Recent development of a method of introduction of predatory mites with compatible chemicals in greenhouse strawberries in Japan

Tetsuo Wada,Arysta LifeScience Corporation, 38F, St.Luke’s Tower, 8-1, Akashi-cho, Chuo-ku, Tokyo 104-6591, Japan

Abstract: The Japanese growers have chosen a “safe and reliable IPM”, where predatory mite introduction and application of miticides of a few numbers are rationally combined. By adopting this strategy, the number of miticide treatments drastically reduced from 11 to 2 times during growing period of 6-7 months. Since it is warmer in Japan than in the Netherlands and UK, it is extremely difficult to detect zero level or low level population of pests in greenhouses when plants are transplanted in greenhouses from September to October. This is because the greenhouses are basically semi-opened and pests can freely enter into the greenhouses in the warmer countries.
So it is almost impossible to recommend growers early releases of natural enemies when the pest density level is still low. Under such pest free or extremely low pest level condition, reduction of Tetrancychus urticae Koch is successfully achieved together with by pre-application of the following miticides with their designated residual interval before introduction of Phytoseiulus persimilis (Athias-Henriot) andNeoseiulus californicus (Macregor).

3 weeks before introduction: pyflubumide (15%F) + fenpyroximate (5%F) mixture combination
2 week before introduciton: emermectin (1%EC)
1 week before introduction: milbemectin (1%EC)

6,000 P.persimilis and 5,000 N.californicus are introduced for 1,000 m2 in a greenhouse in November.
And 6,000 P.persimilis are introduced additionallyin February. Availability of compatible miticides was very limited by 1995. Nowadays, a considerable number of miticides with less adverse effect has been developed mainly by the Japanese companies which overturned the old concept of non chemical interruption method. Miticides which can be used after the predatory mite introduction are bifenazate 20%, cyenopyrafen 30%, and cyflumetofen 20%. These miticides are used only when the above pre-introduction method results in failure.
So, this is the 2nd safety defence to succeed in controlling the mite explosion when the predatory mite reproduction is not active.
Against other hemipteran and lepidopteran insect pests, flonicamid 50% for aphids, cyantranileprole 10% (harmful to honeybee for a few days) for thrips control are recommended as less adverse products compared with conventional insecticides.
For disease control, Bacillus subtilus and Talaromyces flavus are recommeded for resistant management even though still many chemical fungicides such as flutianil 5%, mepanipirim 40% are commonly used.
It is estimated that the usage of predatory mites in Japan is 2nd largest after the USA California Salinas valley strawberry fields in 2016. Especially, in Tochigi prefecture where has the most strawberry cultivated area in Japan, N.californicus were introduced in 463ha which is 72% of strawberry there in 2016.

Key words: biological control, mites, compatible chemicals, Japan, strawberry, Neoseiulus californicus