Phytoseiulus persimilis Henriot

Phytoseiulus persimilis was imported from the Glasshouse Crops Research Institute, Littlehampton, U.K. in 1984. Since then it is maintained on Tetranychus urticae Koch which in turn is being multiplied on bean plants.

Phytoseiulus persimilis preferred in descending order T. urticae, T. fijiensis Hirst, T. cinnabarinus (Boisduval), T. ludeni Zacher and T. neocaledonicus Andre. For mass rearing, T. urticae is found to be an ideal host.

Multiplication of nucleus culture is carried out in glass tubes 20 x 2 cm. The bottom 1.5-2 cm of the tube is filled with water and after this level a tight wad of cotton is kept which in turn is covered by one or two layers of filter paper. An infested leaf containing over 1,000 spider mites and 15-20 Phytoseiulus persimilis is kept in each tube & its mouth is secured tightly with cotton stopper (prepared out of cotton covered with muslin cloth). The tubes are kept in racks at room temperature. With proper food after 3 days from 15-20 predatory mites it is possible to get about 100 eggs and larvae. After 8-10 days the population of predatory mites in the tube reaches around 200. Phytoseiid mites in the tubes are reared for 10 days. The food is changed every 2-3 days by keeping a bean leaf fully infested with spider mites. In 1-2 hr the predatory mite shifts to the leaf provided which is then shifted to the new tube, the process is continued.

For large scale rearing the trays with spider mites infested plants are inoculated with predatory mites. Schedule for planting, infesting and harvesting is at set intervals. The number of units is calculated based on the predatory mite requirement.

The storage process is initiated by rearing at fluctuating temperature (day 18-20°C) and 12 hour day length. Before the predatory mite is kept for storage, it is placed for a day on bean leaves with spider mite in a clean tube. The tube with predatory mite is preferably kept for storage in the evening. The tubes are kept in the dessicator, where 90-98% RH is maintained. The dessicator is kept at 3-5°C. Soybean leaves and females are best for storage. The predatory mites could be stored without loss for 60 days further storage upto 80-100 days results in 60% mortality. Few P. persimilis survives upto 162 days.