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Browsing by Author "Rashed, Arash"

Now showing 1 - 4 of 4
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    Alternatives to chlorpyrifos in Virginia type peanut production for control of southern corn rootworm
    Hoar, Elijah Kael (Virginia Tech, 2024-06-05)
    Historically, the organophosphate insecticide chlorpyrifos was used to protect peanuts (Arachis hypogaea L.) from soil-dwelling insect pests. In 2022, its registration was canceled by the Environmental Protection Agency (EPA) for all food crops. The southern corn rootworm, Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae) (SCR), was the major pest of developing peanut previously managed by chlorpyrifos and there are no known alternative insecticides for its control. The SCR larvae can cause economic damage by feeding on developing pods and pegs. Field condition is an important factor in SCR survival as the larvae rely on soil moisture to survive, and larvae cannot feed on fully developed pods. The dependency of SCR on soil moisture and host availability allows for cultural modifications (e.g., planting date, judicious irrigation practices, selecting fields based on soil characteristics) to reduce losses to this pest. Alternatively, or in addition to these strategies, identifying varieties with resistance to SCR can provide growers with non-chemical methods to mitigate losses. Therefore, this project was developed to identify sources of resistance in commercial cultivars and advanced breeding lines of Virginia type peanuts to SCR and examine whether early digging can reduce SCR injury. Implementing an effective integrated pest management (IPM) plan relies on a clear understanding of the pest life cycle in relation to the susceptible stage of the crop. We also evaluated SCR phenology in relation to peanut development. Replicated field trials were used to screen cultivars and investigate the effect, if any, of early digging in reducing pod injury. We monitored SCR adult populations over time using sticky traps. Our research will help manage a problematic pest in this region with limited, or no, reliance on insecticides.
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    Ecology and management of wireworms (Coleoptera: Elateridae) in conventional and organic production systems
    Nikoukar, Atoosa (Virginia Tech, 2024-06-12)
    Wireworms are the subterranean larval stage of click beetles (Coleoptera: Elateridae), generalist herbivores that feed on a wide range of crops and cause serious damage. Wireworm management is challenging due to their long life cycle, subterranean habitat, wide range of host plants, and lack of effective chemical approach in most crops. Thus, developing an effective alternative control approach is an urgent need. The overall aim of this research study was to evaluate alternative [to insecticides] tactics that could be used as components of effective IPM strategies against wireworms. In Chapter 1 we provide an overview of wireworm's biology and management practices. In Chapter 2 we focused on biological control to evaluate the efficacy of entomopathogenic nematodes and fungi as single and mixed application against Limonius californicus and L. infuscatus in organic vegetable farms. The results showed the higher efficacy of commercial EPN, Steinernema feltiae, against Limonius species than entomopathogenic fungi. In Chapter 3, we focused on cultural control as a component of integrated pest management for wireworm control. We evaluated the efficacy of brown and yellow mustard and their byproducts, including defatted seed meal and seed meal concentrated extract against Limonius spp. Our finding indicated the effectiveness of brown mustard concentrated extract on reducing the wireworm population. However, it has a negative impact on the field-residing entomopathogenic nematodes. In Chapter 4, in the component of cultural control, we evaluated the wireworm, L. californicus, preference to three different crops, pea, bean, and wheat, for identifying an effective trap crop. We also quantified CO2 and organic volatile compounds released from each plant's root and evaluated the wireworm response toward the synthetic volatiles. Detailed results are provided in chapter 4. Finally, we looked at the novel new technology of RNA interference to find the effective target genes in wireworms for application as bioinsecticides and/or transgenic plants to control wireworms. In the concluding chapter, Chapter 6, we summarized our findings on the efficacy of different management tactics, biological, cultural, and molecular, to control Limonius species in cereals and organic production systems.
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    Integrated Pest Management of Wireworms (Coleoptera: Elateridae) and the Rhizosphere in Agroecosystems
    Nikoukar, Atoosa; Rashed, Arash (MDPI, 2022-09)
    The name 'wireworm' refers to the subterranean larvae of click beetle (Coleoptera: Elateridae) species, of which several are serious pests of a wide range of crops. The limited effectiveness of the available insecticides, their wide host range, their long life cycle, and their cryptic subterranean habitat make wireworms a challenging pest to control. Integrated pest management (IPM) strategies have been recommended to reduce wireworm damage. Although IPM is generally considered to be an approach that is relatively more compatible with the environment and non-target organisms, the implementation of some of the tactics of managing subterranean wireworms is expected to induce stress in the rhizosphere and the established ecological interactions within, some of which could negatively impact various soil health parameters and, subsequently, plant growth. In this paper, we highlight some of the IPM tactics against wireworms and their effects on the rhizosphere and soil microbiome. Awareness of the potential impacts of IPM approaches to the management of subterranean pests will help professionals to develop and implement IPM strategies that minimize disturbance in the rhizosphere and support agroecosystem sustainability. The rhizosphere is where plant roots, physical soil, and subterranean organisms interact to contribute to soil fertility and plant growth. In agroecosystems, the nature of the ecological interactions within the rhizosphere is highly dynamic due to constant disruptions from agricultural practices. The concept of integrated pest management (IPM) was developed in order to promote an approach which is complementary to the environment and non-target organisms, including natural enemies, by reducing the sole reliance on synthetic pesticides to control pests. However, some of the implemented integrated cultural and biological control practices may impact the rhizosphere, especially when targeting subterranean pests. Wireworms, the larval stage of click beetles (Coleoptera: Elateridae), are generalist herbivores and a voracious group of pests that are difficult to control. This paper introduces some existing challenges in wireworm IPM, and discusses the potential impacts of various control methods on the rhizosphere. The awareness of the potential implications of different pest management approaches on the rhizosphere will assist in decision-making and the selection of the control tactics with the least long-term adverse effects on the rhizosphere.
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    Virginia Vegetable Specialist Team
    Reiter, Mark S.; Kuhar, Thomas P.; Lopez, Lorena; Mullins, Chris; Nartea, Theresa; Rideout, Steve; Singh, Vijay; South, Kaylee; Strawn, Laura K.; Torres Quezada, Emmanuel; Vallotton, Amber; Githinji, Leonard; Higgins, Doug; Zeng, Yuan; Rashed, Arash; Mersha, Zalalem; Gu, Sanjun (2023-03-15)
    Specialists on the Virginia Vegetable Team are committed to assisting growers, regardless of business size, with obtaining the freshest, highest quality, and most efficiently produced vegetables with the idea of safety and economic viability in mind. Please reach out to your local Cooperative Extension agent and/or vegetable team specialist to answer any vegetable related questions important to Virginia growers. Please click on the specialist’s name to be directed to their university’s webpage. The team routinely conducts applied research, presents information to growers and industry, publishes farmer friendly fact sheets, and works towards training Agriculture and Natural Resource (ANR) Extension agents and governmental employees through in-service trainings to ensure information is disseminated to the masses.