Tetranychus urticae Koch

A simple method has been developed for mass-rearing of Tetranychus urticae on potted french beans under glasshouse conditions.

For raising french beans enamel trays (40x40x6.25 cm) are filled with equal mix of soil from river bed deposit and compost or red soil, sand and compost. The trays are irrigated regularly to create optimum moisture. 25 seeds of beans (pre-soaked for 48 hrs) are dribbled at equidistance. The trays are kept in illuminated glasshouse (where about 27°C temperature is maintained). High humidity (above 70% RH) is maintained in the glasshouse meant for raising plants. The bean plants are ready for spider mite infestation (3-5 leaf stage) in about 10-12 days.

The plants are kept in illuminated room (with temperature 30± 2°C and RH 40-50%) for the multiplication of spider mite. For speeding up infestation 2-3 plants already severally infested with spider mite T. urticae are kept randomly among the healthy ones in one or two days the spider mites shift to fresh plants and multiply on them. The bean leaves are covered with spider mites in 14 days.

For the multiplication of spider mite temperature from 25 to 30°C and 35-55% RH are suitable, but the predatory mite requires 80-90% RH for the successful multiplication.

The methods for mass multiplication of spider mites are consistently improved and are being mechanized for factory scale production of predatory mites.

The female lays 2-4 eggs per day (maximum-6). When optimum food is made available, the female lays 50-80 eggs (maximum-100) in 18-24 days.