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ABSTRACT
Tetranychus urticae Koch (Acari: Tetranychidae) and Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) are major pests in greenhouse crops. Recently, Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) was shown to be an effective biological control agent of both pests. Therefore, the prey preference of A. swirskii was determined using immature stages of T. urticae and B. tabaci in three various treatments based on Manly's β preference index (β). These treatments consisted of immature stages of two prey species (egg, first and second instar nymphs) with densities 12:12, 6:6 and 3:3, respectively, and with 13 replicates. After 24 h starvation, same-aged females of A. swirskii were added to the leaf discs. All experiments were done on bean leaf discs in Petri dishes (8 cm in diameter) in laboratory conditions with 25 ± 2°C, 70 ± 5% relative humidity and the photoperiod of 16L:8D hours. Comparing the preference indices using t-tests indicates a significant preference of the predator on eggs (t = 10.80, df = 24, P < 0.0001) and second instar nymphs (t = 8.17, df = 24, P < 0.0001) of T. urticae than B. tabaci. Our findings suggest that developmental stages of prey have effect on the prey selection by A. swirskii.
Acknowledgements
The authors would like to thank the University of Tehran and Shahrood University of Technology for supporting their study and to Dr Marla Schwarzfeld (Mite Systematics, Canadian National Collection of Insects, Arachnida & Nematodes, Agriculture and Agri-Food Canada, Ottawa, Canada) for their comments which helped to improve the manuscript.
Disclosure statement
No potential conflict of interest was reported by the authors.