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General
Practices |
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Place a six-week-old potted cabbage plant
inside a nylon net cage (50 cm x 50 cm x 40 cm) with a wooden
board floor. Place the disinfected oviposition foil (bearing
about 800 eggs) on the cabbage plant and allow larvae to emerge
and feed on the cabbage leaves until they are in the 2nd or 3rd
instar. Second instars are about 3 mm long and 3rd instars are
about 5.5 mm long. These larvae are ready to be used to rear
any one of the three larval parasites. |
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Place about 200 pupae of Diadegma or
Cotesia or Microplitis in a cage and allow the
parasite adults to emerge. Hang a plastic sheet smeared with
10% honey solution in the cage. Spray the honey solution on the
plastic sheet daily. Better yet, in addition to the spray, pour
about 40 to 50 ml of honey solution into a petri dish containing
absorbent cotton. Change this food source once every two days.
Hang a black cloth curtain inside the cage to cover the door
opening. This will minimize escape of parasite adults during
opening and closing of the cage. |
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Parasite adults emerging from pupae feed on
the honey solution in the petri dish or on the plastic sheet.
From this stage onwards, all operations should be done at the
following temperatures for each species: Diadegma, 20
to 22 °C; Cotesia, 26 to 28 °C; Microplitis,
24 to 26 °C. |
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Place a potted cabbage plant containing about
800 2nd instar DBM larvae inside the parasite adult cage. Cover
the exposed soil in the pot with aluminum foil. On the cage floor
surrounding the clay pot, place a single layer of fresh cabbage
leaves to trap DBM larvae descending from the plant when parasites
try to oviposit. Let the parasites oviposit in the DBM larvae
for 24 hours. |
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Remove the cabbage plant with parasitized
larvae from the cage and carefully strip all leaves, making sure
larvae do not fall off. Place two to three of these leaves containing
about 150 leaves on a fresh 6-week-old potted cabbage plant placed
in a similar but parasite-free cage. At this time transfer all
DBM larvae fallen on the leaves placed on the floor of the previous
cage on to the fresh cabbage plant. When food supply from the
old excised leaves is exhausted, larvae will migrate readily
to the fresh leaves of the new plant. The biomass of the 6-week-old
plant provides enough food for larvae until pupation in 15 days. |
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Collect pupae carefully and store them
at 8 to 10 °C until use. Pupae can be stored at this temperature
for 15 to 30 days without significant loss of viability.
Now that we know how to rear them, let's
carefully examine the characteristics of the pupae and adults
of Diadegma, Cotesia and Microplitis. |
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