Effect Of Weed Control On The Distribution Of Cucumber Beetles Acalymma Vittatum Fabricius And Diabrotica Undecimpunctata Howardi Barber Coleoptera Chrysomelidae On Melons

Author : Molly E. Dieterich Mabin
Publisher :
ISBN 13 :
Total Pages : 74 pages
Book Rating : 4.:/5 (1 download)

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Download or read book Effects of Conservation Biological Control Practices on Predatory Arthropod Assemblages and Molecular Identification of Cucumber Beetle Biological Control Agents written by Molly E. Dieterich Mabin and published by . This book was released on 2017 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: The predatory arthropod assemblage often differs in abundance and richness between organic and conventional agroecosystems, likely due to habitat management practices that are more common on organic farms, such as the use of smaller fields, reduced tillage, and increased natural area. Such practices may allow growers of specialty crops to minimize their use of pesticides by enhancing predator populations. However, this conservation biological control does not always result in increased pest suppression, perhaps because different predatory taxa may benefit from different habitat management practices. Thus, effective integration of conservation biological control into a production system depends on accurate identification of the guild of predators that provide pest suppression. Cucurbits are a specialty crop plagued by striped and spotted cucumber beetles (Acalymma vittatum and Diabrotica undecimpunctata howardi), which feed on fruits and foliage, and transmit the causal pathogen of bacterial wilt. One goal of this research was to determine whether the increase in abundance and richness of predators that is often observed in strip tillage and organic management translates to an increase in biocontrol of cucumber beetles. To do this, we used pitfall traps to ascertain the predator assemblage, and a sentinel egg study with video surveillance to determine rates of D. undecimpunctata howardi egg predation and identity of egg predators. These experiments were conducted in cucurbits grown within strip tillage versus conventional tillage with plastic mulch under organic versus conventional management. Another goal of this research was to identify the predators that consume A. vittatum using PCR-based molecular gut content analysis. Such techniques enable researchers to accurately determine predators of a focal pest in an un-manipulated system. Predators were collected from organic and conventional farms located in Ohio. DNA was extracted from all samples and PCR used to amplify A. vittatum DNA, if present within the gut contents of a sample. In addition, predatory arthropods were sampled at each farm using pitfall traps, and a sentinel egg study was conducted. Here we show that while strip tillage often resulted in enhanced predator populations within cucurbits produced under both conventional and organic management, this did not translate into increased biological control in our study system. Of 1,215 predators tested for the presence of A. vittatum DNA, 139 were positive (11.4%); there was no effect of organic versus conventional management on proportion testing positive. Approximately 40% of Coccinellidae, 14% of Opiliones and Carabidae, 6% of Lycosidae and Chilopoda, and 1% of Formicidae and Staphylinidae tested positive. Our sentinel egg studies identified Formicidae, Coleoptera, Diptera, Gastropoda, and Opiliones as important predators of above-ground cucumber beetle eggs. This research is the first to use molecular gut content methods to identify the guild of predators that consume A. vittatum. Additionally, we show that sentinel prey studies may not identify important contributors to biological control and may inflate the importance of certain taxa to pest suppression.