Vol.:(0123456789) 1 3 Oecologia https://doi.org/10.1007/s00442-018-4169-4 COMMUNITY ECOLOGY – ORIGINAL RESEARCH Predator and parasitoid insects along elevational gradients: role of temperature and habitat diversity Daria Corcos 1,2  · Pierflippo Cerretti 1  · Maurizio Mei 1  · Augusto Vigna Taglianti 1  · Dino Paniccia 3  · Giacomo Santoiemma 2  · Alessio De Biase 1  · Lorenzo Marini 2 Received: 20 July 2017 / Accepted: 16 May 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Elevational gradients are characterized by strong abiotic variation within small geographical distances and provide a powerful tool to evaluate community response to variation in climatic and other environmental factors. We explored how temperature and habitat diversity shape the diversity of holometabolous predator and parasitoid insects along temperate elevational gradients in the European Alps. We surveyed insect communities along 12 elevational transects that were selected to sepa- rate efects of temperature from those of habitat diversity. Pitfall traps and pan traps were placed every 100 m of elevation increment along the transects ranging from 120 to 2200 m a.s.l. Sampling took place once a month from June to September 2015. Four groups characterized by having at least one life stage behaving as predator or parasitoid were examined: tachinids (Diptera), hoverfies (Diptera), sphecids (Hymenoptera) and ground beetles (Coleoptera). Species richness and evenness changed with elevation, but the shape and direction of the elevation–diversity patterns varied between groups. The efect of temperature on species richness was positive for all groups except for hoverfies. Habitat diversity did not afect species richness, while it modulated the evenness of most groups. Often, elevational patterns of species richness and evenness were contrasting. Our study indicates that natural enemies characterized by diverse ecological requirements can be diferentially afected by temperature and habitat diversity across the same elevational gradients. As climate warming is predicted to increase mean annual temperatures and exacerbate weather variability, it is also expected to strongly infuence natural enemies and their ability to regulate herbivore populations. Keywords Altitudinal gradient · Climate change · Global warming · Natural enemies · Third trophic level Introduction Elevational gradients are characterized by strong environ- mental changes within small geographical distances and provide a powerful tool to evaluate community response to variation in climatic and other environmental factors (Körner 2007; Axmacher and Fiedler 2008; McCain 2009; Malhi et al. 2010). Elevation–diversity patterns vary among taxa and functional groups and among mountain ranges with diferent climates (McCain 2009; McCain and Grytnes 2010; Sundqvist et al. 2013; Chamberlain et al. 2016). Many stud- ies have tried to identify the factors driving this variability, usually focusing on climatic variables such as temperature and rainfall (Körner 2007; Bishop et al. 2014). The pre- dicted pattern is decreasing diversity with decreasing tem- perature, because of the decreased annual thermal budget for growth and development (Hodkinson 2005; Mittelbach et al. 2007; McCain 2009), while the efect of rainfall is less Communicated by Ingolf Stefan-Dewenter. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00442-018-4169-4) contains supplementary material, which is available to authorized users. * Daria Corcos daria.corcos@uniroma1.it 1 Department of Biology and Biotechnology “Charles Darwin”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy 2 DAFNAE-Entomology, University of Padova, Viale dell’Università 16, 35020 Legnaro, Padua, Italy 3 Via Colle 13, 03100 Frosinone, Italy