Date of Graduation

5-2018

Document Type

Thesis

Degree Name

Master of Science in Entomology (MS)

Degree Level

Graduate

Department

Entomology

Advisor/Mentor

Johnson, Donn T.

Committee Member

Alzate, Oscar

Second Committee Member

Kirkpatrick, Terrence L.

Third Committee Member

Szalanski, Allen L.

Keywords

Blackberries; Broad Mites; Mites; Pest Management

Abstract

Worldwide, blackberries (Rubus L. subgenus Rubus) are an economically important crop. In 2007, Polyphagotarsonemus latus (Banks) (broad mites), were first reported damaging primocane-fruiting blackberries in Fayetteville, Arkansas. Since this time, broad mite damage to blackberries and yield loss has been reported in many states and countries. Despite the increasing reports of this blackberry pest, little is known about their population dynamics, and few treatments are available. Growers with broad mite populations need a pest management program to minimize yield loss. Therefore, there was a need to develop sampling techniques, describe broad mite seasonal phenology in blackberry fields, and determine efficacy of various control tactics. The first step was to evaluate a modified two-step floatation water, sugar-water (WSW) method to extract broad mites from Tullgren funnel sample debris and compare counts across sample substrates. Then, broad mite seasonal densities were determined through biweekly sampling of leaves, leaf litter, and soil samples from a blackberry field in Arkansas. From November to late-February, Polyphagotarsonemus latus was found in highest numbers in the leaf litter. Sample counts also showed that the broad mite is highly aggregated prior to uniform distribution in the blackberry field (late May). Laboratory leaf-dip bioassays found that Agri-Mek caused 100% broad mite mortality after 24 hrs; after 72 hours, M-Pede, Microthiol Disperss, and JMS Stylet Oil caused >90% percent mortality and Quillaja caused 83% mortality. The results of these bioassays were used by the Agri-Mek manufacturer to label it for use in caneberries (blackberries) against broad mites in AR and several other states. Field tests were conducted to determine the efficacy of 4 different predatory mite species and sulfur (Amblyseius andersoni (Chant), Neoseiulus californicus (McGregor), N. cucumeris (Oudemans) and N. swirskii (Athias-Henriot). Individually, all four species of predatory mites had statistical differences from control plots in at least one field; species efficacy was different by location. Data collected from the seasonal study, bioassays and field trials was used to develop a broad mite fact sheet describing the recommended integrated pest management program for broad mites on blackberries.

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