title: Below-ground herbivory limits induction of extrafloral nectar by above-ground herbivores.
abstract: OBJECTIVE
  Many plants produce extrafloral nectar (EFN), and increase production following above-ground herbivory, presumably to attract natural enemies of the herbivores. Below-ground herbivores, alone or in combination with those above ground, may also alter EFN production depending on the specificity of this defence response and the interactions among herbivores mediated through plant defences. To date, however, a lack of manipulative experiments investigating EFN production induced by above- and below-ground herbivory has limited our understanding of how below-ground herbivory mediates indirect plant defences to affect above-ground herbivores and their natural enemies.
  
  
  METHODS
  In a greenhouse experiment, seedlings of tallow tree (Triadica sebifera) were subjected to herbivory by a specialist flea beetle (Bikasha collaris) that naturally co-occurs as foliage-feeding adults and root-feeding larvae. Seedlings were subjected to above-ground adults and/or below-ground larvae herbivory, and EFN production was monitored.
  
  
  RESULTS
  Above- and/or below-ground herbivory significantly increased the percentage of leaves with active nectaries, the volume of EFN and the mass of soluble solids within the nectar. Simultaneous above- and below-ground herbivory induced a higher volume of EFN and mass of soluble solids than below-ground herbivory alone, but highest EFN production was induced by above-ground herbivory when below-ground herbivores were absent.
  
  
  CONCLUSIONS
  The induction of EFN production by below-ground damage suggests that systemic induction underlies some of the EFN response. The strong induction by above-ground herbivory in the absence of below-ground herbivory points to specific induction based on above- and below-ground signals that may be adaptive for this above-ground indirect defence.
authors: Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, China, Department of Ecology and Evolutionary Biology, Rice University, Houston, TX 77005, USA and Department of Entomology, Purdue University, West Lafayette, IN 47907, USA.
authors: Wei
authors: W
authors: Huang
authors: Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, China, Department of Ecology and Evolutionary Biology, Rice University, Houston, TX 77005, USA and Department of Entomology, Purdue University, West Lafayette, IN 47907, USA.
authors: Evan
authors: E
authors: Siemann
authors: Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, China, Department of Ecology and Evolutionary Biology, Rice University, Houston, TX 77005, USA and Department of Entomology, Purdue University, West Lafayette, IN 47907, USA.
authors: Juli
authors: J
authors: Carrillo
authors: Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, China, Department of Ecology and Evolutionary Biology, Rice University, Houston, TX 77005, USA and Department of Entomology, Purdue University, West Lafayette, IN 47907, USA dingjianqing@yahoo.com.
authors: Jianqing
authors: J
authors: Ding
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000502:physiology*; D019665:Euphorbiaceae / Q000737:chemistry* / Q000502:physiology; D060434:Herbivory; D006790:Host-Parasite Interactions; D007814:Larva; D018515:Plant Leaves / Q000737:chemistry / Q000502:physiology; D057048:Plant Nectar / Q000378:metabolism*; D018517:Plant Roots / Q000737:chemistry / Q000502:physiology; D018520:Plant Shoots / Q000737:chemistry / Q000502:physiology
chemical_list: D057048:Plant Nectar
keywords: Bikasha collaris; Extrafloral nectar; Triadica sebifera; above- and below-ground interactions; flea beetle; herbivory; indirect defence; induced defence; specificity; tallow tree