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Prism trap surveys

Objectives:
To determine whether emerald ash borer (EAB) is present in a local area, or to delimit the range of EAB within a wider geographic area. This method will not determine whether a certain tree is infested with EAB.

Limitations and considerations:
When EAB populations are low, this trapping method may not detect the presence of EAB (i.e. a false negative). When budgeting, consider the cost of the trap & lure as well as trap installation and servicing costs.

Traps:
A prism trap made from corrugated plastic coated with adhesive and baited with a lure is used. Green prism traps are typically used in Canadian surveys; they are baited with a green leaf volatile lure (Z-3 hexenol) and are hung in the canopy of the ash tree. The traps attract feeding EAB adults and usually catch more male than female beetles. Purple prism traps are more often used in American surveys and are baited with a bark volatile (Manuka oil). To find trap suppliers, see resources.

prism trap Green prism trap being installed in ash tree canopy.
Helen Sereda, Silv-Econ Ltd.

Method:
Prism traps are suspended from a branch with either a plastic hanger, which can be attached to the tree branch with rope, or a metal spreader and hook system that allows the trap to be easily installed with an extendible painting pole with a hook attachment. Traps are hung in the mid-canopy on the south side of an edge tree or an open growing tree to maximize catch of EAB, which prefers warmer conditions. Large trees with sturdy branches that can support the weight of the trap are needed.

Trap maintenance:
Traps need to be serviced at least once during the EAB flight season. Suspected EAB specimens are removed from traps during servicing since some beetle may be lost from the traps over time. At the same time, trap maintenance can be performed – excessive debris may need to be removed, or additional adhesive added (aerosol Tangletrap works well for this). Traps sometimes fall from the tree especially in high winds so will need to be re-hung, or replaced if they are severely damaged. The trap can be secured with fishing line attached to the bottom of the trap and tied to the tree trunk if this is an ongoing problem. Lures are occasionally lost due to tampering by birds or small mammals.

Timing:
Traps should be deployed just before EAB adults are expected to emerge and can be removed at the end of the beetle's flight season. The optimum timing of trap deployment depends on weather and climate; beetles start to emerge after 250 degree days above 10°C (usually late May to mid June in southern Ontario) and trapping should continue until approximately August[39].

The CFIA's prism trapping protocol is available by contacting your area survey biologist.

Trap catch:
If you are outside of the regulated areas for EAB, submit your specimens of suspected EAB to the CFIA: 1-866-463-6017.


References


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