Easy. Wiping the key groups, like top predators or pollinators

In any case, destroying is not the right verb here, "changing" the ecosystem would be a better fit. Often for worse.

> There is no evidence of neonics disrupting food webs

There's plenty of evidence. This article is just one more. No wild bees and other pollinators -> no apples, plums, peaches, pears, onions, lattice, pumpkins, carrots, peas, peanuts, caffe, honey... I think that this qualifies as a case of "food web in trouble".

> Most of the food crops we depend on both directly and indirectly are grasses and are wind pollinated (corn, wheat, etc.)

Yes human diet is mostly based in cereals. The problem is that a lot of areas in N of Europe, Russia USA or South America aren't suitable to temperate or tropical cereals like corn or rice, because weather. Thus they need either spend gas for bringing cereals to the population, or rely on potatoes, apples, cabbages and other crops that stand frost and short summers. The 'big' cereals can be also difficult in desertic or high mountain areas, because they need a lot of water and soil is too poor. Legumes and other desertic crops (fruit tree cacti for example) are awesome in this cases. If you use all the water in culturing lattice, the wild organisms suffer obviously.