Gymnetron antirrhini: Photo by Greg McDermott, from slide show Biological Control of Noxious Weeds by Reeves Petrof.
Insect Links Photos: Adult Larva Eggs Damage to plant
Gymnetron antirrhini: Photo by Greg McDermott, from slide
show Biological
Control of Noxious Weeds by Reeves Petrof.
Origin- introduced:
in
the1900's in
Life Cycle
1) during the winter it spends its time as an adult in leaf litter or
in toadflax (yellow mainly, or Dalmatian) seed capsules.
2) Adults emerge in May - June.
3) Eggs are layed in within toadflax flowers, within ovary wall.
4) Larval stage lasts from 3 to 5 weeks in the seed capsules.
Larvae feed on "inactivated," abnormal seeds.
5) The mature larvae construct oval cells w/in seed capsules where
pupation
occurs.
6) After several weeks, adults eclose (emerge) and may feed on toadflax
shoots for a short period of time before entering diapause (going
dormant for the winter). By this time the year-old adults have
layed
their eggs and are mostly dead.
7) Adults are about 2.5 mm long; the gray weevils feed on young shoots
and
flowers of toadflax in May- June. (1, 2) (3, 4)
Damage to Host stage-
Larval seed feeding and somewhat adult feeding on young shoots and
flowers.
Plant
species- yellow toadflax
and somewhat Dalmatian toadflax.
Location-
larval: attack
immature seeds inside the seed capsules. Adult: shoots
and flowers. (1, 2)
It reduces yellow toadflax seed reproduction, but its effect on
Dalmatian is unclear. (3, 4)
Host Impact-Method- damage shoots
and flowers. Focus- they focus on mainly yellow toadflax and not
so much Dalmatian toadflax. (1)
Favorable Places
The most favorable places for theses insects are places with heavily
shaded
areas with lots of rainfall. (1, 2)
Unfavorable Places
Unfavorable places would include areas lacking in heavily shaded areas
and/or
with very little rainfall. (1, 2)
They
do not do as well in the cold but can survive in the cold. (3, 4)
Collecting
You can collect these insects wherever there is yellow toadflax.
You
will most
likely find adults using a sweep net. You also can find them in
insectaries
with permission to catch them from the person who owns the
insectaries.
(1, 2)
Transporting Them
To transport these insects when they are adults, place them in a
suitable
container such as a paper can with some fresh toadflax foliage and then
keep
them in a cooler with a small ice pack. You can also transport
infected
seed capsules but realize that you are transporting seeds as well. (1,2,3) Release in places where there
is lots of yellow toadflax; make sure
there are
heavily shaded areas and lots of rainfall. Try to not put them
anywhere
that it
is very cold and make sure that there is not a lot of snow. (2,
3) Release the Dalmatian strain where Dalmatian toadflax is
present. (4)
Redistribution
It is best to use a sweep net on the yellow toadflax plants, sweep low
to the
plant near the roots where they spent their time if it is cold
out. These
weevils usually redistribute themselves quite well by flight and tend
to be
found where ever yellow toadflax occurs. (2, 3) The
Dalmatian strain seems to be spreading on Dalmatian toadflax in our
part of SW Montana and is collectable in the same way. (4)
Links:
http://ceris.purdue.edu/napis/bio/gyan/index.html
http://www.nysaes.cornell.edu/ent/biocontrol/weedfeeders/gymnetron_antirrhini.html
http://sci.agr.ca/lethbridge/weedbio/agents/agymnet_e.htm
http://www.forestryimages.org/browse/detail.cfm?imgnum=0024013
http://www.aphis.usda.gov/ppq/permits/tag/petition.html
http://www.npwrc.usgs.gov/resource/plants/explant/linavulg.htm
http://weeds.ippc.orst.edu/pnw/weeds?02W_BIOC03.dat
http://scarab.msu.montana.edu/People/RKDPeterson/Sing_et_al._2005.pdf
Bibliography
1) Biological Control Agent Matrix, 1997, Ministry of Forests,
2) Hansen, Rich,
USDA-APHIS-PPQ, Forestry Sciences
Lab,
3) Arnold, R. M. 1982.
Pollination, predation and seed set in
Linaria vulgaris (Scrophulariaceae).
American
4) Breitenfeldt, Todd A.,
Personal Interview, Whitehall Schools, P.O. Box 1109, Whitehall, Mt,
59759,
(406) 287-4862, 9-14-99.
By: Zach Housman last
updated by: Nic Fellows, 2006.
Published By: Matt Jensen