A pheromone trap for pea crab biocontrol

Scientists at Leigh Marine Laboratory, including Oliver Trottier, are investigating biocontrol approaches that could limit pea crab infestation on green-lipped mussel farms. In this video, Oliver describes how one biocontrol approach – a pheromone trap – might stop male pea crabs from finding females that are ready to mate. He also describes some of the advantages to using biocontrol, rather than other control methods, to limit pea crab numbers.

Focus question: What are the advantages of biocontrol of pea crabs over other control methods?

Teaching point: Students could design a pheromone trap for trapping male pea crabs on mussel farms. Some points to consider:

• Where on the farm could the trap be placed?

• How could crabs be prevented from leaving the trap?

• How could the pheromone be released?

• How could any distress to the male crabs be minimised?

Transcript

Oliver Trottier (Leigh Marine Laboratory)

I know the population is 90% female and 10% male, so anything I can do to make life even harder for the male pea crabs could have a beneficial effect on reducing pea crab infection levels, and the idea of a pheromone trap is to take the pheromone that the female is producing or recreate it synthetically, set up a trap on the farm that would release this chemical cue to say we’re ready, and the males would crawl into that trap and be disposed of or die or be stuck there.

What’s really attractive about biocontrol is, if you think of some parasites within aquaculture, is you’ll treat them with really harsh chemicals. They can be bathed in them, they can be dipped in them – it happens in salmon, for instance – and these chemicals are just released into the environment after it’s sort of done in the wild.

But a pheromone trap would be specific for pea crabs. It would only affect that particular species hopefully. I mean that is something you need to of course determine, but it’s very likely that a pheromone trap would only affect pea crabs.

Acknowledgements: Oliver Trottier – Leigh Marine Laboratory, Auckland University.