Munger Cage Inoculation Protocol

Materials and Equipment Needed

  1. Thrips
  2. Munger cages
  3. Rubber bands (#8)
  4. Stakes
  5. Floral wire
  6. Small clothespins
  7. Labels
  8. Inoculation unit
  9. Tubing
  10. Vacuum regulation device
  11. Carbon dioxide cylinder and regulator
  12. Modified Gladware container
  13. Clock/watch

Safety Issues

Don't inhale the carbon dioxide.

Time Required

2-3 minutes per cage plus set up and clean up with 2 people

Procedure

Step Image
Set up materials as shown at right.  Avoid placing extra cages inside the hood to reduce contamination with thrips.  The cylinder is filled to a given level with water.  The difference between the level of the water and the bottom of the tubing in the cylinder determines the amount of vacuum.

Turn the carbon dioxide cylinder on 10-15 minutes before starting inoculation to allow Gladware container to fill with gas.  Open the cylinder valve.  The needle value should be opened a small amount.  Adjust pressure regulator as needed, leaving it on the same setting throughout the inoculation. 
Plants should have previously been randomized and tagged with a number (return address labels cut to fit).  Bring plant to be inoculated into the hood.

Turn vacuum line on.  Insert cage into the inoculation unit as shown.  Have a bottom cage piece within reach.  Hold the unit together tightly enough for small bubbles to come out of the tubing in the cylinder.

 
Collect desired number of thrips.  Five adult females damage impatiens sufficiently to be evaluated after 3 days.  Leaving the insects in the cages much longer or using greater numbers of insects causes the leaf tissue to be so damaged by feeding that the insects escape.  The screening on the cages will not prevent instars from escaping.
Insert the collection device through the hole in the Gladware container to expose the insects to the carbon dioxide.  About 20 sec seems to work well, however time needed may vary with insect population and rate of carbon dioxide flow.
After exposure to the carbon dioxide, quickly remove cage from inoculation unit without turning the cage right side up.  Hold cage near leaf and turn leaf over on top of the cage. 
Place the bottom cage piece on the underside of the leaf.  Carefully turn unit over.
Place a rubber band on each side of the cage, checking rubber bands first for defects which might cause them to break.  Strips of 1/4" tape should also be wrapped around each side of the cage next to the rubber bands.  Experience has shown cages may come apart if only rubber bands are used.
Insert stakes into pot and position clips such that they hold the cage in the desired position without breaking the leaf petiole (tape strips not shown on cage).

Repeat with other plants.  If inoculating with multiple populations of insects the hood needs to be cleaned between polulations.

 
When finished, turn off carbon dioxide cylinder and spray hood with alcohol to eliminate any escaped insects.