A main reason I’m uncertain about the sign of crop cultivation is that I don’t know if it reduces total invertebrate populations. Especially when irrigation and fertilization are used, crop net primary productivity can be somewhat higher than that of native grassland, although I also get the impression that farm fields can also be less rich in soil fauna than native ecosystems (maybe partly due to pesticides?).
so pest control might have almost no effect on population size
I assume that insecticides are usually pretty effective at reducing populations of target (and probably at least some non-target) insect species.
OTOH, crops fields can sometimes breed much larger insect infestations than would occur in a wild ecosystem. Berryman (2008): “growing extensive monocultures of a particular plant genotype may provide a huge amount of highly susceptible food for insects that feed on that crop, and/or may create an environment that is less hospitable for some of the natural predators and parasites that attack them.” That said, I feel like wild plants can also have big insect infestations. I’ve seen hundreds of aphids on a single wild plant near my house.
A main reason I’m uncertain about the sign of crop cultivation is that I don’t know if it reduces total invertebrate populations. Especially when irrigation and fertilization are used, crop net primary productivity can be somewhat higher than that of native grassland, although I also get the impression that farm fields can also be less rich in soil fauna than native ecosystems (maybe partly due to pesticides?).
I assume that insecticides are usually pretty effective at reducing populations of target (and probably at least some non-target) insect species.
OTOH, crops fields can sometimes breed much larger insect infestations than would occur in a wild ecosystem. Berryman (2008): “growing extensive monocultures of a particular plant genotype may provide a huge amount of highly susceptible food for insects that feed on that crop, and/or may create an environment that is less hospitable for some of the natural predators and parasites that attack them.” That said, I feel like wild plants can also have big insect infestations. I’ve seen hundreds of aphids on a single wild plant near my house.