Environmental Services: Missing the Water
The term “environmental services” — if you’ve ever heard it at all — can seem so large an effect as to be incomprehensible: the cooling of the air by forests; the carbon-holding ability of the same; the mosquito-eating zika virus control that birds provide.
This year, I think I might be missing a more local environmental service I had become used to and taken for granted. We miss the water only when the well runs dry.
And it might just be me — only my gardener’s experience in this one place in the world, and nothing to worry about at all. But then again, there are so many smoking guns out there that I wonder if my personal observation might be a real sign of environmental failure, up close and personal.
Here’s my concern. This is the first time in almost 50 years since my first attempt at growing tomatoes that tomato hornworms threaten my plants unopposed by the former biological controls that nature has always provided.
The environmental service I speak of is the predation of tomato hornworm caterpillars by braconid wasps. Never in decades of gardening have I found a single tomato hornworm that was not covered in the white rice-like pupa cases of the tiny wasps that use caterpillar flesh as food for their eggs. This year so far I have found nine unblemished freely-feeding caterpillars and no wasp activity apparent.
These are very tiny wasps in a group that contains some 17 thousand named and many more unnamed species. You are not likely notice them, and so their presence or absence for most of us is only evident when we don’t observe their usual services on behalf of our tomatoes. And this year, I’m missing the water.
Since Floyd County, Virginia, is not a place where there is heavy use of herbicides and pesticides (especially in this remote corner where we live), if the wasps are truly reduced in numbers or diversity of species, it would most likely be the result of some larger-scale perturbation — like climate chaos causing subtle breakdown in the former “normal” but very specific life requirements for braconid wasps.
Subtle breakdown. Subtle to human senses, at least. It is happening below the radar across forests, coral reefs, prairies and tundra. Lost biodiversity is invisible until it becomes apparent in some realm of human enterprise — like our backyard garden or the larger food web or on the grocery store shelves. And by then, the subtle disturbance has passed a tipping point and we can’t put the toothpaste back in the tube.
More on this subject perhaps another time.
