Experimental and Applied Acarology (2015) 67, 21-34

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Rebecca A. Schmidt-Jeffris, Elizabeth H. Beers and David W. Crowder (2015)
Phytoseiids in Washington commercial apple orchards: biodiversity and factors affecting abundance
Experimental and Applied Acarology 67 (1), 21-34
Abstract: Galendromus occidentalis (Nesbitt) is an important biological control agent of spider mites (Acari: Tetranychidae) in Washington apple orchards. It was thought to be essentially the sole phytoseiid existing in this system, due in part to its resistance to commonly used orchard pesticides, and organophosphates in particular. To test this assumption, we conducted a survey of 102 commercial apple blocks in Washington to characterize the community of phytoseiid species. Seven phytoseiid species were found in our samples; G. occidentalis and Amblydromella caudiglans (Schuster) were found in the greatest abundance. We hypothesized that the gradual shift away from the use of organophosphates in recent decades may have caused the change in phytoseiid community structure. The survey data and information regarding the management, location, and surrounding habitat of each block were used to determine what factors affect phytoseiid abundances. Galendromus occidentalis abundance was positively affected by the use of conventional (vs. organic) spray programs, and the use of the acaricide bifenazate. Amblydromella caudiglans abundance was negatively affected by bifenazate use and positively affected by herbicide strip weediness; it was also less prevalent in 'Golden Delicious' blocks compared to other cultivars. These results indicate that A. caudiglans reaches higher abundances in orchards that lack certain agricultural disturbances, whereas G. occidentalis can survive in more disturbed environments. Surveys of this nature can provide valuable insight to potential drivers of community structure, allowing for the improvement of integrated pest management programs that incorporate conservation of newly recognized biological control agents such as A. caudiglans.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Rebecca A. Schmidt, David W. Crowder, Elizabeth H. Beers

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Galendromus occidentalis (predator) U.S.A. (NW)
Anthoseius caudiglans (predator) U.S.A. (NW)