Climate change impact on neotropical social wasps.

Alain Dejean (1, 2) , Régis Céréghino (2) , James M Carpenter (3) , Bruno Corbara (4) , Bruno Hérault (5) , Vivien Rossi (6) , Maurice Leponce (7) , Jérome Orivel (1) , Damien Bonal (8)

1 ECOFOG - Ecologie des forêts de Guyane
2 LEFE - Laboratoire Ecologie Fonctionnelle et Environnement
3 Division of Invertebrate Zoology, American Museum of Natural History [New York, USA]
4 LMGE - Laboratoire Microorganismes : Génome et Environnement
5 UAG - Université des Antilles et de la Guyane
6 Cirad - Centre de Coopération Internationale en Recherche Agronomique pour le Développement
7 IRSNB - Institut Royal des Sciences Naturelles de Belgique
8 EEF - Ecologie et Ecophysiologie Forestières [devient SILVA en 2018]

Establishing a direct link between climate change and fluctuations in animal populations through long-term monitoring is difficult given the paucity of baseline data. We hypothesized that social wasps are sensitive to climatic variations, and thus studied the impact of ENSO events on social wasp populations in French Guiana. We noted that during the 2000 La Niña year there was a 77.1% decrease in their nest abundance along ca. 5 km of forest edges, and that 70.5% of the species were no longer present. Two simultaneous 13-year surveys (1997-2009) confirmed the decrease in social wasps during La Niña years (2000 and 2006), while an increase occurred during the 2009 El Niño year. A 30-year weather survey showed that these phenomena corresponded to particularly high levels of rainfall, and that temperature, humidity and global solar radiation were correlated with rainfall. Using the Self-Organizing Map algorithm, we show that heavy rainfall during an entire rainy season has a negative impact on social wasps. Strong contrasts in rainfall between the dry season and the short rainy season exacerbate this effect. Social wasp populations never recovered to their pre-2000 levels. This is probably because these conditions occurred over four years; heavy rainfall during the major rainy seasons during four other years also had a detrimental effect. On the contrary, low levels of rainfall during the major rainy season in 2009 spurred an increase in social wasp populations. We conclude that recent climatic changes have likely resulted in fewer social wasp colonies because they have lowered the wasps' resistance to parasitoids and pathogens. These results imply that Neotropical social wasps can be regarded as bio-indicators because they highlight the impact of climatic changes not yet perceptible in plants and other animals.

Mots clés: CLIMATE CHANGE; NEOTROPICAL; ANIMAL; WASPS

Domaines: Biodiversité et Ecologie; Biologie animale

Alain Dejean, Régis Céréghino, James M Carpenter, Bruno Corbara, Bruno Hérault, et al.. Climate change impact on neotropical social wasps.. PLoS ONE, 2011, 6 (11), pp.e27004. ⟨10.1371/journal.pone.0027004⟩. ⟨hal-00825825⟩