Graduate Thesis Or Dissertation
 

Enhancing pest mite biological control by Typhlodromus pyri (Acari: Phytoseiidae) in Pacific Northwest vineyards

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  • The predatory mite Typhlodromus pyri (Acari: Phytoseiidae) is the predominant species in cool climate Pacific Northwest vineyards and a principal predator of pest mites including the grapevine rust mite Calepitrimerus vitis (Acari: Eriophyidae). In recent years vineyards have been experiencing C. vitis population outbreaks leading to increased economic damage from mite-related symptoms. It is believed that T. pyri is an effective biological control agent of C. vitis; however, information is limited regarding the factors that influence the success of T. pyri in Oregon vineyards. The goal of the current research is 1) examine the suitability of T. pyri to control C. vitis based on their respective temperature-related development and population parameters 2) determine the impact of commonly applied vineyard pesticides on T. pyri in laboratory bioassays and 3) evaluate the effect of synthetic methyl salicylate (MeSA) in laboratory and field experiments on the behavior and abundance of T. pyri. The data presented from life table experiments conducted at seven constant temperatures displayed successful development from egg to adult at 15 to 30ºC. Upper, lower and optimal developmental temperatures were estimated in addition to determining the intrinsic rate of population increase. Based on these biological parameters, T. pyri appears to be a suitable predator of C. vitis at temperatures below 25ºC. Results from pesticide laboratory bioassays found lethal effects greater than 50% in T. pyri directly exposed to parafinnic oil. The five other compounds tested displayed predatory mite mortalities less than 50%, which were not significantly different from control treatments. Fecundity rates were reduced in adult female mites exposed to sulfur and mancozeb as developing juveniles. These results indicate that parafinnic oil and sulfur should be limited in integrated management programs to avoid negative effects on T. pyri field populations. T. pyri adult females were significantly attracted to the herbivore induced volatile, MeSA at three doses in laboratory olfactometer bioassays. No repellency effect was observed, suggesting MeSA may be employed in vineyards to enhance the abundance of native T. pyri populations. Field experiments conducted using synthetic MeSA lures displayed variable responses of T. pyri to MeSA at the two experimental sites over two seasons. MeSA lures may be more effective in increasing predatory mite densities in vineyards with suitable prey resources. Results from this research should assist the Pacific Northwest viticulture industry to develop integrated management programs geared toward conservation and enhancement of T. pyri and other beneficial arthropods.
  • Keywords: plant volatiles, conservation, mites, biological control, developmental parameters
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file details GadinoAngelaN2011.pdf 2017-08-08 Pubblico Scaricare