Resistant Individuals Research Articles

Development and validation of a larval bioassay and selection protocol for insecticide resistance in Drosophila suzukii.

The rapid invasion of Drosophila suzukii (Matsumura) throughout Europe and the Americas has led to an increased reliance on calendar-based broad-spectrum insecticide programs among berry and cherry growers. Relatively few active ingredients (AIs) are currently available for effective D. suzukii management, and studies from multiple growing regions indicate that susceptibility to at least some of these materials is declining. Greater effort is needed to understand the status of susceptibility across field populations and the potential for increased resistance to develop, as well as the possible fitness costs incurred by resistant individuals. However, current bioassay protocols used for resistance monitoring and selection studies (i.e. resistance risk assessments) are labor-intensive and costly, making large-scale studies difficult to conduct. Here, we first present a novel bioassay protocol using larvae that requires little effort or cost to implement beyond what is needed for basic D. suzukii laboratory colony maintenance. We then perform dose-response bioassays using this protocol to identify larval lethal concentrations for three commonly used insecticides (malathion, spinosad and zeta-cypermethrin) in a susceptible population. Finally, resistance risk assessments were conducted using a population of D. suzukii from commercial caneberry fields near Watsonville, CA. We find that five generations of larval selection with a discriminating dose is sufficient to significantly increase both larval (malathion and spinosad) and adult (spinosad) resistance to the target AIs. This approach provides a simple, cost-effective tool for assaying susceptibility of D. suzukii populations to insecticides and for selecting resistant insect lines for resistance management research.

MHC IIβ diversity of Oreochromis niloticus and its association with the susceptibility/resistance to Gyrodactylus cichlidarum (Monogenea) infection

Nile tilapia, Oreochromis niloticus, is among the most highly recommended species by the FAO for culture, and has become the second most abundantly farmed fish species in the world. In aquaculture systems, however, this species is vulnerable to various pathogens including Gyrodactylus cichlidarum (Monogenea). The major histocompatibility complex (MHC), a highly polymorphic gene superfamily, plays vital roles in immunity and expression of this group of genes is associated with disease resistance. In the present study, the relationship between MHC IIβ polymorphism of O. niloticus and the susceptibility/resistance to G. cichlidarum infection were analyzed. A total of 46 alleles of MHC IIβ were identified, which demonstrated a high level of polymorphism representing a variability of 96.8 % amino acid sites. In the peptide-binding region (PBR) and entire region, the values of dN/dS were 1.094 and 1.027, respectively. Infection experiments revealed that the resistance of O. niloticus to G. cichlidarum infection was positively correlated with MHC IIβ polymorphism. Among alleles, Orni-DAB*1401 was highly associated with resistance (P < 0.05), while Orni-DAB*0901 and Orni-DAB*3501 were significantly associated with susceptibility (P < 0.05). The expressions of immune-related genes (MHC IIβ, IL1β and TLR7) in the resistant individuals (with Orni-DAB*1401) are significantly higher than other individuals (P < 0.05). The results suggested that diversity of the MHC IIβ allele was associated with the susceptibility/resistance of tilapia to this monogenean, which can potentially contribute to the study of MHC diversity maintenance and molecular-assisted selection of O. niloticus to enhance disease resistance.

SALT-SENSITIVITY IN HEALTHY NORMOTENSIVE MEN IS ASSOCIATED WITH IMPAIRED BAROREFLEX SENSITIVITY

Objective: Blood pressure (BP) responses to Na+ intake show great variability, discriminating sodium sensitive (SS) from salt resistant (SR) individuals. The pathophysiology behind salt-sensitivity is still not fully elucidated. A pivotal role for the sympathetic nervous system to BP increase after sodium loading is suggested. Therefore, we aimed to investigate the effect of the sympathovagal balance on Na+-induced BP effects and if Na+-induced effects on sympathetic activation contribute to salt-sensitivity. Design and method: We performed a randomized cross-over study in 31 young healthy men with normal BMI and eGFR. Subjects followed both an 8-day low Na+ diet (LSD, &lt; 50mmol/d) and high Na+ diet (HSD, &gt; 200mmol/d), in 18 subjects the diets were extended to 14-days. SS was defined as an increase of three or more mmHg standardized measured office MAP after HSD. Cardiac-output (CO) and cross correlation baroreflex sensitivity (xBRS) were measured with continuous non-invasive finger photoplethysmography. Systemic vascular resistance (SVR) was calculated as the ratio of MAP by CO. Results: After HSD, SS men (19%) showed a mean 6.2 (±2.1 SD) mmHg increase in MAP. No absolute differences in Na+-induced effects on CO and SVR could be observed between groups. After HSD, xBRS was 34% lower in SS men compared to SR men (Fig1A). Sodium loading resulted in a mean xBRS decrease of 3.4 (±6.5 SD) ms/mmHg in SS men, whilst xBRS increased with 2.3 (±6.3 SD) ms/mmHg in SR men (p = 0.06). HSD xBRS values were significantly correlated with Na+-induced BP changes in the complete group when corrected for age and BMI (Fig1B). Conclusions: Salt-sensitivity of BP in young normotensive men seems to be predominantly driven by changes in sympathovagal balance. The significant correlation between xBRS and delta BP further suggests a continuous relation between sympathetovagal balance and salt exposure. Further studies are needed to unravel pathophysiological mechanisms underlying Na+-effects on sympathetic regulation.

215-LB: Silencing of Fructose 1,6-Bisphosphatase (FBP1) in Liver Improves Glucose Homeostasis in Insulin-Resistant Rodent and Human Models

Insulin resistant individuals display elevated fasting and post-prandial glucose levels which are mainly driven by inadequate inhibition of gluconeogenesis (GNG) and are rarely normalized. The aim of this study was to investigate whether direct inhibition of GNG could be a new therapeutical approach to improve glucose homeostasis using in vitro and in vivo models of insulin resistance. Fructose 1,6-bisphosphatase (FBP1) is key in controlling GNG in liver and kidney and loss of function patients display hypoglycaemia episodes and lactate acidosis. Systemic FBP1 inhibition using small molecules has shown to improve glucose homeostasis. To assess the clinical efficacy and safety potential of silencing FBP1 selectively in the liver we dosed insulin resistant DIO rats with a hepatocyte specific GalXC-FBP1 siRNA entity. GalXC-FBP1 siRNA markedly reduced FBP1 mRNA level in the liver by over 90%. This was associated with a complete lack of glucose excursion following a pyruvate challenge indicating inhibition of GNG. Blood glucose level decreased similarly in rats treated with GalXC-FBP1 siRNA or vehicle during an insulin challenge or a prolonged fast suggesting that hepatic FBP1 silencing is not inducing hypoglycaemia. Insulin sensitivity and hyperinsulinemia were improved. Plasma lactate and liver enzymes were not elevated, but a significant 2-fold increase in liver triglycerides was observed in the GalXC-FBP1 siRNA group. Using human hepatocytes in a Liver-on-Chip in vitro model FBP1 silencing reduced glucose production by 30% supporting the relevance of this approach in humans. Collectively these data suggest that liver specific FBP1 silencing has the potential to improve insulin sensitivity in DIO rats without inducing hypoglycaemia but may be associated with a risk of liver steatosis overtime. This concept highlights the difficulty of blocking liver GNG without re-directing the metabolic intermediates fluxes toward triglycerides accumulation in liver. Disclosure C. Fledelius: Employee; Novo Nordisk A/S. D. Demozay: Employee; Novo Nordisk A/S. H. Iversen: None. R. S. Ingvorsen: None. L. B. Eriksen: None. A. Blois: Employee; Novo Nordisk. Y. Montauban: None. R. Rijnbrand: Employee; Novo Nordisk. W. Han: None. J. F. Jeppesen: Employee; Novo Nordisk A/S.

534-P: Sustained Improvement of Whole-Body Oxidative Capacity but Not Insulin Sensitivity after Detraining of People with Type 2 Diabetes

High-intensity interval training (HIIT) improves skeletal muscle mitochondrial oxidative capacity in humans with different degrees of insulin sensitivity, whereas it increases insulin sensitivity along with number of circulating small extracellular vesicle (SEV) mainly in insulin resistant individuals with or without T2D (T2D, IR) . In order to examine the sustainability of metabolic effects induced by HIIT, this study tested whether the observed effects on insulin sensitivity, oxidative capacity and SEV number remain and/or differ between insulin sensitive (IS) , IR and T2D humans. Twenty T2D and age- and BMI-matched IR and 12 IS individuals (HbA1c in %: 7.2±0.2, 5.4±0.1, 5.4±0.1; M-value in mg*kg-1*min-1: 3.0±0.4, 4.2±0.4, 7.4±0.4) performed a 12-week HIIT cycling protocol for 3 d/week. Whole-body insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamps, physical fitness (VO2max) by spiroergometry and myocellular pathways of insulin sensitivity by immunoblotting of muscle biopsies at baseline, 72 h after the last HIIT bout and 4 weeks (detraining) later. SEV were isolated from serum by size exclusion chromatography. Compared to HIIT, insulin sensitivity decreased in T2D after detraining (p&amp;lt;0.01) , instead VO2max decreased in T2D and IR (p&amp;lt;0. and p&amp;lt;0.05) , although it remained higher than baseline (p&amp;lt;0.0 and p=0.05) . Of note, HIIT-induced reduction of the nuclear factor-κB protein (p&amp;lt;0.vs. baseline) disappeared in IR after detraining, whereas decreased protein kinase Cε activity was sustained in T2D (p&amp;lt;0.vs. HIIT and p&amp;lt;0.vs. baseline) , who also showed higher circulating SEV number (p&amp;lt;0.vs. baseline) . In conclusion, HIIT-induced increases in physical fitness and SEV number, but not insulin sensitivity are maintained at least after short-term detraining in T2D. Characterization of SEV cargo might help to better understand the differences in metabolic responses to detraining in individuals with and without T2D Disclosure L.Mastrototaro: None. J.Szendroedi: Advisory Panel; Boehringer Ingelheim International GmbH. M.Roden: Advisory Panel; Eli Lilly and Company, Research Support; Boehringer Ingelheim International GmbH, Nutricia, Speaker's Bureau; Novo Nordisk. M.Apostolopoulou: n/a. N.Saatmann: None. C.Granata: None. S.Hartwig: None. Y.Karusheva: None. S.Gancheva: None. S.Lehr: None. H.Al-hasani: Consultant; Bayer AG.

Multiple resistance to ACCase- and ALS-inhibiting herbicides in black-grass (Alopecurus myosuroides Huds.) in China

Two black-grass (Alopecurus myosuroides Huds.) populations (R2105 and R1027) that were suspected to be resistant to clodinafop-propargyl, an acetyl-CoAcarboxylase (ACCase) inhibitor, were found in winter wheat fields in China. Research was carried out to investigate whether resistance to clodinafop-propargyl was present and the molecular mechanism of herbicide resistance in these two populations. Dose–response assays confirmed high level resistance to clodinafop-propargyl in both R2105 and R1027 populations, with resistance indexes 25.1 and 22.1. ACCase gene sequence comparison revealed three amino acid mutations (Trp-1999-Leu, Ile-2041-Asn, or Asp-2078-Gly) in R2105 population and Ile-2041-Asn mutation in R1027 population. Sensitivity to other herbicides assays indicated that R2105 and R1027 populations were cross resistant to fenoxaprop-P-ethyl and multiple resistant to pyroxsulam and mesosulfuron-methyl. The ALS gene sequence analysis revealed that all resistant individuals in R2105 and R1027 populations had the Trp-574-Leu mutation. Applying malathion, significantly decreased the rate of metabolism of clodinafop-propargyl in both R2105 and R1027 populations. This is the first report of multiple resistance to ACCase- and ALS-inhibiting herbicides conferred by target-site mutations and enhanced metabolism in black-grass in China.

Host Plant Reaction to Rice Yellow Mottle Virus and Allelic Diversity of RYMV1 Gene in Rice Cultivars in Uganda

Rice Yellow Mottle Virus (RYMV) disease is endemic to Africa where it affects rice production. Host plant resistance would form a cost effective and sustainable option for managing the disease. However, there is still lack of knowledge on the reaction of rice germplasm and the genetic basis of their resistance/susceptibility to RYMV coupled with lack of molecular markers to facilitate the development of RYMV resistant varieties. We screened 56 rice accessions drawn from breeding lines and varieties commercially cultivated in Uganda for their resistance/susceptibility to RYMV. We also sought to develop and validate allele specific markers for RYMV1 alleles. The rice accessions showed variation in their reaction to RYMV; 14, 12, 17 and 13 accessions were categorized as resistant, moderately resistant, moderately susceptible and susceptible respectively. Among the resistant accessions, five possessed a single SNP (G/A) corresponding to the rymv1-2 allele. The new accessions can be deployed as resistant cultivars and/or used to introgress rymv1-2 allele into susceptible adapted cultivars throughout Africa. We developed two functional allele specific markers, which co-segregated with the rymv1-2 resistance allele in an F2 population and clearly differentiated between the susceptible and resistant individuals in the F2 population. The functional allele specific marker developed in this study can be used in MAS programs for introgression of rymv1-2 resistance allele.

Assessment of Variability and Association on Bruchine Resistance Traits (Callosobruchus maculatus F.) among Segregating Populations of Blackgram [Vigna mungo (L.) Hepper

Background: Bruchine is one of the notorious pests that renders both the quantity and quality of pulses stored produce especially blackgram. Hence the present study was carried out to ascertain the essential selection indices among the bruchine resistance traits involved. Methods: A laboratory experiment was conducted to estimate the variability parameters for traits related to bruchine infestation in various crosses of blackgram viz., MDU1 × TU68, VBN6 × TU68 and VBN8 × TU68 at National Pulses Research Centre, Vamban. Observations were recorded for eight bruchine resistance traits on each single plants from three crosses. Result: The results indicated that all traits viz., total number of adult emergence, developmental time, mean developmental period, index of susceptibility, seed damage (%) and seed weight loss (%) recorded high PCV and GCV in all crosses except developmental time which had moderate to low variation. All traits also recorded high heritability and genetic advance as per cent of mean in all crosses except developmental time. Developmental time had moderate to high heritability and genetic advance over the crosses. Considering skewness and kurtosis, the cross MDU 1 × TU 68 had a wide variation for total number of adult emergence and seed damage. Hence the cross MDU 1 × TU 68 could be selected for the selection of bruchid resistant individuals. The association studies revealed that traits viz., developmental time, total number of adult emergence, index of susceptibility and seed damage were reliable selection indices for the seed weight loss.

SNPs in a Large Genomic Scaffold Are Strongly Associated withCr1R, Major Gene for Resistance to White Pine Blister Rust in Range-Wide Samples of Sugar Pine (Pinus lambertiana)

Sugar pine, Pinus lambertiana Douglas, is a keystone species of montane forests from Baja California to southern Oregon. Like other North American white pines, populations of sugar pine have been greatly reduced by the disease white pine blister rust (WPBR) caused by a fungal pathogen, Cronartium ribicola, that was introduced into North America early in the twentieth century. Major gene resistance to WPBR segregating in natural populations has been documented in sugar pine. Indeed, the dominant resistance gene in this species, Cr1, was genetically mapped, although not precisely. Genomic single nucleotide polymorphisms (SNPs) placed in a large scaffold were reported to be associated with the allele for this major gene resistance (Cr1R). Forest restoration efforts often include sugar pine seed derived from the rare resistant individuals (typically Cr1R/Cr1r) identified through an expensive 2-year phenotypic testing program. To validate and geographically characterize the variation in this association and investigate its potential to expedite genetic improvement in forest restoration, we developed a simple PCR-based, diploid genotyping of DNA from needle tissue. By applying this to range-wide samples of susceptible and resistant (Cr1R) trees, we show that the SNPs exhibit a strong, though not complete, association with Cr1R. Paralleling earlier studies of the geographic distribution of Cr1R and the inferred demographic history of sugar pine, the resistance-associated SNPs are marginally more common in southern populations, as is the frequency of Cr1R. Although the strength of the association of the SNPs with Cr1R and thus, their predictive value, also varies with geography, the potential value of this new tool in quickly and efficiently identifying candidate WPBR-resistant seed trees is clear.

An Allelic Variant of the Broad-Spectrum Blast Resistance Gene Ptr in Weedy Rice Is Associated with Resistance to the Most Virulent Blast Race IB-33.

Rice resistance (R) genes have been effectively deployed to prevent blast disease caused by the fungal pathogen Magnaporthe oryzae, one of the most serious threats for stable rice production worldwide. Weedy rice competing with cultivated rice may carry novel or lost R genes. The quantitative trait locus qBR12.3b was previously mapped between two single nucleotide polymorphism markers at the 10,633,942-bp and 10,820,033-bp genomic positions in a black-hull-awned (BHA) weed strain using a weed-crop-mapping population under greenhouse conditions. In this study, we found a portion of the known resistance gene Ptr encoding a protein with four armadillo repeats and confers a broad spectrum of blast resistance. We then analyzed the sequences of the Ptr gene from weedy rice, PtrBHA, and identified a unique amino acid glutamine at protein position 874. Minor changes of protein conformation of the PtrBHA gene were predicted through structural analysis of PtrBHA, suggesting that the product of PtrBHA is involved in disease resistance. A gene-specific codominant marker HJ17-13 from PtrBHA was then developed to distinguish alleles in weeds and crops. The PtrBHA gene existed in 207 individuals of the same mapping population, where qBR12.3b was mapped using this gene-specific marker. Disease reactions of 207 individuals and their parents to IB-33 were evaluated. The resistant individuals had PtrBHA whereas the susceptible individuals did not, suggesting that HJ17-13 is reliable to predict qBR12.3b. Taken together, this newly developed marker, and weedy rice genotypes carrying qBR12.3b, are useful for blast improvement using marker assisted selection.

Maternal Western‐style diet and obesity during pregnancy reduces mitochondrial Complex I‐linked oxidative capacity in tandem with decreased oxidative stress in skeletal muscle of adolescent Japanese macaque offspring

BackgroundExposure to an obesogenic gestational environment during early development increases offspring risk of developing obesity and cardiometabolic diseases. Skeletal muscle of obese and insulin resistant individuals show signs of mitochondrial dysfunction including reduced oxidative capacity and increased oxidative stress. Subsequent oxidative damage is caused by reactive oxygen species (ROS) generated primarily by mitochondrial Complex I (CI). Previous work in our non‐human primate model shows decreased oxidative capacity in fetal skeletal muscle from obesogenic pregnancies, a phenotype we have confirmed is retained into adolescence. The purpose of this study was to evaluate how this reduced oxidative capacity correspond with ROS production in skeletal muscle of lean adolescent offspring.Experimental DesignLean (body fat &lt;25%) adult female Japanese macaques were maintained on a control diet (CD) or Western‐style diet (WD) prior to and throughout pregnancy and lactation. Dams chronically consuming WD with body fat &gt;30% were classified as obese and included in this study. Male and female offspring were weaned to CD and moved to independent housing at 7 months of age. Muscle samples were collected from offspring gastrocnemius (gastroc) and soleus at 40 months. Offspring data were analyzed by Student’s t‐test.ResultsExposure to maternal WD during pregnancy showed moderate but significant reductions in oxidative damage and a modest (but insignificant) decrease in ROS generation in gastroc of offspring from obese pregnancies. In the soleus, ROS production was significantly reduced in these offspring. Both nuclear‐ and mitochondrial‐encoded genes for CI were decreased with maternal obesity/WD pregnancy, indicating transcriptional regulation of CI in exposed offspring. Finally, CI protein abundance was also decreased in primary myotubes from these offspring in lieu of additional metabolic challenges, providing further evidence of lasting metabolic reprogramming in skeletal muscle.ConclusionsWe find that early life exposure to maternal WD‐induced obesity leaves a lasting impression on offspring skeletal muscle metabolism that persists into young adulthood. It is possible that transcriptional suppression of CI activity is a protective adaptation to mitigate oxidative damage caused by mitochondrial ROS. While long‐term consequences of altered oxidation patterns relating to ROS flux require further investigation, the loss of CI content and diminished oxidative capacity in these lean offspring likely drive their increased susceptibility for cardiometabolic diseases – particularly when faced with metabolic stress and environmental insults throughout the lifespan.

Homogeneity of agriculture landscape promotes insecticide resistance in the ground beetle Poecilus cupreus.

The intensification of agriculture leads to increased pesticide use and significant transformation from small fields towards large-scale monocultures. This may significantly affect populations of non-target arthropods (NTA). We aimed to assess whether the multigenerational exposure to plant protection products has resulted in the evolution of resistance to insecticides in the ground beetle Poecilus cupreus originating from different agricultural landscapes. Two contrasting landscapes were selected for the study, one dominated by small and another by large fields. Within each landscape the beetles were collected at nine sites representing range of canola coverage and a variety of habitat types. Part of the collected beetles, after acclimation to laboratory conditions, were tested for sensitivity to Proteus 110 OD-the most commonly used insecticide in the studied landscapes. The rest were bred in the laboratory for two consecutive generations, and part of the beetles from each generation were also tested for sensitivity to selected insecticide. We showed that the beetles inhabiting areas with medium and large share of canola located in the landscape dominated by large fields were less sensitive to the studied insecticide. The persistence of reduced sensitivity to Proteus 110 OD for two consecutive generations indicates that either the beetles have developed resistance to the insecticide or the chronic exposure to pesticides has led to the selection of more resistant individuals naturally present in the studied populations. No increased resistance was found in the beetles from more heterogeneous landscape dominated by small fields, in which spatio-temporal diversity of crops and abundance of small, linear off-crop landscape elements may provide shelter that allows NTAs to survive without developing any, presumably costly, resistance mechanisms.

The association between hypomagnesemia and poor glycaemic control in type 1 diabetes is limited to insulin resistant individuals

In a cohort of adults with type 1 diabetes, we examined the prevalence of hypomagnesemia and the correlation of serum magnesium levels with metabolic determinants, such as glycaemic control (as HbA1c), inflammatory markers and circulating cytokines. Furthermore, we assessed if a surrogate for insulin resistance is essential for the possible association of serum magnesium with metabolic determinants. Individuals with type 1 diabetes, aged above 18 years, were included and clinical characteristics were obtained from questionnaires and clinical records. In venous blood samples we measured cytokines and adipose-tissue specific secretion proteins. Serum magnesium concentrations were measured and correlated with clinical data and laboratory measurements using univariate and multivariate regression models. Hierarchical multiple regression of serum magnesium with insulin resistance was adjusted for diabetes and potential magnesium confounders. The prevalence of hypomagnesemia (serum magnesium levels < 0.7 mmol/L) was 2.9% in a cohort consisting of 241 individuals with type 1 diabetes. The magnesium concentration in the cohort was not associated with HbA1c (r = − 0.12, P-value = 0.068) nor with any inflammatory marker or adipokine. However, insulin dose (IU/kg), a surrogate measure of resistance in type 1 diabetes, moderated the association of serum magnesium (mmol/L) with HbA1c (mmol/mol) with a B coefficient of − 71.91 (95% CI: − 119.11; -24.71), P-value = 0.003) and Log10 high-sensitivity C-reactive protein (Log10 mg/L) − 2.09 (95% CI: − 3.70; − 0.48), P-value = 0.011). The association of low serum magnesium levels with glycaemic control (HbA1c) and high-sensitivity C-reactive protein in individuals with type 1 diabetes is limited to subjects using a high insulin dose and suggests that insulin resistance, a type 2 diabetes feature, is a prerequisite for hypomagnesemia.

Identification and Validation of Quantitative Trait Loci for Wheat Dwarf Virus Resistance in Wheat (Triticum spp.).

Wheat dwarf virus (WDV) is transmitted by the leafhopper Psammotettix alienus. As a major pathogen in wheat and other cereals, WDV causes high yield losses in many European countries. Due to climate change, insect-transmitted viruses will become more important and the restrictions in the use of insecticides efficient against P. alienus renders growing of WDV resistant/tolerant varieties the only effective strategy to control WDV. So far, there is little information about the possible sources of resistance and no known information about the genome regions responsible for the resistance. In a screening for WDV resistance using artificial inoculation in gauze houses, a panel of 500 wheat accessions including cultivars, gene bank accessions, and wild relatives of wheat was phenotyped for virus titer, infection rate, as well as plant height and yield parameters relative to healthy controls of the same genotype. Additionally, 85 T. aestivum-Ae. tauschii intogression lines were tested for WDV resistance in the greenhouse. A subset of 250 hexaploid wheat accessions was genotyped with the 15k iSelect SNP Chip. By genome-wide association study (GWAS), the quantitative trait loci (QTL) for partial WDV resistance were identified. Within these studies, one cultivar was identified showing an average infection rate of only 5.7%. By analyzing single seed descent (SSD) and doubled haploid (DH) populations comprising 153 and 314 individuals for WDV resistance and by genotyping these with the 25k iSelect SNP Chip, QTL for yield per plant, thousand-grain weight, and relative virus titer were validated on chromosomes 1B, 2B, 3B, 4B, 4A, 5A, 6A, and 7A. These results will be the basis for marker-assisted selection for WDV resistance to replacing the laborious, time-consuming, and technically challenging phenotyping with WDV bearing leafhoppers.

(Mis)Information, Fears and Preventative Health Behaviours Related to COVID-19.

Social and mass media platforms (SMM) are essential tools for keeping people informed about health-promoting practices. However, the potential to spread misinformation or false rumors exists. These might influence preventive health behaviours and incite anxiety and/or fear among the population. A sample of 300 adults participated in a survey to understand information needs, fears and preventive health behaviours related to COVID-19 while analyzing differences in COVID-19 acceptance rates. Descriptive-correlational, between-group comparisons and regression analyses were applied. Most of the sample revealed a willingness to accept COVID-19 vaccines (65.4% vs. 34.5%) and was prone to use and trust different SMM without experiencing significant obstacles in managing COVID-19-related information except for the need to ration it from time to time (χ2(2, N = 298) = 6.654, p = 0.036). Preventive behaviours/measures carried out were similar among the people resistant, hesitant or willing to get vaccinated for COVID-19. However, higher self-efficacy was observed in resistant vaccine individuals (F(2) = 3.163, p = 0.044). Psychological impact (need for psychological support due to COVID-19 situation) in accepting (F(5, 189) = 17.539, p < 0.001, R2 = 0.317) and hesitant individuals (F(5, 77) = 17.080, p < 0.001, R2 = 0.526) was explained by female gender, younger age, threat susceptibility and differential characteristics in terms of psychological symptoms experienced and SMM trust. No explanatory model was obtained for the resistant individuals. SMM could be effective tools to promote COVID-19 health preventive behaviours. However, psychographic characteristics might modulate information-seeking and management as well as self-perceived threat susceptibility and severity. All these factors must be accurately considered when designing different health preventive campaigns for the general public.

Fitness Cost of Sequential Selection with Deltamethrin in Aedes aegypti (Diptera: Culicidae).

In Mexico, Aedes aegypti (L.) is the primary dengue vector, chikungunya, and Zika viruses. The continued use of synthetic pyrethroids has led to the development of resistance in target populations, which has diminished the effectiveness of vector control programs. Resistance has been associated with disadvantages that affect the biological parameters of resistant mosquitoes compared to susceptible ones. In the present study, the disadvantages were evaluated by parameters related to survival and reproduction ('fitness cost') after selection with deltamethrin for five generations. The parameters analyzed were the length of the development cycle, sex ratio, survival, longevity, fecundity, egg viability, preoviposition, oviposition and postoviposition periods, and growth parameters. In the deltamethrin-selected strain, there was a decrease in the development cycle duration, the percentage of pupae, the oviposition period, and eggs viability. Although mean daily fecundity was not affected after the selection process, this, together with the decrease in the survival and fecundity levels by specific age, significantly affected the gross reproductive rate (GRR), net reproductive rate (Ro), and intrinsic growth rate (rm) of the group selected for five generations with deltamethrin compared to the group without selection. Identifying the 'cost' of resistance in biological fitness represents an advantage if it is desired to limit the spread of resistant populations since the fitness cost is the less likely that resistant individuals will spread in the population. This represents an important factor to consider in designing integrated vector management programs.

Determination of The Response of Wild and Cultivated Tomato Genotypes to Some Disease and Pests by Molecular Markers

Fusarium oxysporum f. sp. lycopersici, Verticillium spp., and nematodes, as well as virus diseases that negatively affect production with limited chemical control cause significant losses in greenhouse tomato cultivation. The practical and effective side of controlling diseases is genetic control by breeding. Using a genomic approach for plant breeding is a more sustainable and effective way to control disease and pests. The development of the resistant line is improved by conventional breeding methods that can be conducted over a long period. However, molecular markers make these processes considerably shorter with identifying resistant individuals. In this study, 14 wild and 188 cultivated tomato genotypes have been tested against Fusarium oxysporum f. sp. radicis-lycopersici (FORL), Meloidogyne spp. (root-knot nematodes), Tomato spotted wilt virus (TSWV), Tomato mosaic virus (ToMV), Tomato yellow leaf curl virus (TYLCV) and Verticillum dahliae Kleb. (Ve) diseases and pests with using MAS (Marker- Assisted Selection) technique. According to these results, it has been determined that the selected markers can be used effectively in breeding studies to determine the diseases mentioned above.

Baseline Susceptibility and Resistance Allele Frequency in Ostrinia furnacalis in Relation to Cry1Ab Toxins in China.

Asian corn borer (ACB), Ostrinia furnacalis (Guenée) is a destructive pest of corn and major target of transgenic corn expressing Bt (Bacillus thuringiensis) toxins in China. It is necessary to establish the baseline susceptibility of geographically distinct ACB populations to Cry1Ab protein and estimate the resistance alleles frequency. The median lethal concentration (LC50) and LC95 values of Bt toxin Cry1Ab for 25 geographically distinct populations collected in 2018–2019 ranged from 0.86 to 71.33, 18.58 to 5752.34 ng/cm2, respectively. The median effective concentration (EC50) and EC95 values ranged from 0.03 to 10.40 ng/cm2 and 3.75 to 172.86 ng/cm2, respectively. We used the F2 screening method for estimating the expected frequency of resistance alleles of the 13 ACB populations, to Bt corn (Bt11 × GA21) expressing the Cry1Ab toxin. The neonates could not survive on the leaves of transgenic maize Bt11 × GA21 with cry1Ab gene, the Cry1Ab resistance allele frequency was still low in each geographic population in the field, ranging from 0.0032–0.0048, indicating that the sensitivity of ACB to Cry1Ab was still at a high level, and there were no viable resistant individuals in the field at present. The susceptibility of 25 populations of ACB collected in China showed regional differences, although the Cry1Ab resistance allele frequency in these ACB populations is still at a low level. This provides essential knowledge for making the decision to commercialize Bt maize, and monitoring resistance development and evaluating resistance management strategies in the future in China.

A 6.5kb Intergenic Structural Variation Exacerbates the Fitness Cost of P450-Based Metabolic Resistance in the Major African Malaria Vector Anopheles funestus.

Metabolic-based resistance to insecticides limit the control of medically important pests, and it is extremely detrimental in the ongoing struggle to control disease vectors. Elucidating the fitness cost of metabolic resistance in major malaria vectors is vital for successful resistance management. We established the fitness cost of the 6.5kb structural variant (6.5kb-sv) between the duplicated CYP6P9a/b P450s using the hybrid strain generated from the crossing between two An. funestus laboratory strains. Furthermore, we assessed the cumulative impact of this marker with the duplicated P450 genes. We established that individuals that were homozygote for the resistant structural variant (SV) presented reduced fecundity and slow development relative to those that were homozygote for the susceptible SV. Furthermore, we observed that 6.5kb act additively with CYP6P9a and CYP6P9b to exacerbate the reduced fecundity and the increased development time of resistant mosquitoes since double/triple homozygote susceptible (SS/SS/SS) significantly laid more eggs and developed faster than other genotypes. Moreover, a restoration of susceptibility was noted over 10 generations in the insecticide-free environment with an increased proportion of susceptible individuals. This study highlights the negative impact of multiple P450-based resistance on the key physiological traits of malaria vectors. Such high fitness costs suggest that in the absence of selection pressure, the resistant individuals will be outcompeted in the field. Therefore, this should encourage future strategies based on the rotation of insecticides to reduce selection pressure and to slow the spread of pyrethroid resistance.

Comparative transcriptome and RNA interference reveal CYP6DC1 and CYP380C47 related to lambda-cyhalothrin resistance in Rhopalosiphum padi

The bird-cherry-oat aphid, Rhopalosiphum padi, is a serious agricultural pest of Triticeae crops, and pyrethroids are the most widely used chemical pesticides for the control of the aphid. Our previous studies found that some R. padi field populations have developed resistance against pyrethroids; an M918L target-site mutation of the voltage gated sodium channel was present in the pyrethroid resistant individuals, while the high-level resistance to lambda-cyhalothrin revealed the presence of other mechanisms in the pest. Here, we conducted genome-wide transcriptional analysis for the lambda-cyhalothrin susceptible (SS) and resistant (LC-RR) strains of R. padi. Results indicated that 2457 genes were differently expressed between the SS and LC-RR strains. In the LC-RR, a total of 1265 and 1192 genes were up- and down-regulated, respectively. KEGG analysis implicated enrichment of P450 involved in insecticide metabolic pathways in the resistant transcriptome. qRT-PCR results confirmed that two P450 genes (CYP6DC1 and CYP380C47) were significantly overexpressed in the LC-RR individuals. Furthermore, RNA interference (RNAi) of CYP6DC1 or CYP380C47 significantly increased mortality of R. padi exposure to lambda-cyhalothrin. These results suggest that the overexpression of CYP6DC1 and CYP380C47 contributed to the lambda-cyhalothrin resistance in the pest. This study provides knowledge for further analyzing the molecular mechanism of resistance to pyrethroids in R. padi.