[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Wasp statistics and Re: generalizations





> Anyone have any good data on the number of paper wasps needed to keep an
> area essentially caterpillar free?  I have three large nests with two
> species near my yard.  With a total of approximately 50 wasps.  Since
> the nests became well established, I have not seen but a few
> caterpillars and the damage to my lettuce and cabbage has been
> negligible.  I am also interested in information on how I might increase
> their numbers earlier in the season so that my spring losses are
> smaller.
> 

> 
> Anyone have any good data on the number of paper wasps needed to keep an
> area essentially caterpillar free?  I have three large nests with two
> species near my yard.  With a total of approximately 50 wasps.  Since
> the nests became well established, I have not seen but a few
> caterpillars and the damage to my lettuce and cabbage has been
> negligible.  I am also interested in information on how I might increase
> their numbers earlier in the season so that my spring losses are
> smaller.

You are one of the few people on the ng's who has an appreciate for these
insects. 

I know of no studies on this particular topic. I suspect that the answer
would be quite variable, depending on the crops and caterpillars in
question. If I get a chance, I'll see what I can find on the subject. BTW,
you might ask on sci.bio.entomology.misc if anyone knows of a reference
offhand. 

I think that increasing their numbers will require you to change the
habitat to encourage them. The most likely limiting factors are nesting
sites and food. Someone else has already posted some info on providing more
nesting sites, so I won't belabor that. There have to be a thousand ways
you could make small structures that would work.

As for food, you need plants that are around early and get caterpillars on
them. Apparently, you do have this going. Wasps also like nectar, so having
plants that flower early might be good. You might also try planting some of
the late season things that the wasps forage upon just before
overwintering. Goldenrod seems like a great example. (It attracts all
manner of pollinators, predators and parasitoids...). 

Water sources are important too. If there isn't already something in your
area for that, a pan of pebbles filled with water is good. (Bottoms for
clay or plastic pots work well for this.) I assume you have some exposed,
untreated wood source for them, too...

When I remember or can look up the particular overwintering sites used by
these wasps, I will post that too. Having them overwinter near where you
want them seems like a good practice. If you don't already have some good
sites, it shouldn't be too hard to make some...but back with that later. 

Still, I suspect that you will have some difficult getting high numbers
early on. The queens to be come out of overwintering and start the nests
either singly or in small groups. It takes a while for the first brood to
emerge and for numbers to build. 

I want to suggest a small experiment for you, though. As you know, the
wasps do not reuse their nests. (Sometimes leaf-cutter or other solitary
bees do, but you can provide alternative habitat for them). What you may
not know is that before each wasp emerges from its cell, it deposits a
meconium (fecal pellet) in the closed end of the cell. Reused cells may
have several, one for each previous resident. The interesting thing is that
these meconia can harbor live caterpillar viruses. At one point, I provided
some nests to a friend of mine who was an insect virologist at a large
chemical company. He extracted some viruses, and was able to demonstrate
their effectiveness against some lab strains of caterpillars.

Now, you can't possibly do what he did, but there is no reason you can't
throw part of a nest into a blender with some water, puree it, strain out
the coarser materials and spray it on the caterpillars in question. I do
*not* know if this will work, but it is something I have wanted to try for
awhile (I just haven't located any nests lately). This is something that
could be done fairly easily and cheaply, and there is a legitimate reason
to suspect that it might work. If it does work, it might help you bridge
that "awkward age" in the spring when the caterpillars are present but the
wasps aren't yet numerous.

If you're interested to give this a shot, let me know. I would be willing
to organize a sort of group trial on this for next year with whomever would
be inclined to participate. (I'll just bet Allyn Weaks and Don Chapman
could be arm-twisted into taking part.) I'd be most interested (of course)
in setting things up with real controls, quantification of data and such.
There is no reason (IMO) that we should not take advantage of the net to
organize experiments of this nature. Sure fits with the name of the group,
anyway.

And BTW, if anyone is willing to provide some nests, I'd be happy to have a
few, and/or to serve as a routing agent to get nests from people who have
them to people who would like to use them in this way.

I'll revisit this idea in a week or so if I get some responses, and will
probably throw it over to r.g and r.g.ed, as well. When I do, I'll go into
a bit more detail about nest collection and such. The hard part will be
figuring out the data collection...

In the meantime, I'd be interested in hearing your thoughts (and those of
others on the group) on this topic.

Regards,
Bill

-- 
Bill Morgan
wtmorgan@pilot.msu.edu
Center for Room Temperature Confusion

---------------------------------------------------------

The rec.gardens.ecosystems FAQ can be found at the group's homepage
http://sunsite.unc.edu/InterGarden/rge.html

submissions can be mailed to: ecosys-submit@sunsite.unc.edu
the moderators can be contacted at: ecosys-admin@sunsite.unc.edu


References: