From the Cover: Climbing,falling, and jamming during ant locomotion in confined environments

Locomotion emerges from effective interactions of an individual with its environment. Principles of biological terrestrial locomotion have been discovered on unconfined vertical and horizontal substrates. However, a diversity of organisms construct, inhabit, and move within confined spaces. Such animals are faced with locomotor challenges including limited limb range of motion, crowding, and visual sensory deprivation. Little is known about how these organisms accomplish their locomotor tasks, and such environments challenge human-made devices. To gain insight into how animals move within confined spaces, we study the locomotion of the fire ant Solenopsis invicta, which constructs subterranean tunnel networks (nests). Laboratory experiments reveal that ants construct tunnels with diameter, D, comparable to body length, L = 3.5 ± 0.5 mm. Ants can move rapidly (> 9 bodylengths per s) within these environments; their tunnels allow for effective limb, body, and antennae interaction with walls, which facilitate rapid slip-recovery during ascending and descending climbs. To examine the limits of slip-recovery in artificial tunnels, we perform perturbations consisting of rapid downward accelerations of the tunnels, which induce falls. Below a critical tunnel diameter, D_s = 1.31 ± 0.02 L, falls are always arrested through rapid interaction of appendages and antennae with tunnel walls to jam the falls. D_s is comparable to the size of incipient nest tunnels (D = 1.06 ± 0.23 L), supporting our hypothesis that fire ants construct environments that simplify their control task when moving through the nest, likely without need for rapid nervous system intervention.     

Immunotherapy of hypersensitivity to hymenoptera venom

Insect sting allergy is a common condition with a risk of life-threatening anaphylaxis. After a severe reaction, the fear of being restung can significantly reduce quality of life. Venom immunotherapy (VIT) is a highly effective treatment of the underlying type I-sensitisation. This review addresses the mechanisms of immune modulation by VIT and outlines current clinical application. Although highly effective in the majority of patients, VIT fails in a few individuals. It can also cause systemic allergic side effects, restricting its application to physicians trained in the treatment of anaphylaxis. This review discusses several new strategies to overcome these problems, which are presently a promising focus of research. These include the use of new adjuvants, of recombinant and genetically engineered venom allergens, as well as vaccination with peptides.     

Increased rate and greater severity of allergic reactions to insect sting among schoolchildren with atopic diseases

The question of whether atopic diseases are a risk factor for allergic reactions to insect sting is still unresolved. The aim of this study was to evaluate the association between atopic diseases (asthma, allergic rhinitis, atopic eczema) and allergic reactions to insect stings among schoolchildren in Israel. A self‐report questionnaire of the International Study of Asthma and Allergies in Childhood was administered to a national sample of 13–14‐yr‐old schoolchildren. Questions regarding reactions to insect stings were added. A total of 10,021 questionnaires were available for analysis. Among the children who reported insect stings (56.3%), the prevalence of current asthma was 6.0%, of allergic rhinitis, 10.5%, and of atopic eczema, 8.7%, with no significant differences from the whole study population. Among children with any of the atopic diseases, 36.9% reported an allergic reaction to insect sting compared to 24.8% of the non‐atopic children (p < 0.0001). On multivariate analysis, asthma, allergic rhinitis, and atopic eczema were found to be significant risk factors for allergic reactions of any severity. Children in the atopic group had a significantly higher rate of severe allergic reactions than the non‐atopic children, and relatively higher rates of milder ones (p < 0.0001). Asthmatic patients with severe allergic reactions had more parameters of severe asthma than asthmatic patients with mild or no reactions. In conclusions, allergic diseases are associated with a higher rate and greater severity of allergic reactions to insect sting in children. The severity of the allergic reaction is related to the severity of the asthma symptoms.     

Characteristics of the genome of Arsenophonus nasoniae, son-killer bacterium of the wasp Nasonia

We report the properties of a draft genome sequence of the bacterium Arsenophonus nasoniae , son-killer bacterium of Nasonia vitripennis . The genome sequence data from this study are the first for a male-killing bacterium, and represent a microorganism that is unusual compared with other sequenced symbionts, in having routine vertical and horizontal transmission, two alternating hosts, and being culturable on cell-free media. The resulting sequence totals c . 3.5 Mbp and is annotated to contain 3332 predicted open reading frames (ORFs). Therefore, Arsenophonus represents a relatively large genome for an insect symbiont. The annotated ORF set suggests that the microbe is capable of a broad array of metabolic functions, well beyond those found for reproductive parasite genomes sequenced to date and more akin to horizontally transmitted and secondary symbionts. We also find evidence of genetic transfer from Wolbachia symbionts, and phage exchange with other gammaproteobacterial symbionts. These findings reflect the complex biology of a bacterium that is able to live, invade and survive multiple host environments while resisting immune responses.     

Different roles of host and bacterial factors in Escherichia coli extra-intestinal infections

Many host and bacterial factors contribute to the development of different Escherichia coli extra-intestinal infections. The aim of this study was to evaluate the roles of host and bacterial factors in different extra-intestinal E. coli infections. A total of 221 E. coli isolates collected from urine, bile and peritoneal fluid were included in this retrospective study. Four main phylogenetic groups of E. coli , 14 genetic determinants, static biofilm formation and antimicrobial resistance data were assessed, as well as the immunological status of the hosts. Group B2 was the most common phylogenetic group (30%), especially in cases of asymptomatic bacteriuria (ABU), urinary tract infection (UTI), acute appendicitis/gastrointestinal perforation, and spontaneous bacterial peritonitis (SBP), and was associated with elevated prevalence of papG  III , fimH , sfa , iha , hlyA , cnf1 , ompT and usp . Phylogenetic group A was most common in the isolates from asymptomatic bacteriocholia, biliary tract infection, and peritoneal dialysis (PD)-related peritonitis. There was similarity with respect to both phylogenetic groups and virulence factors in strains from faeces and ABU, and in strains from faeces and SBP/PD-related peritonitis. Host characteristics were important in patients with ABU, UTI, and SBP/PD-related peritonitis. Immunocompetence of hosts was associated with a relatively high prevalence of papG  II , afa and iha , and relatively low antimicrobial resistance to fluoroquinolones. This study demonstrates that, in most E. coli extra-intestinal infections, phylogenetic group B2 was predominant and was more virulent than the three other phylogenetic groups in the Taiwanese population studied. The diverse patterns of host and bacterial factors demonstrate that there were different host and bacterial factors dominating in different extra-intestinal E. coli infections.     

Plant sex and the evolution of plant defenses against herbivores

Despite the importance of plant–herbivore interactions to the ecology and evolution of terrestrial ecosystems, the evolutionary factors contributing to variation in plant defenses against herbivores remain unresolved. We used a comparative phylogenetic approach to examine a previously untested hypothesis (Recombination-Mating System Hypothesis) that posits that reduced sexual reproduction limits adaptive evolution of plant defenses against arthropod herbivores. To test this hypothesis we focused on the evening primrose family (Onagraceae), which includes both sexual and functionally asexual species. Ancestral state reconstructions on a 5-gene phylogeny of the family revealed between 18 and 21 independent transitions between sexual and asexual reproduction. Based on these analyses, we examined susceptibility to herbivores on 32 plant species representing 15 independent transitions. Generalist caterpillars consumed 32% more leaf tissue, gained 13% greater mass, and experienced 21% higher survival on functionally asexual than on sexual plant species. Survival of a generalist feeding mite was 19% higher on asexual species. In a field experiment, generalist herbivores consumed 64% more leaf tissue on asexual species. By contrast, a specialist beetle fed more on sexual than asexual species, suggesting that a tradeoff exists between the evolution of defense to generalist and specialist herbivores. Measures of putative plant defense traits indicate that both secondary compounds and physical leaf characteristics may mediate this tradeoff. These results support the Recombination-Mating System Hypothesis and suggest that variation in sexual reproduction among plant species may play an important, yet overlooked, role in shaping the macroevolution of plant defenses against arthropod herbivores.     

Logging residue assessment by line intersect sampling

Line intersect sampling is applied in various aspects of forest management. One of the more common applications is to estimate the quantity of logging residue remaining on the ground following harvesting operations. The estimate of residue quantity can be used to develop residue models for yield prediction and to monitor harvesting operations to ensure prescribed utilisation levels are achieved. The application of line intersect sampling to quantifying logging residue has not always been as efficient as may be desired.

Alternatives to the traditional application of the method have been developed using regular polygons with odd numbers of sides and circular sample lines. These shapes are more robust in overcoming the bias in the orientation of logging residue. Monte Carlo simulation was used to develop a model to predict the sample size required to achieve a specified precision of the estimate of residue for nine-sided polygonal (nonagonal) sample lines. Budget functions derived from time studies of logging residue assessment trials provide the basis for planning assessment programs. The improved method is applied to radiata pine (Pinus radiata D.Don) plantations managed in South Australia by Primary Industries South Australia (PISA) Forestry and CSR Softwoods.     

Distribution and hypoxia‐regulation of haemocyanin in springtails (Collembola)

Haemocyanin is the copper‐containing respiratory protein present in many arthropods. In the hexapods, respiratory proteins had long been considered unnecessary as sufficient O₂ was thought to be obtained via the trachea. Nevertheless, many ametabolous and hemimetabolous hexapod species actually possess haemocyanin. Here we investigated the occurrence of haemocyanin in Collembola (springtails). Haemocyanin was found in 22 collembolan species of the suborders Symphypleona, Tomoceroidea and Entomobryomorpha, demonstrating its widespread occurrence. No haemocyanin was identified in 16 species of these taxa, and it appears to be absent in Poduromorpha. The presence of haemocyanin does not correlate with either the phylogenetic history or lifestyle of the investigated species. We further investigated the function of haemocyanin in Folsomia candida (Entomobryomorpha) by applying different hypoxia regimes. Whereas short‐term (1 h) and mild (10% O₂) hypoxia led to a decrease in haemocyanin mRNA, strong hypoxia (24 h, 1.5% O₂) resulted in a ～4300‐fold increase in haemocyanin expression. Hypoxia induction of haemocyanin could not be demonstrated in evolutionarily more advanced Hexapoda, where it is restricted to the embryo. The results indicate (1) an important role of haemocyanin in the oxygen supply of F. candida, which may be adaptive in the potentially hypoxic environment in the soil, and (2) a change in haemocyanin function in hexapod evolution.