Vantaux A.,CNRS Biological Evolution and Diversity Laboratory |
Roux O.,Ecolab |
Roux O.,CNRS Functional Ecology & Environment Laboratory |
Roux O.,French National Center for Scientific Research |
And 5 more authors.
Biotropica | Year: 2010
A variety of arthropods, particularly insects, have developed myrmecophilous interactions with ants to gain access to resources and/or for protection. Among these myrmecophiles, only a few examples have been documented in the Coccinellidae, most of them involving species able to feed on ant-tended Hemiptera. We report here a new case of obligate myrmecophily in the coccinellid Diomus thoracicus. Larvae are invariably and exclusively found in the nests of the ant Wasmannia auropunctata and seem to rely on ant brood as their only food source. Not only do ant workers show no aggressiveness toward the D. thoracicus larvae in their behavioral interactions at the colonial level, but also at the species level; while coccinellid adults are always attacked. The integration of the larvae inside of the ant nests is based on their chemical mimicry of the host's cuticular cues. Therefore, given the presence of the D. thoracicus larvae inside of the ant's nest, their predation on Wasmannia brood and their chemical mimicry, this species can be considered a specific parasite of W. auropunctata. Overall, this new case of myrmecophily not only specifically involves a highly invasive ant species, but also provides insights into the evolution of myrmecophily and myrmecophagy in coccinellids.Abstract in French is available at http://www.blackwell-synergy.com/loi/btp. © 2010 The Author(s). Journal compilation © 2010 by The Association for Tropical Biology and Conservation.
Dyer J.-O.,Institute Of Readaptation Gingras Lindsay Of Montreal |
Dyer J.-O.,University of Montreal |
Maupas E.,Center University Champollion |
Maupas E.,University Paul Sabatier |
And 6 more authors.
Journal of NeuroEngineering and Rehabilitation | Year: 2011
Background: Abnormal coactivation of leg extensors is often observed on the paretic side of stroke patients while they attempt to move. The mechanisms underlying this coactivation are not well understood. This study (1) compares the coactivation of leg extensors during static contractions in stroke and healthy individuals, and (2) assesses whether this coactivation is related to changes in intersegmental pathways between quadriceps and soleus (Sol) muscles after stroke. Methods. Thirteen stroke patients and ten healthy individuals participated in the study. Levels of coactivation of knee extensors and ankle extensors were measured in sitting position, during two tasks: maximal isometric voluntary contractions in knee extension and in plantarflexion. The early facilitation and later inhibition of soleus voluntary EMG evoked by femoral nerve stimulation were assessed in the paretic leg of stroke participants and in one leg of healthy participants. Results: Coactivation levels of ankle extensors (mean ±SEM: 56±7% of Sol EMG max) and of knee extensors (52 10% of vastus lateralis (VL) EMG max) during the knee extension and the ankle extension tasks respectively were significantly higher in the paretic leg of stroke participants than in healthy participants (26±5% of Sol EMG max and 10±3% of VL EMG max, respectively). Early heteronymous facilitation of Sol voluntary EMG in stroke participants (340±62% of Sol unconditioned EMG) was significantly higher than in healthy participants (98±34%). The later inhibition observed in all control participants was decreased in the paretic leg. Levels of coactivation of ankle extensors during the knee extension task were significantly correlated with both the increased facilitation (Pearson r = 0.59) and the reduced inhibition (r = 0.56) in the paretic leg. Measures of motor impairment were more consistently correlated with the levels of coactivation of biarticular muscles than those of monoarticular muscles. Conclusion: These results suggest that the heteronymous pathways linking quadriceps to soleus may participate in the abnormal coactivation of knee and ankle extensors on the paretic side of stroke patients. The motor impairment of the paretic leg is strongly associated with the abnormal coactivation of biarticular muscles. © 2011 Joseph-Omer et al; licensee BioMed Central Ltd.
Carayon J.-L.,Center University Champollion |
Tene N.,Center University Champollion |
Bonnafe E.,Center University Champollion |
Alayrangues J.,University Paul Sabatier |
And 3 more authors.
Environmental Science and Pollution Research | Year: 2014
Thymol is a natural substance increasingly used as an alternative to pesticides in the fight against the Varroa destructor mite. Despite the effectiveness of this phenolic monoterpene against Varroa, few articles have covered the negative or side effects of thymol on bees. In a previous study, we have found an impairment of phototaxis in honeybees following application of sublethal doses of thymol-lower or equal to 100 ng/bee-under laboratory conditions. The present work shows the same behavioral effects on bees from hives treated with Apilife Var®, a veterinary drug containing 74 % thymol, with a decrease in phototactic behavior observed 1 day after treatment. Thus, thymol causes disruption of bee phototactic behavior both under laboratory conditions as well as in beehives. The bee exposure dose in treated hives was quantified using gas chromatography coupled to mass spectrometry (GC-MS), giving a median value of 4.3 μg per body 24 h after treatment, with 11 ng in the brain. The thymol level in 20 organic waxes from hives treated with Apilife Var® was also measured and showed that it persists in waxes (around 10 mg/kg) 1 year after treatment. Thus, in the light of (1) behavioral data obtained under laboratory conditions and in beehives, (2) the persistence of thymol in waxes, and (3) the high load on bees, it would appear important to study the long-term effects of thymol in beehives. © 2013 Springer-Verlag Berlin Heidelberg.