The biological control
of strawberry in Japan
Yoko Saiki, Tetsuo Wada
Arysta LifeScience Corporation,
St. Luke’s Tower, 8-1, Akashi-cho, Chuo-ku, Tokyo 104-6591, Japan
Abstract: The easy introduction method of Phytoseiulus
persimilis and Aphidius colemani in strawberry makes good control
of Tetranychus urticae, Myzus persicae and Aphis gossypii. This
method is easy enough for the aged growers and the usage of these
natural enemies are growing year by year. On the other hand, the
effective method to control Frankliniella occidentalis biologically
is not established yet, and chemical measure not to disturb above
beneficials was taken for the insects.
Key words: Phytoseiulus persimilis, Aphidius
colemani, Tetranychus urticae, Myzus persicae, Aphis gossypii,
Frankliniella occidentalis, strawberry
In Japan, the main pests of strawberry are spider mite, aphid
and thrips. Since strawberry cultivation period from September
to April, and sometimes growers do not use heating system throughout
the cultivation, it is said to be difficult to use the biological
control agent in strawberry. But recently, the scheduled introduction
of Phytoseiulus persimilis and Aphidius colemani is found out
to show the stable efficacy to control spider mites and aphids.
Through 1998-2003 the biological method to control thrips which
occurs from February has been evaluated. Amblyseius cucumeris,
Orius strigicollis, Amblyseius degenerans and Franklinothrips
vespiformis has been tested but made no good results. Also, Beauveria
bassiana and Verticillium lecanii are not effective enough under
low temperature climate. At present, spraying of biologically
compatible chemical pesticides are used against thrips.
Control of spider mite
The concept is to introduce Phytoseiulus persimilis before the
occurrence of Tetranychus urticae and not to make T.urticae occur
through the end of year, since it is difficult for growers to
find the first occurrence of T. urticae, and explosive growth
of P. persimillis cannot be expected during the winter time.
In Japan, the planting of strawberry is done in September without
roof and most growers use granule pesticides such as Acetamiprid
or Imidacloprid to control various early pests. In October, house
roofs are covered by plastic 7-10days after roofing, and then
P. persimilis is introduced at the rate of 2/m2 without checking
the occurrence of Tetranychus urticae. If growers notice that
there is already occurrence of T. urticae, they should spray Fenbutatin
oxide or Hexythiazox before introduction.
One month after the first introduction, the second introduction
will be done at the same rate. If there is one or two hot spots
of T. urticae, P. persimilis should be sprinkled there heavily.
If there are more hot spots or even occurrence throughout the
field, Fenbutatin oxide, Hexythiazox or Bifenazate should be sprayed
to lower the population of T.urticae.
In the end of January or the beginning of February, just before
spring occurrence of T.urticae, third introduction of P. persimilis
should be made at the rate of 2/m2. The timing is decided according
to the climate condition. Also spraying should be considered if
The fourth introduction is optional. If the cultivation continues
till May or, controlling of T.urticae is not satisfactory enough,
the fourth introduction should be done one month after the third
For growers to search for T.urticae at ordinal 1,000m2 plastic
house, they should choose 4 beds, and from each bed, evenly choose
20 plants. For each 20 plants, they should look for 1 leaf to
find the occurrence of T.urticae.
Table 1. Introduction schedule of P.persimilis
Control of aphid
Contrary to spider mite, in strawberry, usually the introduction
of Aphidius colemani, after growers notice the occurrence of Myzus
persicae or Aphis gossypii, is effective enough, since the aphid
population growth is slow in autumn and winter.
If the aphid is just found on the back of leaves, A.colemani should
be introduced at the rate of 0.5/m2 for 2 weeks. If some aphids
are found on the stems, introduction rate should be 2/m2, 3weeks.
If the stems are covered by aphid colony, A.colemani introduction
should be after spraying of Pymetrozine. Also, after introduction,
when some hot spots of aphids are found, the spot spraying of
Acetamiprid is effective.
If the mummies of A.colemani are found 2 weeks after the first introduction
and aphids do not increase rapidly, it could be analyzed as aphid
is almost controlled. And if the parasite rate increases to 80%
4-6 weeks after the final introduction, the control is successful.
When aphids are growing throughout the crop, the Pymetrozine should
Table 2. Introduction of A.colemani (upon occurrence of aphids)
Control of thrips
Frankliniella occidentalis usually starts to build up population
from February. Some exists in green house through the winter and
many of them invade into the house when growers open the side window.
Some biological methods have been tested but not effective enough
and so as biological compatible pesticides, Lufenuron and Flufenoxuron
◆Results and discussion
Test results of introduction of P.persimilis and
Those are test data of spider mite and aphid control.
Table 3. Population of spider mites per compound leaf
: P. persimilis
: Spray of mitecide
(Adopted from Takemoto, 2001)
Figure 1. Efficacy of A.colemani against aphids (Takemoto, 2003)
The usage of biological control method in strawberry
This method drives forward many growers to IPM. They have hesitated
to try natural enemies since it was difficult for them to decide
the introduction timing. In the season of 2003 autumn ? 2004 spring,
about 700ha (estimate) of strawberry growers use biological control
methods, which is about 10% of total 7,300 ha cultivation of strawberry
in Japan. And it is expected to rise to 20% in the near coming years.
Figure 2. Estimated area of introduction of P.persimils (Strawberry)
We wish to express our gratitude to Mr. Hiroyuki Takemoto, Fukuoka
Agricultural Research Center for technical advice and his dedication
to biological control in the prefecture.
Takemoto, H. 2003: How to control aphids by the parasitic wasp
in early raising strawberry. Fukuoka.(in Japanese)