author(s)
Mehran Rezaei, Javad Karimzadeh, Jahanshir Shakarami and Shahriar Jafary

abstract
Cotesia vestalis, one of the most important biocontrol agents of the diamondback moth, Plutella xylostella. The present study aimed to explore some simple ways to optimize the mass rearing of C. vestalis. Here, the effects of space and plant-host biomass on the quality of produced wasps were investigated. Experiment was conducted in four replication and each one of them concludes four treatments such as: 1) a small cage (40×20×40 cm), a plant and 20 P. xylostella larvae, 2) a small cage, two plants and 40 P. xylostella larvae, 3) a big cage (40×40×40 cm), two plants and 40 P. xylostella larvae, and 4) a big cage, four plants and 80 P. xylostella larvae. There was a significant effect of space and plant-host biomass on the sex ratio of produced wasps. The third treatment was the best in this regard. A mass rearing of C. vestalis can be recommended with the cage size of 40×40×40 cm and 40 host larvae established on two plants exposed to 5 female wasps for 24 h.