Development of Cucumeris and its future prospect

Tetsuo Wada
Tomen Corporation
Agro Ecology Department

1. Introduction
The biological control has been a big trend in north western Europe and north America
for the past 10 years. This trend is further expanding to other southern and eastern
European countries.
On the other hand, the biological control using arthropods in Japan is still its infant
stage.
In 1995 two natural enemies for greenhouse uses were firstly registered, namely Spidex
for strawberries, a predatory mite, phytoseiulus persimilis and Enstrip for tomatoes, a
parasite wasp, Encarsia formosa against Tetranychus urticae and Trialeurodes
vaporariorum respectively.
But it is difficult to achieve a complete IPM program with only two insects.
Cucumeris for egg plants and strawberries, a predatory mite, Amblyseius cucumeris, against Thrips palmi and Frankliniella occidentalis, is expected to fill the gap in this natural enemy crunch status in Japan. Cucumeris was registered in April, 1998.
As of December, 1998, 6 kinds of arthropod natural enemies are registered.

2. Development of Amblyseius cucumeris preparation
Since 1991 one of major Japanese chemical corporation, Nippon Kayaku Company, has been studying the rearing method and usage of Amblyseius cucumeris in cooperation work with the Ministry of Agriculture, Forestry and Fishery .
It has to be mentioned that the main reason of development of A.cucumeris by Nippon
Kayaku was the serious damage by several thrips damage to important vegetables and
difficulty of importing A.cucumeris from Europe or the U.S.A. due to the Japanese
regulation that no insect pests should be imported to Japan commercially as A.cucumeris
preparation contains plant insect pests called live tyrophagus mites as feeding material
during transportation.
The strain firstly used was introduced from north America.
It is well known fact that A.cucumeris can be reared with tyrophagus nymph and adult.
Nippon Kayaku's method to rear the mites is to rear tyrophagus first with
wheat bran.
The mite-inoculated bran is kept with very high RH for the all rearing stage.
The rearing cycle is about 30 days at 25 degree centigrade.
Currently A.cucumeris is produced by Techno Green Company, a subsidiary company of Nippon Kayaku Company.
Distribution is through Tomen Corporation.
Now two companies are jointly developing further uses of A.cucumeris in Japan.

3. Usage of Amblyseius cucumeris
At first stage, the natural enemy was tested against Thrips palmi on Egg plants.
Because the main insect pests on egg plants which are not easy to control with
chemical insecticides was Thrips palmi in early 1990.
A. cucumeris with wheat bran can be either sprinkled over leaves of egg plants or
small paper bag which contains both A.cucumeris and bran with high moisture
is hung on each plant.
Registration detail:
Crop Pest Dosage Release time No.of release release method
Strawberry Frankliniella .occidentalis 100 A.c./plant At the beginningof insect occurrence unlimitednumber Sprinklingat plant base
Cucumber Thrips palmi
Eggplant Thrips plami 50-100 A.c./plant

4.Registration
At this moment, the bag system is not registered in Japan because there are two
reasons.
One is because it is more costly to produce such paper bags and another is the
Japanese pesticide law requires additional bioefficacy data for new use form
registration. This is because the Japanese pesticide regulation law clearly included
natural enemies in the realm of all the pesticides and other relevant chemicals and
natural products which could regulate any advantageous and disadvantageous effects on
plants when the law was enforced in 1950.
Nowadays it is difficult to elucidate who wrote the law draft but the part is rigidly
existing since then.
There are some opinion that natural enemies should be waived from registration system
but also other opinions that it is worthwhile because the system can verify the
efficacy and both environmental and ecological concerns if the natural enemies were
non-indigenous species.
It is unexpected by product that this natural enemy regulation in Japan was already
covering most part of the recent United Nation's recommendation on import/export of
biological control material.

5. Efficacy results
A. cucumeris performs very well against many kinds of thrips provided they are
released at the right timing and right conditions.
It is very important to study and learn the characteristics of this predatory mites
otherwise it seems the natural enemy does not work well even though there always
are full of such failures and oversights.
Followings are main biological aspects of A.cucumeris.

i) Temperature limitation 15 to 35 degree
ii) Dispersal between plants is low. It has to be released on each plant when the plants were not so dense.
iii) Could tolerate granular insecticides such as imidacloprid.
iv) Could be used from the transplanting timing or it is more common usages to start
from the transplanting time.
v) At least consecutive 2 to 3 weekly releases are recommended.
vi) It can only prey on 1st and 2nd instar of thrips but with 2 to 3 applications
it could virtually suppress the whole population of thrips.
vii) Rediscovering of A.cucumeris on leaves is very encouraging to growers to continue this

biological control method. It usually flees against light so you will find its rear
part
hiding its head in the leaf tissue.

viii) Blowing with air of dried pollen or frozen ephestia eggs accelerates the
efficacy.
ix) A.cucumeris can feed on tetranychus, tarsonemus spp. but it is not a major natural enemy against these mites.
x) Orius spp. is well known as a good natural enemy against thrips. Combination of A.cucumeris and Orius spp. in thrips control is commonly conducted.
xi) One time it is said Orius is more superior to A.cucumeris in controlling thrips. This
hypothesis is fading recent years because only A.cucumeris did a good job without
Orius spp.
This is partially due to high cost of Orius production, as A.cucumeris is a relatively low cost beneficial.

6. Discussion
When talking about "Biological Control", people tend to insist certain beneficials are good
enough to control certain insect pests without evaluation of cost benefit.
Growers are interested in biological control but if it is not commercially beneficial, they will not continue the system or even start to use those beneficials.

Cucumeris is the first domestically mass reared natural enemies for greenhouses.
In the near future, there will be more insects will be reared in Japan.
Local productin of Encarsia formosa, Phytoseiulus persimilis, Aphidius colemani, Chrysoperla carnea, Harmonia axyridis are already being planned by some Japanese companies.
The important point is producing these insects with very competitive cost frame
to be accepted by growers and to establish an original economical rearing system and its
distribution.
Because there is no patent protection for these naturally available living creature in general, it means there will be always harsh competition in this world of biological control.