Host plant location by chemotaxis in an aquatic beetle
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Interactions between plants and aquatic insects are poorly documented, especially for turbid freshwater ecosystems. Many Swiss lakes offer such habitats, several of which are inhabited by the leaf beetle Macroplea appendiculata (Panzer 1794). This donaciid beetle is the only coleopteran species known to complete its life cycle entirely under water, where it lives primarily on perfoliate pondweed (Potamogeton perfoliatus L.), with Eurasian watermilfoil (Myriophyllum spicatum L.) as an alternative host plant. Direct observations during diving trips, aquatic olfactometer bioassays, and stir bar sorptive extractions (SBSE) coupled with GC–MS analysis were used to understand how these beetles locate their patchily distributed host plants and congeners in a harsh, often swirling environment. In olfactometer assays we observed that the aquatic beetle is strongly attracted to water extracts of pondweed, whereas neither mature males nor females beetles seem to produce attractive cues. The chemical analyses revealed that perfoliate pondweed releases one dominating compound, eucalyptol. Olfactometer assays confirmed that this is a potent attractant for the beetle. We also observed attraction to phytol, which is released by the main, as well as the alternative host plant. These finding are somewhat surprising as eucalyptol has never been reported for aquatic plants and phytol is poorly soluble in water. In addition, both are frequently described as insect repellents in terrestrial ecosystems. We suggest that these terpenoids normally have a defensive function against herbivores and pathogens, but that the highly specialized leaf beetle has evolved to exploit its host’s defence chemistry for optimal foraging.
KeywordsAquatic beetle Plant-herbivore interactions Freshwater Macrophytes Host location Macroplea appendicultata Chemical attractants
We thank Aline Verdon for help with the figures, Aurélien Labhardt for his constructive input, Albert Ros for aquarium material, the Organe d’exécution du service civil ZIVI, the Swiss Biological Records Center, and the Centre national de données et d’informations sur la flore de Suisse for helpful collaboration and information.
Compliance with ethical standards
Conflict of interest
Submission of the manuscript has been approved by all relevant authors and institutions, and all persons entitled to authorship have been so named.
- Brocher F (1912) Recherches sur la respiration des insectes aquatiques adultes–les Haemonia. In: Rousseau E (ed) Annales de biologie lacustre. Bruxelles, p 5–26Google Scholar
- Chapman RF (2007) Foraging and food choice of phytophagous insect. In: Hardege JD (ed) Chemical ecology. Encyclopedia in life support systems (EOLSS), p 71–101Google Scholar
- Forel FA (1904) In: Cie FR (ed) Le Léman, monographie limnologique, Lausanne, p 715Google Scholar
- Glomski LAM, Wood KV, Nicholson RL, Lembi CA (2002) The search for exudates from Eurasian watermilfoil and Hydrilla. J Aquat Plant Manag 40:17–22Google Scholar
- Gross EM, Kornijow R (2002) Investigation on competitors and predators of herbivorous aquatic Lepidoptera (Acentria ephemerella) on submersed macrophytes in a large prealpine lake. Verh Internat Verein Limnol 28:721–725Google Scholar
- Lays P (2006) A fleur d’eau Les donacies. Insectes 140:9–13Google Scholar
- Mann JS, Crowson RA (1983) Observations on the internal anatomy and classification of Donaciinae (Col, Chrysomelidae). Entomol Month Mag 119:17–27Google Scholar
- Mohr KH (1985) Beiträge zur Insektenfauna der DDR: Coleoptera–Chrysomelidae: Donaciinae, Orsodacninae, Criocerinae, Clythrinae. Beitr Entomol 35:219–262Google Scholar
- Nelson B, Walsh J, Foster G (2007) Finding jewels amongst the reeds: a review of the Irish Donaciine beetles (Coleoptera: Chrysomelidae). Bull Ir Biogeog Soc 31:117–193Google Scholar
- Owen JA, Menzies SI (1996) A note on the life history of Macroplea appendicultata (Panzer) (Col: Chrysomelidae). Entomol Rec J Var 108:317–318Google Scholar
- Reinecke A, Hilker M (2014) Plant semiochemicals–perception and behavioural responses by insects. In: Voelckel C, Jander G (eds), vol 47, chap 4, Annual plant reviews insect-plant interactions, Wiley, UKGoogle Scholar
- Schoonhoven LM, van Loon JJA, Dicke M (2005) In: OUP Oxford (ed), Insect-plant biology 2nd edn. Oxford University, Oxford, p 440Google Scholar
- Smith CS, Barko JW (1990) Ecology of Eurasian watermilfoil. J Aquat Plant Manag 28:55–64Google Scholar
- Städler E (1992) Behavioral responses of insects to plant secondary compounds. In: Rosenthal GA, Berenbaum MR (eds.) Herbivores–their interactions with secondary plant metabolites 2nd edn. Academic Press Inc, San Diego, vol 2, p 45–79Google Scholar
- R Development Core Team (2008) R: a language and environment for statistical computing. R Foundation for Statistical Computing Vienna. http://www.R-projectorg
- Wetzel RG (2001) Bacterioplankton & Detritus: organic carbon cycling and ecosystem metabolism. In: Limnology: lake and river ecosystems. Academic Press, London, p 489–525 (731–783) Google Scholar