Funasshi wrote:I am ashamed to admit that I have next to no knowledge about the mysterious and wonderful world of insects.
Well with summer just around the corner you are soon going to have plenty of opportunities to become accustomed to those insects in all their wonder and glory
, although it might not seem like that when they are busy munching your prized veggies. Just think of it all as a valuable learning experience
Funasshi wrote:Again, I often think about if promoting insects of this sort in one's farm will naturally eliminate the need of pesticide, or if still some additional bio-pesticide is needed on top of that. I have almost no hands-on experience yet, so I was wondering how well the friendly insects work in reality.
I'm not sure if there is any gentle way to put this but predators will generally be vastly outnumbered by pests/prey, think lions to wilderbeast or some other predator/prey ratio. We've rarely found on our land that natural predators keep pests under control naturally, they do have an effect but quantifying that is not easy and some crops can be devastated. Take the humble Nekirimushi mentioned above as an example, we plant 30 - 40 thousand carrots twice a year and several times that amount of baby leaf salad. Patrolling that every day scouting for Nekirimushi would take a sizeable chunk out of your morning during which time other jobs wouldn't get done. So introducing predator nematodes in very large numbers becomes economically viable and a real time saver. The same would be true for other predatory insects, by flooding the environment with very large numbers of predators, over and above what would naturally be found completely upsets the natural balance between predator and prey and gives you the opportunity to eradicate a pest species for a short while.
Or you could use a biopesticide to reduce the pest numbers down to a level where the natural predators can then keep it under control.
Funasshi wrote:Ah, that's good to know. So there is some focus on what insects are targeted.
Yes and no, whilst something like bacillus thuringiensis is fairly specific in what it affects beauveria bassiana (Botanigard) on the other hand is fairly unspecific and will infect any insect that spray droplets land on. When using beauveria bassiana you have to be really careful not to spray beneficial insects and bees as they will get infected, so spray only in the early evening when bees are not active and always keep an eye out for praying mantis, ladybirds or other beneficials. To give you an example, right now we generally spray beauveria bassiana between rows of crops to try an kill as many young grasshoppers as we can but don't spray the crops themselves with Botanigard, that way we get many grasshoppers but don't risk hitting the praying mantis lurking amongst the crops. By reducing the numbers of young grasshoppers now we let the resident mantises control their numbers later on in the year.
When using biopesticides you have to understand how they work and their mode of action so that you can limit collateral damage to insects you want to preserve whilst at the same time getting the best results from your efforts. If one were to spray willy nilly you could cause just as much damage as using conventional pesticides. Even something as benign as neem oil can still smother very small ladybird larvae or other small beneficial insects so a thorough understanding is essential IMHO.
This is a sweeping genralisation here but flooding the environment with vast numbers of predator species is possibly more specific than using a biopesticide and apart from nematodes generally works best in a closed environment like a vinyl house.
That really is only just touching on the topic in a very brief way but nevertheless I hope it helps. Perhaps you can drop by again sometime and I can show you some of our practices.