Relative Fitness Research Articles

Standardization and Adaptation as a Coconstituted Process: The Pursuit of Relational Fit in International Markets

Marketing products/services internationally entails a bold decision that has high-cost implications and significant performance consequences: Should the firm standardize or adapt its marketing strategy across borders? The dilemma is a seminal issue, and perhaps the most enduring in international marketing scholarship. However, despite the voluminous work on the topic, an ontological assumption induces inconclusive conceptualizations and impedes theoretical advancement. The author contends that a self-contained, atomistic representation of the standardization/adaptation decision is such an impediment. This work problematizes a portrayal of the decision as if it is taken following a detached, own judgment of broad environmental contingencies. In turn, the study builds on fit literature and promotes an alternative perspective that acknowledges relational imperatives for requisite theorizing. Hence, standardization/adaptation is framed as a coconstituted process toward relational fit, with international marketing strategies being contingent on the role of significant “others.”

Why Do Bi-Factor Models Outperform Higher-Order g Factor Models? A Network Perspective.

Bi-factor models of intelligence tend to outperform higher-order g factor models statistically. The literature provides the following rivalling explanations: (i) the bi-factor model represents or closely approximates the true underlying data-generating mechanism; (ii) fit indices are biased against the higher-order g factor model in favor of the bi-factor model; (iii) a network structure underlies the data. We used a Monte Carlo simulation to investigate the validity and plausibility of each of these explanations, while controlling for their rivals. To this end, we generated 1000 sample data sets according to three competing models-a bi-factor model, a (nested) higher-order factor model, and a (non-nested) network model-with 3000 data sets in total. Parameter values were based on the confirmatory analyses of the Wechsler Scale of Intelligence IV. On each simulated data set, we (1) refitted the three models, (2) obtained the fit statistics, and (3) performed a model selection procedure. We found no evidence that the fit measures themselves are biased, but conclude that biased inferences can arise when approximate or incremental fit indices are used as if they were relative fit measures. The validity of the network explanation was established while the outcomes of our network simulations were consistent with previously reported empirical findings, indicating that the network explanation is also a plausible one. The empirical findings are inconsistent with the (also validated) hypothesis that a bi-factor model is the true model. In future model selection procedures, we recommend that researchers consider network models of intelligence, especially when a higher-order g factor model is rejected in favor of a bi-factor model.

Flexible B12 ecophysiology of Phaeocystis antarctica due to a fusion B12–independent methionine synthase with widespread homologues

Coastal Antarctic marine ecosystems are significant in carbon cycling because of their intense seasonal phytoplankton blooms. Southern Ocean algae are primarily limited by light and iron (Fe) and can be co-limited by cobalamin (vitamin B12). Micronutrient limitation controls productivity and shapes the composition of blooms which are typically dominated by either diatoms or the haptophyte Phaeocystis antarctica. However, the vitamin requirements and ecophysiology of the keystone species P. antarctica remain poorly characterized. Using cultures, physiological analysis, and comparative omics, we examined the response of P. antarctica to a matrix of Fe-B12 conditions. We show that P. antarctica is not auxotrophic for B12, as previously suggested, and identify mechanisms underlying its B12 response in cultures of predominantly solitary and colonial cells. A combination of proteomics and proteogenomics reveals a B12-independent methionine synthase fusion protein (MetE-fusion) that is expressed under vitamin limitation and interreplaced with the B12-dependent isoform under replete conditions. Database searches return homologues of the MetE-fusion protein in multiple Phaeocystis species and in a wide range of marine microbes, including other photosynthetic eukaryotes with polymorphic life cycles as well as bacterioplankton. Furthermore, we find MetE-fusion homologues expressed in metaproteomic and metatranscriptomic field samples in polar and more geographically widespread regions. As climate change impacts micronutrient availability in the coastal Southern Ocean, our finding that P. antarctica has a flexible B12 metabolism has implications for its relative fitness compared to B12-auxotrophic diatoms and for the detection of B12-stress in a more diverse set of marine microbes.

Effect of Specific Training Package on Skill Related Physical Fitness of Kabaddi Players

Abstract: The study was an attempt to ascertain the effect of a specific training package on skill related physical fitness of Kabaddi players. Sixty numbers of professional students acted as subjects being divided equally into Control and Experimental Groups. The Specific training package was given to experimental group for a period of six weeks. Among the six variables of the skill related physical fitness all the variables except reaction time variable showed significant differences at .05 level of confidence of experimental group. This was indication that short duration training package is not suitable for enhancing the reaction time.

Fitness trade-offs of multidrug efflux pumps in Escherichia coli K-12 in acid or base, and with aromatic phytochemicals.

Multidrug efflux pumps are the frontline defense mechanisms of Gram-negative bacteria, yet little is known of their relative fitness trade-offs under gut conditions such as low pH and the presence of antimicrobial food molecules. Low pH contributes to the proton-motive force (PMF) that drives most efflux pumps. We show how the PMF-dependent pumps AcrAB-TolC, MdtEF-TolC, and EmrAB-TolC undergo selection at low pH and in the presence of membrane-permeant phytochemicals. Competition assays were performed by flow cytometry of co-cultured Escherichia coli K-12 strains possessing or lacking a given pump complex. All three pumps showed negative selection under conditions that deplete PMF (pH 5.5 with carbonyl cyanide 3-chlorophenylhydrazone or at pH 8.0). At pH 5.5, selection against AcrAB-TolC was increased by aromatic acids, alcohols, and related phytochemicals such as methyl salicylate. The degree of fitness cost for AcrA was correlated with the phytochemical's lipophilicity (logP). Methyl salicylate and salicylamide selected strongly against AcrA, without genetic induction of drug resistance regulons. MdtEF-TolC and EmrAB-TolC each had a fitness cost at pH 5.5, but salicylate or benzoate made the fitness contribution positive. Pump fitness effects were not explained by gene expression (measured by digital PCR). Between pH 5.5 and 8.0, acrA and emrA were upregulated in the log phase, whereas mdtE expression was upregulated in the transition-to-stationary phase and at pH 5.5 in the log phase. Methyl salicylate did not affect pump gene expression. Our results suggest that lipophilic non-acidic molecules select against a major efflux pump without inducing antibiotic resistance regulons.IMPORTANCEFor drugs that are administered orally, we need to understand how ingested phytochemicals modulate drug resistance in our gut microbiome. Bacteria maintain low-level resistance by proton-motive force (PMF)-driven pumps that efflux many different antibiotics and cell waste products. These pumps play a key role in bacterial defense by conferring resistance to antimicrobial agents at first exposure while providing time for a pathogen to evolve resistance to higher levels of the antibiotic exposed. Nevertheless, efflux pumps confer energetic costs due to gene expression and pump energy expense. The bacterial PMF includes the transmembrane pH difference (ΔpH), which may be depleted by permeant acids and membrane disruptors. Understanding the fitness costs of efflux pumps may enable us to develop resistance breakers, that is, molecules that work together with antibiotics to potentiate their effect. Non-acidic aromatic molecules have the advantage that they avoid the Mar-dependent induction of regulons conferring other forms of drug resistance. We show that different pumps have distinct selection criteria, and we identified non-acidic aromatic molecules as promising candidates for drug resistance breakers.

The Role of Flagellum and Flagellum-Based Motility on Salmonella Enteritidis and Escherichia coli Biofilm Formation.

Flagellum-mediated motility has been suggested to contribute to virulence by allowing bacteria to colonize and spread to new surfaces. In Salmonella enterica and Escherichia coli species, mutants affected by their flagellar motility have shown a reduced ability to form biofilms. While it is known that some species might act as co-aggregation factors for bacterial adhesion, studies of food-related biofilms have been limited to single-species biofilms and short biofilm formation periods. To assess the contribution of flagella and flagellum-based motility to adhesion and biofilm formation, two Salmonella and E. coli mutants with different flagellar phenotypes were produced: the fliC mutants, which do not produce flagella, and the motAB mutants, which are non-motile. The ability of wild-type and mutant strains to form biofilms was compared, and their relative fitness was determined in two-species biofilms with other foodborne pathogens. Our results showed a defective and significant behavior of E. coli in initial surface colonization (p < 0.05), which delayed single-species biofilm formation. Salmonella mutants were not affected by the ability to form biofilm (p > 0.05). Regarding the effect of motility/flagellum absence on bacterial fitness, none of the mutant strains seems to have their relative fitness affected in the presence of a competing species. Although the absence of motility may eventually delay initial colonization, this study suggests that motility is not essential for biofilm formation and does not have a strong impact on bacteria's fitness when a competing species is present.

Regularized regression can improve estimates of multivariate selection in the face of multicollinearity and limited data.

The breeder's equation, , allows us to understand how genetics (the genetic covariance matrix, G) and the vector of linear selection gradients β interact to generate evolutionary trajectories. Estimation of β using multiple regression of trait values on relative fitness revolutionized the way we study selection in laboratory and wild populations. However, multicollinearity, or correlation of predictors, can lead to very high variances of and covariances between elements of β, posing a challenge for the interpretation of the parameter estimates. This is particularly relevant in the era of big data, where the number of predictors may approach or exceed the number of observations. A common approach to multicollinear predictors is to discard some of them, thereby losing any information that might be gained from those traits. Using simulations, we show how, on the one hand, multicollinearity can result in inaccurate estimates of selection, and, on the other, how the removal of correlated phenotypes from the analyses can provide a misguided view of the targets of selection. We show that regularized regression, which places data-validated constraints on the magnitudes of individual elements of β, can produce more accurate estimates of the total strength and direction of multivariate selection in the presence of multicollinearity and limited data, and often has little cost when multicollinearity is low. We also compare standard and regularized regression estimates of selection in a reanalysis of three published case studies, showing that regularized regression can improve fitness predictions in independent data. Our results suggest that regularized regression is a valuable tool that can be used as an important complement to traditional least-squares estimates of selection. In some cases, its use can lead to improved predictions of individual fitness, and improved estimates of the total strength and direction of multivariate selection.

Fitness effects of a demography-dispersal trade-off in expandingSaccharomyces cerevisiaemats.

Fungi expand in space and time to form complex multicellular communities. The mechanisms by which they do so can vary dramatically and determine the life-history and dispersal traits of expanding populations. These traits influence deterministic and stochastic components of evolution, resulting in complex eco-evolutionary dynamics during colony expansion. We perform experiments on budding yeast strains genetically engineered to display rough-surface and smooth-surface phenotypes in colony-like structures called 'mats'. Previously, it was shown that the rough-surface strain has a competitive advantage over the smooth-surface strain when grown on semi-solid media. We experimentally observe the emergence and expansion of segments with a distinct smooth-surface phenotype during rough-surface mat development. We propose a trade-off between dispersal and local carrying capacity to explain the relative fitness of these two phenotypes. Using a modified stepping-stone model, we demonstrate that this trade-off gives the high-dispersing, rough-surface phenotype a competitive advantage from standing variation, but that it inhibits this phenotype's ability to invade a resident smooth-surface population via mutation. However, the trade-off improves the ability of the smooth-surface phenotype to invade in rough-surface mats, replicating the frequent emergence of smooth-surface segments in experiments. Together, these computational and experimental findings advance our understanding of the complex eco-evolutionary dynamics of fungal mat expansion.

Feeding behavior and life-history parameters of Therioaphis trifolii (Hemiptera: Aphididae) on 2 alfalfa cultivars.

Alfalfa, Medicago sativa, is a link connecting crop production and animal husbandry and plays a dominant role in the development of the livestock sector. The productivity of alfalfa is adversely affected by aphids' feeding damage and their capacity to transmit viral plant pathogens. To increase alfalfa forage yield, it is imperative to control pest insects and use resistant varieties. The aim of this study was to identify the mechanism of M. sativa resistance to aphids by examining changes in the physiology, feeding behavior, and life history of the pests. The leaves of Gannong No. 5 (HA-3, aphid-resistant cultivar) had denser, longer trichome and thicker cortical parenchyma cell, and greater xylem thicknesses than those of Hunter River (Hu, aphid-susceptible cultivar). Nonprobing behaviors suggested that the spotted alfalfa aphid, Therioaphis trifolii, became more active in searching for suitable feeding sites on HA-3 than on Hu plants. Additionally, T. trifolii showed shorter durations for salivating into sieve elements and ingesting phloem sap on HA-3 plants. Life-table analysis showed that T. trifolii on HA-3 had longer developmental duration, higher mortality rate, and lower fecundity, net reproductive rate, intrinsic rate of increase, finite rate of increase and gross reproduction rate values than that on Hu plants. Moreover, relative fitness was significantly reduced in T. trifolii on HA-3 plants. The results of this study provided a basis for developing better control strategies for T. trifolii and studying the mechanisms of alfalfa resistance to aphids.

Challenges and pitfalls of inferring microbial growth rates from lab cultures

IntroductionAfter more than 100 years of generating monoculture batch culture growth curves, microbial ecologists and evolutionary biologists still lack a reference method for inferring growth rates. Our work highlights the challenges of estimating the growth rate from growth curve data. It shows that inaccurate estimates of growth rates significantly impact the estimated relative fitness, a principal quantity in evolution and ecology. Methods and resultsFirst, we conducted a literature review and found which methods are currently used to estimate growth rates. These methods differ in the meaning of the estimated growth rate parameter. Mechanistic models estimate the intrinsic growth rate µ, whereas phenomenological methods – both model-based and model-free – estimate the maximum per capita growth rate µmax. Using math and simulations, we show the conditions in which µmax is not a good estimator of µ. Then, we demonstrate that inaccurate absolute estimates of µ are not overcome by calculating relative values. Importantly, we find that poor approximations for µ sometimes lead to wrongly classifying a beneficial mutant as deleterious. Finally, we re-analyzed four published data sets, using most of the methods found in our literature review. We detected no single best-fitting model across all experiments within a data set and found that the Gompertz models, which were among the most commonly used, were often among the worst-fitting. DiscussionOur study suggests how experimenters can improve their growth rate and associated relative fitness estimates and highlights a neglected but fundamental problem for nearly everyone who studies microbial populations in the lab.

Increased mutations in lipopolysaccharide biosynthetic genes cause time-dependent development of phage resistance in Salmonella.

Understanding how bacteria evolve resistance to phages has implications for phage-based therapies and microbial evolution. In this study, the susceptibility of 335 Salmonella isolates to the wide host range Salmonella phage BPSELC-1 was tested. Potentially significant gene sets that could confer resistance were identified using bioinformatics approaches based on phage susceptibility phenotypes; more than 90 potential antiphage defense gene sets, including those involved in lipopolysaccharide (LPS) biosynthesis, DNA replication, secretion systems, and respiratory chain, were found. The evolutionary dynamics of Salmonella resistance to phage were assessed through laboratory evolution experiments, which showed that phage-resistant mutants rapidly developed and exhibited genetic heterogeneity. Most representative Salmonella hosts (58.1% of 62) rapidly developed phage resistance within 24 h. All phage-resistant mutant clones exhibited genetic heterogeneity and observed mutations in LPS-related genes (rfaJ and rfaK) as well as other genes such as cellular respiration, transport, and cell replication-related genes. The study also identified potential trade-offs, indicating that bacteria tend to escape fitness trade-offs through multi-site mutations, all tested mutants increased sensitivity to polymyxin B, but this does not always affect their relative fitness or biofilm-forming capacity. Furthermore, complementing the rfaJ mutant gene could partially restore the phage sensitivity of phage-resistant mutants. These results provide insight into the phage resistance mechanisms of Salmonella and the complexity of bacterial evolution resulting from phage predation, which can inform future strategies for phage-based therapies and microbial evolution.

Dynamic responses of Salmonella Typhimurium to re-exposure to sublethal ciprofloxacin.

This study was designed to evaluate the history-dependent behaviors of Salmonella Typhimurium re-exposed to sublethal levels of ciprofloxacin. The S. Typhimurium cells were pre-exposed to 0 (CON), 1/16 (LOW), 1/8 (MED), and 1/4 (HIGH) minimum inhibitory concentrations (MICs) of ciprofloxacin, followed by re-exposure to the same concentrations. The bacterial growth, postantibiotic effect (PAE), relative fitness, and swimming motility of treatments were evaluated in the absence of ciprofloxacin. The lag phase duration (LPD) was estimate to assess bacterial recovery under ciprofloxacin exposure. A disk diffusion assay was used to determine the cross-resistance and collateral sensitivity of CON, LOW, MED, and HIGH treatments to ciprofloxacin (CIP), ceftriaxone (CEF), erythromycin (ERY), gentamicin (GEN), and polymyxin B (POL). The S. Typhimurium cells pre-exposed to ciprofloxacin were susceptible in antibiotic-free media, showing delayed growth. The highest PAE (>1h) and bacterial fluctuation (CV=5%) were observed at the High treatment compared to the CON. The HIGH treatment had the lowest relative fitness levels (0.87) and swimming motility (55mm). The LPD was significantly decreased at the LOW treatment (1.8h) when re-exposed to 1/16×MIC of ciprofloxacin. The LOW, MED, and HIGH treatments showed the cross-resistance to POL and the collateral sensitivity to CEF, ERY, and GEN. The pre-exposure to ciprofloxacin could induce phenotypic diversity, corresponding to the history-dependent behaviors. These results provide important insights for the dynamic nature of bacterial populations when re-exposed to sublethal concentrations of antibiotics.

Impact of Yog Asanas on the health related physical fitness of cricket players at college level

Impact of Yog Asanas on the health related physical fitness of cricket players at college level

Selecting an Appropriate Cognitive Diagnostic Model for Eighth Grade Math Questions: TIMSS 2019 Study

Background and Objective: Traditional assessment methods have been criticized for neglecting the cognitive processes required by test-takers to provide correct responses. To address these issues, cognitive diagnostic models have been introduced by researchers. This study aimed to explore and apply cognitive diagnostic models to estimate the psychometric properties of published eighth-grade math questions from TIMSS 2019. Methods and Materials: The research method employed in this study is mixed-methods, conducted with a retrofitting approach to existing tests. The statistical population of this study consisted of all Iranian eighth-grade students who participated in the TIMSS 2019 study. The population size included 1,095,026 students from 23,895 schools. The sample consisted of 5,980 Iranian eighth-grade students from 220 schools, selected through a two-stage cluster sampling method, with an average age reported as 14.1 years. Findings: Using a qualitative method, 16 skills across four content domains—knowledge, application, and reasoning—were identified and the Q-matrix was developed. Then, in the quantitative section, the fit of the DINA model as a compensatory model, the DINO model as a non-compensatory model, and the G-DINA model as a general model were examined with data from students' responses to math questions in blocks 1, 2, 3, and 5. The findings showed that in terms of model fit, the G-DINA model had the weakest fit, while the DINA model had the best fit. Absolute fit indices of the models also indicated that the DINA model was better, and the DINO model did not fit. Relative fit indices of the models showed no significant difference between the G-DINA model and the other two models, and overall, the non-compensatory DINA model demonstrated the best fit. Conclusion: The results indicated that the DINA model had the best fit with the data and can be considered the optimal model for analyzing the eighth-grade mathematics questions in TIMSS 2019.

Do epiphytes affect the fitness of their phorophytes? The case of Tillandsia recurvata on Bursera copallifera

Abstract The studies about the negative effect of epiphytes on their phorophytes show contradictory results and are based on limited variables (e.g., shoot survival). On branches of Bursera copallifera, we experimented with the transplantation/removal of Tillandsia recurvata and artificial tussocks, measuring shoot survival, growth, generation of new shoots, and production of inflorescences and fruits. Most single traits did not differ between treatments. The generation of new shoots was lower in the treatments where T. recurvata was present and increased in the branches where it was removed. The lowest shoot survival was in the treatments where T. recurvata was present or was removed. Removing T. recurvata increased plant relative fitness, and it was 43% lower in branches with T. recurvata. Tillandsia recurvata is a structural parasite of B. copallifera. A negative effect of epiphytes on their phorophytes appears counterintuitive since it would not be evolutionarily stable for an epiphyte to shorten the lifespan of its support. Tillandsia recurvata populations are concentrated on B. copallifera branches between 2-4 cm in diameter, while smaller branches are mostly empty, so it is possible that the negative effect of T. recurvata occurs in the smallest branches, explaining why T. recurvata populations are biased to larger branches.

Exploring the adoption of risk governance structures within the Turkish banking field: an institutional theory lens, 2006-2009

Purpose- The purpose of this study is to investigate the adoption patterns of transnationally imposed risk governance structures within the Turkish banking field employing an institutional theory perspective. Building on institutional complexity, which stems from the conflict between transnational and national institutional influences, our study examines two different periods where transnational and national institutional arrangements were in relative fit or misfit. Methodology- The methodology of this study includes the analysis of the publicly available panel data of banks. The annual reports of all 15 banks are used to gather the banks’ risk governance, risk management and performance indicators. All the reports are reached from Public Disclosure Platform (www.kap.gov.tr) or the corporate web sites of the banks. Findings- A risk governance index is constructed to measure the varying levels of adoption among the banks, covering the period from 2006 to 2019. According to the findings, the risk governance index may include the dimension of risk committee, the dimension of chief risk officer, the risk appetite framework of the institution, and corporate governance. However, the risk performance of the banks may vary on different indicators. Conclusion- It is uncovered that banks displayed a relatively homogenous adoption pattern during the 2006-2012 period when transnational and national institutional arrangements were in harmony. However, the adoption patterns diverged among banks when national institutional arrangements began to differ from transnational standards starting from 2013. It is also found that the adoption of transnational templates about risk governance did not result in significant performance increases in risk or corporate performance metrics, indicating a ritual adoption behavior by the majority of the banks, which fail or intendedly decline to entrench corresponding practices associated with these templates. Keywords: Risk governance, adoption, institutional field, transnational institutions, banking JEL Codes: D21, G21, G32, L20, M10

Light partitioning strategies impact relative fitness of weeds and cover crops when drill-interseeding in corn

AbstractDrill-interseeding cover crops into corn (Zea mays L.) is an emerging establishment method in northern U.S. production regions. However, cover crop performance in interseeded systems remains variable, and creating environments that are conducive to cover crop but not weed growth is challenging. Cultural practices that partition resources between corn and interseeded cover crops have potential to improve performance if weeds are adequately managed. This study evaluated interactions among corn hybrids differing in leaf architecture (upright, pendulum), corn row spacing (76 cm, 152 cm), and interseeding timing (V3, V6) on light transmittance, relative fitness of cover crop species (cereal rye [Secale cereale L.], annual ryegrass (Lolium multiflorum Lam), red clover [Trifolium pratense L.]) and weeds, and corn grain yield at three U.S. Northeast locations. Results showed that light transmittance through the corn canopy was greater in 152-cm row spacing compared with 76-cm row spacing at the V6 growth stage, with the magnitude of difference increasing at the V10 corn growth stage. Corn hybrids had a marginal effect on light transmittance. The effect of row spacing and interseeding timing on fall cover crop biomass varied across cover crop species and locations. In 76-cm rows, interseeding earlier (V3) increased cover crop biomass production. The relative fitness of cover crops was greater than that of weeds in each combination of cultural practices that included narrow spacing (76 cm), whereas the relative fitness of weeds was greater than that of cover crops when interseeding in wide rows (152 cm). The effect of row spacing on corn yield varied among locations, with higher yields observed in 76-cm row spacing compared with 152-cm at two of three locations. Our results show that interseeding early (V3) on 76-cm row spacing can balance cover crop and corn production management goals, while placing cover crops at a relative fitness advantage over weeds.

The Relationship of the PROMIS® Pediatric Physical Activity Measure with Cardiorespiratory Fitness.

A The PROMIS® Pediatric Physical Activity (PA) measure is a new instrument with established validity that measures a child self-report on short bouts of moderate to rigorous physical activity. The purpose of this study was to explore the relationship of the PROMIS® Pediatric PA item bank with cardiorespiratory fitness and self-efficacy. The study was conducted at the Minnesota State Fair. Youth ages 8 to 18 years completed the PROMIS® Pediatric PA and the Self-Efficacy for PA measures on an iPad. Participants performed 3-min step test with heart rates measured 1 min posttest. Participants (N = 182) were 53% female. The PROMIS® Pediatric PA had a weak, significant negative correlation with the step test measurement (r = -0.23, p = 0.001) and a weak, significant positive correlation with self-efficacy (r = 0.27, p < 0.001). Measurements did not differ between groups by sex or age group (school-age and adolescent). Youth who were obese had significantly higher heart rates post step test (p = 0.004); BMI percentile groups did not differ in other measures. Self-report of PA and the physiologic measure of heart rate are from two related but different physical fitness domains which supports their significant but weak relationship.

Integrated resistance management for acaricide use on Varroa destructor

The global beekeeping industry faces an escalating challenge in the form of Varroa destructor. Synthetic chemicals serve as a cornerstone for varroa management, although they face a major challenge in the form of acaricide resistance. Here, I examine acaricide resistance in varroa under the framework of Insecticide Resistance Management (IRM). I assess the potential of diverse IRM strategies, such as pesticide rotation and mixtures, refuge utilization, synergists and the integration of non-persistent chemicals. The peculiar life history of varroa, characterized by its incestuous breeding system, challenges conventional IRM strategies. There is little published evidence that pesticide rotation is beneficial for resistance management in varroa, with several studies showing resistance is maintained despite rotation. Fitness costs associated with pesticide resistance are often an essential component for IRM strategies, but there are no current data from varroa demonstrating such specific fitness costs (e.g., a reduced relative oviposition rate) associated with resistance. The single published experimental study directly examining relative fitness found that here was little or no reproductive fitness cost associated with pyrethroid resistance. More work is needed on fitness effects of the key acaricides, which would better guide the use of rotation and refuge strategies. A key prospect for future work that has been identified through simulation modeling is offered by pesticide mixtures and the role of synergists to elevate acaricide efficacy. Additional tools for varroa IRM include ‘soft’ acaricides, including oxalic acid, and biopesticides such as dsRNA. In light of the widespread prevalence of acaricide resistance and an increasing varroa problem, there is an urgent need for nuanced, data-driven varroa IRM strategies.

Meta-analysis of influence of yoga activities on reaction time as a component of skill related fitness

Introduction: Yoga practices are known to have beneficial effect on cognitive functions. Reaction is a purposeful voluntary response to external stimuli. Reaction time is a component of skill related fitness. Humans gives response to different external environmental stimuli with different speed. Majority of daily work is done in response to visual and auditory stimuli. Yoga practices may improve reaction time. Objectives: To study influence of yoga practices on auditory reaction time and visual reaction time. Methods: Researchers used the Preferred Reporting Items for Systematic Reviews and Meta- Analyses (PRISMA) guidelines for reporting systematic reviews and meta-analysis. Researchers searched articles on PubMed, Google scholar and by manual search. Searched articles were screened for relevancy. By use of inclusion and exclusion criteria potential articles were selected. Results: Out of 287articles, finally 5 studies included in current meta-analysis. Yoga activities has effect on visual reaction time (VRT): SMD = 3.06, 95% CI = –0.66–6.78, P &lt; 0.01 and auditory reaction time (ART): SMD = 2.86, 95% CI = –0.37–6.09. Conclusion: Yogic activities can provide beneficial effect on reaction time. Improved reaction time is important for reactive activity like sports. Yoga can be useful as a part of training in skill related work. There is wide scope for further studies to evaluate beneficial effects of yoga activities.