Amblyseius tetranychivorus (Gupta)

Hexapod larvae Amblyseius tetranychivorus are seldom found feeding at 31.1°C and 65-75% RH. The incubation period is 1. 71 days, and larval period is 0.66 day, while the protonymph lasts 1.06 days and deutonymph 1.17 days. Both males and females are sexually mature as soon as they attain adult stage. Adults are multinuptial. The preoviposition period is 1.32 days. Females do not oviposit unless they copulate. Total time taken to complete one generation is about 5.92 days, which is almost half the generation period of the tetranychid Tetranychus ludeni Zacher, which is 10-11 days (at room temperature). A. tetranychivorus lays 0.4 eggs per day (depending upon the availability and quality of food material)

Amblyseius tetranychivorus is multiplied on castor pollen. The basic production unit for rearing A. tetranychivorus consists of an aluminium pan 20 x 20 x 4 cm and a wooden platform 10 x 7 x2 cm, a glass plate 14 x 12x 0.20 cm covered with black paint on one side and wet cotton strips to prevent mites from escaping.

The wooden platform is kept in the centre of the aluminium pan. The glass plate is kept over the platform in such a way that the painted surface faces down to form a good background for observation. A strip of wet cotton is kept all around the glass plate to prevent the predatory mites from escaping. Sufficient water is maintained in the pan to keep the bottom strip saturated and maintain high relative humidity (85-90%) essential for successful rearing of the mites. Cotton strands are stuck on the glass plate to provide sites for oviposition and resting.

Castor pollen grains are used to rear A. tetranychivorus which readily accepts the pollen grains, feed voraciously and lays eggs on cotton-wool strands provided. Pollen grains are removed from castor inflorescence by gentle tapping during the early hours of the day. The pollen grains could also be artificially removed by keeping the flowers in petri dish under a 60 w electric lamp for about 5 minutes. The pollen grains are then brushed off from the petriplates for feeding or storage. Pollen grains could be stored at 3-4°C in a refrigerator for at least 2 weeks or in a deep freeze for several months.

The rearing units are kept in a rack in a partially darkened chamber. The cultures are maintained in room (with temperature 30± 2°C and RH 45-50%). Individual tray cultures remain in satisfactory conditions for more than 10 weeks. Strands of cotton wool are changed at regular interval to get better egg production. Pollen grains are provided once in two days and approximately 4 mg are required for about 500 adult mites. The culture tray units are convenient to handle and the developing predacious mites could be closely examined with a binocular microscope.

To start a new unit, 200 to 250 fresh adults are collected from the old tray using a fine camel hair brush. After 2-3 weeks the population usually increases sufficiently to provide enough material for field liberations.

Many Amblyseius species could be reared successfully on castor pollen grains. However, Phytoseiules species and several other predatory mites could not be reared on pollen, therefore tetranychid mites are produced and provided for mass multiplication of predatory mites of this category as mentioned above.