TY  - JOUR
JF  - Acarologia
T1  - Assessing the Possible Side Effects of Various Chemicals on the Performance and Behavior of the Predatory Mite Phytoseiulus persimilis
VL  - 66
IS  - Suppl
SP  - 266
EP  - 266
PY  - 2026
SN  - 0044-586X
SN  - 2107-7207
PB  - Les Amis d'Acarologia
AU  - Mery Joyce, Armas
AU  - Efrat, Gavish-Regev
AU  - Adi, Kliot
UR  - https://doi.org/10.24349/5toa-z4df
DO  - 10.24349/5toa-z4df
DA  - 2026-07-20
ET  - 2026-07-20
KW  - Phytoseiulus persimilis
KW  - Tetranychus urticae
KW  - Biological control
KW  - High temperatures
KW  - Chemical compatibility
AB  - Understanding the effects of various chemicals on predatory mites is important for successful pest control. The predatory mite Phytoseiulus persimilis Athias-Henriot, 1957, is a biological control agent of the phytophagous pest Tetranychus urticae Koch, 1836, commonly known as the two-spotted spider mite. Phytoseiulus persimilis has a high predation rate and can consume up to 10 adults or 20–30 larvae or eggs per day under suitable temperature and humidity conditions. This predation rate allows it to suppress T. urticae’s rapid reproduction. Nevertheless, in Israel, we often witness outbreaks of T. urticae during the hot season, indicating a failure of the predator in controlling the pest. High temperatures combined with applications of various chemicals such as pesticides, fungicides, growth regulators, and surfactants may cause lethal and sublethal effects on these predatory mites, including reduced survival, predation, and fecundity, thereby decreasing their effectiveness. However, the information on the compatibility of many of these commonly used chemicals under different exposure applications and at higher temperatures remains limited. The objective of this study is to evaluate the side effects of several commonly used chemicals at commercial formulations simulating field application rates on P. persimilis under temperate conditions, and to further evaluate them at higher temperatures and other exposure types (direct exposure, exposure via prey, and exposure via sprayed leaves). We initiated by assessing the effects of two commercial compounds: the pesticide Emamectin Benzoate and a Silicate-based biostimulant. The assessment was done under temperate conditions (25°C) by spraying the two compounds directly on P. persimilis adult females. Each compound was sprayed at the maximum concentration recommended by the manufacturer, and each treatment included 30 replicates. Three biological parameters: mortality, predation rate, and fecundity, were assessed. Controlled environmental conditions were maintained at 25 ± 1 °C, 55±5% relative humidity, and a 14:10h (L:D) photoperiod. We found that Emamectin Benzoate and Silicate had variable effects on P. persimilis. Emamectin Benzoate caused complete mortality after 24 hours, and was the most toxic treatment, while the Silicate biostimulant had intermediate mortality, and was less toxic, with reduced fecundity and predation throughout the observation period. These results showed that the two chemicals are not compatible with P. persimilis under temperate conditions. Identifying chemicals compatible with P. persimilis under temperate and higher temperature conditions will provide growers with evidence-based recommendations for integrating chemical and biological control methods against T. urticae without compromising P. persimilis’ effectiveness.
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