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Tetranychus turkestani as an Emerging Pest in Israeli Almond Orchards: Resistance Development to Pesticides and Management Challenges

Gal, Zamir ; Adi, Kliot ; Efrat, Gavish-Regev and Moshe, Zaguri


2026 - Volume: 66 Issue: Suppl pages: 248

https://doi.org/10.24349/gnh7-83kr

ICA 2026 - XVII International Congress of Acarology, 20-24 July 2026, Montpellier

Keywords

Tetranychus turkestani Pesticide resistance Integrated Pest Management Biological control Almond orchards

Abstract

Until recently, spider mites were considered a secondary pest in Israeli almond orchards, likely due to historically low infestation levels. However, outbreak frequency and severity have increased in recent years. Mite’s feeding causes leaf abscission, tree stress, and potential yield losses in the following season. Current management relies heavily on chemical control despite the limited number of acaricides registered for almonds, raising concerns regarding rapid resistance development. The objectives of this study were to: (1) identify pest mite species associated with almond orchards in Israel; (2) evaluate their susceptibility to commonly used acaricides; and (3) assess the occurrence of natural enemies. The study included two main components: (i) in-season collection and identification of mites from infested orchards, and (ii) a pre-harvest nationwide survey of natural enemies. From April to July, mites were collected from infested orchards based on reports from growers and pest inspectors. Specimens were identified using morphological keys and molecular analyses. In addition, Laboratory bioassays evaluated susceptibility to acaricides registered for almonds, as well as compounds registered for other deciduous fruit crops. Mortality rates were compared to water-treated control. Two weeks prior to harvest, a nationwide survey was conducted in 12 orchards. Natural enemies were collected by branch beating onto a tray and identified in the laboratory. The predominant mite species identified was the strawberry spider mite Tetranychus turkestani (Ugarov & Nikolskii, 1937). Bioassays revealed reduced mortality of adult mites exposed to the two main acaricidal active ingredients currently used in almond orchards. Mean mortality rates ranged from 50% to 80%, while negligible mortality was observed in the water-treated control. According to published thresholds, these mortality levels may indicate the early stages of resistance development. Reduced mortality was also observed within the same orchard during a single growing season, decreasing from approximately 85% to 45% following field applications of a specific active ingredient. In contrast, acaricides registered for other deciduous fruit crops achieved nearly 100% mortality. The survey documented four natural enemies associated with spider mites: the phytoseiid predatory mites Amblyseius swirskii (Athias-Henriot, 1962) and Typhlodromus athiasae Porath & Swirski , 1965, the coccinellid predator Stethorus gilvifrons (Mulsant, 1850), and the lacewing Chrysoperla carnea (Stephens, 1836). Overall, the findings highlight the dominance of T. turkestani in Israeli almond orchards, indicate potential onset of acaricide resistance, and demonstrate the presence of natural enemies that may support future biological control strategies.

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Article editorial history
Date published:
2026-07-20

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License
2026 Gal, Zamir; Adi, Kliot; Efrat, Gavish-Regev and Moshe, Zaguri
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