David Hill wrote:

"............ I also understand perfectly well why some farmers do apply
expensive poisons - which are often more toxic than those available to the
general public. The molluscides are applied to increase yield and profit.
These molluscides are at least implicated, directly or indirectly, in the
decline of various bird species. ........"

No....The reason is that the "Public" wont buy veg with ant sign of Damage,
let alone with the possibility of finding a slug or caterpillar in their
lettuce, it would be straight back to the supermarket with it and probably a
complaint to environmental health.
If the public would accept these things then the use of insecticides etc
would be reduced drastically.

Not to say our desire for cheap food.

I never cease to be amazed watching people in supermarkets carefully
picking over fruit and veg, looking for blemishes but never smelling
what they're buying. Although, since it has often just come out of cold
store, any smell can be difficult to detect.
--
Larry Stoter