Conservation and global change

Researchers: Prof. Pierre Rasmont, Prof. Denis Michez, Dr. Thomas Lecocq, Maxence Gérard, Nicolas Brasero, Morgane Folschweiller, Sarah Vray

We are involved in federal and international conservation programs such as the European STEP program (Status and Trends of European Pollinators www.step-project.net ) or the Belgian BELSPO program named BELBEES (Multidisciplinary assessment of BELgian wild BEE decline to adapt mitigation management – l www.belbees.be). We also contributed to the production of the IUCN Red List for wild bees (http://www.iucnredlist.org/search) and collaborate with many institutions (cities, nature conservation associations, etc.) on wild bees’ conservation issues. Finally, we are involved in the Web Impact (lien vers la page “projects”) project, that aims to evaluate the impact of pollination web modifications in wild bee decline.

Pollinator decline

Pollinators, such as bees, are essential for plant reproduction in both natural ecosystems and crops. Pollinators and bee decline is therefore of great concern because it could affect stability of food production and conservation of wild plants.

Bee decline has been detected in many part of the world. In 1993 we already showed that in Belgium, the faunistic drift of Apoidea Apiformes (i.e. wild bees) was drastic. 91 of the 360 studied species were severely decreasing, which represents 25% of the Belgian wild bees.

According to recent studies about pollinator declines, four main drivers can be identified: habitat loss and fragmentation, agrochemicals, pathogens, and climate change. Today, scientists’ main goal is to understand (i) how and why these drivers may impact wild bees; (ii) which species are declining, stable or increasing. New evidence are needed to establish conservation plans and to adapt mitigation policies.

We are developing researches on the effects of habitat degradation (e.g. landscape fragmentation, eutrophication …) and climate change (including heat waves) on the population, the phenology and the distribution of solitary bees and bumblebees. To do so, we use long term datasets (including data from museum’s collections), from 1750 to today, to analyse trends and factors impacting on wild bees in Belgium, in Europe, or in the Arctic Circle.

Climate change and wild bees’ decline

Nowadays big challenge is to understand the current and future effects of climate change on wild bees. Indeed, if wild bees are affected, the whole plant-pollinator network, and thus the pollination services, may be impacted. We currently investigate the effects of climate change on bee’s phenology that is to say the time of the year at which they accomplish seasonal activities such as reproduction, nesting, diapause, etc… A better understanding of phenological changes in wild bees (for instance, an earlier emerging in spring) is very important. Especially to examine if bees’ and plant’s phenology remain synchronized.

Consequences of climate change and habitat fragmentation on bumblebee populations in Belgium.

Habitat fragmentation and loss affect the functioning of populations because they reduce the total amount of habitat available and alter the flow of individuals between populations through dispersal. Fragmentation of bumblebees’ habitats comes from a diminution of open landscapes, due to increased forest and urban areas, and to agricultural intensification. In Belgium, increased urbanization and agricultural intensification have dramatically changed the landscapes over the last decades, and could continue to do so in the coming decades. More recently, several studies have implicated changes in climate in the bumblebee decline. Furthermore, climate and landscape changes are assumed to underlie a multitude of environmental pressures that may have a greater joint impact on biodiversity than when operating in isolation. For instance, the loss of habitat may reduce a species to small, marginal areas where it is more exposed to meteorological changes. Our aim is therefore to qualify and quantify the relationship between landscape changes, climate change and changes in populations of bumblebees. We use a comparative approach based on past and present landscape composition and structure, historical climate records and bumblebees data in Belgium. This will provide key elements for understanding the processes responsible for the decline of populations of bumblebees, which will in the longer term allow designing conservation strategies to halt biodiversity loss of these essential pollinators.

Tools for biological conservation

Most of conservation plans are assessed on the basis of occurrence and proportion of endemic taxa. However, delimitations of species and subspecies are still confusing and controversial. From a practical point of view, these disagreements make it difficult for government agencies and non-governmental organizations to initiate conservation measures. We develop a pragmatic integrative taxonomic approach on the basis of molecular and eco-chemical criteria. Regardless of the taxonomic assessment the method facilitates diagnosis of evolutionarily significant units and rank taxa according to their distinctiveness. This approach provides useful data sets for policy-makers and conservation organizations. Selected publication: Lecocq et al. 2014. Animal Conservation in press. See also used of integrative taxonomy (lien vers page “integrative taxonomy”) We are also developing new tools based on morphology to assess the decline of wild bees. Geometric morphometric analyses on wing shape are used to identify diploid males (a genetic load for bees) and assess the level of fluctuating asymmetry (FA). This level of FA could be correlated on genetic diversity and, in addition of morphological diploid males identifiers, could be used as an estimator of the genetic health for bees in the future.