Stimulatory Effects Of Magnetic Field On The Predatory Mitephytoseiulus persimilis and its prey Tetranychus urticae

Abstract

The mite, Phytoseiulus persimilis Athias(Arachnida: Phytoseiidae) is an important predator of Tetranychus urticae Koch. (Arachnida: Tetranychidae). Impact of magnetic fields (MF) on mites was evaluated at the laboratory of Gemmiza Agricultural Research Station, Gharbia Governorate. MF exposures were designed to generate 12.5, 86, and 99 mT. Predator incubation period, immature durations and life cycle period decreased as the MF increased, which means a better predatism performance of P. persimilis. P. persimilis oviposition period decreased, while female longevity increased due to exposure to 99.0 mT. The application of MFs significantly increased predator laid eggs, from 100/ female in the control to 110.00, 230.00 and 210.00 eggs/ female 12.5, 86.0 and 99.0 mT, respectively. However, exposure of this predatory mite to MF had no effect on egg hatchability compared to the check, with the exception of 99.0 mT that reduced hatchability to 90.47%. T. urticae oviposition period in the control group was 18.00 days, significantly decreased to 16.00, 13.00, and 9.00 days when exposed to 12.5, 86.0, and 99.0 mT, respectively. The use of a 12.5 mT raised the number of T. urticaelaid eggs from 87.33 in the control group to 90.00, 160.00, and 200.0 eggs/female at 12.5, 86.0, and 99.0 mT, respectively. T. urticae exposure to MF reduced hatchability to 56.03 and 39.66% when exposed to 86.0, and 99.0 mT, respectively. The stimulatory effects of MF for biological aspects of the predatory mite, P. persimilis show the importance of MFs as an effective physical approach in enhancing the role of this predator in pest control within the integrated pest management programs.