While fruit flies and plant diversity have
co-evolved in the neotropics, new research shows geography and other factors
also play an important role in generating insect diversity. Photo courtesy
of Marty Condon, Cornell College.
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Fruit Fly Diversity Is in the Details
By Ann Perry
May 16, 2008 Many scientists attribute the diversity
of plant-feeding insects to plant diversity and to the many ways insects can
survive on host plants. An article published this week in Science explores how these
niches are used by one group of insectsand also examines evidence that
using niche diversity alone to estimate species diversity can result in an
undercount. The authors conclude that for this insect group, diversity is
greater than the sum of plant parts.
Molecular biologist
Sonja
Scheffer, in the Agricultural Research Service (ARS)
Systematic
Entomology Laboratory in Beltsville, Md., teamed up with three colleagues
to study the ecological links between tropical fruit flies in the
Blepharoneura genus and their host plants. The other researchers were
Marty Condon, a biology professor at Cornell College in Mount Vernon, Iowa;
ARS support scientist
Matthew
Lewis, and Susan Swenson, a biology professor at New Yorks
Ithaca College.
Blepharoneura fly larvae feed within the flowers or fruits of plants
in the cucumber family. For their study, the researchers collected and raised
2,857 different Blepharoneura specimens from 24 neotropical host plant
species. DNA analysis indicated there were at least 52 distinct species in the
collection.
The researchers found that only one of the fruit fly species they raised ate
two kinds of plant partsseeds and flowers. All the others ate only one or
the other, and many of the flower-eaters were so specialized that they ate only
male or only female flowers.
Most of the fly species were associated with only one host plant species. On
the other hand, many of the plants hosted a range of species. One plant species
supported at least 13 species of the fruit flies.
Location also played a role in the findings. Some of the fly species were
geographically widespread. But others could only be found within a limited
geographic range, even though the range of the host plant was much more
extensive.
The team concluded that host plant and niche diversity plays a significant
role in the extraordinary diversity of Blepharoneura flies. But
geographical factorsand the passage of timemay play an even greater
role.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.