Functional bases of host-acceptance behaviour in the aphid parasitoid Aphidius ervi

Abstract.  The host acceptance behaviour in Aphidius ervi is investigated, assessing the role of both external and internal host-associated cues, offered to the experimental parasitoids with parafilm-made aphid dummies. The reaction to internal cues present in the host haemolymph is clearly evident, and its intensity is enhanced by external cues. Parasitoid females lay few eggs in aphid dummies filled with host haemolymph. A significant increase in the number of both oviposition reactions (host stinging) and egg laying is observed only when these dummies are coated with cornicle secretion. However, this enhancement is not observed when the aphid dummies contain distilled water. Thus, the host acceptance behaviour of A. ervi females appears to be controlled by the integration of both external and internal chemical cues. The physiological basis of this behavioural response is investigated with a detailed study on the anatomy and ultrastructure of A. ervi ovipositor. The detection of chemical cues present in the host haemolymph that act as kairomones is made possible by the presence of gustatory sensilla on the tip of the ovipositor. These sensilla consist of porous areas, reached by unbranched dendrites running inside both the lower valves (i.e. first valvulae) and the unpaired upper valve (i.e. second valvulae). The mechanosensory function during oviposition appears to be provided mostly by the basiconic sensilla found on the tip of external valves (i.e. third valvulae). A tentative functional model accounting for the observed oviposition behaviour of A. ervi is proposed.     

Molecular phylogeography of the microturbellarian Monocelis lineata (Platyhelminthes: Proseriata) in the North‐East Atlantic

Monocelis lineata is a complex of cryptic species (three in the Mediterranean and one in the Atlantic) widespread in midlittoral habitats. Throughout the range, populations with or without an ocular pigmented shield are found. We investigated the genetic structure of the North‐East Atlantic populations with the aim of shedding light on their phylogeography and reconstructing possible patterns of recolonization after the Würmian glaciation. Fourteen samples were investigated using cytochrome c oxidase subunit I (COI) and 13 by inter‐simple sequence repeats (ISSRs). COI did not exhibit a clear pattern of decreased genetic diversity along a latitudinal gradient. Populations from Ferrol (Spain), Doolin (Ireland), and Helsingør (Denmark) showed a higher genetic variability, whereas a reduction in the number of haplotypes was found at the northernmost edge of the distribution and in northern Ireland and Scotland. Two genetically differentiated areas (southern Europe and south‐western Ireland versus northern Atlantic) were revealed by ISSR data. The results obtained provided evidence of three refugia (Iberian Peninsula, south‐western Ireland, and North Sea), and the occurrence of secondary contacts that shaped the genetic variability of some of the populations examined. Two different recolonization pathways of north‐western Europe during the post‐Würmian glaciations have been detected. Furthermore, ISSR analysis provided evidence of genetic divergence among populations with and without pigmented eyespot, suggesting the action of ecological differentiation. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 117–135.     

Feedbacks between phosphorus deposition and canopy cover: The emergence of multiple stable states in tropical dry forests

Dry forests represent a large percentage of tropical forests and are vulnerable to both anthropogenic and natural disturbances, yet important aspects of their sensitivity to disruption remain poorly understood. It is particularly unclear how changes in land-use or tropical storm patterns may affect the resiliency of phosphorus (P)-limited neotropical forests. In these systems, vegetation is sustained in the long-term by atmospheric P-inputs through rainfall, dust, or fog. Past research supports the idea that dust and fog deposition are dependent on canopy density (e.g. leaf area index). Thus, the canopy may function as a 'trap' for P, enabling a positive feedback between vegetation and P-deposition. We developed a conceptual model to investigate how Neotropical vegetation may respond to reduced P-deposition due to canopy losses. The model suggests that a canopy-deposition feedback may induce bistable vegetation dynamics; under some conditions, forests may be unable to naturally recover from relatively small disturbances.     

European and Mediterranean oaks (Quercus L.; Fagaceae): SEM characterization of the micromorphology of the abaxial leaf surface

This paper examines micromorphological characteristics (trichomes, waxes, stomata) of the abaxial leaf surface of European and Mediterranean oaks. Observations were performed In-scanning electron microscopy, and the purpose of the investigation was to ascertain whether it is possible to distinguish the different species taxonomically using these features. Several species, as well as some subspecific entities and taxa considered doubtful, were taken into consideration. Subgenera appear to be well-defined: e.g. the subgenus Quercus is characterized by waxes arranged in vertical scales, the subgenera Cenis and Sclerophyllodris by smooth waxes. They differ because the former has markedly elliptical stomata, while the latter two have roundish stomata. The different species are also fairly easy to distinguish, and this fact confirms the taxonomical validity of the parameters we have taken into consideration. In some cases subspecific entities and doublful species do not diflcr at all from the related species, but in others they present such marked variations that it is difficult even to classify them with certainty. The most critical taxonomic groups (i.e. those which include a number of specific and subspecific entities often too difficult to distinguish from each other) are the series Quercus robur – Quercus petraea,– Quercus pubescens and the Quercus faginea,– Quercus Insitanica Quercus canariensis group.     

CONSUMER ACCEPTABILITY OF VEGETABLE SOUPS

The aim of this study was to investigate whether product label information “produced with organic ingredients” and “stabilization technology” affects consumer acceptability of vegetable soups. Three focus group interviews were preliminarily conducted in order to gain information about the appropriate terminology to use in the next consumer test. In all, 109 subjects were recruited by means of a background questionnaire. They were then divided into three groups according to age, gender and soup preference. Each group evaluated three different types of soup in two phases, first blind and then with information. At the end of the second phase, the participants filled in a conjoint analysis questionnaire. The results demonstrated that if consumers were informed that soup is prepared with organic ingredients, they would improve their acceptability scores, whatever the soup type. Stabilization technology information had no effect. Conjoint results revealed that consumers appreciate soups made with organic legumes and cereals and without seasoning. However, differences among subgroups were found.     

A molecular phylogeny of the cosmopolitan hyperdiverse genus Hydraena Kugelann (Coleoptera,Hydraenidae)

With almost 900 described species, Hydraena Kugelann (Hydraenidae) is one of the largest genera among Coleoptera. The subgeneric classification of Hydraena has been controversial, with 11 subgeneric names having so far been attributed to it. Some of these, Haenydra Rey and Spanglerina Perkins, have been treated as valid genera, as subgenera or as species groups. The most recent complete treatment of the genus, based on a cladistic analysis of morphological characters, recognized two major lineages, and only these were classified as subgenera: Hydraenopsis (mainly Gondwanan distribution), and Hydraena s.str. (mainly Laurasian). Here, we reconstruct the phylogeny of Hydraena using 212 species plus several outgroups and approximately 4 kb of sequence data from two nuclear (SSU and LSU) and four mitochondrial genes (cox1, rrnL, trnL and nad1). Data were aligned with two different strategies of multiple alignment (implemented in mafft and prank ), and the phylogenies reconstructed using maximum likelihood and Bayesian methods. We estimated approximate ages of the main nodes using a relaxed molecular clock with Bayesian methods, and an a priori evolutionary rate of 0.01 substitutions/site/million years (Ma) plus a calibration point based on a biogeographical split. We found strong support for the monophyly of Hydraena and many of the clades recognized with morphological data. The following clades are considered as subgenera: Phothydraena Kuwert, Spanglerina Perkins, Holcohydraena Kuwert, Hydraenopsis Janssens and Hydraena s.str. The placement of three species groups, two Neotropical (H. multispina group, H. paeminosa group) and one South African/Madagascan (H. monikae group), is uncertain, and they are considered incertae sedis within Hydraena. The origin of the genus was estimated to be in the Lower Eocene, with many species complexes diversifying in the Pleistocene. Dispersal events seem to have played a key role in order to determine the current distribution of the species groups in the southern hemisphere (mainly in Hydraenopsis).     

A simple predictive density based on the p*-formula

The predictive density proposed by Harris (1989) is based onintegrating the density for a new observation with respect tothe estimated sampling distribution of the maximum likelihoodestimator of the unknown parameter. This has good properties,but is rather complicated to compute even for simple models.An approximation to the Harris proposal is considered whichconsists of approximating the sampling distribution of the maximumlikelihood estimator of the unknown parameter by Barndorff-Nielsen's(1983) p*-formula, and then using a Laplace approximation withO(n^–1) correction terms for integrating out the parameter.The result can generally be expressed in terms of standard likelihoodderivatives, and takes a quite simple form for exponential familiesand for location models.     

Do non‐native fish as prey favour the conservation of the threatened indigenous Eurasian otter?

1. Biological invasions are considered a major threat to biodiversity. Most research has focused on the distribution, biology and impacts of non‐native species on native fauna and flora. However, few studies have explored their role as prey for native predators of conservation concern. 2. To assess the incidence and intensity of predation by the Eurasian otter Lutra lutra on established non‐native fish species, data were collated from the published literature. To be selected, studies had to cover at least 1 year, analyse more than 100 spraints and report the study period and percentage relative frequency (%RF) of all prey fish species. 3. To permit reliable, time‐related comparisons with %RF of non‐native fishes in otter diet, we also reviewed available information about both the distribution of non‐native fishes and history of their introductions to European countries, revealing a decrease with longitude in the number of naturalised non‐native fishes taken (ranging between 5 and 34) and their percentage in each fish assemblage. 4. Our selective criteria were met by 30 dietary studies from 44 study areas in 15 European countries during 1970–2010. The extent to which otters rely on non‐native fishes was almost negligible (mean %RF = 4.8), with the number of non‐native fishes preyed upon by otters decreasing with both latitude and longitude. 5. The %RF of non‐native fish in the diet increased slightly with time, with otters preying significantly more on non‐native fish in study areas where alterations of the fish assemblage had been highlighted in the reference papers. No relationship was found between otter diet breadth and the occurrence of non‐native fishes in their diet. 6. The current role of non‐native species in otter diet suggests that effective otter conservation management plans should focus on the maintenance and/or enhancement of native fish assemblages.     

The shape of the mandibular corpus in large fissiped carnivores: allometry,function and phylogeny

Mandibular corpus shape variability was investigated in seven families of both extant and extinct mammalian carnivores using two‐dimensional landmarks and geometric morphometric methods. The landmark configuration represents the position of the fourth premolar relative to the canine and the lower carnassial, plus related features of the corpus profile. Between families, the corpus manifests differences in shape and allometry. Additionally, families differ in the relationship between the angle α (a carnassial trait proxy for hypo‐hypercarnivory) and mandibular corpus shape. When phylogenetic relatedness is taken into account using five different phylogenies as covariates, interspecific scaling is still present but the relationship between α and corpus shape is no longer significant. This suggests that the allometric relationship reflects the physical constraints of mastication, resulting in relatively increased corpus depth with higher loads. In contrast, the angle α is related to corpus curvature and this relationship is phylogenetically constrained by the reduction of the molar battery in large feliforms early during the carnivore radiation. In summary, large fissiped carnivores show extensive functional convergence in mandibular corpus shape although the evolutionary routes leading to such functional convergence are different. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 832–845.