Effects of different diets on life table parameters of the predatory mite Phytoseius plumifer (Acari: Phytoseiidae)

The predatory mite Phytoseius plumifer (Canestrini and Fanzago) (Acari: Phytoseiidae) is an effective predator of phytophagous mites in several countries worldwide. Plant pollen is an important alternative food for generalist predatory mites, ensuring survival and fostering population growth during periods of prey scarcity. The objective of this study was to compare the effects of a diet of a natural prey, Oligonychus afrasiaticus (McGregor 1939) (Acari: Tetranychidae), and a diet of pollens, e.g. corn pollen or date palm pollen, on P. plumifer life table parameters under laboratory conditions. The total developmental time was significantly shorter for P. plumifer females fed on O. afrasiaticus than corn or date palm pollen. However, diet type did not affect P. plumifer survival rate. Survivorship during immature development varied from 96 to 99% on the three tested diets. Adult females that fed on O. afrasiaticus lived longer, produced more eggs, and had longer oviposition periods. The highest mean of daily oviposition of P. plumifer was recorded when predator was fed on O. afrasiaticus 2.26 eggs/♀/day, while the lowest mean of daily oviposition was recorded when predator was fed with corn pollen 1.53 eggs/♀/day. The average number of preys consumed daily by the protonymphs, deutonymphs and adult female individuals was 8.09, 11.20 and 18.18, respectively. Throughout the whole life-span P. plumifer female fed on an average of 739.26 prey, of these more than 96% were consumed during the adult stage. The highest intrinsic rate of increase (r<sub>m</sub>), net reproduction rate (R<sub>o</sub>) and finite rate of increase (λ) were recorded when predator fed on O. afrasiaticus. Mean generation time (T) was shorter for P. plumifer fed on O. afrasiaticus than date palm pollen or corn pollen. Based on the findings, in the scarcity or absence of the main prey in the environment, the date palm pollen or corn pollen can be suggested as an alternative or supplementary food for P. plumifer. Also, the predatory mite, P. plumifer has good potential to suppress O. afrasiaticus populations and can be used in the biological control strategies against this pest.