Management of apple orchards to conserve generalist phytoseiid mites suppresses two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae)

Abstract

To improve the success of integrated pest management (IPM) in apple orchards, we investigated whether generalist phytoseiid mites have suppressed the occurrence of Tetranychus urticae. In Akita Prefecture, northern Japan, in 2012 and 2013, two types of experimental plot were compared. Conservation plots had been managed for the conservation of generalist phytoseiid mites by selective chemical spraying without mowing since 2009. Conventional plots were managed by non-selective chemical spraying with regular mowing. The conservation plots had significantly fewer T. urticae adult females per tree in both years. Two species of generalist phytoseiid mites-Typhlodromus vulgaris and Amblyseius tsugawai-were continuously present in the conservation plots, with only a few T. urticae. The conservation plots had significantly more A. tsugawai adult females in the undergrowth in both years, and significantly more T. vulgaris adult females on apple leaves in 2012. Typhlodromus vulgaris was continuously present in the conservation plots but was scarce from late May to early August in the conventional plots. In the presence of T. vulgaris, low numbers of T. urticae did not increase on apple leaves. These results indicate that the generalist phytoseiid mites serve as important biological control agents in IPM in apple orchards.

Non‐target effects of herbicides on Tetranychus urticae and its predator, Phytoseiulus persimilis: implications for biological control

“…For instance, weedy ground cover has been shown to increase phytoseiid abundance in orchard systems . Retention of weedy areas through reduced herbicide use or mowing can promote phytoseiid populations and enhance biological control . This has been attributed to the availability of weed pollen as a food resource and to the shelter from ultraviolet radiation and desiccation provided by weedy ground cover .…”

“…11,13,49 Retention of weedy areas through reduced herbicide use or mowing can promote phytoseiid populations and enhance biological control. 13,15,50 This has been attributed to the availability of weed pollen as a food resource 51 and to the shelter from ultraviolet radiation and desiccation provided by weedy ground cover. 50 Therefore, reduced weed management on field margins and row middles in vegetable production could increase non-prey resources for beneficial arthropods and improve biological control, in addition to reducing the potential for herbicide non-target effects.…”

“…that are known for their broad host range and use of weeds as alternative hosts in both annual and perennial cropping systems . Generalist phytoseiids can use pollen from weeds as a secondary food source and incidentally visit weedy areas near crops . These associations with weeds result in the risk of predatory mite exposure to herbicides.…”

“…[10][11][12] Generalist phytoseiids can use pollen from weeds as a secondary food source and incidentally visit weedy areas near crops. [13][14][15] These associations with weeds result in the risk of predatory mite exposure to herbicides.…”

Gut-content analysis of predatory phytoseiid mites using fluorescent-labeled polymerase chain reaction: age of spider-mite eggs influences detection rates

“…Several phytoseiid mite species (Acari: Phytoseiidae) are candidates for natural enemies of spider mites. Studies have attempted to identify the most effective phytoseiid predators and increase their populations for spider-mite control (e.g., AbadMoyano et al, 2009;Funayama et al, 2015;Hoddle et al, 2000;Katayama et al, 2006;Kishimoto, 2002;Oliveira et al, 2007;Toyoshima, 2003). However, with reduced acaricide use, many phytoseiid species are present in the field, and their small size causes difficulties in determining true spider-mite predators through field observations.…”