Manitoba Agriculture, Food and Rural Initiatives
Trap Assembly and Monitoring Protocol for Diamondback Moth
Purpose of Monitoring Program
Diamondback moths can be serious pests of canola and cruciferous vegetables in Manitoba. It is the larval stage that is damaging to the plants, however the adult stage appears in Manitoba before the larvae are present. This provides an opportunity to assess in advance the risk of a potential outbreak.
The pheromones used by female diamondback moths to attract male moths are known and are synthesized for use in monitoring programs. These synthetic pheromone lures are very effective at attracting male moths to traps, which have been designed to capture the moths. This monitoring program, combined with other relevant data, provides a relatively simple and effective method of predicting outbreaks of the damaging larval stage of diamondback moth.
The purpose of this monitoring program is to determine the regional risk of an outbreak in advance of the appearance of the damaging (larval) stage. This gives farmers, farm production advisors, agronomists, chemical dealers, and others involved in pest management some advanced warning of a potential outbreak, and enables them to place proper emphasis on monitoring for the larvae. It also provides time for agriculture retailers to have the appropriate insecticides in place.
At no time should a decision to use insecticides to control diamondback moth be made based only on information from the traps for adults of this insect. Such decisions need to be made after later sampling for the damaging (larval) stages of diamondback moth and determining if the levels of larvae present in the field are above the economic threshold. Weather can affect the success of mating and laying eggs, and many mortality factors could reduce the numbers of eggs and larvae before they develop to the damaging stage.
When to Monitor
Diamondback moth do not overwinter in the Canadian prairies in significant numbers, but high populations may be blown in on winds from the south. They are at a higher risk of being a problem in years when high populations blow in and establish early (May or early June). Thus the primary goal of this monitoring program is to determine when diamondback moth populations arrive, and in what number. This, combined with considering what the environmental conditions are like when they arrive, will determine the risk of them being a significant problem.
Diamondback moth traps should be placed in fields during the first week in May, or as close to this date as possible, and first moth counts should be made the following week.
Traps for diamondback moth can be placed in fields regardless of whether canola has, or
will be, seeded into the field. Having traps near fields that are or will be seeded to
canola is ideal, but it is more important to place the traps at the proper time than
to wait and see where canola is seeded.
Assembling the Traps
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Figure 1 |
Figure 2 |
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Figure 3 |
Figure 4 |
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Insert the wires through the holes in the top of the trap as in Figure 2. Bend the wires to secure them to the trap.
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Insert the T-shaped plastic attachment on the lure (rubber stopper containing pheromone) through the middle hole in the top of the trap (Figure 3). The rubber stopper containing the pheromone should hang from the top of the trap. Remember not to touch the pheromone with your hands.
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Unfold the sticky insert and place in the bottom of the trap (Figure 4).
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Press in the front and back flaps until they clip into the slits in the sides of the trap (Figure 5). This will secure the sticky bottom in place.
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Figure 5 |
Figure 6 |
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T bars can be inserted into hollow metal poles, which are hammered into to ground, so there is a horizontal surface to hang the traps from.
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The wire that extends from the top of the diamondback moth trap can be wrapped around one of the horizontal ends of the T-shaped bar to secure the trap in place (Figure 6).
Tips for Setting Up the Traps
If more than one trap is being placed in a field, leave at
least 100 meters between traps. Do not handle the lures
with your bare hands. Please wear rubber or latex gloves
if handling the lures.
Replacing the Pheromone
Pheromone lures for the diamondback moth
traps should be replaced after three weeks of use. Please
remember to not handle lures being placed in the
traps with
your bare hands.
Checking the Traps
Traps should be checked and the number of diamondback moths counted once a week over a six-week period. If a late influx of diamondback moths appear, the diamondback moth traps may be left out for a period longer than six weeks.
If there are only a few moths on the insert of the diamondback moth traps when they are checked, these moths can be removed from the sticky surface with tweezers and the insert reused. If the insert is heavily covered with insects, it should be replaced with a new insert.
For further information on monitoring diamondback moth please contact:
John
Gavloski
Extension Entomologist
Manitoba Agriculture, Food
and Rural Initiatives
Crops Knowledge Centre
Box 1149
Carman, Manitoba R0G OJO
Phone: 204-745-5668
Links
For further information, contact your GO representative.
