Sex pheromone component ratios and mating isolation among three Lygus plant bug species of North America

The plant bugs Lygus hesperus, Lygus lineolaris, and Lygus elisus (Hemiptera: Miridae) are major pests of many agricultural crops in North America. Previous studies suggested that females release a sex pheromone attractive to males. Other studies showed that males and females contain microgram amounts of (E)-4-oxo-2-hexenal, hexyl butyrate, and (E)-2-hexenyl butyrate that are emitted as a defense against predators. Using gas chromatography–mass spectrometry, we found that female L. lineolaris and L. elisus have a 4:10 ratio of hexyl butyrate to (E)-2-hexenyl butyrate that is reversed from the 10:1 ratio in female L. hesperus (males of the three species have ~10:1 ratio). These reversed ratios among females of the species suggest a behavioral role. Because both sexes have nearly equal amounts of the major volatiles, females should release more to attract males. This expectation was supported because L. hesperus females released more hexyl butyrate (mean of 86 ng/h) during the night (1800–0700 hours) than did males (<1 ng/h). We used slow-rotating pairs of traps to test the attraction of species to blends of the volatiles with a subtractive method to detect synergism. Each species’ major butyrate ester was released at 3 μg/h, the minor butyrate according to its ratio, and (E)-4-oxo-2-hexenal at 2 μg/h. The resulting catches of only Lygus males suggest that (E)-4-oxo-2-hexenal is an essential sex pheromone component for all three species, (E)-2-hexenyl butyrate is essential for L. elisus and L. lineolaris, and hexyl butyrate is essential for L. hesperus. However, all three components are recognized by each species since ratios of the butyrate esters are critical for conspecific attraction and heterospecific avoidance by males and thus play a role in reproductive isolation among the three species. Because L. hesperus males and females are known to emit these major volatiles for repelling ant predators, our study links defensive allomones in Lygus bugs with an additional use as sex pheromones.     

Are there any job resources capable of moderating the effect of physical demands on work ability? A study among kindergarten teachers

Background. It is recognized that teaching in a preschool context is physically demanding. Despite this, the consequences of physical demands on psychophysical health (including work ability) are significantly understudied among kindergarten teachers. Objectives. The aim of the present study is to examine (a) the association between physical demands and work ability and (b) whether psychosocial job resources buffer the negative impact of physical demands among kindergarten teachers. Method. A total of 426 kindergarten teachers employed in the municipal educational services of a city in northwest Italy filled out a self-reported questionnaire. Results. High association was found between physical demand and work ability. Moderated hierarchical regressions showed that decision authority, skill discretion, reward and meaning of work buffer the hampering effect of physical demands and work ability. No buffering effects were observed for support from superiors and colleagues. Conclusion. The present study has relevant, practical implications, highlighting the importance of investing in interventions encompassing a holistic perspective (e.g., psychosocial and ergonomic) in order to effectively combat the hampering effect of physical demands on work ability.     

A study of osteological and molecular differences in populations of Aphanius fasciatus Nardo 1827, from the central Mediterranean (Teleostei, Cyprinodontidae)

Nine populations of Aphanius fasciatus Nardo, 1827 from the central Mediterranean were analysed by examining the mitochondrial control region and the morphology of the bony elements of the skull and vertebral column, to study the degree of intraspecific differentiation of A. fasciatus considering the level of isolation of the different populations and the palaeogeographic history of the central Mediterranean area. Both the molecular and morphological analyses differentiate between the populations, even if the topologies of the two trees are different. Molecular and osteological investigations have consistently demonstrated a well-supported differentiation of the south-eastern Sicilian populations both within the same group (Tigano et al. in Ital J Zool 71:1124–1133, 2004a; Tigano et al. in Abstract volume XI European Congress of Ichthyology, Tallin, Estonia, 2004b), and from the populations from western Sicily, Tunisia and the island of Malta. The molecular results show that the nine populations are characterised by haplotypes that are well defined in relation to a probably limited gene flow; while, as regards the morphological data the differentiation found could be explained in terms of the geographic isolation of the various populations, although the influence of environmental factors, which differ greatly between the various sites where the populations live, cannot be ruled out.     

Sediment organic matter and meiofauna community response to long-term fish-farm impact in the Ligurian Sea (Western Mediterranean)

Quantitative and qualitative changes in meiofauna community structure were investigated to assess the impact of a fish farm, which was operating continuously for 15 years (La Spezia Gulf, W Mediterranean). Sediment samples were collected in June, July, September, October 2000 and February 2001 for the analysis of phytopigments (chlorophyll-a and phaeopigments), the biochemical composition of organic matter (proteins, carbohydrates and lipids) and related to meiofaunal parameters.

Sediment organic matter reached extremely high concentrations beneath the fish cages when compared to the control. Particularly lipids, carbohydrates and chlorophyll-a were significantly higher in fish-farm sediments. On a long-term basis meiofauna displayed adaptations in sediments beneath the cages resulting in an increase of density. Organic impact on meiofaunal community structure was evident in terms of an increase of the nematodes to copepods (Ne/Co) and nauplius to copepods (Na/Co) ratios in fish farm sediments. Cumaceans and kinorhynchs were encountered in control sediments, but disappeared in fish-farm samples. These data suggest that meiofauna is a sensitive tool for evaluating the effects of organic enrichment in fish farm impacted areas.     

Positive long-term effect of mulching on species and functional trait diversity in a nutrient-poor mountain meadow in Central Europe

Oligotrophic mountain meadows are threatened biodiversity hotspots throughout Europe. The traditional summer hay-making followed by autumn grazing is no longer economic and question is whether alternative managements can maintain both plant species and functional diversity typical of these habitats. In the Bohemian Forest Mts., we applied three treatments (mowing once a year - i.e., cutting and removing the biomass, mulching once a year - cutting and leaving the crushed biomass to decompose in situ, fallowing - no cutting) in order to assess temporal changes in meadow vegetation, plant trait composition and biomass production in a 13-year experiment. We recorded for each species twenty-five traits as to be most informative of plant strategies related to growth, resource acquisition and carbon-water economy. We compared different components of trait composition (community averages that mostly reflect traits of dominant species vs. the Rao index of functional diversity that reflects trait dissimilarity among species) and their impact on biomass production. We show that mulching promotes species and functional diversity by facilitating heliophilous forbs and legumes with more acquisitive strategies in resource use and release, e.g., higher foliar N and P content. This occurs at the expense of tall grasses (with resource-retentive strategies, e.g., high leaf dry matter content) which dominate the mown and fallow plots. The divergence in most quantitative traits indicates that niche complementarity is the dominant assembly process in mulched plots, which can prevent competitive exclusion and enable species coexistence. The divergent development was detected only after 5-6 years. This slow floristic and functional response is caused by acidity of soil and severe mountain climate that preclude rapid responses of vegetation to land-use changes. We conclude that mulching represents a good compromise maintaining both plant species and functional diversity as well as a relatively high biomass production. Mowing without grazing leads to gradual nutrient loss and thus reduces the productivity and diversity in these oligotrophic ecosystems. Fallowing causes gradual loss in diversity by increased grass competition and litter accumulation.     

Effect of agricultural activities on surface water quality from páramo ecosystems

Environmental Science and Pollution Research - Páramos are high mountain ecosystems strategic for water provision in South America. Currently, páramos are under threat due to agricultural...     

Airborne concentrations of SARS-CoV-2 in indoor community environments in Italy

Environmental Science and Pollution Research - COVID-19 pandemic raised a debate regarding the role of airborne transmission. Information regarding virus-laden aerosol concentrations is still...     

Phytotoxic effects of phenolic acids from <Emphasis Type="Italic">Merostachys riedeliana,</Emphasis> a native and overabundant Brazilian bamboo

Merostachys riedeliana Rupr. is a native and overabundant bamboo species in the Brazilian Atlantic Forest. Moderate to strong allelopathic activity may be one mechanism that explains this super-dominance and the changes in structure and composition of forest areas occupied by bamboo. This study evaluated the phytotoxic effect of M. riedeliana extracts and fractions and identified their putative allelochemicals. We investigated the presence of allelochemicals in soil collected from stands occupied by M. riedeliana. Furthermore, we evaluated the putative effect of tree allelochemicals, individually and combined, on germination and growth. The aqueous extract of leaves and its ethyl acetate fraction presented the highest inhibitory effects on seed germination and seedling growth. The effect of the extracts and fractions on the target species was species-specific. Neither the individual nor the combined phenolic acids significantly inhibited seed germination; however, a pronounced growth inhibition was observed in M. bimucronata seedlings treated with vanillic acid and in E. verna and M. bimucronata seedlings treated with combined phenolic acids. Isovitexin, vitexin, isoorientin, orientin, and their O-glycoside derivatives, the lactonic dimer of the p-hydroxybenzoic acid and 3,4-methylenedioxymandelic acid were identified in the aqueous extracts and ethyl acetate fraction by Liquid Chromatography-Diode Array Dectector/Electrospray Ionization/Mass Spectrometry (LC-DAD/ESI–MS/MS). The Gas Chromatography-Mass Spectrometer (GC–MS) profile of the same extract and fraction showed the presence of benzoic, benzeneacetic, salicylic, p-hydroxybenzoic, p-hydroxyphenylacetic, vanillic, p-coumaric, protocatechuic, syringic, gallic, m-coumaric vanillylmandelic, 4-methylmandelic, 3,4-methylenedioxymandelic and trans-ferulic acids. The p-benzoic acid and the apigenin 6-C-glucoside (isovitexin) were identified in the soil extract collected from under bamboo-growing areas. Even though laboratory bioassays are not completely predictive of the allelopathic effects that occur in nature, the results of this study provide preliminary evidence of allelopathy as a possible species-specific inhibition mechanism of native species that explain the impoverishment of floristic richness and the functional groups in areas where M. riedeliana is overabundant.