NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/sci/space/18695

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Subject: Insects in Biosphere 2
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Date: 4 Jan 93 22:29:07 GMT
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There have been some questions regarding insects in the Biosphere
which I can say something about.

When first looking at the insects that would be needed for Biosphere 2
we looked at them by function, what do they do in Biosphere 1 and what
do we need the insects to do in Biosphere 2.  This can be broken down
simply as follows: Pollinators, detritivores, herbivores, insects as food for
other animals and beneficial insects used in  Integrated Pest
Management (IPM). We have not included predatory insects among our main
insect lists, excepting those used for IPM as we have many other insect
predators in the form of lizards, frogs etc. and we needed the insect
populations to establish themselves before we started putting heavy
predatory stress on them.  However, some scorpions and many spiders
volunteered their presences in the Biosphere as have dragon and damsel
flies.

For the pollinators we wanted to use mainly bees that are generalists, that
would visit many different types of flowers.  We did not want them as
energy intensive as the honey bee which makes large colonies which
would probably not make it in the Biosphere in the start-up years of the
the Biomes.  Unfortunately the pollinators have not done well and we will
be doing a lot more work on establishing colonies of solitary bees, such as
the Carpenter bee which is a local insect, and colinizing bees, such as
bumble bees.

The detritivores have done very well for the most part.  The ants,
millipedes, cockroaches and sow bugs have all done extremely well and
we will most likely be looking for a good cockroach predator.  We will be
doing a detailed survey of all the insects at the end of this 2 year
experiment at which point we will be able to determine how well the
aquatic detritivores have done.

We have tried to eliminate the herbivores from the agriculture area as
much as possible, but they are needed in the Wilderness biomes for
nutrient cycling.  The fly screen between the the 2 areas is the only
physical barrier between any of the biomes with the exception of the
human habitat, although the air does cycle through all biomes.  The
insects and other animals in the wilderness areas are free to roam
wherever they will within the wilderness biomes.

When we looked at what insects we would need for the other animals to
be included in Biosphere 2 we tended to look at them morphologically.
For example, for one particular kind of frog we may have needed a 0.5"
soft bodied, nocturnal, arboreal insect.  We then had to find out how
many of these insects this frog would eat in a day and then extrapolate
from that how many such insects we would need to introduce into the
Biosphere to sustain this one species of frog.

Regarding the IPM insects many species of predators and parasites were
introduced on several occasions into the agriculture area, and also into the
wilderness.  However, a number of these species have not survived and a
great deal more work is needed to make the food web much more
complex to withstand the fluxes of pest populations, and more perrennial
habitats available for these beneficial insects to survive during "off"
seasons.

The major survey of the insect populations will be done at the end of the
2 year experiment.  It will be compared with the survey done prior to
closure to see how the populations of insects have faired and adjustments
to species and population numbers will be made where necessary.

Jane Poynter