Herbivore-Induced Plant Volatiles Can Serve as Host Location Cues for a Generalist and a Specialist Egg Parasitoid

Herbivore-induced plant volatiles are important host finding cues for larval parasitoids, and similarly, insect oviposition might elicit the release of plant volatiles functioning as host finding cues for egg parasitoids. We hypothesized that egg parasitoids also might utilize HIPVs of emerging larvae to locate plants with host eggs. We, therefore, assessed the olfactory response of two egg parasitoids, a generalist, Trichogramma pretiosum (Tricogrammatidae), and a specialist, Telenomus remus (Scelionidae) to HIPVs. We used a Y-tube olfactometer to tests the wasps’ responses to volatiles released by young maize plants that were treated with regurgitant from caterpillars of the moth Spodoptera frugiperda (Noctuidae) or were directly attacked by the caterpillars. The results show that the generalist egg parasitoid Tr. pretiosum is innately attracted by volatiles from freshly-damaged plants 0–1 and 2–3 h after regurgitant treatment. During this interval, the volatile blend consisted of green leaf volatiles (GLVs) and a blend of aromatic compounds, mono- and homoterpenes, respectively. Behavioral assays with synthetic GLVs confirmed their attractiveness to Tr. pretiosum. The generalist learned the more complex volatile blends released 6–7 h after induction, which consisted mainly of sesquiterpenes. The specialist T. remus on the other hand was attracted only to volatiles emitted from fresh and old damage after associating these volatiles with oviposition. Taken together, these results strengthen the emerging pattern that egg and larval parasitoids behave in a similar way in that generalists can respond innately to HIPVs, while specialists seems to rely more on associative learning.

Landscape context on generalist and specialist aphid natural enemies

Report for the scientific sojourn at the University of Lund, Sweden, between May and September 2007. A landscape-scale research approach has been highlighted by a growing body of literature as essential for understanding important ecosystem services as biological control. Aphids are victims of a diversity of enemies making the aphid-enemy interaction a nice example for the role of enemy diversity for the functioning of biological control. Here it is examined the effects of landscape complexity on cereal aphids and associated natural enemies that varied in the degree of specialization. Parasitoids wasps abundance did not differ between landscape types but was strongly negatively related to the percentage of arable land. In contrast, abundances of generalist predators like Coccinellidae were significantly higher in simple landscapes since can benefit from the high availability of a variety of alternative resources within cropping systems. Consequently coccinellidae-to-aphid ratio was significantly higher in fields in homogenous landscapes as compared to fields included in an heterogeneous landscape, suggesting that enemy pressure on cereal aphids increases with landscape simplification. The landscape effect will depend mainly on the degree of specialization of functionally dominant natural enemies, so that the results imply that conservation actions aiming to optimise abundance for one taxonomic group in the agricultural landscape will not automatically increase abundance of other groups. Given that the strength of natural enemy impact on biocontrol depends on landscape features and the role of functionally dominant natural enemies. So, therefore it is essential to focus the future empirical work in examining the schedule of agricultural landscapes that maintain a diversity of generalist and specialist natural enemies.

Assessing continental-scale risks for generalist and specialist pollinating bee species under climate change

Increased risks of extinction to populations of animals and plants under changing climate have now been demonstrated for many taxa. This study assesses the extinction risks to species within an important genus of pollinating bees (Colletes: Apidae) by estimating the expected changes in the area and isolation of suitable habitat under predicted climatic condition for 2050. Suitable habitat was defined on the basis of the presence of known forage plants as well as climatic suitability. To investigate whether ecological specialisation was linked to extinction risk we compared three species which were generalist pollen foragers on several plant families with three species which specialised on pollen from a single plant species. Both specialist and generalist species showed an increased risk of extinction with shifting climate, and this was particularly high for the most specialised species (Colletes anchusae and C. wolfi). The forage generalist C. impunctatus, which is associated with Boreo-Alpine environments, is potentially threatened through significant reduction in available climatic niche space. Including the distribution of the principal or sole pollen forage plant, when modelling the distribution of monolectic or narrowly oligolectic species, did not improve the predictive accuracy of our models as the plant species were considerably more widespread than the specialised bees associated with them.

Experimental evolution for generalists and specialists reveals multivariate genetic constraints on thermal reaction norms

Theory predicts the emergence of generalists in variable environments and antagonistic pleiotropy to favour specialists in constant environments, but empirical data seldom support such generalist–specialist trade-offs. We selected for generalists and specialists in the dung fly Sepsis punctum (Diptera: Sepsidae) under conditions that we predicted would reveal antagonistic pleiotropy and multivariate trade-offs underlying thermal reaction norms for juvenile development. We performed replicated laboratory evolution using four treatments: adaptation at a hot (31 °C) or a cold (15 °C) temperature, or under regimes fluctuating between these temperatures, either within or between generations. After 20 generations, we assessed parental effects and genetic responses of thermal reaction norms for three correlated life-history traits: size at maturity, juvenile growth rate and juvenile survival. We find evidence for antagonistic pleiotropy for performance at hot and cold temperatures, and a temperature-mediated trade-off between juvenile survival and size at maturity, suggesting that trade-offs associated with environmental tolerance can arise via intensified evolutionary compromises between genetically correlated traits. However, despite this antagonistic pleiotropy, we found no support for the evolution of increased thermal tolerance breadth at the expense of reduced maximal performance, suggesting low genetic variance in the generalist–specialist dimension.

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Formal professional relationships between general practitioners and specialists: possible associations with patient health and pharmacy costs

This article investigates whether the strength of formal professional relationships between general practitioners (GPs) and specialists (SPs) affects either the health status of patients or their pharmacy costs. To this end, it measures the strength of formal professional relationships between GPs and SPs through the number of shared patients and proxies the patient health status by the number of comorbidities diagnosed and treated. In strong GP–SP relationships, the patient health status is expected to be high, due to efficient care coordination, and the pharmacy costs low, due to effective use of resources. To test these hypotheses and compare the characteristics of the strongest GP–SP connections with those of the weakest, this article concentrates on diabetes—a chronic condition where patient care coordination is likely important. Diabetes generates the largest shared patient cohort in Hungary, with the highest traffic of specialist medication prescriptions. This article finds that stronger ties result in lower pharmacy costs, but not in higher patient health statuses. Key points for decision makers • The number of shared patients may be used to measure the strength of formal professional relationships between general practitioners and specialists. • A large number of shared patients indicates a strong, collaborative tie between general practitioners and specialists, whereas a low number indicates a weak, fragmented tie. • Tie strength does not affect patient health—strong, collaborative ties between general practitioners and specialists do not involve better patient health than weak, fragmented ties. • Tie strength does affect pharmacy costs—strong, collaborative ties between general practitioners and specialists involve significantly lower pharmacy costs than weak, fragmented ties. • Pharmacy costs may be reduced by lowering patient care fragmentation through channelling a general practitioner’s patients to a small number of specialists and increasing collaboration between general practitioner and specialists. • Limited patient choice is financially more beneficial than complete freedom of choice, and no more detrimental to patient health.

A gyógyszerkiadás és a betegek egészségi állapota a háziorvosi és szakorvosi kapcsolatok függvényében = Formal professional relations between general practitioners and specialists. Possible links with patient health and pharmacy cost

Arra a kérdésre keressük a választ, hogy a szoros háziorvosi-szakorvosi szakmai kapcsolatoknak van-e hatásuk a betegek gyógyszerkiadására, illetve egészségi állapotára. Az orvosok közötti szakmai kapcsolatok szorosságát a közösen gondozott betegek száma alapján határoztuk meg, míg a betegek egészségügyi állapotát a diagnosztizált és kezelt társbetegségek számával mértük. Hipotézisünk egyrészt az volt, hogy a hatékonyabb koordinációnak köszönhetően a szoros kapcsolatban kezelt betegek jobb egészségi állapotúak, másrészt kezelésük az erőforrások hatékonyabb felhasználása miatt kisebb gyógyszerköltséggel jár. E két hipotézist a cukorbetegekre teszteltük. Azért esett erre a krónikus betegségre a választásunk, mert itt a háziorvosok és a szakorvosok együttműködése elsődleges fontosságú. Magyarországon a cukorbetegek esetében a legnagyobb a közösen kezelt betegek populációja, valamint itt a legmagasabb a szakorvosi javaslatra felírt háziorvosi receptek száma. Azt az eredményt kaptuk, hogy a szoros kapcsolatban kezelt betegek nem rendelkeznek sem jobb, sem rosszabb egészségi állapottal, miközben a kapcsolódó gyógyszerkiadásuk szignifikánsan alacsonyabb. ____ The article considers whether strong formal professional relations between GPs and specialists in shared care affect either the health of patients or the pharmacy costs they incur. The strength of such relations is measured by the number of shared patients; patient health is proxied by number of co-morbidities diagnosed and treated. The first hypothesis is that patients treated amid strong GP-specialist relations have better health status than those treated amid weak ones, due to enhanced efficiency of care coordination. The second is that patients treated in such strong relations incur lower pharmacy costs high numbers of shared patients are assumed to promote appropriate, effective use of resources. The article tests these hypotheses and compares the outcomes of the strongest and weakest GP-specialist relations through the example of diabetes, a chronic condition where patient-care coordination is important. Diabetes generates the largest shared patient cohort in Hungary, with the highest number of specialist medication prescriptions. This article finds that stronger ties result in significantly lower pharmacy costs, but not a higher patient health status.

Host specialist clownfishes are environmental niche generalists.

Why generalist and specialist species coexist in nature is a question that has interested evolutionary biologists for a long time. While the coexistence of specialists and generalists exploiting resources on a single ecological dimension has been theoretically and empirically explored, biological systems with multiple resource dimensions (e.g. trophic, ecological) are less well understood. Yet, such systems may provide an alternative to the classical theory of stable evolutionary coexistence of generalist and specialist species on a single resource dimension. We explore such systems and the potential trade-offs between different resource dimensions in clownfishes. All species of this iconic clade are obligate mutualists with sea anemones yet show interspecific variation in anemone host specificity. Moreover, clownfishes developed variable environmental specialization across their distribution. In this study, we test for the existence of a relationship between host-specificity (number of anemones associated with a clownfish species) and environmental-specificity (expressed as the size of the ecological niche breadth across climatic gradients). We find a negative correlation between host range and environmental specificities in temperature, salinity and pH, probably indicating a trade-off between both types of specialization forcing species to specialize only in a single direction. Trade-offs in a multi-dimensional resource space could be a novel way of explaining the coexistence of generalist and specialists.

Expanded food choice as a possible factor in the evolution of sociality of Vespidae (Hymenoptera)

A recent theory suggests that economic considerations are more important than genetic ones in the emergence and maintenance of social behavior. Evolution of social behavior in wasps, thus, could be based on the development of worker castes, which increase the efficiency of brood care and energy use of the colony. If so, social wasps should collect a larger range of prey, favoring polyethism, as social behavior should increase the adaptive value of social species among wasps by increasing the range of prey accessible. We explored the literature and showed that the Eumeninae, which are mostly solitary, draw prey from significantly fewer orders of arthropods than wasps in the subfamily Vespinae and Polistinae, which are mainly social, supporting the hypothesis that social behavior may have emerged as a more efficient way to feed and care for the young by opening a wider range of food sources, increasing the amount of food and quality of care provided to the young. Two alternative explanations of this data are also discussed.

Comparison of pollinators and natural enemies: a meta-analysis of landscape and local effects on abundance and richness in crops

To manage agroecosystems for multiple ecosystem services, we need to know whether the management of one service has positive, negative, or no effects on other services. We do not yet have data on the interactions between pollination and pest-control services. However, we do have data on the distributions of pollinators and natural enemies in agroecosystems. Therefore, we compared these two groups of ecosystem service providers, to see if the management of farms and agricultural landscapes might have similar effects on the abundance and richness of both. In a meta-analysis, we compared 46 studies that sampled bees, predatory beetles, parasitic wasps, and spiders in fields, orchards, or vineyards of food crops. These studies used the proximity or proportion of non-crop or natural habitats in the landscapes surrounding these crops (a measure of landscape complexity), or the proximity or diversity of non-crop plants in the margins of these crops (a measure of local complexity), to explain the abundance or richness of these beneficial arthropods. Compositional complexity at both landscape and local scales had positive effects on both pollinators and natural enemies, but different effects on different taxa. Effects on bees and spiders were significantly positive, but effects on parasitoids and predatory beetles (mostly Carabidae and Staphylinidae) were inconclusive. Landscape complexity had significantly stronger effects on bees than it did on predatory beetles and significantly stronger effects in non-woody rather than in woody crops. Effects on richness were significantly stronger than effects on abundance, but possibly only for spiders. This abundance-richness difference might be caused by differences between generalists and specialists, or between arthropods that depend on non-crop habitats (ecotone species and dispersers) and those that do not (cultural species). We call this the ‘specialist-generalist’ or ‘cultural difference’ mechanism. If complexity has stronger effects on richness than abundance, it might have stronger effects on the stability than the magnitude of these arthropod-mediated ecosystem services. We conclude that some pollinators and natural enemies seem to have compatible responses to complexity, and it might be possible to manage agroecosystems for the benefit of both. However, too few studies have compared the two, and so we cannot yet conclude that there are no negative interactions between pollinators and natural enemies, and no trade-offs between pollination and pest-control services. Therefore, we suggest a framework for future research to bridge these gaps in our knowledge.

Generalists versus specialists: toward a typology of batterers in prison

In this study we apply the versatile/specialist offender debate to the research of intimate partner violence. We propose the existence of two types of imprisoned male batterers: the generalist and the specialist batterer. The individual, family, and community characteristics of these types of batterers are further explored in 110 imprisoned males in the Penitentiary of Villabona (Spain). As for the individual characteristics, results indicate that the generalist batterer present higher levels of psychopathology (specially antisocial and borderline personality), sexist attitudes, and substance dependence. Specialist batterers presented higher levels of conflict in their family of origin. Finally, generalist batterers reported coming from more socially disordered communities and showed lower levels of participation and integration in these communities than the specialist batterer. These results suggest that the classical distinctions among batterers based on psychopathology and context of violence (whether general or family only) might be of little utility when applied to imprisoned male batterers.