Alpine newts (Ichthyosaura alpestris) avoid habitats previously used by parasite exposed conspecifics

Many organisms avoid habitats posing risks of parasitism. Parasites are not generally conspicuous however, which raises the question of what cues individuals use to detect parasitism risk. Here, we provide evidence in alpine newts (Ichthyosaura alpestris) that non-visual cues from parasite-exposed conspecifics inform habitat avoidance. Alpine newts breed in aquatic habitats and occasionally move among adjacent terrestrial habitat during breeding seasons. We completed experiments with newts whereby individuals had access to both habitats, and the aquatic habitats varied in prior occupancy by conspecifics with different histories of exposure to the parasitic skin fungus, Batrachochytrium dendrobatidis (Bd). Continuous filming of newt activity for 2 days provided little evidence that prior use of aquatic habitats by conspecifics, regardless of their Bd exposure history, immediately influenced newt habitat use. However, newts that encountered aquatic habitats used specifically by Bd-exposed conspecifics on day 1 spent less time aquatic on day 2, whereas other newts did not alter habitat use. Responses could have been elicited by cues generated by Bd stages on the conspecifics or, perhaps more likely, cues emitted by the conspecifics themselves. In either case, these observations suggest that newts use non-visual cues sourced from exposed conspecifics to detect Bd risk and that those cues cause newts to avoid aquatic habitats. Bd may therefore influence host behaviour in early phases of interactions, and possibly before any contact with infectious stages is made, creating potential for non-consumptive effects

Efeito de iscas tóxicas sobre o parasitoide Diachasmimorpha longicaudata (Hymenoptera: Braconidae).

O objetivo do trabalho foi avaliar o efeito de iscas tóxicas sobre o parasitoide D. longicaudata por meio de testes por ingestão

Diversidade molecular entre populações de Spodoptera frugiperda no Brasil avaliada por marcadores AFLP.

O objetivo deste trabalho foi avaliar a diversidade molecular, por meio de marcadores AFLP, de seis populações de Spodoptera frugiperda coletadas na cultura do milho, em diferentes regiões geográficas do Brasil. O DNA foi extraído de lagartas de quarto instar, e as reações de AFLP foram realizadas com sete combinações de oligonucleotídeos iniciadores. A partir das seis populações de S. frugiperda estudadas, foi identificado um grupo principal formado por três populações geneticamente mais relacionadas. As populações de S. frugiperda analisadas mostram alta variabilidade genética, com máximo de 58% de similaridade

Seletividade de herbicidas à cultura da erva-mate.

A erva-mate (Ilex paraguariensis St. Hil.) é uma espécie florestal arbórea nativa da América do Sul. Dentre os fatores que afetam o desenvolvimento das plantas, a interferência por plantas daninhas é um dos mais importantes. Nesse sentido o objetivo desse trabalho foi avaliar a seletividade de herbicidas em plantas de erva-mate de um e dois anos de idade. O experimento foi desenvolvido em casa de vegetação, com delineamento inteiramente casualizado, com arranjo fatorial 2 x 18, com quatro repetições. O fator A foi composto por plantas de erva-mate com 1 e 2 anos de idade, enquanto o fator B era composto por testemunha; clethodim+haloxifop (72+36); imazethapyr (100); chlorimuron (17,5); metsulfuron (6); nicosulfuron (45); nicosulfuron safener (60); diclosulam (25,2); atrazine+s-metalochlor (1295+805); bentazone (720); diquat (400); saflufenacil (24,5); fomesafen (250); oxyfluorfen (720); glyphosate (1440); glufosinate (420); florpyrauxifen (15,93); e fluroxypyr (149,8 g de i.a. ou e.a. ha-1). Foram avaliadas as variáveis fitotoxicidade e altura de plantas. Para a variável altura de plantas os tratamentos não apresentaram diferença estatisticamente significativa. As plantas de 1 ano apresentaram menores níveis de fitotoxicidade quando comparadas às plantas de 2 anos (exceto para glufosinate). Os herbicidas clethodim + haloxifop, imazethapyr e diclosulam apresentaram baixa fitotoxicidade e são uma possibilidade para o uso em erva-mate. Em plantas de 1 ano, todos os inibidores da ALS testados apresentaram baixa fitotoxicidade

Ancient genomes show social and reproductive behavior of early Upper Palaeolithic foragers

Present-day hunter-gatherers (HGs) live in multilevel social groups essential to sustain a population structure characterized by limited levels of within-band relatedness and inbreeding. When these wider social networks evolved among HGs is unknown. Here, we investigate whether the contemporary HG strategy was already present in the Upper Paleolithic (UP), using complete genome sequences from Sunghir, a site dated to ~34 thousand years BP (kya) containing multiple anatomically modern human (AMH) individuals. Wedemonstrate that individuals at Sunghir derive from a population of small effective size, with limited kinship and levels of inbreeding similar to HG populations. Our findings suggest that UP social organization was similar to that of living HGs, with limited relatedness within residential groups embedded in a larger mating network

Shaping bursting by electrical coupling and noise

Gap-junctional coupling is an important way of communication between neurons and other excitable cells. Strong electrical coupling synchronizes activity across cell ensembles. Surprisingly, in the presence of noise synchronous oscillations generated by an electrically coupled network may differ qualitatively from the oscillations produced by uncoupled individual cells forming the network. A prominent example of such behavior is the synchronized bursting in islets of Langerhans formed by pancreatic \beta-cells, which in isolation are known to exhibit irregular spiking. At the heart of this intriguing phenomenon lies denoising, a remarkable ability of electrical coupling to diminish the effects of noise acting on individual cells. In this paper, we derive quantitative estimates characterizing denoising in electrically coupled networks of conductance-based models of square wave bursting cells. Our analysis reveals the interplay of the intrinsic properties of the individual cells and network topology and their respective contributions to this important effect. In particular, we show that networks on graphs with large algebraic connectivity or small total effective resistance are better equipped for implementing denoising. As a by-product of the analysis of denoising, we analytically estimate the rate with which trajectories converge to the synchronization subspace and the stability of the latter to random perturbations. These estimates reveal the role of the network topology in synchronization. The analysis is complemented by numerical simulations of electrically coupled conductance-based networks. Taken together, these results explain the mechanisms underlying synchronization and denoising in an important class of biological models

Cuticular Compounds Bring New Insight in the Post-Glacial Recolonization of a Pyrenean Area: Deutonura deficiens Deharveng, 1979 Complex, a Case Study

Background: In most Arthropod groups, the study of systematics and evolution rely mostly on neutral characters, in this context cuticular compounds, as non-neutral characters, represent an underexplored but potentially informative type of characters at the infraspecific level as they have been routinely proven to be involved in sexual attraction. Methods and Findings: The collembolan species complex Deutonura deficiens was chosen as a model in order to test the utility of these characters for delineating four infraspecific entities of this group. Specimens were collected for three subspecies (D. d. deficiens, D. d. meridionalis, D. d. sylvatica) and two morphotypes (D. d. sylvatica morphoype A and B) of the complex; an additional species D. monticola was added. Cuticular compounds were extracted and separated by gas chromatography for each individual. Our results demonstrate that cuticular compounds succeeded in separating the different elements of this complex. Those data allowed also the reconstruction of the phylogenetic relationships among them. Conclusions: The discriminating power of cuticular compounds is directly related to their involvement in sexual attraction and mate recognition. These findings allowed a discussion on the potential involvement of intrinsic and paleoclimatic factors in the origin and the diversification of this complex in the Pyrenean zone. This character type brings the first advanc