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SysEB

Poster

Category: Poster

Poster: SysEB

Death feigning in a parasitoid wasp (Hymenoptera: Pteromalidae): Influence of environment and correlation with metabolic rate

Poster
 Ryan D. Morris and B. H. King
Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115-2861, U.S.A. (email: a1873387@mail.niu.edu)
 
Abstract: Death feigning in a parasitoid wasp (Hymenoptera: Pteromalidae): influence of environment and correlation with metabolic rate

  1. Death feigning, is more accurately called tonic immobility or thanatosis and is a motionless posture that an organism adopts for several seconds to a few hours when threatened or harassed, e.g., by a predator, competitor, or mating attempts. During tonic immobility, an organism may be unable to respond to many types of stimuli. Tonic immobility has been documented in a taxonomically diverse array of insects, but studied in detail in relatively few.

  2. In the present study, tonic immobility was examined in the parasitoid wasp Spalangia cameroni (Hymenoptera: Pteromalidae). When disturbed, e.g., by contact, Spalangia cameroni and some confamilials fall onto their back, retract their legs and antennae, and remain immobile for seconds to minutes.

  3. S. cameroni was subject to several experimental treatments: low temperature versus room temperature, differences in food availability, presence versus absence of conspecifics, sudden exposure to light, and access to cover or not. Each wasp was poked up to five times until it exhibited tonic immobility, and the duration of the tonic immobility was recorded. Whether wasps with lower resting metabolic rate had higher expression of tonic immobility was also examined. Metabolic rate was measured in multiple wasps simultaneously with an inexpensively made respirometer.