Intrinsic competition between two European egg parasitoids of the brown marmorated stink bug

Following the accidental introduction and spread of the invasive polyphagous agricultural pest Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), the two European egg parasitoids Anastatus bifasciatus (Geoffroy) (Hymenoptera: Eupelmidae) and Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae) have been investigated for inundative biological control. Since the competititve outcome between the two generalist parasitoids is difficult to predict, intrinsic competition was investigated with a time-course development study. Both species readily oviposited in H. halys eggs containing eggs and early instar larvae of the competitor, but oviposition decreased when eggs contained late instar larvae and pupae. Ooencyrtus telenomicida offspring emergence from multiparasitized eggs was significantly lower than that from rearing controls, independent of the order of parasitization. Anastatus bifasciatus offspring emergence was not influenced by the presence of O. telenomicida when it parasitized as the first species, but emergence was decreased after oviposition in eggs containing O. telenomicida larvae and pupae. There was no indication that O. telenomicida can act as a facultative hyperparasitoid of A. bifasciatus. These results suggest that A. bifasciatus is the superior intrinsic competitor and no or minor negative implications for A. bifasciatus are expected if released in combination with O. telenomicida.     

Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the Anthropocene

The sea otter (Enhydra lutris) is a marine mammal hunted to near extinction during the 1800s. Despite their well‐known modern importance as a keystone species, we know little about historical sea otter ecology. Here, we characterize the ecological niche of ancient southern sea otters (E. lutris nereis) using δ¹³C analysis and δ¹⁵N analysis of bones recovered from archaeological sites spanning ~7,000 to 350 years before present (N = 112 individuals) at five regions along the coast of California. These data are compared with previously published data on modern animals (N = 165) and potential modern prey items. In addition, we analyze the δ¹⁵N of individual amino acids for 23 individuals to test for differences in sea otter trophic ecology through time. After correcting for tissue‐specific and temporal isotopic effects, we employ nonparametric statistics and Bayesian niche models to quantify differences among ancient and modern animals. We find ancient otters occupied a larger isotopic niche than nearly all modern localities; likely reflecting broader habitat and prey use in prefur trade populations. In addition, ancient sea otters at the most southerly sites occupied an isotopic niche that was more than twice as large as ancient otters from northerly regions. This likely reflects greater invertebrate prey diversity in southern California relative to northern California. Thus, we suggest the potential dietary niche of sea otters in southern California could be larger than in central and northern California. At two sites, Año Nuevo and Monterey Bay, ancient otters had significantly higher δ¹⁵N values than modern populations. Amino acid δ¹⁵N data indicated this resulted from shifting baseline isotope values, rather than a change in sea otter trophic ecology. Our results help in better understanding the contemporary ecological role of sea otters and exemplify the strength of combing zooarchaeological and biological information to provide baseline data for conservation efforts.     

Lasting the distance: The survival of alien birds shipped to New Zealand in the 19th century

Invasive alien species are a major threat to biodiversity and human activities, providing a strong incentive to understand the processes by which alien invasion occurs. While it is important to understand the determinants of success at each of several invasion stages—transport, introduction, establishment, and spread—few studies have explored the first of these stages. Here, we quantify and analyze variation in the success of individual animals in surviving the transport stage, based on shipping records of European passerines destined for New Zealand. We mined the original documents of Acclimatisation Societies, established in New Zealand for the purpose of introducing supposedly beneficial alien species, in combination with recently digitized newspaper archives, to produce a unique dataset of 122 ships that carried passerines from Europe to New Zealand between 1850 and 1885. For 37 of these shipments, data on the survival of individual species were available. Using generalized linear mixed models, we explored how survival was related to characteristics of the shipments and the species. We show that species differed greatly in their survival, but none of the tested traits accounted for these differences. Yet, survival increased over time, which mirrors the switch from early haphazard shipments to larger organized shipments. Our results imply that it was the quality of care received by the birds that most affected success at this stage of the invasion process.     

Impaired chloroplast positioning affects photosynthetic capacity and regulation of the central carbohydrate metabolism during cold acclimation

Photosynthesis Research - Photosynthesis and carbohydrate metabolism of higher plants need to be tightly regulated to prevent tissue damage during environmental changes. The intracellular position...     

Recalculating Australian water scarcity characterisation factors using the AWARE method

The International Journal of Life Cycle Assessment - Quantifying the impacts of water consumption on available water resources forms one of the core indicators of many life cycle assessments...     

An optimized FM-index library for nucleotide and amino acid search

In computational structural biology, structure comparison is fundamental for our understanding of proteins. Structure comparison is, e.g., algorithmically the starting point for computational studies of structural evolution and it guides our efforts to predict protein structures from their amino acid sequences. Most methods for structural alignment of protein structures optimize the distances between aligned and superimposed residue pairs, i.e., the distances traveled by the aligned and superimposed residues during linear interpolation. Considering such a linear interpolation, these methods do not differentiate if there is room for the interpolation, if it causes steric clashes, or more severely, if it changes the topology of the compared protein backbone curves. To distinguish such cases, we analyze the linear interpolation between two aligned and superimposed backbones. We quantify the amount of steric clashes and find all self-intersections in a linear backbone interpolation. To determine if the self-intersections alter the protein’s backbone curve significantly or not, we present a path-finding algorithm that checks if there exists a self-avoiding path in a neighborhood of the linear interpolation. A new path is constructed by altering the linear interpolation using a novel interpretation of Reidemeister moves from knot theory working on three-dimensional curves rather than on knot diagrams. Either the algorithm finds a self-avoiding path or it returns a smallest set of essential self-intersections. Each of these indicates a significant difference between the folds of the aligned protein structures. As expected, we find at least one essential self-intersection separating most unknotted structures from a knotted structure, and we find even larger motions in proteins connected by obstruction free linear interpolations. We also find examples of homologous proteins that are differently threaded, and we find many distinct folds connected by longer but simple deformations. TM-align is one of the most restrictive alignment programs. With standard parameters, it only aligns residues superimposed within 5 Ångström distance. We find 42165 topological obstructions between aligned parts in 142068 TM-alignments. Thus, this restrictive alignment procedure still allows topological dissimilarity of the aligned parts. Based on the data we conclude that our program ProteinAlignmentObstruction provides significant additional information to alignment scores based solely on distances between aligned and superimposed residue pairs.     

How does plant population density affect the biomass of Ravenna grass?

Ravenna grass, Tripidium ravennae (L.) H. Scholz, is known to produce an abundance of biomass, but how plant density affects its biomass potential remains unknown. The objectives were to determine the effects of plant density on biomass yield; plant growth traits; biomass?carbon, nitrogen, and ash concentrations; heating value; nitrogen removal; and sucrose concentration in leaves and culms. The treatments consisted of five plant densities (1,250; 2,500; 5,000; 10,000; and 20,000 plants per hectare) in a randomized complete block design with four blocks. Plots were nonirrigated, unfertilized, and harvested once during the dormant season each year. Data were collected from 2015?2019. Dependent variables that varied with plant population density (p < .05) were biomass yield, number of reproductive culms per plant, reproductive culm diameter, reproductive culm sucrose concentration, and nitrogen removal with biomass. Biomass yield ranged from 5.6 to 16.3 Mg/ha for plant densities of 1,250–20,000 plants per hectare, respectively. Combined over years, nonlinear regression of the data showed the equation for biomass yield to plateau at 16.2 Mg/ha at a plant density of 10,640 plants per hectare. As plant density increased, the number of reproductive culms per plant, culm diameter, and culm sucrose concentration significantly decreased. At 1,250 plants per hectare, the number of reproductive culms per plant, culm diameter, and culm sucrose averaged 70, 10.2 mm, and 63.2 g/kg, respectively. Nitrogen removed with biomass significantly increased as biomass yield increased with plant density. At a density of 10,000 and 20,000 plants per hectare, the amount of nitrogen removed annually in the harvested biomass averaged 88 kg/ha. The data suggest that 10,000 plants per hectare would produce the greatest annual biomass yields; however, research is needed to determine the nutrient requirement for Ravenna grass to sustain biomass production at that density.     

A QTL on the Ca7 chromosome of chickpea affects resistance to the root-lesion nematode Pratylenchus thornei

Molecular Breeding - Plant height is vital for crop yield by influencing plant architecture and resistance to lodging. Although lots of quantitative trait loci (QTLs) controlling plant height had...