Identification of host‐plant chemical stimuli for the European grape berry moth Eupoecilia ambiguella

Olfaction is of major importance for survival and reproduction in moths. Males possess highly specific and sensitive olfactory receptor neurones to detect female sex pheromones. However, the capacity of male moths to respond to host‐plant volatiles is relatively neglected and the role that such responses could play in the sensory ecology of moths is still not fully understood. The present study aims to identify host‐plant stimuli for the European grape berry moth Eupoecilia ambiguella Hb. (Tortricidae, Lepidoptera), a major pest of vine in Europe. Headspace volatiles from Vitis vinifera L. cv. Pinot Noir, Vitis vinifera subsp. sylvestris and five other host‐plant species comprising five different families are analyzed by gas chromatography linked to electroantennogram (EAG) recording from male E. ambiguella antennae and by gas chromatography‐mass spectrometry. This procedure identifies 32 EAG‐active compounds, among them the aliphatic compounds 1‐hexanol, (Z)‐3‐hexenol, (Z)‐3‐hexenyl acetate and 1‐octen‐3‐ol; the terpenes limonene, β‐caryophyllene and (E)‐4,8‐dimethyl‐1,3,7‐nonatriene; and the aromatic compounds benzaldehyde and methyl salicylate. Male and female E. ambiguella show similar EAG response amplitudes to individual chemical stimuli and also to mixtures of plant volatiles, as represented by essential oils from ten other plant species. This possibly indicates a common role for plant compounds in the sensory ecology of the two sexes of E. ambiguella.     

Molecular phylogeny of the Raphidiidae (Raphidioptera)*

We present a molecular phylogeny of the family Raphidiidae including representatives of 21 of the 26 genera. Sequences from the nuclear gene for the large subunit ribosomal RNA (28S rRNA) and the mitochondrial cytochrome c oxidase subunit 3 gene (cox3) were used. For the phylogenetic reconstructions we applied automated and manual approaches for sequence alignment and different evolutionary models and tree building algorithms. The trees based on the two alignment approaches were rather similar in their overall topology. A combination of both marker sequences increased the resolution of the trees. The six clades within the raphidiid family that emerged represent either single genera or groups of genera, namely: (i) the Nearctic genus Agulla Navás, (ii) the Nearctic/Central American genus Alena Navás, (iii) the Central Asiatic and Eastern Palaearctic genus Mongoloraphidia H. Aspöck & U. Aspöck, (iv) the Palaearctic Puncha clade, (v) the western Mediterranean Ohmella clade, and (vi) the Palaearctic Phaeostigma clade. The New World taxa Agulla and Alena are placed as successive out‐groups to a monophyletic Palaearctic clade. The Mongoloraphidia clade is distributed in the eastern Palearctic while the remaining three clades are exclusively (Ohmella clade) or mainly distributed in the western Palaearctic. The early radiation of extant Raphidiidae is interpreted based on the phylogenetic tree obtained in the present study, and the geological and palaeobiological processes around the K–T boundary.     

Impact of altering the water table height of an acidic fen on N2O and NO fluxes and soil concentrations

The impact of experimentally intensified summer drought and precipitation on N₂O and NO turnover and fluxes was investigated in a minerotrophic fen over a 2‐year period. On three treatment plots, drought was induced for 6 and 10 weeks by means of roofs and drainage and decreased water table levels by 0.1–0.3 m compared with three nonmanipulated control plots. When averaged over the three treatment plots, both N₂O and NO emission showed only little response to the drought. On the single plot scale, however, a clear impact of the treatment on N₂O and NO fluxes could be identified. On the plot with the weakest water table reduction hardly any response could be observed, while on the plot with the greatest drainage effect, N₂O and NO fluxes increased by 530% and 270%, respectively. Rewetting reduced NO emissions to background levels (0.05–0.15 μmol m^?2 h^?1), but heavily enhanced N₂O emission (18–36 μmol m^?2 h^?1) for several days in the plots with largest water table reduction. These peaks contributed up to 40% to the cumulative N₂O fluxes and were caused by rapid N₂O production according to isotope abundance data. According to N₂O concentrations and isotope abundance analysis N₂O was mostly produced at depths between 0.3 and 0.5 m. During water table reduction net N₂O production in 0.1 m depth steadily increased in the most effectively dried plot from 2 up to 44 pmol cm^?3 day^?1. Rewetting immediately increased net N₂O production in the topsoil of the drought plots, showing rates of 18–174 pmol cm^?3 day^?1. This study demonstrates that drought and rewetting can temporarily increase N₂O emission to levels that have to date only been reported from nutrient rich and degraded fens that have been drained for agricultural purposes.     

The response of heterotrophic activity and carbon cycling to nitrogen additions and warming in two tropical soils

Nitrogen (N) deposition is projected to increase significantly in tropical regions in the coming decades, where changes in climate are also expected. Additional N and warming each have the potential to alter soil carbon (C) storage via changes in microbial activity and decomposition, but little is known about the combined effects of these global change factors in tropical ecosystems. In this study, we used controlled laboratory incubations of soils from a long‐term N fertilization experiment to explore the sensitivity of soil C to increased N in two N‐rich tropical forests. We found that fertilization corresponded to significant increases in bulk soil C concentrations, and decreases in C loss via heterotrophic respiration (P< 0.05). The increase in soil C was not uniform among C pools, however. The active soil C pool decomposed faster with fertilization, while slowly cycling C pools had longer turnover times. These changes in soil C cycling with N additions corresponded to the responses of two groups of microbial extracellular enzymes. Smaller active C pools corresponded to increased hydrolytic enzyme activities; longer turnover times of the slowly cycling C pool corresponded to reduced activity of oxidative enzymes, which degrade more complex C compounds, in fertilized soils. Warming increased soil respiration overall, and N fertilization significantly increased the temperature sensitivity of slowly cycling C pools in both forests. In the lower elevation forest, respired CO₂ from fertilized cores had significantly higher Δ¹⁴C values than control soils, indicating losses of relatively older soil C. These results indicate that soil C storage is sensitive to both N deposition and warming in N‐rich tropical soils, with interacting effects of these two global change factors. N deposition has the potential to increase total soil C stocks in tropical forests, but the long‐term stability of this added C will likely depend on future changes in temperature.     

Phylogeny and biogeography of Neotropical spittlebugs (Hemiptera: Cercopidae: Ischnorhininae): revised tribal classification based on morphological data

The spittlebug family Cercopidae is currently divided into two subfamilies: the paraphyletic Old World Cercopinae and the monophyletic New World Ischnorhininae. The most recent classification scheme proposed by Fennah in 1968 divided the New World Cercopidae into four tribes: Tomaspidini, Ischnorhinini, Hyboscartini and Neaenini. Herein we present a phylogenetic analysis of Ischnorhininae using 108 morphological characters and including 53 of the 59 recognized genera, to evaluate the tribal‐level classification and understand the processes underlying the current distributional patterns of these genera. We found significant support for the monophyly of many Neotropical genera, but Fennah's tribal classification is revised because tribes Neaenini, Ischnorhinini and Tomaspidini were recovered as polyphyletic. Hyboscartini was synonymized with Tomaspidini. A taxonomic key to tribes and genera of Neotropical spittlebugs is provided based mostly on recovered apomorphies. The biogeographical analysis suggests a Neotropical origin of ischnorhinines, more specifically in northwestern South America. This was possibly coincident spatially and temporally with the origin of grasses, with ancestral range expansions southward to the Amazonian and Paraná regions, and posterior vicariant events, possibly related to the expansion of forests in the Chacoan region, the South America diagonal of open formations. Dispersals to the Chacoan region and to the Nearctic region are hypothesized to have occurred only within genera. In the Chacoan region it is associated with more recent events, such as the diversification of C4 grasses and establishment of the savannas and seasonally dry forests.     

The impact of agro‐pastoral abandonment on the Rock Partridge Alectoris graeca in the Apennines

Human depopulation of rural mountain areas and the consequent abandonment of traditional land management are among the greatest driving forces behind changes in mountain ecosystems in Western Europe. Tree and shrub encroachment lead to an increase in landscape matrix uniformity and habitat fragmentation. For some animal species, this represents an unusual case of habitat loss caused by secondary succession. The animal species associated with this agro‐pastoral habitat may suffer from decreased connectivity as a consequence. The Rock Partridge Alectoris graeca is a species endemic to European mountains that represents a model for investigating the impact of habitat loss. We compared the habitat suitability of the Apennine Rock Partridge prior to abandonment of traditional agro‐pastoral activities by aerial photography with the current landscape, in order to investigate the effect of secondary succession on the distribution and viability of the species. We assessed the historical distribution (c. 1900–1950) by quantifying anecdotal evidence from interviews, and the current distribution (2005) from survey data. We applied ecological niche factor analysis and connectivity approaches to evaluate change in habitat suitability over this time scale. Moreover, to quantify landscape connectivity, we evaluated the relative importance of each patch in the two periods. Results indicated that to maintain a viable population in the Apennines, the species requires an ensemble of ecological conditions considerably different from the current situation. We observed a drastic decrease in connectivity as a result of a reduction in numbers and size of high suitability patches. This is most probably the primary cause of the current decline of the Rock Partridge population in the Apennines.     

TIME COURSE OF BIOCHEMICAL AND IMMUNOHISTOLOGICAL ALTERATIONS DURING EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS

A comprehensive biochemical, immunological and histological study was undertaken during different stages of experimental allergic encephalomyelitis (EAE). Wistar rats with EAE induced by sensitization with bovine myelin showed a maximum decrease of body weight 14–16 days post-inoculation (dpi), coincident with the appearance of the paralysis symptom (acute period). Quantitation of some brain components indicated a temporal dissociation among the alterations observed. The higher diminution of myelin basic protein (MBP) occurred at 6 dpi and then increased to reach 21 dpi, a normal value. Also, the activity of 2′,3′-cyclic nucleotide 3′-phosphohydrolase was reduced by 40% with respect to control animals only at 6 dpi. The total lipid content was normal; however, among the individual lipids, sulfatides were principally degraded during the acute stage but the amount of cerebrosides was decreased during the recovery period (29–40 dpi). Free cholesterol was similar in both groups of animals, whereas cholesterol esters were detected in EAE animals from 14 to 40 dpi. Central nervous system meningeal and parenchymal infiltration with mononuclear cells was recognized principally at 14 dpi, but some of cells were still present at 40 dpi. Deposits of immunoglobulins in the infiltrated regions as well as in spinal cord motor neurons were observed among 14–29 dpi. Total circulating antibodies to MBP began to increase at 14 dpi, reaching a plateau at 21 dpi and then maintaining this value until 40 dpi. However, the population of anti-MBP antibodies that also recognizes the neuronal protein synapsin was only present at 14 dpi. The present results suggest that the neurological symptoms can be related to some early changes in the myelin membrane followed by alterations involving neuronal structures. The existence of immunological factors against some epitopes in MBP that also recognize a synaptosomal protein might account, at least in part, for the axonal damage and disruption of the normal interneuronal activity in EAE and lead together with the alterations in some specific myelin constituents and the concomitant CNS inflammatory process to the observed hindlimb paralysis. Copyright © 1996 Elsevier Science Ltd     

Species‐specific levels of ant attendance mediate performance costs in a facultative myrmecophilous butterfly

Trophobiont butterfly larvae offer caloric rewards to ants through specialised glands and, in return, gain ant‐derived protection from natural enemies. Thus, from the larva's perspective, the major cost of myrmecophily comprises the reward production. Larvae of the butterfly Parrhasius polibetes (Stoll) (Lycaenidae) are facultatively tended by several ant species, which might differ in the intensity of tending behaviour. The performance costs (development time, survival, pupal mass and adult dry mass) of P. polibetes are examined when tended by two ant species differing in size and foraging strategies (Camponotus melanoticus Emery and Camponotus crassus Mayr), along with the corresponding intensity of tending behaviour towards late instars. Untended larvae serve as controls. Larvae tended by C. melanoticus take longer to pupate compared with both C. crassus and control larvae. By contrast, pupae whose larvae are tended by C. crassus are lighter than control larvae but do not differ from those tended by C. melanoticus. No differences are found in the adult stage, indicating compensation in all cases. Both at short‐ and long‐term scales, C. melanoticus tends larvae of P. polibetes more intensely than C. crassus. The increase in tending activity of C. melanoticus presumably delays the development time of larvae tended by this ant species. The results of the present study show that tending intensity varies depending on the ant species, and that P. polibetes has compensatory mechanisms to minimise myrmecophily costs, regardless of tending intensity. To the authors' knowledge, this is the first experimental evidence that intensity of ant‐tending behaviour is species‐specific and affects performance in a trophobiont insect.     

Sabotaging behaviour and minimal latex of Asclepias curassavica incur no cost for larvae of the southern monarch butterfly Danaus erippus

1. The southern monarch, Danaus erippus, uses mainly Asclepias curassavica as its host in the Neotropics, a plant species bearing articulated anastomosing laticifers. When artificially severed, A. curassavica has been shown to release significantly less latex than other Asclepias species. 2. The present study tested the hypothesis that sabotaging behaviour changes during the ontogeny of D. erippus and recorded latex outflow of A. curassavica during sabotaging and feeding. Larvae displayed vein‐cutting behaviour, which was initially observed in the second instar, became more pronounced in the third and fourth instars, and less frequent in the fifth instar. When present, latex outflow was never more than 1 µl at a time during either vein cutting or feeding, regardless of the instar. 3. Mandibular and midrib morphometrics revealed that larvae selected thicker midrib sites for severing as instars progressed; however, no correlation between mandibular size and midrib size severed was found within instars. 4. Costs of sabotaging behaviour and the effects of A. curassavica latex outflow on D. erippus larvae were also examined. Sabotaging behaviour did not incur growth costs for larvae, and only latex exudation volumes at least 10‐fold greater than those observed due to D. erippus sabotaging or feeding, caused significantly higher larval mortality than controls. 5. Since latex outflow is minimal or non‐existent in A. curassavica, sabotaging behaviour in D. erippus is mostly limited by morphological constraints and is probably driven by chemical stimulants rather than latex defence. In turn, latex does not constitute a major defence of A. curassavica against D. erippus.