While other biologists are demonstrating new ecological models out on the showroom
floor, the entomologist tends to find himself perpetually doing the inventory in a back
room. There he is, happily hunched over his microscope, muttering cheerfully to himself,
"One thousand two hundred and forty-three species of beetles1, 1,244,
1,245, 1,246, ...." The apparently endless enumeration of species extends beyond
faunal lists to include ecological studies that one might think would be relatively
simple.
In 1997, for example, the Archbold Entomology Lab began a
survey of insect visitors on saw palmetto flowers. This produced 109 species of
flies, 91 bees and wasps, 43 beetles, 20 moths and butterflies, and 31 miscellaneous
insects, for a total of 294 species. These occur at various levels of abundance in various
places on the Station, and at different times of day. Fortunately, the student intern
working on this project, Kim Keyser (Wake Forest Univ.) was able to stay awake
through the night to catch moths, crickets, roaches, and beetles that are not active by
day. Most of the palmetto flower insects are just stopping by to fuel, like commuters at a
doughnut shop on the way to work. Males of many bees, wasps, and flies, however, hang
around the flowers after feeding, watching for potential mates. Their advances disrupt the
feeding of females, often driving them to an inflorescence on another palmetto plant.
Hassling by cruising males may be an important facilitator of cross-pollination in saw
palmetto. Almost all the insects feeding at palmetto flowers have other ecological roles
as predators or herbivores, or pollinators of other plant species. The burst of spring
flowering in saw palmettos supports hundreds of other ecological relationships. In some
years this whole system is severely perturbed by masses of exotic honey bees or love bugs,
which charge through the pollinator community like a Mongol horde sacking Byzantium. How
does the insect ecologist deal with all this diversity, complexity, and variability?
Apparently learning no prudence from this bewildering
experience with saw palmetto, in 1998 the denizens of the Entomology Lab began a project
on the insect visitors of gallberry (Ilex glabra). Karl Krombein (Archbold
Research Associate) and Beth Norden were instigators in this study. So far, only 72
species have been found on gallberry flowers, but even this is a large number of species
to study simultaneously. A special feature of gallberry is that it is both highly clonal
and dioecious. This means that bees which are gathering pollen probably have little effect
on pollination, as they do not visit the female plants. Nectar feeders, such as hover
flies, visit both male and female plants. The smaller species of nectar feeders, however,
may do most of their foraging within a single clone. All this should be quantified by
following flower visitors, but there are so many visitors buzzing about so quickly amid
the tangle of shrubs that it is difficult to get any useful data. Gallberry shares many of
its flower visitors with saw palmetto, so the two systems are linked in some obscure way.
Parasitic Wasps. Intensive, specialized studies, such
as those of flower visitors, usually reveal some species of insects not previously
recorded from the Station. Even these intensive studies, however, pale in the production
of novelties compared with a new technique of general collecting. In 1998 the Canadian
hymenopterist Lubomir Masner came swooping down from his aerie in the Canadian
National Collection, armed with a new collecting method, the "yellow bowl
system." This uses small, plastic, yellow dessert dishes that are set out and filled
with water and a few drops of detergent. For some unknown reason, many tiny insects throw
themselves into these bowls. Insects that feed on yellow flowers are not particularly
attracted. Insects that breed in water almost never fall into these bowls. Among the
commonest insects in the bowls are small parasitic wasps. If one puts out 50 of these
bowls in a small area, after a day or so one can strain out a total of a tablespoon of
granular sludge. Under the microscope this proves to be thousands of specimens of
minuscule flies and wasps. Many of these are specimens of insects unknown from the
Station. In any such harvest there are usually several species unknown to science. There
is little in common in the species composition from different habitats, such as the
disturbed hammock around the main buildings, the scrub up on Red Hill, and the shore on
the west side of Lake Annie. Masner is especially interested in parasitic wasps of the
family Scelionidae, which live in the eggs of other insects. Since each wasp completes its
development in a single egg of its host, they are very small. A few species were known
from the Station before the advent of Dr. Masner; the actual number could be in the
hundreds, based on our impression of the shape of the species accumulation curves and the
disconcerting faunal changes from one habitat to another. Most of the genera of these egg
parasites are specialized, so there is a genus in cricket eggs, another in the eggs of
spiders, another in the eggs of web spinners (Embioptera), and so on.
On global, state, and local scales, the biological diversity
of the world is in decline. Every day there are fewer species on earth than in all of the
history of mankind, and every day there are more species than there ever will be again,
even should human culture persist for a million years. Here at the Archbold Biological
Station, however, we enjoy a glorious illusion: the recorded biological diversity of small
animals seems to be expanding explosively before our eyes.
The years 199798 in the Entomology Lab were not
completely filled with huge, open-ended projects. About a dozen or more modest studies
actually got completed, written, and published during this time. These deal with
pollination ecology; a new species of grasshopper and of a fly; the ant fauna of the
Bahama Islands; and the adaptations of a beetle that feeds on millipedes. There were
ongoing projects on species of spiders, bees, pygmy mole crickets, and ants. The Ants
of Florida project produced descriptions of several new species, accumulated new
distribution data, and unraveled some taxonomic problems.
1
The current number of beetle species known from
Archbold Biological Station.
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Phone: 863-465-2571, FAX: 863-699-1927, Email: archbold@archbold-station.org