"Gareth" wrote
I have 12 chilli plants in a greenhouse and a number of the plants have
been affected by ants - 1 in particular has clearly been damaged and isn't
bearing much if any fruit as a result of mechanical damage to the roots
caused by the ants.

I'm unclear as to why the ants are attracted to the plants but they are
and I guess that it's due to the nectar.

Does anyone have a suggestion of what insecticide I could use on the
plants to kill the ants? I really don't want to use insecticide and I
don't use it anywhere else in the garden or on other plants but I don't
think I have a choice.

Alternatively would an ant bait placed close to the plants do the trick?

I'm not going to have a surviving chilli plant left at the fast rate the
ants are destroying the plants - any help would be appreciated.

For those that may think ants can't damage roots.....
I came back from holiday and found some sick looking plants in our
greenhouse which turned out to be because black ants had made them into an
extended nest. They had removed some soil from the pots to make walkways
between the pots, even up the staging to the next level, and the soil in
the pots was riddled with holes and passageways full of ants and their eggs
etc. I got the impression that somehow they had made the soil in these pots
less able to soak up water but it may just be an illusion, the soil was
certainly a lot dryer than I expected.
I gathered them all up and repotted them putting the soil/ants nest in a
plastic sack which I took down to my allotment and tipped out in a pile in
some long grass. I washed out the pots and replanted the plants in fresh
compost.

To get rid of your ants use "Nippon", it has to be fresh and it's always
worked for me. Just follow the instructions.
Your plants will probably need repotting afterwards.
--
Regards
Bob
In Runnymede, 17 miles West of London