title: Use of von Frey filaments to assess nociceptive sensitization in the hornworm, Manduca sexta.
abstract: BACKGROUND
  The hornworm Manduca sexta exhibits a defensive strike to noxious assaults, a response that is robust and is easily observed by experimenters. Von Frey filaments and methods typical for studying nociception in other animals were used to assess the strike response in M. sexta.
  
  
  METHODS
  A series of von Frey filaments was applied to the body wall in ascending order and the data generated were used to determine the strike threshold by (i) the up-and-down method, (ii) the first response method, and (iii) the simplified up-and-down order method (SUDO). The effect of a noxious pinch on strike threshold was assessed.
  
  
  METHODS
  To our knowledge none of these methods has been used on M. sexta previously, making the use of the up-and-down and SUDO methods the first in an invertebrate. The use of the first response method has been used in other invertebrates, and the method appears equally suited to M. sexta.
  
  
  RESULTS
  All three methods were successful in monitoring the threshold sensitivity to touch, which was lowered (sensitized) by tissue damage induced with a pinch. Sensitization lasted 19h.
  
  
  CONCLUSIONS
  All three methods of assessing nociception were successfully applied to quantify the defensive strike response in M. sexta, although the SUDO method required empirical assessment of which filament to start the test sequence with. The results revealed both short- and long-term sensitization. These methods should prove to be useful for quantifying sensitization in M. sexta.
authors.affiliation: Department of Biology, San Francisco State University, 1600 Holloway Ave, San Francisco, CA 94132, USA. Electronic address: mzmcmackin@gmail.com.
authors.forename: Marissa Zubia
authors.initials: MZ
authors.lastname: McMackin
authors.affiliation: Institute for Biodiversity Science and Sustainability Director Center for Exploration and Travel Health, California Academy of Sciences, 55 Music Concourse Dr., Golden Gate Park, San Francisco, CA 94118, USA. Electronic address: mlewin@calacademy.org.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Lewin
authors.affiliation: Department of Biology, San Francisco State University, 1600 Holloway Ave, San Francisco, CA 94132, USA. Electronic address: dennis.r.tabuena2@gmail.com.
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Tabuena
authors.affiliation: Department of Biology, San Francisco State University, 1600 Holloway Ave, San Francisco, CA 94132, USA. Electronic address: arreola.eric85@gmail.com.
authors.forename: F Eric
authors.initials: FE
authors.lastname: Arreola
authors.affiliation: Department of Biology, San Francisco State University, 1600 Holloway Ave, San Francisco, CA 94132, USA. Electronic address: moffatt@sfsu.edu.
authors.forename: Christopher
authors.initials: C
authors.lastname: Moffatt
authors.affiliation: Department of Biology, San Francisco State University, 1600 Holloway Ave, San Francisco, CA 94132, USA. Electronic address: fuse@sfsu.edu.
authors.forename: Megumi
authors.initials: M
authors.lastname: Fuse
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D007814:Larva; D018402:Manduca; D059225:Nociception; D017288:Pain Threshold; D010812:Physical Stimulation / Q000295:instrumentation* / Q000379:methods*
keywords: Defensive strike response; Insect; Larva; SUDO method; Up-and-down method; Von Frey filaments