Diamondback Moth Larval Collection and Field Testing

UGA Protocol 2019 (J. Bennett and D. Riley, UGA Tifton Campus, contact: dgr@uga.edu)

Materials

  • Styrofoam Cups with Lids (20 fl 0z)

  • Syringes (1 ml) capable of measuring to one-tenth of a milliliter

  • Holding container to securely hold the cups

  • Sharpie marker for appropriate labeling

  • Latex gloves to avoid chemical exposure

  • Disposable stir-rod for agitating chemical mixture

On-site Materials

  • Insecticides (minimum 10) for running tests with the Insecticide Bioassay Rate Table

  • Water source for chemical mixture and Kinetic to condition the mixture

  • Leaf source for test (preferably untreated, but if not available, use field site collected leaves)

  • Diamondback moth larvae, minimum 10 healthy 3rd instars per treatment

On-site Materials

  • Take Styrofoam cups and label each cup with the respective chemical that will be used in the
    test for that cup. A check cup with no chemical needs to be included in the test as well.
    Warning: A skull and cross bones-poison symbol should be on the cup so they are not reused!
    o Also, label each cup with the amount of each chemical needed for 500 ml.

  • Using the measuring cup, measure 500 ml of water and put into each cup.

  • To each cup, add the required amount of chemical using the syringe. Use a clean syringe for
    each chemical. You will need a syringe for each chemical and one for Kinetic.

  • Add 0.5 ml of sticker spreader to each cup using a clean syringe. The same syringe can be used
    for distributing the sticker spreader to each chemical.

  • Stir each chemical with a disposable stir rod. Ensure that a clean stir rod is used for each cup.

Steps for creating test:

  • For each chemical mixture cup, make an additional dry cup labeled for that corresponding
    chemical, i.e., you will have the dipping cup and dry cup for each treatment.

  • Using the best, untreated leaf source, cut/rip a single piece of leaf that will fit in the cup.
    o Dip the piece of leaf into the chemical and shake off the excess liquid.
    o Place the dipped leaf into the corresponding labeled cup for testing.
    o Repeat this process for each chemical being tested.

  • To each test cup, add diamondback moth larvae (preferably 2nd to 3rd instar)
    o Use 5-15 larvae for each test depending on the amount of larvae available.
    o Try to use equal amounts and quality of larvae across cups (Ex: 10 larvae for all, etc.)

  • Place a lid on each test cup and place each test cup into a holding container (for example, a
    carryout 4-cup sturdy paper holder).

  • Spray out the chemical mixtures as per the label, triple rinse and dispose of cups and syringes.

  • Store the holding container with the test cups in a room temperature location for the 72 hours.

  • Check every cup at 24 hours, 48 hours, and 72 hours from the beginning of the test.

  • Record the findings for each check.
    o Determine the condition for each larvae in each test labeling them Live, Moribund/Down, Dead, or Pupae. If not moving when poked with a pencil, it is dead.

  • Rank the mortality to determine the chemical best suited for control at that site and date.

  • If you are saving larvae for DNA screening, place live larvae in a 7 ml vial with RNAlater™ (with
    location, date, treatment data) refrigerate and send in a cold pack envelope to Dr. Champagne,
    UGA Entomology, 413 Biological Sciences Building, Athens, GA 30602 Tel. 706-542-2279.

For questions, please contact the Georgia Cooperative Extension Service office nearest you.