Polyphagy and florivory prevail in a leaf-beetle community (Coleoptera: Chrysomelidae) inhabiting the canopy of a tropical lowland rainforest in southern Venezuela

ABSTRACT

Embedded within the interdisciplinary research project ‘Towards an understanding of the structure and function of a Neotropical rainforest ecosystem with special reference to its canopy’ organised by the Austrian Academy of Science, the canopy beetle fauna was surveyed by means of a 42 m tall tower crane. This paper presents results of the chrysomelid beetle fauna observed and collected at canopy trees for 1 year. A total of 1783 adult leaf beetles were collected, representing 117 morphospecies (Bruchinae are not included) including 31 singletons. The most abundant family was Galerucinae sensu stricto with 827 individuals (46% of collection). The most speciose subfamilies were Galerucinae sensu stricto followed by Alticini, Cryptocephalinae and Eumolpinae. Nineteen species collected with at least two individuals were restricted to a single tree species whereas 68 species were found to feed on several canopy host trees. Only a few species fed on leaves; these were in Cassidinae, Cryptocephalinae, Eumolpinae and Galerucinae. Strikingly, most canopy chrysomelids were collected at flowers of canopy trees, although some species fed also on extrafloral nectaries or fruits. Alticini were restricted predominantly to flowers, but Cryptocephalinae, Eumolpinae and Galerucinae revealed broader plasticity in host tissue selection. Insights into beetle seasonality, diurnal/nocturnal activity and intra-canopy migration are provided. Abundant flower-visiting species occurred on their host trees commonly over the entire flowering season, with their abundances often correlated with the number of open flowers. After termination of one tree’s flowering season, many flower-visiting leaf beetles moved to other flowering trees. Certain congeneric species of Galerucinae and Eumolpinae occurred together at their host plants within the same periods.

KEYWORDS:

• biodiversity
• Neotropics
• seasonality
• host plants
• diet
• behaviour

Acknowledgements

The Austrian Academy of Sciences and colleagues are gratefully acknowledged for their support and invitation to join the Surumoni project. Aragua Cedeño (Universidad Central de Venezuela) helped mainly with contacting Venezuelan scientists and authorities. The fieldwork was supported, in part, by a travel grant from the ESF Tropical Canopy Programme and a grant from the Stiftung der Deutschen Wirtschaft. Author SK cordially thanks Lev N. Medvedev (Severtsov Institute for Problems of Ecology and Evolution, Moscow, Russia), Shawn M. Clark (Brigham Young University, USA) and Davide Sassi (Università degli Studi di Milano, Italy) for the determination of some leaf beetles. Harald Schillhammer (Natural History Museum, Vienna) supported the study with equipment and the possibility to take photos of the leaf beetles. Lourdes Chamorro, Shawn Clark, Wills Flowers, David Furth, Davide Sassi, Charles Staines, Jessica Viana and Rob Westerduijn contributed to identification on the basis of photos. Plants were mainly identified by the botanists H. Rainer (University of Vienna) and J. Wesenberg (University of Leipzig). We thank Brett Ratcliffe for his encouragement as well as Federico Agrain, Shawn Clark, Wills Flowers, David Furth and Matthias Schöller for reviewing some taxonomic names. We acknowledge Vilma Savini, Michael Schmitt and Thomas Wagner as well as two anonymous reviewers for their valuable comments on the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Geolocation information

The study site is located in the upper Orinoco region state of Amazonas, Venezuela: 3°10’N, 65°40’W.

Additional information

Funding

This work was supported by the ESF Tropical Canopy Programme [travel grant]; and the Stiftung der Deutschen Wirtschaft (3-year fulltime scholarship).