Ignorance about insects is not bliss

Insects

 

The staggering amount of what we don’t know about nature was brought home to me recently during a visit to the National Collection of Insects in Ottawa.

The collection has 15 million specimens, two thirds of which are insects from North America. Most are variations of individual species. It’s estimated that Canada has about 67,000 species. However, only about 35,000 have been identified, and for almost all of them, « We simply don’t know what their role is in the ecology,’’ according to Robert Foottit, research scientist in insect biosystematics at the National Collection.

Those whose roles are understood « number in the hundreds, not the thousands,’’ he says.

The collection is housed in the Eastern Cereal and Oilseed Research Centre at the federal government’s Eastern Experimental Farm in Ottawa.

« Some insects we’ve studied for years, and we still don’t know what they do — where they fit in,’’ Foottit says.

An example, he says, is the six-millimetre-long tarnished plant bug — lygus lineolaris — which has been studied for decades. It’s a pest that attacks seed alfalfa, cotton, mustard, vegetables, and fruit. Its marginally shorter cousin, the western tarnished plant bug — lygus hesperus — is a major threat to canola in Western Canada.

« We know what the bugs are doing now in agriculture. But we’ve changed their habitat.’’ What used to be their function in the ecology, and where do they now fit? He answers his own question: « We simply don’t know.’’

There are 50 species of lygus insects in North America. Only three are economic pests. But will the rest become pests as habitats change? Again, says Foottit, we don’t know.

Lygus insects feed on a wide variety of weeds, including shepherd’s-purse, ragweed, pigweed, Russian thistle, hoary cress, flixweed, tumble mustard, lamb’s quarters, horseweed, wild carrot, perennial pepperweed, and voluntary alfalfa.

Because they have such a widespread feeding ability, they can be quick to adapt to change — and that’s what happened in the west. When vast tracts of land were planted in canola, the western tarnished plant bug, which previously was not a pest, quickly multiplied to take advantage of the new food supply.

Since the two tarnished plant bugs are such severe pests, they have been studied extensively in both the United States and Canada. But many questions remain, says Foottit. For instance, most insects have a very narrow range of plants on which they can feed. Did tarnished and western tarnished plant bugs always feed so widely? Or did they adapt? And if so, why? And what are the limits of temperature and humidity within which they can survive?

In addition, they’re continuing to evolve. And, some are developing resistance to pesticides. « But,’’ asks Foottit, « are they evolving because of agriculture. Or are they changing and adapting for other reasons?’’

As I wandered through rooms filled with what looked like oversized, steel gym lockers, each containing twenty and more trays, with each tray holding dozens of insects delicately mounted on pins, the magnitude of ignorance that Foottit was describing began to sink in.

In the world of insects, what we don’t know is far greater than what we do know. And even when we do have knowledge, it’s in bits and pieces — patchworks that leave us guessing at how they all fit together.

« What bothers me most,’’ says Foottit, « is we know we’re losing species, but we don’t know what it means.’’ Once again, the main reason for extinction is habitat loss.

It was another reminder that the federal Liberals, over seven years in office, have failed to enact endangered species legislation. The bill introduced by Environment minister David Anderson died with the calling of the election — which is a good thing, so weak was the bill.

When a new government is formed, maybe it will turn for inspiration to the model endangered species bill drafted by the Standing Committee on Environment and Sustainable Development chaired by Charles Caccia. I hope so. It’s focus is precisely on preserving habitat to prevent extinctions.

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