Sister predatory mites collectively protect their eggs against predators.

Group-living animals sometimes cooperatively protect their offspring against predators. This behavior is observed in a wide range of taxa but, to the best of our knowledge, this is the first report of its occurrence in arthropods that are not eusocial. Adult female predatory mites Gynaeseius liturivorus protect their eggs against egg predators, the predatory mite species Neoseiulus californicus. In the field, several adult female G. liturivorus were often found on the same plant structures such as folded leaves. We tested whether these females might protect their eggs cooperatively, focusing on kinship between the females. When two adult female G. liturivorus were kept in the absence of egg predators, their reproduction was not affected by their kinship. The presence of egg predators reduced the number of G. liturivorus eggs. However, reproduction of two G. liturivorus sisters was higher than that of two non-sisters. Together, sisters guarded the oviposition site longer than non-sisters. We further tested if non-sisters increased egg guarding by having developed together from eggs to adults and found no such effect. Although it remains unclear how adult female G. liturivorus recognize conspecifics as kin or sisters, our results suggest that G. liturivorus sisters reduced predation on their offspring by cooperatively guarding their eggs.

Imperfect diet choice reduces the performance of a predatory mite.

Two mutually unexclusive hypotheses prevail in the theory of nutritional ecology: the balanced diet hypothesis states that consumers feed on different food items because they have complementary nutrient and energy compositions. The toxin-dilution hypothesis poses that consumers feed on different food items to dilute the toxins present in each. Both predict that consumers should not feed on low-quality food when ample high-quality food forming a complete diet is present. We investigated the diet choice of Phytoseiulus persimilis, a predatory mite of web-producing spider mites. It can develop and reproduce on single prey species, for example the spider mite Tetranychus urticae. A closely related prey, T. evansi, is of notorious bad quality for P. persimilis and other predator species. We show that juvenile predators feeding on this prey have low survival and do not develop into adults. Adults stop reproducing and have increased mortality when feeding on it. Feeding on a mixed diet of the two prey decreases predator performance, but short-term effects of feeding on the low-quality prey can be partially reversed by subsequently feeding on the high-quality prey. Yet, predators consume low-quality prey in the presence of high-quality prey, which is in disagreement with both hypotheses. We suggest that it is perhaps not the instantaneous reproduction on single prey or mixtures of prey that matters for the fitness of predators, but that it is the overall reproduction by a female and her offspring on an ephemeral prey patch, which may be increased by including inferior prey in their diet.

Gender differences in risk factor management and pharmacological treatment among CHD patients: Belgian results of the EUROASPIRE IV and EUROASPIRE V surveys.

AIMS: The aim of this study was to provide an up-to-date overview of gender differences or similarities in risk factor control and medical management in the Belgian CHD population. METHODS: All analyses are based on the ESC EORP EUROASPIRE IV and EUROASPIRE V (European Survey Of Cardiovascular Disease Prevention And Diabetes) surveys. Patients between 18 and 80 years old, hospitalised for a first or recurrent coronary event, were included in the survey. RESULTS: Data were available for 10,519 patients, of which 23.9% were women. Women had a worse risk factor profile compared to men. Women were more physical inactive (OR = 1.31, 95% CI = 1.19-1.44), had a higher prevalence of obesity (OR = 1.37, 95% CI = 1.25-1.50) and had a worse LDL-C control (OR = 1.52, 95% CI = 1.36-1.70). Moreover, women were less likely to use ACE-I/ARBs (OR = 0.84, 95% CI = 0.76-0.94) and statins (OR = 0.79, 95% CI = 0.70-0.90). In addition, little gender differences were found in patients' risk factor awareness, except on cholesterol awareness. Women were more aware about their total cholesterol levels (OR = 1.37, 95% CI = 1.21-1.56). CONCLUSION: Despite little to no gender differences in the management of CHD patients, women still have a worse risk factor profile, both in Belgian and in other European high-income countries.

Review: predatory soil mites as biocontrol agents of above- and below-ground plant pests.

Biological pest control is becoming increasingly important for sustainable agriculture. Although many species of natural enemies are already being used commercially, efficient biological control of various pests is still lacking, and there is a need for more biocontrol agents. In this review, we focus on predatory soil mites, their role as natural enemies, and their biocontrol potential, mainly in vegetable and ornamental crops, with an emphasis on greenhouse systems. These predators are still underrepresented in biological control, but have several advantages compared to predators living on above-ground plant parts. For example, predatory soil mites are often easy and affordable to mass rear, as most of them are generalist predators, which also means that they may be used against various pests and can survive periods of pest scarcity by feeding on alternative prey or food. Many of them can also endure unfavourable conditions, making it easier for them to establish in various crops. Based on the current literature, we show that they have potential to control a variety of pests, both in greenhouses and in the field. However, more research is needed to fully understand and appreciate their potential as biocontrol agents. We review and discuss several methods to increase their efficiency, such as supplying them with alternative food and changing soil/litter structure to enable persistence of their populations. We conclude that predatory soil mites deserve more attention in future studies to increase their application in agricultural crops.

Artificial selection for timing of dispersal in predatory mites yields lines that differ in prey exploitation strategies.

Dispersal is the main determinant of the dynamics and persistence of predator-prey metapopulations. When defining dispersal as a predator exploitation strategy, theory predicts the existence of a continuum of strategies: from some dispersal throughout the predator-prey interaction (the Milker strategy) to dispersal only after the prey had been exterminated (the Killer strategy). These dispersal strategies relate to differences in prey exploitation at the population level, with more dispersal leading to longer predator-prey interaction times and higher cumulative numbers of dispersing predators. In the predatory mite Phytoseiulus persimilis, empirical studies have shown genetic variation for prey exploitation as well as for the timing of aerial dispersal in the presence of prey. Here, we test whether artificial selection for lines that differ in timing of dispersal also results in these lines differing in prey exploitation. Six rounds of selection for early or late dispersal resulted in predator lines displaying earlier or later dispersal. Moreover, it resulted-at the population level-in predicted differences in the local predator-prey interaction time and in the cumulative numbers of dispersers in a population dynamics experiment. We pose that timing of dispersal is a heritable trait that can be selected in P. persimilis, which results in lines that show quantitative differences in local predator-prey dynamics. This opens ways to experimentally investigate the evolution of alternative prey exploitation strategies and to select for predator strains with prey exploitation strategies resulting in better biological control.

Estimating intrinsic growth rates of arthropods from partial life tables using predatory mites as examples.

The intrinsic rate of natural increase of a population (rm) has been in focus as a key parameter in entomology and acarology. It is considered especially important in studies of predators that are potential biological control agents of fast-growing pests such as mites, whiteflies and thrips. Life-table experiments under controlled laboratory conditions are standard procedures to estimate rm. However, such experiments are often time consuming and may critically depend on the precise assessment of the developmental time and the fecundity rate early in the reproductive phase. Using selected studies of predatory mites with suitable life-table data, we investigated whether and how measurements of growth rates can be simplified. We propose a new method for estimating rm from partial life tables, in which the researcher can choose a level of precision based on a stand-in measure of relative error. Based on this choice, the procedure helps the researcher to decide when a life-table experiment can be terminated. Depending on the chosen precision, significant amounts of experimental time can be saved without seriously compromising the reliability of the estimated growth parameter.

Enhanced top-down control of herbivore population growth on plants with impaired defences.

Herbivore densities can be regulated by bottom-up and top-down forces such as plant defences and natural enemies, respectively. These forces can interact with each other to increase plant protection against herbivores; however, how much complementarity exists between bottom-up and top-down forces still remains to be fully elucidated. Particularly, because plant defences can hinder natural enemies, how these interactions affect herbivore performance and dynamics remains elusive.To address this topic, we performed laboratory and greenhouse bioassays with herbivorous mite pests and predatory mites on mutant tomato plants that lack defensive hairs on stems and leaves. Particularly, we investigated the behaviour and population dynamics of different phytophagous mite species in the absence and presence of predatory mites.We show that predatory mites do not only perform better on tomatoes lacking defensive hairs but also that they can suppress herbivore densities better and faster on these hairless plants. Hence, top-down control of herbivores by natural enemies more than compensated the reduced bottom-up herbivore control by plant defences.Our results lead to the counter-intuitive insight that removing, instead of introducing, plant defence traits can result in superior protection against important pests through biological control. Read the free Plain Language Summary for this article on the Journal blog.

Biodiversity in and around Greenhouses: Benefits and Potential Risks for Pest Management.

One of the ecosystem services of biodiversity is the contribution to pest control through conservation and stimulation of natural enemies. However, whether plant diversity around greenhouses is beneficial or a potential risk is heavily debated. In this review, we argue that most greenhouse pests in temperate climates are of exotic origin and infest greenhouses mainly through transportation of plant material. For indigenous pests, we discuss the potential ways in which plant diversity around greenhouses can facilitate or prevent pest migrations into greenhouses. As shown in several studies, an important benefit of increased plant diversity around greenhouses is the stimulation of indigenous natural enemies that migrate to greenhouses, where they suppress both indigenous and exotic pests. How this influx can be supported by specific plant communities, plant characteristics, and habitats while minimising risks of increasing greenhouse pest densities, virus transmission, or hyperparasitism needs further studies. It also requires a better understanding of the underlying processes that link biodiversity with pest management. Inside greenhouses, plant biodiversity can also support biological control. We summarise general methods that growers can use to enhance pest control with functional biodiversity and suggest that it is particularly important to study how biodiversity inside and outside greenhouses can be linked to enhancement of biological pest control with both released and naturally occurring species of natural enemies.

Pesticides do not significantly reduce arthropod pest densities in the presence of natural enemies.

Chemical pesticides remain the main agents for control of arthropod crop pests despite increased concern for their side effects. Although chemical pesticide applications generally result in short-term decreases of pest densities, densities can subsequently resurge to higher levels than before. Thus, pesticide effects on pest densities beyond a single pest generation may vary, but they have not been reviewed in a systematic manner. Using mathematical predator-prey models, we show that pest resurgence is expected when effective natural enemies are present, even when they are less sensitive to pesticides than the pest. Model simulations over multiple pest generations predict that pest resurgence due to pesticide applications will increase average pest densities throughout a growing season when effective natural enemies are present. We tested this prediction with a meta-analysis of published data of field experiments that compared effects of chemical control of arthropod plant pests in the presence and absence of natural enemies. This largely confirmed our prediction: overall, pesticide applications did not reduce pest densities significantly when natural enemies were present, which concerned the vast majority of cases. We also show that long-term pesticide effectiveness is underreported and suggest that pest control by natural enemies deserves more attention.

Experimental evolution of cowpea mild mottle virus reveals recombination-driven reduction in virulence accompanied by increases in diversity and viral fitness.

Major themes in pathogen evolution are emergence, evolution of virulence, host adaptation and the processes that underlie them. RNA viruses are of particular interest due to their rapid evolution. The in vivo molecular evolution of an RNA plant virus was demonstrated here using a necrotic isolate of cowpea mild mottle virus (CPMMV) and a susceptible soybean genotype submitted to serial inoculations. We show that the virus lost the capacity to cause necrosis after six passages through the host plant. When a severe bottleneck was imposed, virulence reduction occurred in the second passage. The change to milder symptoms had fitness benefits for the virus (higher RNA accumulation) and for its vector, the whitefly Bemisia tabaci. Genetic polymorphisms were highest in ORF1 (viral replicase) and were independent of the symptom pattern. Recombination was a major contributor to this diversity - even with the strong genetic bottleneck, recombination events and hot spots were detected within ORF1. Virulence reduction was associated with different sites in ORF1 associated to recombination events in both experiments. Overall, the results demonstrate that the reduction in virulence was a consequence of the emergence of new variants, driven by recombination. Besides providing details of the evolutionary mechanisms behind a reduction in virulence and its effect under viral and vector fitness, we propose that this recombination-driven switch in virulence allows the pathogen to rapidly adapt to a new host and, potentially, switch back.

Optimising implementation of European guidelines on cardiovascular disease prevention in clinical practice: what is needed?

Cardiovascular disease is a model example of a preventable condition for which practice guidelines are particularly important. In 2016, the joint task force created by the European Society of Cardiology (ESC) together with 10 other societies released the new version of the European guidelines on cardiovascular disease prevention. To facilitate the implementation of the ESC guidelines, a dedicated prevention implementation committee has been established within the European Association of Preventive Cardiology. The paper will first explore potential barriers to the guidelines' implementation. It then develops a discussion that seeks to inform the future development of the committee's work, including a new definition of the guidelines' stakeholders (health policy-makers, healthcare professionals and health educators, patient organisations, entrepreneurs and the general public), future activities within four specific areas: strengthening awareness of the guidelines among stakeholders; supporting organisational changes to facilitate the guidelines' implementation; motivating stakeholders to utilise the guidelines; and present ideas on new implementation strategies. Providing multifaceted cooperation between healthcare professionals, healthcare management executives and health policy-makers, the novel approach proposed in this paper should contribute to a wider use of the 2016 ESC guidelines and produce desired effects of less cardiovascular disease morbidity and mortality. Furthermore, the solutions presented within the paper may constitute a benchmark for the implementation of practice guidelines in other medical disciplines.

Standardization and quality improvement of secondary prevention through cardiovascular rehabilitation programmes in Europe: The avenue towards EAPC accreditation programme: A position statement of the Secondary Prevention and Rehabilitation Section of the European Association of Preventive Cardiology (EAPC).

Despite the proven efficacy and cost-effectiveness of contemporary cardiovascular rehabilitation programmes, the referral to/uptake of and adherence to cardiovascular rehabilitation remains inadequate. In addition, heterogeneity persists amongst different cardiovascular rehabilitation centres in Europe, despite the available scientific documents describing the evidence-based rehabilitation format/content. This position statement was elaborated by the Secondary Prevention and Rehabilitation (SP/CR) section of EAPC. It defines the minimal and optimal cardiovascular rehabilitation standards. In addition, it describes the relevant quality indicators of cardiovascular rehabilitation programmes to date. Compliance of European cardiovascular rehabilitation centres with these standards will improve cardiovascular rehabilitation process standardization in Europe and hence increase the quality of cadiovascular rehabilitation programmes.

Validity of a Norwegian version of the Desire Thinking Questionnaire (DTQ): Associations with problem drinking, nicotine dependence and problematic social media use.

The aim of the current study was to test the validity of the Norwegian version of the Desire Thinking Questionnaire (DTQ). Three cross-sectional surveys were conducted investigating the psychometric properties of the DTQ in alcohol use (N = 588), nicotine use (N = 446) and social media use (N = 359). Principal components and confirmatory factor analyses supported the original two-factor solution consisting of verbal perseveration (VP) and imaginal prefiguration (IP); however, one item was removed to obtain good fit. Internal consistency was acceptable. Both IP and VP showed significant correlations with problem drinking, nicotine dependence and problematic social media use. Regression analyses, controlling for demographics and negative affect, found IP and VP to be significantly associated with all dependent variables. The results confirm that desire thinking is an important construct across different addictive behaviours.

Males cannibalise and females disperse in the predatory mite Phytoseiulus persimilis.

Cannibalism is a widespread phenomenon in nature, often occurring when food is scarce, for example among predators that have overexploited a local prey population. Instead of cannibalising, predators can disperse, thereby avoiding being cannibalised or cannibalising related conspecifics, which results in inclusive fitness loss. Theory on prey exploitation in ephemeral predator-prey systems predicts that predators may be selected to display prudent predation by dispersing early, thus saving food for their remaining offspring. This is especially advantageous when average relatedness in the local population is high. Less prudent predators refrain from dispersing until all prey are exterminated. These prey exploitation strategies may also have repercussions for cannibalism, especially when it is driven by food shortage. We therefore investigated to what extent adult females and males cannibalise or disperse after prey have been exterminated locally. We used two lines of the haplodiploid predatory mite Phytoseiulus persimilis that were selected for early and late dispersal, respectively. In wind tunnels, we observed the cannibalistic and dispersal behaviour of individual adult predators of these lines on a rose leaf with only conspecific larvae as food. Both selection lines behaved similarly, indicating that selection on dispersal behaviour did not result in correlated effects on cannibalism behaviour. Male predators stayed significantly longer on the leaf and engaged more often in cannibalism than females. The results suggest that there might be gender-specific differences in cannibalistic tendency in relation to dispersal. Future theoretical studies on the evolution of cannibalism and dispersal should take differences between the genders into account.

The distribution of herbivores between leaves matches their performance only in the absence of competitors.

Few studies have tested how plant quality and the presence of competitors interact in determining how herbivores choose between different leaves within a plant. We investigated this in two herbivorous spider mites sharing tomato plants: Tetranychus urticae, which generally induces plant defenses, and Tetranychus evansi, which suppresses them, creating asymmetrical effects on coinfesting competitors. On uninfested plants, both herbivore species preferred young leaves, coinciding with increased mite performance. On plants with heterospecifics, the mites did not prefer leaves on which they had a better performance. In particular, T. urticae avoided leaves infested with T. evansi, which is in agreement with T. urticae being outcompeted by T. evansi. In contrast, T. evansi did not avoid leaves with the other species, but distributed itself evenly over plants infested with heterospecifics. We hypothesize that this behavior of T. evansi may prevent further spread of T. urticae over the shared plant. Our results indicate that leaf age determines within-plant distribution of herbivores only in absence of competitors. Moreover, they show that this distribution depends on the order of arrival of competitors and on their effects on each other, with herbivores showing differences in behavior within the plant as a possible response to the outcome of those interactions.

High-quality alternative food reduces cannibalism in the predatory mite Amblyseius herbicolus (Acari: Phytoseiidae).

Predatory mites of the Phytoseiidae family are important biological control agents. Many species of this family are omnivores, i.e., besides on prey, they can feed on plant resources such as nectar and pollen. It has been shown that the addition of alternative food for predators to a crop enhances biological control. However, factors such as food availability and quality can also affect interactions such as cannibalism, and thus influence biological control. We investigated the role of quality of the alternative food in the tendency of Amblyseius herbicolus to engage in cannibalism, a common ecological interaction in many phytoseiid mite species. Cannibalism on eggs by A. herbicolus was significantly reduced in the presence of high-quality food (cattail pollen) compared to egg cannibalism without alternative food, whereas this was not the case in the presence of low-quality food (cotton pollen). This suggests that cattail pollen is a high-quality alternative food, not only because it results in increased development and reproduction of predators, but also because it can minimize cannibalism.

Positive and negative metacognitions about alcohol: Validity of the Norwegian PAMS and NAMS.

A growing body of research has demonstrated that metacognitions are associated with alcohol use and other addictive behaviours. In the present study (N = 588), we investigated the validity of the Positive Alcohol Metacognitions Scale (PAMS) and the Negative Alcohol Metacognitions Scale (NAMS). The results supported two-factor solutions for both the PAMS and NAMS, but three items from the PAMS were deleted. These metacognitive measures distinguished between participants in low, moderate, and high-risk groups. Significant correlations were observed with alcohol use, and both PAMS and NAMS were unique significant predictors of alcohol use whilst controlling for demographics and negative affect. The validity of the Norwegian versions of PAMS and NAMS confirm previous findings and provide further support for the importance of metacognitions in alcohol use.