Read the passage below and label the tunnels on the diagram .
Introducing dung beetles into a pasture is a simple process:
approximately 1,500 beetles are released, a handful at a time, into fresh cow
pats in the cow pasture. The beetles immediately
disappear beneath the pats digging and tunnelling and, if they successfully adapt
to their new environment, soon become a permanent, self-sustaining part of the local
ecology. In time they multiply and
within three or four years the benefits to the pasture are obvious.
Dung beetles work from the inside of the pat so they are sheltered
from predators such as birds and foxes.
Most species burrow into the soil and bury dung in tunnels directly
underneath the pats, which are hollowed out from within. Some large species originating from France
excavate tunnels to a depth of approximately 30 cm below the dung pat. These beetles make sausage-shaped brood
chambers along the tunnels. The
shallowest tunnels belong to a much smaller Spanish species that buries dung in
chambers that hang like fruit from the branches of a pear tree. South African
beetles dig narrow tunnels of approximately 20 cm below the surface of the
pat. Some surface-dwelling beetles, including
a South African species, cut perfectly-shaped balls from the pat, which are rolled
away and attached to the bases of plants.
For maximum dung burial in spring, summer and autumn, farmers
require a variety of species with overlapping periods of activity. In the cooler environments of the state of Victoria,
the large French species (2.5 cms long), is matched with smaller (half this
size), temperate-climate Spanish species.
The former are slow to recover from the winter cold and produce only one
or two generations of offspring from late spring until autumn. The latter, which multiply rapidly in early
spring, produce two to five generations annually. The South African ball-rolling species, being
a sub-tropical beetle, prefers the climate of northern and coastal New South
Wales where it commonly works with the South African tunneling species. In warmer
climates, many species are active for longer periods of the year.
No comments:
Post a Comment