Effect of pollens and preys on various biological parameters of the generalist mite Cydnodromus californicus

The generalist phytoseiid mite Cydnodromus californicus (McGregor) (Mesostigmata Phytoseiidae) is considered a very important biocontrol agent of the spider mite Tetranychus urticae Koch both in greenhouses and field. Its capacity to feed alternative foods allows the increase of the population in field, even when the primary prey is not available. To investigate the effect of various alternative food substances present in the Mediterranean agroecosystems on the biological parameters of C. californicus, laboratory trials were carried out using 17 pollens and 3 preys. As it was expected, T. urticae was the best food for both the postembryonic development and the oviposition rate (100% of attained adulthoods and 2.65 eggs/female/day were laid). Good results were obtained also with pollens of Carpobrotus edulis (L.) and Scrophularia peregrina L.: on both pollens, 84% of eggs reached the adulthood and the oviposition rate was 2.00 and 1.81 eggs/female/day for the two pollens respectively. Interesting results were obtained with the alternative prey Petrobia hartii (Ewing), very common on Oxalis spp., a weed widespread in Mediterranean orchards (72% of attained adulthoods and 0.57 eggs/female/day). On the other hand, the effect of Mentha piperita L. was not positive on the juvenile development (only 28% of eggs reached the adulthood), while it was positive on the oviposition rate (1.12 eggs/female/day).