Mary A. Rogers

Plant Volatiles-based Insect Pest Management in Organic Farming

Organic agriculture is increasing in popularity worldwide due to the rapidly growing market for organic products. In organic production, insects present a major pest challenge that negatively impacts crop health and yield. To successfully manage an organic farmland, an effective insect pest management program is key. In this review, we first describe the approaches currently used for pest management in organic farming. Next, we review natural plant defense mechanisms, especially those based on plant volatile organic compounds. Chemically complex, plant volatiles have multiple ecological roles in plant-insect interactions including attracting pollinators, acting as cues for foraging herbivores as well as functioning as direct defense, indirect defense, or interplant priming. Based on the ecological roles of plant volatiles, we then discuss in-depth how pest management may be improved through a variety of strategies including using resistant cultivars, polyculture, using beneficial microorganisms such as mycorrhizal fungi and endophytes, and using plant-derived pesticides, all of which are reviewed in the context of plant volatiles. Lastly, integration of these different strategies based on the trait of plant volatiles for a successful and sustainable pest management program in organic farming is discussed.

Evaluation of high tunnels for management of Drosophila suzukii in fall-bearing red raspberries: Potential for reducing insecticide use

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is an invasive pest of soft-skinned fruit causing significant damage on a variety of fruit crops in North America, Europe, and Asia. In North America, fall-bearing fruit, such as primocane raspberries, ripen when D. suzukii populations peak and thus are vulnerable to high levels of infestation. In recent years, growers in northern climates have increased raspberry production under protected culture (high tunnels), resulting in season extension, increased yield, and improved fruit quality. High tunnels may be used as a pest management tool by physically excluding insect pests. This study investigated whether D. suzukii can be excluded from fall-bearing raspberries cultivated under tunnels covered with plastic or fine mesh netting, and whether this production technique can improve fruit marketability and serve as an alternative to insecticide application. We found that berries in plastic-covered tunnels had low season-long levels of infestation by D. suzukii (meanxa0=xa02xa0%), compared to netted tunnels (35xa0%), insecticide-treated open plots (60xa0%) and untreated open plots (81xa0%). Our microclimate data show that temperature and humidity levels inside the plastic-covered tunnels were often outside the previously published optimal temperature range for development, mating, and/or oviposition for D. suzukii, and may have therefore limited overall population growth. We conclude that exclusion and modification of microclimate may be effective and complementary pest management strategies for fall-fruiting raspberry and serve as an alternative to insecticide applications, particularly for small-acreage and organic production systems.

Soil-Applied Imidacloprid Translocates to Ornamental Flowers and Reduces Survival of Adult Coleomegilla maculata, Harmonia axyridis, and Hippodamia convergens Lady Beetles, and Larval Danaus plexippus and Vanessa cardui Butterflies

Integrated Pest Management (IPM) is a decision making process used to manage pests that relies on many tactics, including cultural and biological control, which are practices that conserve beneficial insects and mites, and when needed, the use of conventional insecticides. However, systemic, soil-applied neonicotinoid insecticides are translocated to pollen and nectar of flowers, often for months, and may reduce survival of flower-feeding beneficial insects. Imidacloprid seed-treated crops (0.05 mg AI (active ingredient) /canola seed and 1.2 mg AI/corn seed) translocate less than 10 ppb to pollen and nectar. However, higher rates of soil-applied imidacloprid are used in nurseries and urban landscapes, such as 300 mg AI/10 L (3 gallon) pot and 69 g AI applied to the soil under a 61 (24 in) cm diam. tree. Translocation of imidacloprid from soil (300 mg AI) to flowers of Asclepias curassavica resulted in 6,030 ppb in 1X and 10,400 ppb in 2X treatments, which are similar to imidacloprid residues found in another plant species we studied. A second imidacloprid soil application 7 months later resulted in 21,000 ppb in 1X and 45,000 ppb in 2X treatments. Consequently, greenhouse/nursery use of imidacloprid applied to flowering plants can result in 793 to 1,368 times higher concentration compared to an imidacloprid seed treatment (7.6 ppb pollen in seed- treated canola), where most research has focused. These higher imidacloprid levels caused significant mortality in both 1X and 2X treatments in 3 lady beetle species, Coleomegilla maculata, Harmonia axyridis, and Hippodamia convergens, but not a fourth species, Coccinella septempunctata. Adult survival were not reduced for monarch, Danaus plexippus and painted lady, Vanessa cardui, butterflies, but larval survival was significantly reduced. The use of the neonicotinoid imidacloprid at greenhouse/nursery rates reduced survival of beneficial insects feeding on pollen and nectar and is incompatible with the principles of IPM.

Fluctuations in airway bacterial communities associated with clinical states and disease stages in cystic fibrosis

Bacteria that infect the airways of persons with cystic fibrosis (CF) include a group of well-described opportunistic pathogens as well as numerous, mainly obligate or facultative anaerobic species typically not reported by standard sputum culture. We sequenced the V3-V5 hypervariable region of the bacterial 16S rRNA gene in DNA derived from 631 sputum specimens collected from 111 CF patients over 10 years. We describe fluctuations in the relative abundances of typical CF pathogens, as well as anaerobic species, in relation to changes in patients’ clinical state and lung disease stage. Both bacterial community diversity and the relative abundance of anaerobes increased during exacerbation of symptoms (prior to antibiotic treatment), although this trend was not observed uniformly across disease stages. Community diversity and the relative abundance of anaerobic species decreased during antibiotic treatment. These results support current hypotheses regarding the role of anaerobes in CF pulmonary exacerbations and lung disease progression.

Understanding Farmscapes and Their Potential for Improving IPM Programs

New pest management programs must strive to achieve sustained, improved crop production and profitable agriculture, while simultaneously conserving natural resources and protecting the environment. Redesigning farms to take advantage of natural biological control can improve the sustainability of integrated pest management programs. A technique common in this approach to pest management is farmscaping, which refers to the arrangement or configuration of plants that promote biological pest management by attracting and sustaining beneficial organisms. Farmscaping is an ecologically based, whole-farm approach to enhancing the efficacy and local abundance of arthropod natural enemies through modification of the environment. However, by adding these resources back to simplified agriculture systems, they provide numerous other ecosystem services such as erosion control, reduced runoff, esthetic benefits, increased revenue, nutrient management, pollination services, soil health, as well as improved pest suppression. Herein, we discuss the strategy of farmscaping, review the theory of how it can improve pest management, and discuss the practicalities and risks involved in incorporating farmscapes into integrated pest management programs.

Urban Agriculture as a Tool for Horticultural Education and Youth Development

Youth in urban areas often lack access to natural areas, and thus a connection to plants and the environment. Garden-enhanced learning and place-based learning has experienced renewed interest since the early 1990s, as a way to reconnect youth with the natural environment and to improve health outcomes. School gardens are typically found in urban areas and used to enhance science-based learning outcomes. School gardens and summer and after-school garden programs in urban areas can also be used to improve attitudes and preferences for fruits and vegetables, potentially increasing consumption and leading to positive health outcomes. A comprehensive review of the literature shows that youth gardens can reduce stress, improve attitudes toward school, facilitate collaboration and teamwork and intercultural awareness, improve peer relations and prosocial behavior, and improve self-efficacy and self-esteem. Evaluations of garden programs indicate that involving youth in higher-order responsibilities such as garden planning and decision-making results in higher levels of participation and leadership development. Most urban garden programs are targeted toward elementary and middle school ages, and fewer examples exist in the literature on high school programs, despite the evidence that this cohort can benefit from urban garden-based programs. Literature reviews report a need for more rigorous quantitative evaluation of garden-based programs connecting programmatic activities to positive outcomes that can be used to maximize benefits and inform policy. School gardens tend to be concentrated in high-resource schools and more needs to be done to bring these experiences to underserved schools.

Toxicity and efficacy of novel biopesticides for organic management of cucumber beetles on Galia muskmelons

Spotted (Diabrotica undecimpunctata howardi) and striped (Acalymma vittata) cucumber beetles are significant pests of cucurbits, and organic management options are limited. Beetle feeding results in aesthetic damage and reduction in marketable yields as well as transmission of bacterial wilt resulting in plant mortality. Biopesticides are formulated from naturally occurring organisms such as fungi and bacteria that are pathogenic or toxic to insect pests and may be used in organic production systems. These products are thought to have lower risk to non-target organisms including mammals and beneficial insects. This research examined the potential of novel microbial products and fungal organisms to reduce cucumber beetle damage on melons. Laboratory bioassays were performed to evaluate the efficacy of a bacterial extract of Chromobacterium subtsugae and two common strains of entomopathogenic fungi, Beauveria bassiana and Isaria fumosorosea, on cucumber beetles in a controlled environment. Trials were performed against adult beetles in organic field experiments on muskmelon (Cucumis melo L. cv. reticulatus Ser.). Prior to testing in the field, anti-feedant effects were observed when beetles were exposed to leaves with Chromobacterium subtsugae and Beauveria bassiana in the laboratory. However, in field applications, we did not observe a reduction in beetle populations below the economic threshold levels, and subsequently, there was no yield increase compared to the control. Additional research is needed to improve biopesticide efficacy through formulation and timing of delivery, determine efficacy on multiple life stages of the pest, and understand interactions of microbial biopesticides in the environment and potential for non-target impacts in organic systems.

Organic Vegetable Crop Production in Controlled Environments Using Soilless Media

Organic vegetables produced in greenhouses and other controlled environments may fill a unique market niche as consumers demand local, high vegetables year round. However, limited technical information supports these production systems and more research is needed to provide recommendations for appropriate substrate mixes and nutrient management. Compost can be used as a substitute for peat-based media, and research results vary widely based on feedstock, compost method, and proportion used in mixes. Most studies consider compost in terms of peat-substitute or replacement and not as a source of fertility in soilless systems. Common challenges in using compost in soilless media are due to immaturity of the compost, poor water holding capacity, and unbalanced salinity and pH. It is possible to certify organic soilless production systems; however, the National Organic Program (NOP) of the U.S. Department of Agriculture has not yet provided clear rules and requirements supporting these systems. The objective of this article is to review the literature on soilless organic vegetable production, summarize results from the more widely studied topic of vegetable transplant production, and point to future research for organic agriculture.

Erratum to: Special Issue of Spotted Wing Drosophila

Unfortunately, the special issue note has been missed in the original publication for 4 articles and has been incorrectly published in article