Vanishing Act

Unlike some of those indoor folk who want to spray high and low for “bugs”, fruit tree growers have an appreciation of the insect life around us. We know that pollinators are essential to the production of many fruits, and that predator insects and spiders are our allies in the control of pest insects. But like everything else in the biosphere, insects and other invertebrates are feeling the effects of us humans. And it's not pretty.

Yale University's environment360 is not a gloom-and-doom publication, but in a recent article there,  Vanishing Act: Why Insects Are Declining and Why It Matters, journalist Christian Schwägerl reports on the astounding decline of invertebrate populations around the world. Of course bee populations have been getting most all of the press coverage, but the decline is massive and widespread. A few examples:

--- Since 1989, the average biomass of insects caught in field traps set by researchers in Germany has declined from 1.6 kilograms to just 300 grams.

--- German scientists have also observed a decline in butterfly and Burnet moth species from 117 in 1840 to 71 in 2013, in a Bavarian nature reserve.

--- Stanford researchers have calculated a 45 percent decline--- yes, almost half--- in global invertebrate populations in just the past 40 years.

Can anyone out there not guess the causes?

--- Pesticide use. Yes, pesticides work. They kill insects. Lots and lots of them.

--- Monocultures. Agricultural monocultures are “biological deserts”, supporting far less invertebrate life.

--- Habitat loss. Urban development, wetland destruction, deforestation, pollution, and other damage and loss of wild terrain simply leave a lot fewer places for invertebrates to live.

The first rule of ecology is that everything is connected to everything else. The decline in insect populations produces a corresponding decline in species that feed on insects, notably many bird species, bats, and amphibians. And in the species that feed on these, and so on. And disrupts plant populations, and the species that feed on plants. And on and on.

Polar bears, otters, and other “charismatic” species make good press to call attention to our impact on our fellow creatures, but those uncuddly six and eight-legged ones may be more important. Scientists are ramping up efforts to monitor populations and to find ways to slow the decline, but no one knows where all this is heading, or where it ends up. Let's hope it's not a world without butterflies.