and November, 2018 in the northeast and northwestern parts of Nigeria. They were carefully reared to adult stage and insecticidal susceptibility tests were conducted.Results:The mosquitoes tested showed high levels of resistance to all the insecticides used with the exception of malathion. Study zone A, recorded 74% mortality after 24h to deltamethrin compared to 81% from zone B and 82% from zone C, respectively. Mosquitoes from zone B exposed to DDT had the highest level of resistance at 37% compared to 40% and 53% from zones A and C, respectively. Resistant to bendiocarb was also observed, with zone A having the lowest mortality of 44% compared to 48% from zone C and 55% from Zone B, respectively. According to the results of knockdown tests, mosquitoes from Zone A exposed to deltamethrin recorded the lowest knockdown across the study locations while zone B recorded the lowest knockdown for DDT.Conclusion:The results of the study provide an insight into the current status of An. gambiae to four major insecticides in northern Nigeria as guideline for mosquitocontrol.

Current resistance status of the brown planthopper Nilaparvata lugens (Stål) to commonly used insecticides in China and Bangladesh

Nilaparvata lugens (Stål) is a serious threat to rice production in Asian countries. Synthetic chemicals are widely used for its control. However, evolution of resistance in this pest to commonly used insecticides has been recorded during the last decades. In this study, we determined and compared current insecticide resistance levels of thirteen N. lugens populations from China and Bangladesh to eight insecticides by rice-stem dipping method. These results showed that N. lugens had developed high levels of resistance to imidacloprid (resistance ratio, RR = 2491.0–8078.5-fold), thiamethoxam (RR = 303.6–1253.6-fold), buprofezin (RR = 175.7–365.1-fold) and dinotefuran (RR = 49.9–596.0-fold), low to moderate levels of resistance to nitenpyram (RR = 12.1–67.3-fold) and sulfoxaflor (RR = 3.8–25.5-fold), but were susceptible to triflumezopyrim (RR = 0.2–1.1-fold) in China. Meanwhile, increased activities of detoxification enzymes (EST, GST and P450) were found in multiple-resistant FY19 field population, which also showed the significant changes in the expression levels of P450s compared to susceptible strain, especially CYP6ER1 (11.04-fold). In contrast, first report of insecticide resistance in Bangladesh showed high levels of resistance to imidacloprid (RR = 3680.1–4430.8-fold) and thiamethoxam (RR = 144.3–737.9-fold), low to moderate levels of resistance to dinotefuran (RR = 38.7–57.9-fold), buprofezin (RR = 28.5–149.1-fold) and nitenpyram (RR = 3.4–14.1-fold). In addition, significant differences in insecticide resistance level of N. lugens to nitenpyram and dinotefuran were observed between two countries in 2020. The present study will be beneficial for implementing effective resistance management strategies to prevent or delay resistance development in N. lugens.

The discovery of a novel knockdown resistance (kdr) mutation A1007G on Aedesaegypti (Diptera: Culicidae) from Malaysia

The usage of insecticide rendered the successful vector control program with the high usage of the pyrethroid. However, the intensive and extensive use of pyrethroid, causing resistance in Aedesaegypti and hampered the control program. Knockdown resistance (kdr) resulting from the Voltage-Gated Sodium Channel (VGSC) is one of the mechanisms of resistance in pyrethroid group insecticide. Investigating the phenotypic status of Ae.aegypti mosquitoes is a lead in knowing the current resistance status and as an indicator of the genotypic resistance. In this study, we investigate the resistance in phenotypic and genotypic of Ae.aegypti with a new kdr mutation point A1007G was detected. Using the adult bioassay, we tested the phenotypic resistance from the Selangor state against 0.75% permethrin, 0.05% deltamethrin with and without the addition of PBO synergist. Permethrin-resistant and deltamethrin-resistant, including susceptible samples, were subjected to genotyping analysis on mutation point in domain II and domain III of Voltage-Gated Sodium Channel (VGSC). Adult bioassay revealed that the Ae.aegypti was highly resistance toward 0.75% permethrin and 0.05% deltamethrin. The bioassay with the presence of PBO synergist showed an increment of mortality rate, but Ae.aegypti status is still resistance towards both insecticides. Genotyping result showed that three common kdr mutations (S989P, V1016G, and F1534C) have existed in the Ae.aegypti population. A new novel mutation on A1007G was also detected in this population, which is the first time reported. This study has brought a piece of information on the current resistance status in Ae.aegypti in Malaysia. The detection of new mutation point of A1007G has added the knowledge on the resistance in mosquitoes. Thus, this study will aid with the decision making in the usage of insecticides in the vector control program; before this invaluable insecticide rendered ineffective in killing mosquitoes.

Analysis of seasonal and annual field-evolved insecticide resistance in populations of Thrips hawaiiensis in banana orchards

Every season over the past decade, efficacious thrips insecticides have been commonly applied for control of Thrips hawaiiensis on banana crops in China. For effective thrips control, some insecticides have been used extensively against the thrips in numerous banana plantations. This study aims to examine the current resistance status and the dynamics regarding the changing frequencies of resistance in the field T. hawaiiensis populations. A total of 13 field samples from banana orchards (Chengmai, Lingao, Dongfang and Ledong located in Hainan Province, China) were collected monthly in 2014 to 2017, and selected individuals were used in bioassays assessing insecticide resistance and metabolic enzyme activity compared to a laboratory-susceptible strain. In 2014, the initial resistance survey found that all sampled populations were susceptible to spirotetramat and cyantraniliprole, while Lingao and Chengmai population showed a moderate resistance to imidacloprid, acetamiprid, abamectin and spinetoram. Further, seasonal and annual analysis of resistance dynamics with imidacloprid, abamectin and spinetoram demonstrated that resistance in field populations of T. hawaiiensis developed quickly within a season (from April to August 2016), but resistance was unstable over subsequent seasons (April 2015, 2016 and 2017). Moreover, synergism experiments using enzyme inhibitors together with metabolic enzyme assays revealed that field-evolved insecticide resistance in T. hawaiiensis was closely associated with the elevated metabolic enzymes. The observed resistance increase within a season was attributed mainly to the intense use of these insecticides and short generation time of thrips. These findings suggest that a rotation system using efficacious thrips insecticides should be implemented for sustainable thrips control to reduce the potential of resistance development.

Current Resistance Status to Synthetic Pyrethroid Insecticides in Aedes aegypti (Diptera: Culicidae) Populations from Different regions of Bogor City, Indonesia

Current Resistance Status to Synthetic Pyrethroid Insecticides in Aedes aegypti (Diptera: Culicidae) Populations from Different regions of Bogor City, Indonesia

Nozokomiyal Diyarelerdeki Clostridium difficile İnsidansı Atlanıyor mu?

Clostridium difficile (C. difficile) is a Gram-positive, obligatory anaerobe, spore-forming microorganism and is highly associated with the nosocomial infections. The incidince of nosocomial diarrhoea and C. difficile-associated nosocomial diarrhoea rates are not clear in our country. To determine the C. difficile-associated nosocomial diarrhoea incidence, to review the current resistance status of C. difficile, and to evaluate diagnostic and therapeutic approaches for this pathogen were the aims of the present study. This prospective clinical study included 100 diarrhoea samples from hospitalized patients in Istanbul University Cerrahpasa Medical Faculty of. The diarrhoea samples were investigated by culture, card test and ELISA methods and bacterial resistance profiles were shown with the E-test method. Toxin A/B was found positive at 30/100 patients (30%) by ELISA. The duration of hospitalization and diarrhoea period were significantly longer in Toxin A/B positive patients than negative patients (p<0.05). Recurrences detected in 41% of Toxin A/B positive patients (statistically not significant but clinically may be important). When ELISA was accepted as the main test, the sensitivity and specificity of culture and card test methods were found as 56%, 75% and 76%, 80%, respectively. The C. difficile resistance rates were determined for metronidazole as 29.4%, for vancomycin and teikopilanin as 2.9%. Our results support that the C. difficile is still an important factor in nosocomial diarrhoea. Furthermore, highness of antibiotic resistance for metronidazole may be caused by difficulties in treatment. The results indicate the necessity of further studies to develop control measures and effective treatment options for patients.

Assessment of field evolved resistance to some broad-spectrum insecticides in cotton jassid, Amrasca devastans from southern Punjab, Pakistan

Resistance management, targeting insect pests is one of the key components in developing integrated pest management strategies. Arguably, resistance monitoring is a scientific undertaking that can support and inform resistance management tactics and strategies. To monitor the current resistance status in Amrasca devastans against conventional insecticides (deltamethrin, bifenthrin, cypermethrin, chlorpyrifos, profenofos, acephate, and methomyl) which are used by the farming community as the predominant means to control this pest. Field populations of A. devastans were collected from six different districts: Multan, Bahawalpur, Khanewal, Lahore, Dera Ghazi Khan and Muzaffargarh from Punjab in Pakistan. The adult populations tested were 11.10–92.87 times more resistant to deltamethrin, 5.87–14.11 times more to bifenthrin, 3.16–17.5 times more to cypermethrin, 2.65–36.42 times more to chlorpyrifos, 7.28–57.71 times more to profenofos, 1.65–11.13 times more to acephate and 2.55–43.31 times more to methomyl as compared to control (lab population). In our study, no to high levels of resistance were observed against pyrethroids and organophosphates. Development of resistance to these pyrethroids and organophosphates might be due to the injudicious use of these types of insecticides in field crops. This study suggests that use of these insecticides should be minimized to avoid development of resistance in A. devastans. Future studies are also recommended to use new chemistry insecticides with novel modes of action and/or insecticide mixtures that may reduce the reliance of the farming communities on these insecticides.

Insecticide Resistance Status of Field Populations of &lt;I&gt;Spodoptera exigua&lt;/I&gt; (Lepidoptera: Noctuidae) From China

Beet armyworm, Spodoptera exigua (Hübner), is a serious pest of vegetables in China, and its control is heavily dependent on chemical insecticides. The current resistance status of nine insecticides was investigated in 16 field populations collected from seven provinces of China during 2009-2012. Compared with the susceptible strain WH-S, some field populations evolved various levels of resistance to eight of the nine insecticides tested: emamectin benzoate (4- to 348-fold), indoxacarb (2- to 41-fold), spinosad (5- to 38-fold), chlorantraniliprole (2- to 44-fold), tebufenozide (2- to 87-fold), chlorfluazuron (3- to 31-fold), cypermethrin (79- to 1240-fold), and chlorpyrifos (8- to 3,080-fold), but no significant resistance was detected to chlorfenapyr (0.4- to 7-fold). This indicates that chlorfenapyr has no cross-resistance with these other currently used insecticides. Four consecutive years' resistance screening at two places shows that resistance patterns were different between populations from Luhe (Jiangsu Province) and Fengxian (Shanghai), which are approximately 300 km apart. Resistance levels to chlorpyrifos were much higher in populations from Luhe (877- to 3,080-fold) than from Fengxian (8- to 110-fold). Fengxian populations developed moderate levels of resistance to tebufenozide (13- to 87-fold), but no resistance in Luhe populations (2- to 6-fold). However, Luhe populations developed moderate levels of resistance to chlorfluazuron (21- to 31-fold), but there was no resistance in Fengxian populations (3- to 5-fold). It is suggested that local insecticide selection determined resistance patterns although S. exigua has long-distance migratory potential. Adaptive resistance management tactics (such as rotations) should be designed and implemented based on the resistance patterns of S. exigua for each geographic area.

Current resistance status to temephos in Aedes aegypti from different regions of Argentina

In Argentina, more than 25,000 cases of dengue were reported in the summer of 2009, even in provinces where the disease was formerly absent. We analysed the susceptibility levels to the larvicide temephos in seven populations of Aedes aegypti, the primary vector of dengue, collected during summer 2007/2008, using the susceptible Rockefeller strain as a control. Although no control failures were observed during the experiment, a majority of the lethal concentration and resistance ratio values indicate an incipient resistance. An integrative program to monitor the resistance of Ae. aegypti to insecticides is needed in the country.

Insecticide resistance of Helicoverpa armigera to endosulfan, carbamates and organophosphates: the Spanish case

Helicoverpa armigera is a major pest on a wide range of crops in Europe, Africa, Asia and Australia. Insecticide treatments are currently indispensable for its control in almost all crops, which has resulted in insecticide resistance occuring in some situations. However, since information about insecticide resistance of H. armigera in Europe is very limited, the current resistance status of this pest was investigated in Spain from 1995 to 1999. Toxicological bioassays were conducted in the laboratory, LD 50's estimated by probit analysis and resistance factors (RF) calculated at the LD 50 level. Eleven chemicals, including endosulfan, carbamates (carbaryl, methomyl, thiodicarb) and organophosphates (chlorpyrifos, fenitrothion, methamidophos, azinphos-methyl, trichlorphon, acephate, monocrotophos) were tested. Ninety-seven percent of insecticide–strain combinations showed susceptibility (RF=1) or low insecticide resistance (RF=2–10) (157 of 162, 97%). Moderate resistance (RF=11–18) was only recorded to carbamates (carbaryl, methomyl and/or thiodicarb) in five strains. Insecticide resistance of H. armigera in Spain was therefore not as high or widespread as in other areas of the world. Since insecticide pressure against the pest in Spain is not likely to be lower, nor IPM implementation better, than elsewhere, additional factors that potentially account for low levels of insecticide resistance of H. armigera, including migration and cropping structure leading to the existence of refugia are discussed from an agroecological perspective.