After decades of using long lasting, evolving and potent pesticides, farmers in various parts of highly pesticided parts of the world are wondering why their bee populations are being decimated. Connect the dot. Bees are needed to pollinate their crops of grasses, fruits and even vegetables and herbs. Long term use of pesticides is the most likely culprit.
Unfortunately, pesticides built for potency and a long active life are hard to break down and build up in the soil, biomass, water and general ecology. After many repeated uses, the build up devastates ALL insects (and other animals, including the ones that eat insects), including the useful ones. Mycelium, the great recycler of carbon based life, will not go near it in high doses. An extremophilic mycelium might, but farmers and scientist will have to find one. The pesticides do not just evaporate come the next spring. It's still there.
Possible solutions include the extremophilic mycelium previously mentioned. There is also the use of unprocessed natural insect repulsing oils (diluted), such as pine, cedar, citronella or lavender.
Seaweed (diluted in liquid, or washed and added to mulch) is excellent for breaking down complex chemicals. So is fermented soy, as in miso (but the salt is not recommended for soil, obviously), so experimenting with soy or soy bi-products could prove beneficial. Vitamin B3 is also good for removing or breaking down pesticides specifically, so adding it somehow into the ecosystem (through mycelium or maybe feeding it in higher doses [but not too high as it can be damaging] to livestock and then applying the manure and urine to the soil and mycelium).
Spiders eat insects and so do certain types of birds. So do preying mantis. If you introduced spiders and insect eating birds in you crop, that would reduce insect populations quite effectively. The conditions would have to be suitable for their nest and web building, such as trees, wood, and other places for them to reside and hunt.
Another way to deal with the problem, once the current pesticides have been reduced to a workable level, is companion planting. If you plant rosemary, cedars, marigolds etc in a harvestable manner around and within your annual or perennial crops, and use basic rotation for the brief types (usually used already), unwanted insects will be reduced.
A change of attitude, also a good thing in cropping, would help. The need to have 100% perfect crop output is maybe a bit self-defeating. It may be OK to have a few bug infested fruits losing maybe 2% of your crop (for the hens and pigs and wildlife) in the short term as opposed to decimating your future crops by rendering them infertile.
The ancient Israelites used to leave 10% of their crops each year for the poor and the wildlife. There was more then charity as the pious motive. If the poor could eat, they did not have to rob and murder to survive. If the wildlife could eat, they did not have to steal and hunt livestock and people to eat. If the actual earth had enough biomass returning back to the ground, it would be more abundant in the coming year and the long run.
Well, there is a bunch of ideas for possible solutions to a very modern problem. The implementing of the ideas might get some resistance from the chemical companies, however, a smart farmer would be able to see through that. We haven't "always" used chemical cocktails to solve age old farming problems. It probably wasn't even used by your grandparents. Planting insect resistant plants (some are even cash crops in themselves) amongst your insect attracting crops or releasing insect eating birds and insects into the fold is a much cheaper, less dangerous and better (long term) planned way to deal with the problem. And no one will be dying of cancer from working in the factories that make the toxic substances that have been killing your wonderful bees (and probably you and the town downriver).