Moderate Levels Of Resistance Research Articles

Distribution and Mechanism of Japanese Brome (Bromus japonicus) Resistance to ALS-Inhibiting Herbicides in China.

Bromus japonicus is a common monocot weed that occurs in major winter wheat fields in the Huang-Huai-Hai region of China. Pyroxsulam is a highly efficient and safe acetolactate synthase (ALS)-inhibiting herbicide that is widely used to control common weeds in wheat fields. However, B. japonicus populations in China have evolved resistance to pyroxsulam by different mutations in the ALS gene. To understand the resistance distribution, target-site resistance mechanisms, and cross-resistance patterns, 208 B. japonicus populations were collected from eight provinces. In the resistant population screening experiment, 59 populations from six provinces showed different resistance levels to pyroxsulam compared with the susceptible population, of which 17 B. japonicus populations with moderate or high levels of resistance to pyroxsulam were mainly from the Hebei (4), Shandong (4) and Shanxi (9) Provinces. Some resistant populations were selected to investigate the target site-resistance mechanism to the ALS-inhibiting herbicide pyroxsulam. Three pairs of primers were designed to amplify the ALS sequence, which was assembled into the complete ALS sequence with a length of 1932 bp. DNA sequencing of ALS revealed that four different ALS mutations (Pro-197-Ser, Pro-197-Thr, Pro-197-Phe and Asp-376-Glu) were found in 17 moderately or highly resistant populations. Subsequently, five resistant populations, QM21-41 with Pro-197-Ser, QM20-8 with Pro-197-Thr and Pro-197-Phe, and QM21-72, QM21-76 and QM21-79 with Asp-376-Glu mutations in ALS genes, were selected to characterize their cross-resistance patterns to ALS inhibitors. The QM21-41, QM20-8, QM21-72, QM21-76 and QM21-79 populations showed broad-spectrum cross-resistance to pyroxsulam, mesosulfuron-methyl and flucarbazone-sodium. This study is the first to report evolving cross-resistance to ALS-inhibiting herbicides due to Pro-197-Phe mutations in B. japonicus.

Bacteriological Evaluation of Surface and Groundwater used for Domestic Purposes in Ibadan

The right to safe and clean drinking water is a human right, unfortunately many communities rely on unsafe and contaminated water for drinking and domestic purposes. Through improper sewage and hospital waste disposal, pathogenic and antibiotic resistant bacteria have found their way to natural water sources used by humans. In this study we aim to profile pathogenic bacteria and resistant Escherichia coli (E. coli) from surface and ground water sources in three local government areas of Oyo state. 30 water samples were collected randomly from the selected local government areas. Bacteriological, biochemical and antibiotic-resistant analysis was carried out on the isolated bacteria from the water samples. E. coli (28.30%) and Kleb pneumoniae (23.77%) were the predominant bacteria isolates, while Shigella (16.22%) and Salmonella (16.22%) also had substantial percentages. Nineteen E. coli was isolated and identified, with high antibiotic resistance rates observed in nalidixic Acid (100%), augmentin (100%), ampiclox (94.74%) and third-generation cephalosporins. Conversely, moderate levels of resistance were observed in nitrofurantoin (55.55%), cefepime (57.89%), and second-generation fluoroquinolones. This study reveals substantial pathogenic bacteria and antibiotic resistant E. coli in water samples which endangers the health of communities’ dependent on these water sources and exposes the inhabitants to antibiotic-resistant organisms from contaminated water used for domestic purposes. It is crucial to put in place water treatment measures and quality monitoring programmes in order to guarantee that the populace has access to clean and safe drinking water.

Optimization of inoculum production of Stemphylium botryosum for large-scale resistance screening of lentils

BackgroundStemphylium blight incited by Stemphylium botryosum poses a significant threat to lentil crops worldwide, inducing severe defoliation and causing substantial yield losses in susceptible varieties under favorable conditions. While some moderate levels of resistance have been identified within lentil germplasm, a low number of resistant cultivars are available to farmers. Adding to the common constraints of resistance breeding, a notable challenge is generating a sufficient number of spores for large-scale screenings, which are essential for pinpointing additional sources of resistance for integration into breeding programs. Therefore, there is a pressing need to improve existing screening methods and tailor them for large-scale material selection. In pursuit of this objective, a protocol for the efficient production of fungal material has been adapted.ResultsOptimization of fungal material production was successfully achieved by comparing the use of fungal mycelia and spores. Spore production was found to be optimal when produced on solid V8-PDA(hi) medium, while liquid Richard’s medium was identified as superior for mycelium yield. Furthermore, a refined screening method was developed by evaluating the resistance of six lentil accessions to stemphylium blight. This assessment included the use of either fungal mycelia (at densities ranging from 1 to 5 g L− 1) or spores (with densities ranging from 5 × 104 to 2 × 105 conidia mL− 1) under three different relative humidity levels (from 50 to 100%). Both humidity levels and inoculum dose significantly influenced the final disease rating (DR) and the relative Area Under the Disease Progress Curve (rAUDPC). Differences among genotypes in final symptom severity (DR) became more pronounced after inoculation with inoculum densities of 5 g L− 1 of mycelium or of 105 and 2 × 105 conidia mL− 1 of spore under 100% relative humidity. Given the challenges associated with the large-scale production of S. botryosum spores, inoculations with 5 g L− 1 of mycelium is highly recommended as a practical alternative for conducting mass-scale screenings.ConclusionsThe findings from this study underscore the critical importance of maintaining high level of humidity during inoculation and disease progression development for accurately assessing resistance to stemphylium blight. The optimization of mycelial production for suspension inoculation emerges as a more reliable and efficient approach for conducting large-scale screening to assess germplasm resistance against stemphylium blight in lentil crops.

Canopy gaps facilitate establishment of invasive plants in a subtropical broadleaved forest of central Nepal

Plant invasions are major threats to the biodiversity and ecosystem function worldwide. In particular, forests are one of the highly affected ecosystems by invasive alien plant species (IAPS). In spite of several previous studies on plant invasion issues in forests, the role of tree canopy gaps in the establishment of IAPS is poorly understood, particularly in Nepal Himalaya. In this study, we examined the effect of tree canopy gaps on IAPS diversity and abundance in Shorea robusta dominated subtropical mixed broadleaved forest in central Nepal. Fifty pairs of plots (10 m × 10 m) were sampled, with a plot of a pair sampled in a canopy gap and its counterpart 20 m away into the forest interior within tree canopy. In every plot, the cover of the individual IAPS was estimated visually, and other environmental variables such as tree canopy, light intensity, slope, litter depth, tree basal area were measured. Higher number of IAPS (9 species) and their cover (31%) were measured in the canopy gaps than in the plots with tree canopy (6 species; 5% cover), suggesting that tree canopy in these forests provide moderate level of resistance to plant invasions. Moreover, the IAPS cover increased with increasing size of canopy gap. Similarly, IAPS richness increased with the age of gap but it was independent of the gap size. Non-metric multidimensional scaling revealed that the IAPS community within forest canopy was a subset of species found in forest gaps, suggesting that the canopy opening has facilitated establishment of IAPS in the studied forests. Therefore, monitoring forest gaps can be helpful in detecting IAPS in their early stage of invasion so that the effective control measures can be implemented before the IAPS are widespread and problematic at the landscape level.

A diallel study to detect genetic background variation for FHB resistance in winter wheat

Breeding for resistance to Fusarium head blight (FHB) relies strongly on a limited number of larger-effect resistance QTL that have been mapped and associated with nearby markers. Smaller-effect (background) resistance QTL may also contribute moderate levels of resistance yet are mostly poorly characterized. Overall resistance of a genotype is determined by the combined action of both types of resistance QTL. This study aimed to identify well-adapted, advanced hard red winter (HRW) wheat breeding lines with useful background resistance QTL. A diallel trial consisting of 11 parents and 55 non-reciprocal F1 hybrids was tested for Type II FHB resistance in a replicated greenhouse experiment. Significant differences were detected among entries for disease severity (DS), general combining ability (GCA) and specific combining ability (SCA) with four parents being identified as the best general combiners with lowest DS. The ratio of GCA:SCA effects suggested that additive QTL effects were of primary importance. Overall, resistance QTL showed incomplete dominance, an excess of dominant alleles, and a greater contribution of positive effect genes. F2 of the six best F1 hybrids with the lowest DS were compared in a second greenhouse FHB trial to select possible transgressive segregates for continued evaluation and line development.

Fenoxaprop-P-ethyl, mesosulfuron-ethyl, and isoproturon resistance status in Beckmannia syzigachne from wheat fields across Anhui Province, China

Severe infestations of American sloughgrass (Beckmannia syzigachne (Steud.) Fernald) in wheat fields throughout Anhui Province, China, pose a significant threat to local agricultural production. This study aims to evaluate the susceptibility of 37 B. syzigachne populations collected from diverse wheat fields in Anhui Province to three commonly used herbicides: fenoxaprop-P-ethyl, mesosulfuron-ethyl, and isoproturon. Single-dose testing revealed that out of the 37 populations, 31, 26, and 11 populations had either evolved or were evolving resistance to fenoxaprop-P-ethyl, mesosulfuron-ethyl, and isoproturon, respectively. Among them, 25 populations displayed concurrent resistance to both fenoxaprop-P-ethyl and mesosulfuron-ethyl, while eight exhibited resistance to all three tested herbicides. Whole-plant bioassays confirmed that approximately 84% of the fenoxaprop-P-ethyl-resistant populations manifested high-level resistance (resistance index (RI) ≥10); 62% of the mesosulfuron-ethyl-resistant populations and 82% of the isoproturon-resistant populations exhibited low- to moderate-level resistance (2 ≤ RI <10). Three distinct target-site mutations were identified in 27% of fenoxaprop-P-ethyl-resistant populations, with no known resistance mutations detected in the remaining herbicide-resistant populations. The inhibition of cytochrome P450s (P450s) and/or glutathione S-transferases (GSTs) substantially increased susceptibility in the majority of resistant populations lacking mutations at the herbicide target site. In conclusion, resistance to fenoxaprop-P-ethyl and mesosulfuron-ethyl was widespread in B. syzigachne within Anhui Province's wheat fields, while resistance to isoproturon was rapidly evolving due to its escalating usage. Target-site mutations were present in approximately one-third of fenoxaprop-P-ethyl-resistant populations, and alternative mechanisms involving P450s and/or GSTs could explain the resistance observed in most of the remaining populations.

1601. Transmitted Drug Resistance in Treatment-Naïve People Living with HIV in Costa Rica

Abstract Background Transmitted drug resistance (TDR) occurs in people living with HIV infection (PLWH) who are not exposed to antiretroviral drugs but who are infected with a virus with mutations associated with resistance. In Costa Rica, HIV genotyping is performed in PLWH failing their first-line ART regimen, but it is not routinely done for all treatment-naïve PLWH before ART initiation, therefore, little is known about TDR prevalence. Methods The aim of this study was to determine the prevalence of TDR and the HIV mutation patterns. During 2020, 162 cases of newly diagnosed treatment-naïve PLWH from all of the country’s HIV clinics were included for a genotyping study. Viral ARN was extracted from plasma samples obtained from the HIV National Reference Laboratory and protease (PR), reverse transcriptase (RT), and integrase (IN) regions were amplified and sequenced. The HIV database Program (Stanford University) and the World Health Organization (WHO) 2009 TDR surveillance mutation list were used for interpretation of resistance-associated mutations. Results The overall prevalence of TDR was 36% (N=59/162). According to ART class, TDR was 22% in the nucleoside reverse transcriptase inhibitors (NRTI), followed by 13% in the non-nucleoside reverse transcriptase inhibitors (NNRTI); for the protease inhibitors (PI) and the integrase inhibitors (INI), TDR was 8% and 3%, respectively. (Figures 1-3). Most common mutations were: in NRTI, M41L (9.9%), and M184I (6.8%); in NNRTI, K103N (7.4%); in PI, M46I (4.3%); in INI, T97A (1.9%). (Table 1). The median age was 32 years-old (range: 16-71), and 91% were male. Median CD4 count was 420 cells/uL (range: 11-1670) and median viral load was 588337 copies/mL (range: 1220-10000000). According to CDC classification, 20% were stage C-3. Source: local database Source: local database Source: local database Conclusion This study population has a moderate level of HIV drug resistance (HIVDR) in ART-naïve PLWH and strongly implies the need to introduce HIVDR surveillance in Costa Rica. These findings confirm the TDR and highlight the need for systematic viral load monitoring and drug resistance testing at diagnosis. Continuous surveillance of newly infected individuals is required to help strategize the best ART regimen for these patients, and should prompt a change in current local recommendations for starting ART. Source: local database Disclosures All Authors: No reported disclosures

English

Whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is a notorious sucking insect pest of cotton and many other crops worldwide. It acts as a vector of various diseases and responsible for causing destruction to economy by damaging major crops. In order to determine, the resistance ratio and efficacy of insecticides against whitefly, field populations of B. tabaci were collected from four districts (Multan, Bahawalpur, Jhang and Toba Tek Singh) of Punjab, Pakistan, during 2020 to 2022. After collection, leaf-dip bioassay method was used to measure resistance level in whitefly populations by insecticides (spirotetramat, buprofezin, pyriproxyfen, diafenthiuron, and bifenthrin). The results showed that B. tabaci developed high to very high resistance against buprofezin (97.26-108.41 fold), high resistance level against bifenthrin (70.65-95.30 fold), moderate to high resistance against pyriproxyfen (35.68-80.46 fold), moderate level of resistance against diafenthiuron (20.72- 30.77 fold), low level of resistance against spirotetramat (11.66-18.60 fold), while comparing with susceptible population. The results of present study i.e., spirotetramat and diafenthiuron may be used as wise choices regarding the selection of insecticides against B. tabaci and delay insecticide resistance

Perbedaan Resistensi Siswa Laki-laki dengan Siswa Perempuan di SMP Telekomunikasi Pekanbaru

This study aimed to investigate the differences in resistance levels exhibited by male and female students towards their teachers. The research employed a quantitative approach with a comparative design, involving 75 students from a Junior High School named SMP Telekomunikasi Pekanbaru. The resistance levels of the students were measured using a resistance scale composed of various indicators. The validity and reliability of the research instrument were established through validity and reliability tests. The obtained data were subjected to Independent T-Test analysis to determine if there were significant differences in resistance between male and female students. The results indicated that both male and female students exhibited moderate levels of resistance towards their teachers. However, the analysis of the Independent T-Test revealed that there was no significant difference in resistance levels between the two genders (p &gt; 0.05). These findings suggest that gender did not play a significant role in influencing the resistance behaviors displayed by the students. In conclusion, the study contributes to the understanding of student resistance towards teachers, indicating that both male and female students exhibit moderate levels of resistance. The absence of significant gender-based differences in resistance levels suggests that other factors, such as teaching methodologies, classroom dynamics, and student perceptions, might be more influential in shaping resistance behaviors. These results highlight the importance of fostering positive teacher-student interactions and creating an environment where students feel heard and understood, regardless of their gender.

Analysis of Psychological Well-Being among Migrant Communities

This qualitative study aims to analysis the reality of psychological well-being (PWB) within immigrant communities in around Unimal Campus, Reuleut, Aceh. The primary objectives are to establish a model of psychological well-being specific to migrant communities in this locality and to identify the key factors that exert influence on their psychological well-being. The factors under investigation include economic status, social support, social networks, religiosity, personality traits, emotional regulation, and loneliness. By adopting a phenomenology qualitative approach, this research seeks to provide a comprehensive understanding of the experiences of immigrant communities in Reuleut. The study's subjects comprise immigrant communities residing in Reuleut, Aceh. Through in-depth interviews and thematic analysis, the research sheds light on the nuanced dimensions of psychological well-being within this context. The findings contribute to the broader understanding of psychological well-being factors that resonate within migrant communities, thereby presenting an informed perspective on the conditions and challenges faced by immigrants in Aceh. The outcomes of this study reveal that gender does not significantly impact the manifestation of resistance behaviors among students. The study underscores that both male and female students exhibit moderate levels of resistance towards teachers. This lack of gender-related distinctions in resistance levels underscores the potential influence of other factors, such as pedagogical approaches, classroom dynamics, and student perceptions. Consequently, this research underscores the imperative of cultivating positive teacher-student interactions and fostering an environment where students' voices are valued and comprehended, irrespective of their gender.

Accuracy and Concurrent Validity of a 5-point Rating of Perceived Exertion Scale for Selecting and Managing Moderate Level Resistance Training Intensity

Introduction: This investigation examined the prediction accuracy and concurrent validity of the Perceived Effort Continuum (PEC) RPE scale for use with two upper body resistance training machines. Methods: Twenty resistance trained participants (M = 14; F = 6) performed one exercise each on the seated row (SR) and chest press (CP) machines to obtain RPE estimation data and surface electromyographic recordings (sEMG). Each exercise was initiated with the lightest possible weight selections (WS) and terminated when the incrementally increased WS elicited a participant report of RPE 5. Results: Strong positive relationships existed between RPE and sEMG for the SR (r = .658, p &lt; .001), RPE and sEMG for the CP (r = .615, p &lt; .001), RPE and WS for the SR (r = .880, p &lt; .001), and RPE and WS for the CP (r = .779, p &lt;.001). The mean WS for RPE levels 1-4 were 12%, 27%, 50%, and 80% and 17%, 31%, 51%, and 80% when normalized to a percentage of the WS of RPE 5 for the CP and SR respectively. Conclusions: The PEC scale is a valid method of assessing perceived exertion during RT performed on a CP and SR and can be used to estimate a moderate level of intensity without subjecting the participant to inadvisable direct maximal testing.

Isoniazid resistance-conferring mutations are associated with highly variable phenotypic resistance

BackgroundHigh-dose isoniazid is recommended in the 9–12 months short-course regimen for multidrug-resistant tuberculosis with inhA mutation. However, there is insufficient evidence to support the assumption of genotypic-phenotypic concordance. This study aimed to identify the genetic mutations associated with high-level phenotypic isoniazid resistance. MethodsClinical isolates from patients with drug-resistant tuberculosis were profiled by whole-genome sequencing and subjected to minimum inhibitory concentration (MIC) testing using MGIT based-method. MICs were performed in concentration ranges based on the mutation present: isolates with no isoniazid resistance-conferring mutations and H37Rv, 0.016–0.256 µg/ml; inhA, 0.256–4.0 µg/ml, katG 1.0–16.0 µg/ml; and inhA + katG, 4.0–64.0 µg/ml. Isolates demonstrating resistance at the upper limit of the concentration range were tested up to the maximum of 64.0 µg/ml. Bootstrap of the mean MICs was performed to increase the robustness of the estimates and an overlap index was used to compare the distributions of the MICs for each mutation profile. ResultsA total of 52 clinical isolates were included in this analysis. Bootstrap MIC means for inhA, katG and inhA + katG were 33.64 (95% CI, 9.47, 56.90), 6.79 (4.45, 9.70) and 52.34 (42.750, 61.66) µg/ml, respectively. There was high overlap between inhA and inhA + katG mutations (eta = 0.45) but not with inhA and katG (eta = 0.19). Furthermore, katG showed poor overlap with inhA + katG mutations (eta = 0.09). Unexpectedly, 4/8 (50.0%) of all InhA mutants demonstrated high-level resistance, while 20/24 (83.3%) of katG mutants demonstrated moderate-level resistance. ConclusionsInhA mutations demonstrated unexpectedly high MICs and showed high overlap with inhA + katG. Contrary to the common belief that katG mutants are associated with high-level resistance, this mutation primarily showed moderate-level resistance.

Molecular mechanisms of resistance to spirodiclofen and spiromesifen in Tetranychus urticae

Ketoenol acaricides have been widely used to control Tetranychus urticae populations across the world. However, control failure due to resistance development is an increasing concern. To sustain resistance management, it is therefore important to understand the molecular mechanisms underlying resistance, as well as understand the level of cross-resistance they convey between different ketoenol acaricides, such as spirodiclofen or spiromesifen. A T. urticae population with moderate levels of resistance to ketoenols was collected from a carnation greenhouse and further selected in the laboratory with spirodiclofen and spiromesifen, separately, until high levels of resistance were achieved. Synergism assays indicated the involvement of P450 monooxygenases and, to a lesser extent, carboxyl/cholinesterases in resistance. Genome-wide gene expression analysis of ketoenol-selected populations compared to the initial field-collected population and a susceptible reference laboratory population further supported the hypothesis of P450-mediated resistance to ketoenols. In addition to metabolic resistance, target-site resistance was also investigated, but no amino acid substitutions in the carboxyl-transferase (CT) domain of the acetyl-CoA carboxylase (ACCase), the target-site of ketoenols, were found in the studied populations. However, increased expression of ACCase was found in the spiromesifen-selected, but not in the spirodiclofen-selected population. Finally, changes in resistance levels of some commonly used acaricides were identified after selection with spiromesifen or spirodiclofen.

Insecticide Susceptibility and Detoxification Enzyme Activity of Frankliniella occidentalis under Three Habitat Conditions.

Frankliniella occidentalis is a highly destructive and invasive agricultural pest that has developed resistance to a variety of insecticide classes. Different planting structures and insecticide use frequency can directly affect the resistance development of F. occidentalis. In this study, the susceptibility of three field strains of F. occidentalis, collected over one year (April to November) from three habitat conditions (facility agriculture area, FA; open field crop area, OF; agroforestry intersection area, AI), to spinetoram, spinosad, emamectin benzoate, chlorfenapyr, acetamiprid, and imidacloprid were monitored and compared. At the same time, the detoxification enzyme activity of F. occidentalis in different habitats was determined. The results showed that the susceptibility of the F. occidentalis population in FA was significantly lower than that of populations from OF and AI. Among them, the F. occidentalis population in FA had developed low levels of resistance to spinetoram (RR = 9.18-fold), emamectin benzoate (RR = 5.47-fold), chlorfenapyr (RR = 6.67-fold), and acetamiprid (RR = 7.49-fold), and had developed moderate level resistance to imidacloprid (RR = 11.67-fold), while still being relatively sensitive to spinosad. The population of F. occidentalis from OF had developed low level resistance to spinetoram (RR = 5.24-fold) but was still relatively sensitive to the other five insecticides. The resistance of F. occidentalis from AI to six insecticides was at relatively sensitive levels. The results of the enzyme activities of detoxification enzymes, including carboxylesterase (CarE), glutathione S-transferase (GST), acetylcholinesterase (AChE), and the cytochrome P450 enzyme system (CYP450), revealed that the activities of the FA population of F. occidentalis were significantly higher than those of the other two populations. The change of CarE activity in F. occidentalis was consistent with that of spinetoram resistance, indicating that CarE may be involved in the metabolic resistance of F. occidentalis to spinetoram. Among the three populations, the resistance and detoxification enzyme activities of F. occidentalis of the FA population to six insecticides were higher than those of the other two populations. Our findings, along with other strategies, are expected to help with the resistance management of F. occidentalis in different habitats.

Middle of the road: the effects of political ideology on social status perceptions of and by political moderates in organisations

Purpose Drawing on research in the social psychology and political science literatures, this research aims to examine how political moderates perceive, and are perceived by, their co-workers with differing political ideologies in an organisational context, with a focus on the perceptions of social status. Design/methodology/approach To test the hypotheses regarding the social status perceptions of and by political moderates in the workplace, the authors conducted an online experiment in which working adults read a hypothetical workplace scenario and then assessed the social status of a co-worker based on the political ideology of that co-worker. Findings The results largely supported the two hypothesised asymmetries of social perceptions of and by political moderates in an organisational context. Specifically, political moderates were perceived to have higher social status by their moderate and conservative co-workers than by their liberal co-workers. In addition, political moderates perceived moderate co-workers to have higher social status than conservative ones. Originality/value This research investigates the influence of political ideology on social status perceptions in organisations by focusing on the previously underexamined political moderates. The findings illustrate the importance of political moderates, who tend to espouse a moderate level of resistance to social change, in the process of developing a functional hierarchy and balancing change and stability in organisations.

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.

First monitoring of resistance and corresponding mechanisms in the green peach aphid, Myzus persicae (Sulzer), to registered and unregistered insecticides in Saudi Arabia

Insecticides are widely used as the primary management strategy for controlling Myzus persicae, the devastating pest ravaging various vegetables, fruits, crops, and ornamentals. This study examined the susceptibility of M. persicae field populations to bifenthrin, fosthiazate, acetamiprid, spirotetramat, afidopyropen, and flonicamid while exploring the possible metabolic mechanisms of resistance. The study findings revealed that M. persicae field populations exhibited susceptible-to-moderate resistance to bifenthrin (resistance ratio (RR) = 0.94–19.65) and acetamiprid (RR = 1.73–12.91), low-to-moderate resistance to fosthiazate (RR = 3.67–17.00), and susceptible-to-low resistance to spirotetramat (RR = 0.70–6.68). However, all M. persicae field populations were susceptible to afidopyropen (RR = 0.44–2.25) and flonicamid (RR = 0.40–2.08). As determined by the biochemical assays, carboxylesterases were involved in the resistance cases to bifenthrin and fosthiazate, whereas cytochrome P450 monooxygenases were implicated in the resistance cases to acetamiprid. However, glutathione S-transferases were not implicated in the documented resistance of M. persicae field populations. Overall, the susceptibility of M. persicae field populations to flonicamid and afidopyropen—two unregistered insecticides in Saudi Arabia—suggests their potential as promising chemicals that can expand the various alternatives available for controlling this devastating pest. Although the detected moderate levels of resistance to bifenthrin, fosthiazate, and acetamiprid indicate a shift in the selection pressure of insecticides for M. persicae due to Saudi regulations, which have resulted in eventual obsolescence of conventional insecticides in favor of novel insecticides. Finally, rotational use of aforementioned insecticides can help in managing insecticide resistance in M. persicae.

The evolution of insecticide resistance in the white backed planthopper Sogatella furcifera (Horvath) of China in the period 2014–2022

The white-backed planthopper, Sogatella furcifera (Horváth), is a kind of important rice pest in China. Chemical control is the most effective method in the field control of S. furcifera. However, due to the intensive use of chemicals, it has developed resistance to multiple insecticides. Here, we conducted insecticide resistance monitoring of 55 field populations of S. furcifera over the period 2014–2022. Monitoring data demonstrated that most of the field populations showed increased resistance to neonicotinoids such as imidacloprid, dinotefuran and thiamethoxam, which had developed moderate resistance levels. All field populations were still susceptible to triflumezopyrim (RR = 0.1–4.1-fold). Nearly all populations developed a low to moderate level of resistance to pymetrozine (RR = 1.0–46.1). About half of the field populations kept high levels of resistance to buprofezin (RR = 18.4–351.6-fold), and nearly all populations kept moderate levels of resistance to chlorpyrifos (RR = 0.1–88.2-fold). Synergism assay was conducted on a field buprofezin-resistant population and no significant synergistic effect was observed for three inhibitors, which implies that other mechanisms may be involved in resistance evolution in white-backed planthopper.

The ryanodine receptor mutation I4728M confers moderate-level resistance to diamide insecticides in Spodoptera litura.

The common cutworm, Spodoptera litura (Fabricius), is one of the most widespread and destructive polyphagous pests in tropical and subtropical Asia. S. litura has evolved resistance to different insecticides, including diamide insecticides. Here, we identified a ryanodine receptor (RyR) mutation (I4728M) associated with target site resistance to diamides in a field-collected population of S. litura. The contribution of this mutation to diamide resistance was investigated through establishing a near-isogenic resistant strain of S. litura. The ND21 population of S. litura, collected from Ningde, Fujian province of China in 2021, exhibited 130.6-fold resistance to chlorantraniliprole compared to the susceptible NJ-S strain. S. litura RyR mutation I4728M, corresponding to Plutella xylostella RyR I4790M, was identified in the ND21 population. SlRyR I4728M mutation of ND21 was introgressed into a susceptible background strain (NJ-S) with marker-assisted backcrossing. The introgressed strain named ND21-R, which was homozygous for the mutant 4728M allele, shared about 94% of the genetic background with the NJ-S strain. ND21-R strain showed moderate levels of resistance to two anthranilic diamides (19.1-fold to chlorantraniliprole, 19.7-fold to cyantraniliprole) and the phthalic diamide flubendiamide (23.4-fold). Genetic analysis showed that chlorantraniliprole resistance was autosomal, incompletely recessive and tightly linked with SlRyR I4728M mutation in the introgressed ND21-R strain of S. litura. Identification of the I4728M mutation and its contribution to diamide resistance in S. litura will help develop allelic discrimination assays for resistance monitoring and guide resistance management practices for diamides in S. litura. © 2023 Society of Chemical Industry.

Large Field Screening for Resistance to Broomrape (Orobanche crenata Forsk.) in a Global Lentil Diversity Panel (GLDP) (Lens culinaris Medik.).

Broomrape (Orobanche crenata Forsk.) is a serious problem causing important losses to lentil (Lens culinaris Medik.) production and productivity in Mediterranean countries. Despite intensive breeding activities, no resistance sources against O. crenata have been identified so far. In this study, a Global Lentil Diversity Panel (GLDP) of 1315 genotypes including local populations, landraces, accessions, improved lines and released varieties were evaluated for their resistance to O. crenata under highly infested field conditions at ICARDA Marchouch research station, Morocco. The trial was conducted according to an augmented design with repeated susceptible checks. The best-performing genotypes were selected based on the correlations between Orobanche infestation parameters and agronomic performance. Results showed significant variation (p < 0.005) among the studied genotypes and between the tested genotypes and checks for BY, D2F, D2M, PH, EODW and NEO. Out of the 1315 tested genotypes, only (1%) showed high to moderate resistance levels to O. crenata. Most of these genotypes are improved lines originating from different breeding programs. the PCA analysis clustered all the tested genotypes into four different groups. Good resistance levels were recorded for the genotypes ILL7723, ILL 7982, ILL 6912, ILL 6415, ILL 9850, ILL 605, ILL 7915, ILL 1861 and ILL 9888 showing a parasitism index and grain yield ranging from 1.69 to 5.99 and 10.97 to 60.19 g m-2, respectively. Person's correlation showed significant negative correlations between agronomic traits and infestation parameters. Both the path and spatial analysis showed that the D2F, NEO, D2OE, SEV and parasitism index (PI) were the strongest driver traits that influenced the seed yield (SY).