Beneficial Insect Species
In recent years, agricultural economists have put estimates on the values of some local insect services to human society. In one 2009 example, the total economic value of insect pollination of agricultural crops worldwide was $220 billion. A sizeable fraction of this pollination occurs in Australia by species such as the European honeybee, and many thousands of native bees and flies.
During the mid nineties, honeybees died in large numbers in Europe and the United States, a phenomenon known as colony collapse disorder (CCD). The cause of CCD is complex and not yet fully understood. But the effects were transparent. Profits from pollinated crops, such as almonds decreased. The prices of some foods increased significantly, because farmers had to pay more for disease-free bees, often importing them from CCD-free Australia.
Another good example is the service that introduced dung beetles provide. Australia’s cattle herd was estimated at 30 million in the 1970s, each animal producing 10 pats per day, covering over 2.5 million hectares of pasture each year.
Millions of bush flies (Musca vetustissima) also bred in the dung. Overseas these dung pats would have been recycled into soil nutrients by the local dung beetles that buried small chunks of the dung in the soil to rear their young. However, Australia’s native dung beetles are adapted to feed on and bury dry, fibrous marsupial dung, and avoid the much more moist cattle dung.
CSIRO introduced dung beetles from Europe and Africa in the 1970s and 1980s that buried cattle dung underground so that it became a fertilizer for use by grass and other plants. The burrowing activity of the beetles also aerated the soil. And it also provided another important service: controlling the bush fly plague by removing and burying the dung that bush flies were breeding in.
Australia’s outdoor café owners probably don’t know it, but they owe at least part of their clientele to the silent work of introduced dung beetles working tirelessly in the agricultural districts surrounding our cities, once the source of most of our bush flies.