Pollinator conservation: the difference between managing for pollination services and preserving pollinator diversity

Our review looks at pollinator conservation and highlights the differences in approach between managing for pollination services and preserving pollinator diversity. We argue that ecosystem service management does not equal biodiversity conservation, and that maintaining species diversity is crucial in providing ecosystem resilience in the face of future environmental change. Management and policy measures therefore need to focus on species not just in human dominated landscapes but need to benefit wider diversity of species including those in specialised habitats. We argue that only by adopting a holistic ecosystem approach we can ensure the conservation and sustainable use of biodiversity and ecosystem services in the long-term

Is the caste-ratio of the oligolectic bumblebee Bombus gerstaeckeri Morawitz biased to queens (Hymenoptera: Apidae) ?

peer reviewedTrois espèces de bourdons butineurs d'Aconitum spp. sont communément observés à Eyne (France, Pyrénées-Orientales): Bombus gerstaeckeri, B. hortorum and B. wurflenii. Nous avons estimé la population de ces trois espèces. Pour B. hortorum et B. wurflenii, la population totale des ouvrières butineuses d'Aconitum spp. était dans les intervalles, respectivement, 101-523 et 156-270. Ces deux espèces butinent ausi d'autres plantes tandis que B. gerstaeckeri visitait uniquement Aconitum spp. La population de B. gerstaeckeri était extrêmement petite, seulement 33 reines fondatrices en 2001. Avec un nombre total d'ouvrières de cette espèce compris entre 40 et 102, le rapport ouvrières/reines est très inhabituel pour une espèce eusociale: 1 à 3 ouvrières par reine. Nous avons aussi observé des reines qui continuaient à butiner durant toute la durée de vie de la colonie. Ce type d'organisation sociale est proche de celui qu'on trouve chez certaines espèces arctiques. Cela peut être interprété comme le résultat d'un syndrome d'insularité

Prehypoxic clonidine administration improves vasomotricity of isolated rat aorta during reoxygenation.

BACKGROUND AND OBJECTIVE: Clonidine, an alpha-2 adrenoceptor (A2A) agonist, improves posthypoxic function of several organs in humans and animal models. Mechanisms underlying these effects are not fully understood. A competent vasomotricity during reperfusion participates in the organ's recovery. This study investigates the specific effect of clonidine administration before hypoxia on posthypoxic vasomotricity in a rodent model. METHODS: Isolated aortic rings from young rats were submitted to hypoxia/reoxygenation (20/40 min). Clonidine (10 mol l), alone or with various receptor antagonists such as rauwolscine (specific A2A antagonist), ARC239 (A2B/C-preferingA antagonist), BRL44408 (A2AA antagonist), nitrogen oxide synthase inhibitor (Nomega-nitro-L-arginine methyl ester) or cyclooxygenase inhibitor (indometacin), was administered in two randomized baths and washed out before hypoxia. Two other baths constituted the control group. In some experiments, clonidine was substituted by UK14.304 (A2A agonist). In all baths, posthypoxic endothelium-dependent dilatation (PED) and posthypoxic contraction were assessed. RESULTS: Clonidine improves PED (P = 0.002) and posthypoxic contraction (P = 0.001). Rauwolscine (P = 0.803) and ARC239 (P = 0.236) abolished clonidine-induced PED improvement. In the presence of BRL44408, clonidine increases posthypoxic endothelial dysfunction (P = 0.001). UK14.304 (P = 0.954) does not mimic the clonidine effect on PED. Concerning posthypoxic contraction, rauwolscine (P = 0.917), endothelial removal (P = 0.687), ARC239 (P = 0.118) or BRL44408 (P = 0.204) prevents the clonidine effect, but UK14.304 induces it (P = 0.005). Nomega-Nitro-L-arginine methyl ester (P = 0.026) does not abolish it. Indometacin prevents it on PED and posthypoxic contraction (P = 0.678 and P = 0.851, respectively). CONCLUSION: Clonidine improves posthypoxic vasomotricity on isolated aortic rings. Concerning PED, two endothelial A2A subtypes are required. The clonidine effect on posthypoxic contraction requires endothelial A2A. Nitrogen oxide does not seem to be involved. Concerning the clonidine effect on PED and posthypoxic contraction, cyclooxygenase metabolites seem to be involved

Ageing influences the effect of pre-hypoxic administration of clonidine, an alpha₂-adrenoceptor agonist, on post-hypoxic vasomotricity.

In a previous study, we showed that clonidine, an α₂-adrenoceptor agonist, administered prior to hypoxia improves post-hypoxic contractility (PC) and endothelium-dependent dilatation (PED) in isolated young rat aortas. These effects were not investigated in old rats. Ageing influences vascular physiology and modifies the response to vasoactive drugs. Some drugs, such as simvastatin, improve endothelial function, a pivotal component of vascular homeostasis. This study intends to investigate the effect of pre-hypoxic clonidine administration on post-hypoxic vasomotricity in old rats with or without simvastatin. Isolated aortic rings from young and old rats were submitted to hypoxia/reoxygenation (20 min/40 min). For each aorta ring from one rat, clonidine (10⁻⁵ M) was administered in two randomised baths and washed out before hypoxia; two other baths constituted the control group. In some experiments, the old rats were treated with simvastatin (10 mg x kg⁻¹ x day⁻¹) 3 days prior to hypoxia. PED and PC were assessed in all baths. Clonidine enhances PED in young rats (p<0.001) but decreases it in old rats (p=0.038). In young rats, clonidine improves PC (p<0.001), but this effect is not present in old rats (p=0.339). Without endothelium, clonidine does not influence PC in young rats (p= 0.687) but decreases it in old rats (p<0.001). In the simvastatin group, clonidine improves PED (p<0.001) but does not influence PC (p=0.203). In young rats, clonidine increases PED and PC, while it decreases PED and does not influence PC in old rats. With simvastatin, clonidine improves PED but does not influence PC