title: High population densities of Macrolophus pygmaeus on tomato plants can cause economic fruit damage: interaction with Pepino mosaic virus?
abstract: BACKGROUND
  The zoophytophagous predator Macrolophus pygmaeus Rambur (Hemiptera: Miridae) is a successful biocontrol agent against several pest species in protected tomato crops. This predator is considered to be harmless for the crop. However, in recent years, Heteroptera feeding punctures on tomato fruit in Belgian and Dutch greenhouses have been misinterpreted as Pepino mosaic virus (PepMV) symptoms. In this study, three hypotheses were tested: (1) M. pygmaeus causes fruit damage that increases with population density and surpasses economic thresholds; (2) the presence of prey or alternative prey reduces the damage; (3) an infection of the tomato plants by PepMV triggers or aggravates M. pygmaeus fruit damage.
  
  
  RESULTS
  At increasing M. pygmaeus densities, the severity of fruit damage increased from a few dimples towards yellowish discoloration and deformed fruits. A correlation with an infection with PepMV was found. The severity of the symptoms was independent of the presence of prey. A minimum economic density threshold was estimated at 0.32 M. pygmaeus per leaf.
  
  
  CONCLUSIONS
  M. pygmaeus can cause economic damage to tomato fruits at densities common in practice. An infection of the plants with PepMV enhances fruit symptoms significantly. Interacting plant defence responses are most likely the key to explaining this, although confirmation is required. © 2015 Society of Chemical Industry.
authors.affiliation: Tomato Research, Research Centre Hoogstraten, Hoogstraten, Belgium.|Evolutionary Ecology Group, University of Antwerp, Belgium.
authors.forename: Rob
authors.initials: R
authors.lastname: Moerkens
authors.affiliation: Research Station for Vegetable Production, Sint-Katelijne-Waver, Belgium.
authors.forename: Els
authors.initials: E
authors.lastname: Berckmoes
authors.affiliation: Institute for Agricultural and Fisheries Research (ILVO), Merelbeke, Belgium.|Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium.
authors.forename: Veerle
authors.initials: V
authors.lastname: Van Damme
authors.affiliation: Scientia Terrae Research Institute, Sint-Katelijne-Waver, Belgium.
authors.forename: Nelia
authors.initials: N
authors.lastname: Ortega-Parra
authors.affiliation: Scientia Terrae Research Institute, Sint-Katelijne-Waver, Belgium.
authors.forename: Inge
authors.initials: I
authors.lastname: Hanssen
authors.affiliation: Research Station for Vegetable Production, Sint-Katelijne-Waver, Belgium.
authors.forename: Martine
authors.initials: M
authors.lastname: Wuytack
authors.affiliation: Research Station for Vegetable Production, Sint-Katelijne-Waver, Belgium.
authors.forename: Lieve
authors.initials: L
authors.lastname: Wittemans
authors.affiliation: Institute for Agricultural and Fisheries Research (ILVO), Merelbeke, Belgium.
authors.forename: Hans
authors.initials: H
authors.lastname: Casteels
authors.affiliation: Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: Tirry
authors.affiliation: Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: De Clercq
authors.affiliation: Research Station for Vegetable Production, Sint-Katelijne-Waver, Belgium.
authors.forename: Raf
authors.initials: R
authors.lastname: De Vis
mesh_terms: D000818:Animals; D000069599:Crop Production; D005638:Fruit / Q000469:parasitology / Q000821:virology; D006430:Hemiptera; D018551:Solanum lycopersicum / Q000469:parasitology / Q000821:virology; D010935:Plant Diseases / Q000469:parasitology / Q000821:virology; D011156:Population Density; D046830:Tymoviridae / Q000472:pathogenicity*
keywords: Macrolophus pygmaeus; Pepino mosaic virus; Solanum lycopersicon; threshold; zoophytophagous predator