Bird-of-paradise, thorn apple and maize pollens are promising alternative diets for the long-term rearing of predatory mite Amblyseius swirskii (Acari: Phytoseiidae)

Abstract

Pollen grains can provide important nutrients for reproduction of different predators such as phytoseiid mites. Since mass rearing of phytoseiid predatory mites may be facilitated by feeding on alternative diets, the current study evaluated the utility of plant pollen as diet for mass rearing of the predatory mite Amblyseius swirskii Athias-Henriot, which is a commercially available biocontrol agent of phytophagous mites and insects. Demographic parameters of A. swirskii fed on pollens of bird-of-paradise (Caesalpinia gilliesii), thorn apple (Datura stramonium), and maize (Zea mays) were determined over 10 continuous generations. In addition, the pollens of common hibiscus (Hibiscus syriacus), and velvetleaf (Abutilon theophrasti) were assessed, but the predatory mite was unable to reach adulthood when fed on these pollens, and most of them died in nymphal stages. This study also evaluated the preying ability of A. swirskii on the natural prey Tetranychus urticae Koch before and after 10 generations. All experiments were conducted in the laboratory under controlled conditions of 25±1°C, 60±5% RH, and a photoperiod of 16:8 (L: D) h. According to the life table parameters, the pollen grains of bird-of-paradise, followed by maize and thorn apple, were shown to be promising diets for the long-term rearing of A. swirskii. Furthermore, the study found that A. swirskii reared on bird-of-paradise pollen had a high predation capability, with a mean of 677 prey per generation after 10 generations. Overall, it is concluded that while bird-of-paradise pollen was the most suitable alternative diet for the predatory mite, both maize and thorn apple pollen grains were also found to be promising diets for A. swirskii. These diets can be used for mass rearing of this predatory mite.