[Nightedge]

Is it correct to use 'on'?

-The task that the scientists, who are from MIT, gave him calls __ both French and German when he wants to address that problem.

My difficulty: 'on' sounds all right to me, but the example sentences from the OALD are not similar to the sentence above, so it's impossible for me as a non-native to decide.

[susan53]

"calls for" would be more usual as it means "needs/requires"
"calls on" means "uses" so it's possible in the context, but I suspect it was "calls for" that was intended. Some examples :

1) needs/requires
Achievement of goals calls for knowledge of the conditions of action and the ability to modify them in use.
This calls for expertise in the fields of data acquisition, risk analysis, geotechnics and hydraulics.

2) used
For these disasters, Polynesians called on their knowledge of famine foods, ...
The panel called on their expertise to help them understand the issues, ...

[Nightedge]

Excellent answer. Thank you.