Switzerland banned Chlorpyrifos
Generally there are two parts to pesticide regulations in Europe - those relating to the approval or otherwise of a given compound in terms of whether it is permitted to be used within the jurisdiction of the body that makes the regulations, and those relating to what residue levels can be present on the crop as sold.
In the case of importing, it is the latter that is applicable. To an extent it is almost irrelevant what has been sprayed on the produce (subject to complying with the applicable regulations for use in wherever it is that the crop was grown), as long as the residual levels comply with the maximum residue limits for the country into which the material is being imported.
I'm not that familiar with Swiss regulations, but this does seem to suggest that the residue limits are largely derived from those set by the EU, which makes life a bit easier.
I don't know if you are fluent in German/French/Italian (there doesn't appear to be an English version), but I think this is probably the first place you need to look: https://www.admin.ch...3405/index.html
N.B. The EU is in the process of banning chlorpyrifos, having withdrawn the authorisations for it and for chlorpyrifos-methyl. This in itself doesn't have any impact on the maximum residue limits, which are part of a separate set of regulations, but unsurprisingly it looks like the EU Commission will lower these to the minimum level of 0.01mg/kg (as close as the EU gets to saying 0mg/kg) next year, so it is possible that this will also affect Switzerland. Personally I'd therefore start planning on the basis that it probably won't be permissible in the very near future ;)