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Palestriped Flea Beetles Feeding on Sunflowers
Update 6-21-02

          

           (Click to enlarge)

Reports of damaging numbers of palestriped flea beetles have recently come from Hughes,
Potter, and Sully counties, where most of sunflowers are grown in South Dakota.

Palestriped flea beetles are about one-eighth of an inch long, black in color with two white
stripes on the back, and can both jump and fly -- hence the name "flea" beetle.

Palestriped flea beetles chew on the true leaves, cotyledons, and hypocotyls causing the
sunflower seedlings to wilt and die. Injured leaves become riddled with holes giving them
a "lacey" appearance.

This is the third straight year that palestriped flea beetles have caused injuries on sunflower
seedlings in north central South Dakota.

Palestriped flea beetles can cause significant stand losses in sunflower seedlings. Spraying
with an insecticide may be justified if 20 percent of the stand -- one out of five seedlings --
shows extensive feeding by the flea beetles.

No insecticides are currently labeled for use specifically against palestriped flea beetles on
South Dakota sunflowers. However, our research has indicated that several insecticides,
already labeled for use against common sunflower insects, would also control palestriped
flea beetles.

Baythroid (2.8 fluid ounces per acre), Sevin XLR Plus (32 fluid ounces per acre), and
Warrior (2.56 fluid ounces per acre) were effective in reducing palestriped flea beetles
in our research near Onida last year (2001).

SDSU Extension Entomology is currently testing various seed treatments and insecticide
sprays for potential use against palestriped flea beetles near Selby and Agar. Funding
for these studies come from the National Sunflower Association and the South Dakota
Oilseeds Council.

Palestriped flea beetles overwinter as adults under the soil and plant residues on the field.
They then resume feeding on weeds in the spring. For some unknown reason, they have
recently started to feed on sunflower seedlings.

Palestriped flea beetles did not use to be a pest of sunflowers in South Dakota. Its
transformation into a pest of cultivated sunflowers is an example of the ability of insects
to change hosts over time.

Scientific records do indicate that palestriped flea beetles have always been in South Dakota.
Their known plant hosts in the United States include various weeds, potato, tomato, carrot,
peanut, corn, oat, cotton, pea, beans, strawberry, watermelon, grape, and pumpkin.
Palestriped flea beetles are considered an important pest of commercially grown vegetables
in California and North Carolina.

Update 6-21-02:

We went to Agar this Thursday (6-20-02) to inspect our entomology research and
found high populations of the palestriped flea beetles in our research plots.

         

Above are pictures of seedlings being infested by the flea beetles taken during
our inspection.  We will be visiting our field weekly and will periodically update
you on our seed treatment research.  It is too early to tell yet whether the seed
treatments were working or not.