The effects of insect–insect interactions on the performance of three biological control agents released against water hyacinth

Insect–insect interactions can have implications for biological control programmes when multiple agent species are released. In many cases there is an increase in the efficacy when more than one species is used; however, there is a possibility that releasing an additional species into a programme could have a negative effect. The interactions between three arthropod agents of water hyacinth Eichhornia crassipes (Martius) Solms-Laubach, Eccritotarsus catarinensis (Carvalho), Neochetina bruchi Hustache and Neochetina eichhorniae Warner were investigated in an experiment to measure the impact that pairwise combinations of the insects may have on their performance. There was a significant interaction between the mirid E. catarinensis and the weevil N. eichhorniae, with significantly fewer weevil feeding scars when in combination with the mirid (approximately 0.2 scars per cm²) than when alone (approximately 0.4 scars per cm²). There were also slightly fewer petioles mined by N. eichhorniae when in combination with the mirid. Interestingly there was a negative interaction between the two weevil species when in combination, with the number of feeding scars being significantly lower per individual when the two species were in combination. None of the insects performed significantly better when in combination with another insect, however, the mirid was never negatively affected by the presence of either weevil species. The interactions observed between the insects tested were identifiable but subtle and are unlikely to have implications on establishment or performance of the insects in the introduced range, South Africa.     

Climate change effects on behavioral and physiological ecology of predator–prey interactions: Implications for conservation biological control

Habitat management under the auspices of conservation biological control is a widely used approach to foster conditions that ensure a diversity of predator species can persist spatially and temporally within agricultural landscapes in order to control their prey (pest) species. However, an emerging new factor, global climate change, has the potential to disrupt existing conservation biological control programs. Climate change may alter abiotic conditions such as temperature, precipitation, humidity and wind that in turn could alter the life-cycle timing of predator and prey species and the behavioral nature and strength of their interactions. Anticipating how climate change will affect predator and prey communities represents an important research challenge. We present a conceptual framework—the habitat domain concept—that is useful for understanding contingencies in the nature of predator diversity effects on prey based on predator and prey spatial movement in their habitat. We illustrate how this framework can be used to forecast whether biological control by predators will become more effective or become disrupted due to changing climate. We discuss how changes in predator–prey interactions are contingent on the tolerances of predators and prey species to changing abiotic conditions as determined by the degree of local adaptation and phenotypic plasticity exhibited by species populations. We conclude by discussing research approaches that are needed to help adjust conservation biological control management to deal with a climate future.     

Divergent effects of compounds on the hydrolysis and transpeptidation reactions of γ-glutamyl transpeptidase

A novel class of inhibitors of the enzyme γ-glutamyl transpeptidase (GGT) were evaluated. The analog OU749 was shown previously to be an uncompetitive inhibitor of the GGT transpeptidation reaction. The data in this study show that it is an equally potent uncompetitive inhibitor of the hydrolysis reaction, the primary reaction catalyzed by GGT in vivo. A series of structural analogs of OU749 were evaluated. For many of the analogs, the potency of the inhibition differed between the hydrolysis and transpeptidation reactions, providing insight into the malleability of the active site of the enzyme. Analogs with electron withdrawing groups on the benzosulfonamide ring, accelerated the hydrolysis reaction, but inhibited the transpeptidation reaction by competing with a dipeptide acceptor. Several of the OU749 analogs inhibited the transpeptidation reaction by slow onset kinetics, similar to acivicin. Further development of inhibitors of the GGT hydrolysis reaction is necessary to provide new therapeutic compounds.     

Working on Sundays–effects on safety, health, and work-life balance

Several attributes of the work schedule can increase the risk of occupational injuries and accidents, health impairments, and reduced social participation. Although previous studies mainly focused on the effects of shiftwork and long working hours on employee health and safety, there is little evidence of a potential negative impact of working Sundays on the incidence of occupational accidents, health impairments, and work-life balance. A representative sample of employed workers in 31 member and associated states of the European Union (n?=?23,934) served as the database for a cross-sectional analysis. The sample was collected via face-to-face interviews in the year 2005. The association of the risks of occupational accidents, health impairments, and decreases in work-life balance with working Sundays was calculated using logistic regression models, controlling for potential confounders, such as shiftwork, workload, and demographic characteristics. The results indicated that working one or more Sundays/month was associated with increase both in the risk of reporting one or more health impairments (odds ratio [OR]: 1.17, 95% confidence interval [CI]: 1.06-1.29) and poorer work-life balance (OR: 1.15, 95% CI: 1.02-1.28). These effects remained after controlling for potentially confounding factors, such as other work schedule attributes, intensity of physical and mental workload, and individual characteristics. Furthermore, working Sundays was also related to increased risk of occupational accidents within the last year (OR: 1.34, 95% CI: 1.03-1.73). Controlling again for individual, workload, and working-time characteristics, a significant association with accident risk, however, remained only in work sectors with low a priori risk of occupational accidents (OR: 1.40, 95% CI: 1.02-1.91), although the increased risk could be observed for both medium and high a priori risk sectors working Sundays (without controlling for additional confounders). The results thus indicate that the detrimental effects of working Sundays on safety, health, and social well-being should be taken into account when designing work schedules. The potential hazards to employees' safety, health, and work-life balance, in particular, should be considered in discussions concerning extending work on Sundays in certain sectors, e.g., retail.     

Sublethal effects on reproduction in native fauna: are females more vulnerable to biological invasion?

Although invasive species are a major threat to survivorship of native species, we know little about their sublethal effects. In soft-sediment marine systems, mat-forming invasive species often have positive effects, facilitating recruitment and enhancing the diversity and abundance of native invertebrates. However, because mat-forming invasive species change the habitat in which they invade, and benthic invertebrates are sensitive to environmental disturbance, important sublethal effects on native species may exist. Using a model marine system we show that the widespread mat-forming invasive alga Caulerpa taxifolia (Vahl) C. Agardh has strong negative effects on the reproductive traits of a native bivalve Anadara trapezia (Deshayes, 1840) (e.g. timing of reproductive development and spawning, and follicle and gamete production) even though the invader has positive effects on recruitment. Moreover, gender specific responses occurred and indicated that females were more susceptible to invasion than males. Our results indicate that sublethal effects of an invasive species on reproductive traits will have severe consequences for fitness of the native species.     

Combined Ring–Mesh Optical Transport Networks

To date in Sonet and DWDM transport environments, we see two dominant principles for network survivability: ring and mesh. Although both are used, they are virtually always deployed and operated on geographically separate networks or regions, or applied on a ring-access and mesh-core principle. We describe a new approach for optimized design of ring and mesh network components in a single hybrid transport network. A key concept in design of these hybrids is the clipping of forcer spans in the mesh network design by strategically added rings. We present a formal optimization model and a heuristic to form sych hybrid designs with lower total cost than a pure-mesh design. These ideas on optical network architecture are especially relevant to industry practice with the advent of OXC systems with integrated add–drop multiplexer functionality and by the development of ultra long reach (ULR) optics. This integration of OXC-OADM functionality effectively removes any extra costs associated with transitions from a ring to mesh environment and ULR optics permit all-optical bypass of OXC nodes which enhances the cost-effectiveness of the hybrid architectures.     

The effects of stenting on coronary endothelium from a molecular biological view: Time for improvement?

Coronary artery stenting following balloon angioplasty represents the gold standard in revascularization of coronary artery stenoses. However, stent deployment as well as percutaneous transluminal coronary angioplasty (PTCA) alone causes severe injury of vascular endothelium. The damaged endothelium is intrinsically repaired by locally derived endothelial cells and by circulating endothelial progenitor cells from the blood, leading to re‐population of the denuded regions within several weeks to months. However, the process of re‐endothelialization is often incomplete or dysfunctional, promoting in‐stent thrombosis and restenosis. The molecular and biomechanical mechanisms that influence the process of re‐endothelialization in stented segments are incompletely understood. Once the endothelium is restored, endothelial function might still be impaired. Several strategies have been followed to improve endothelial function after coronary stenting. In this review, the effects of stenting on coronary endothelium are outlined and current and future strategies to improve endothelial function after stent deployment are discussed.     

Accumulation,degradation and biological effects of lindane on Scenedesmus obliquus (Turp.) Kütz

A study was made of accumulation, degradation and biological effects of lindane (r-BHC) on Scenedesmus obliquus (Turp.) Kütz. The work was conducted in a sewage reservoir in Han-Ku, Tianjin. Experimental results show that at 0.1–10 mgl⁻¹ concentration of lindane, the growth, chlorophyll and carotene content in S. obliquus do not differ much from the control. At concentrations of 50–100 mgl⁻¹, however, growth is inhibited, and chlorophyll and carotene content is low. From the beginning of the experiment until the fifth day, growth rate and pigment content increase constantly. On the seventh day, they start to decrease. Spectrographic analysis shows that pigment content decreases, but pigment structure is not changed even at high concentration of lindane. At 1–10 mgl⁻¹ of lindane, amino acids remain unchanged, with the exception of aspartine, arginine, methionine and phenylalanine. Scenedesmus obliquus (Turp.) Kütz possesses a certain accumulating capacity for r-BHC, which is higher at 1 mgl⁻¹ than at 10 mgl⁻¹. Accumulation is enhanced with time and is better under turbulent conditions. Gas chromatograms show that after treatment for 24 h, there are two more peaks at retention time 1′32″ and 1′53″, respectively, suggesting that a certain degree of lindane degradation occurs. The nature of these degradation products awaits further study. As a conclusion S. obliquus (Turp.) Kütz holds promise in the treatment of lindane-containing wastewaters in the range of 1–10 mgl⁻¹.     

Effects of global environmental changes on parasitoid–host food webs and biological control

Global environmental changes threaten biodiversity and the interactions between species, and food-web approaches are being used increasingly to measure their community-wide impacts. Here we review how parasitoid–host food webs affect biological control, and how their structure responds to environmental change. We find that land-use intensification tends to produce webs with low complexity and uneven interaction strengths. Dispersal, spatial arrangement of habitats, the species pool and community differences across habitats have all been found to determine how webs respond to landscape structure, though clear effects of landscape complexity on web structure remain elusive. The invasibility of web structures and response of food webs to invasion have been the subject of theoretical and empirical work respectively, and nutrient enrichment has been widely studied in the food-web literature, potentially driving dynamic instability and altering biomass ratios of different trophic levels. Combined with food-web changes observed under climate change, these responses of food webs could signal changes to biological control, though there have been surprisingly few studies linking food-web structure to pest control, and these have produced mixed results. However, there is strong potential for food-web approaches to add value to biological control research, as parasitoid–host webs have been used to predict indirect effects among hosts that share enemies, to study non-target effects of biological control agents and to quantify the use of alternative prey resources by enemies. Future work is needed to link food-web interactions with evolutionary responses to the environment and predator–prey interactions, while incorporating recent advances in predator biodiversity research. This holistic understanding of agroecosystem responses and functioning, made possible by food-web approaches, may hold the key to better management of biological control in changing environments.     

Metal–bipyridine complexes in DNA backbones and effects on thermal stability

Modified oligonucleotides are showing potential for multiple applications, including drug design, nanoscale building blocks, and biosensors. In an effort to expand the functionality available to DNA, we have placed chelating ligands directly into the backbone of DNA. Between one and three nucleosides were replaced with 2,2′-bipyridine phosphates in 23-mer duplexes of DNA. An array of metal ions were added (Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, and Pt²⁺) and the influences on duplex stability were examined by melting temperature studies. Titrations and UV–vis absorption spectroscopy were used to provide insights into the nature of the metal complexes formed. We found that Ni²⁺ binding to 2,2′-bipyridine typically provided the greatest increase in duplex stability relative to the other metal ions examined. For example, addition of Ni²⁺ to one 2,2′-bipyridine–DNA duplex increased the melting temperature by 13 °C, from 65.0 ± 0.3 to 78.4 ± 0.9 °C. These studies show that metal ions and backbone ligands can be used to regulate DNA structure and stability.     

Maternal effects on offspring consumption can stabilize fluctuating predator–prey systems

Maternal effects, where the conditions experienced by mothers affect the phenotype of their offspring, are widespread in nature and have the potential to influence population dynamics. However, they are very rarely included in models of population dynamics. Here, we investigate a recently discovered maternal effect, where maternal food availability affects the feeding rate of offspring so that well-fed mothers produce fast-feeding offspring. To understand how this maternal effect influences population dynamics, we explore novel predator–prey models where the consumption rate of predators is modified by changes in maternal prey availability. We address the ‘paradox of enrichment'', a theoretical prediction that nutrient enrichment destabilizes populations, leading to cycling behaviour and an increased risk of extinction, which has proved difficult to confirm in the wild. Our models show that enriched populations can be stabilized by maternal effects on feeding rate, thus presenting an intriguing potential explanation for the general absence of ‘paradox of enrichment'' behaviour in natural populations. This stabilizing influence should also reduce a population''s risk of extinction and vulnerability to harvesting.     

The challenge of predicting temperature effects on short-term predator–prey dynamics

Understanding how interacting species respond to changing temperatures is complicated because both inter- and intraspecific processes can be temperature-dependent, and because the dynamics of interest often occur over short time scales. While efforts to document and integrate inter- and intraspecific effects are ongoing, few broad conclusions have emerged. Here, we use a simple structured predator–prey model to explore whether some such conclusions can be reached with incomplete knowledge about initial population sizes or about how temperature alters predation rates. We find that, despite strong sensitivity of quantitative predictions to the model’s details, qualitative predictions for how predator–prey communities respond to temperature may still be possible. As a case study, we ask whether biological control of the herbivorous insect pea aphid will be strengthened or weakened by increasing temperatures. Our empirically derived parameter estimates suggest biological control will be strengthened, but we caution that this result is not inevitable given what we currently know about the effects of temperature in this system. Our work highlights the complex interaction between inter- and intraspecific effects of temperature in ecological communities.     

Temporal effects of ocean warming and acidification on coral–algal competition

Coral Reefs - While there is an ever-expanding list of impacts on coral reefs as a result of ocean warming and acidification, there is little information on how these global changes influence...