David Grzywacz

Bio: David Grzywacz is an academic researcher from University of Greenwich. The author has contributed to research in topics: African armyworm & Helicoverpa armigera. The author has an hindex of 14, co-authored 32 publications receiving 1454 citations.

Wolbachia in a major African crop pest increases susceptibility to viral disease rather than protects

Abstract: Wolbachia are common vertically transmitted endosymbiotic bacteria found in < 70% of insect species. They have generated considerable recent interest due to the capacity of some strains to protect their insect hosts against viruses and the potential for this to reduce vector competence of a range of human diseases, including dengue. In contrast, here we provide data from field populations of a major crop pest, African armyworm (Spodoptera exempta), which show that the prevalence and intensity of infection with a nucleopolydrovirus (SpexNPV) is positively associated with infection with three strains of Wolbachia. We also use laboratory bioassays to demonstrate that infection with one of these strains, a male-killer, increases host mortality due to SpexNPV by 6-14 times. These findings suggest that rather than protecting their lepidopteran host from viral infection, Wolbachia instead make them more susceptible. This finding potentially has implications for the biological control of other insect crop pests.

Quality control of fungal and viral biocontrol agents - Assurance of product performance

Abstract: An essential feature of the production of all microbial control agents is an effective quality control system. Well-defined product specifications with accompanying quality control procedures help to maximize product performance, ensure product safety, standardize manufacturing costs and reduce the risks of supply failure, thus building user confidence. A production system that does not have a quality control system is one whose output is uncontrolled and a lack of thorough quality feedback can result in batches of product with variable concentrations of active agent. This results in products with variable performance leading to control failures by users and serious loss of user confidence. Strict quality control procedures are not only essential for product consistency, but also for safety. Where quality control is inadequate, microbial contamination of the final product is inevitable. In most of such cases this will merely lead to a loss of efficacy due to dilution of the active ingredient by competing ...

The use of indigenous ecological resources for pest control in Africa

Abstract: Reducing the losses from crop pests will help to increase food availability and boost economic growth in sub- Saharan Africa (SSA). However, the existing crop protection paradigm that relies on synthetic agrochemical pesticides has had only a marginal impact on the productivity of many poor smallholder farmers who constitute a major segment of agri- culture in SSA. This is primarily because many of them are not able to afford or access these imported chemicals. A solution to this crop protection problem may be to harness biologicalresourcesthatarelocallyavailable,suchasendemic insect natural enemies and indigenous pesticidal plant mate- rials. Two specific examples of this already under develop- ment in Africa are the use of the pesticidal plant, Tephrosia vogelii, and the harvesting of the endemic insect baculovirus, Spodoptera exempta nucleopolyhedrovirus (SpexNPV). Both of these can be produced locally and have shown promise in trials as inexpensive and effective tools for pest control in Africa and their use is currently being scaled up and evaluated by African networks of researchers. A focus on these systems illustrates the potential for using locally-available natural re- sources for improved crop protection in Africa. The consider- ation of these pesticidal plants and insect natural enemies in the wider context of natural capital that provide valuable ecosystem services (including pest control), will facilitate greater recognition of their true economic and societal worth. While both of these model systems show promise, there are also very significant challenges to be overcome in developing production, supply and marketing systems that are economi- cally viableand sustainable.Theregulatoryenvironment must also evolve to accommodate and facilitate the registration of new products and the establishment of appropriate supply chains that share the benefits of these resources equitably with the local communities from which they are harvested.

Diamondback Moth Ecology and Management: Problems, Progress, and Prospects

Abstract: Agricultural intensification and greater production of Brassica vegetable and oilseed crops over the past two decades have increased the pest status of the diamondback moth (DBM), Plutella xylostella L., and it is now estimated to cost the world economy US$4–5 billion annually. Our understanding of some fundamental aspects of DBM biology and ecology, particularly host plant relationships, tritrophic interactions, and migration, has improved considerably but knowledge of other aspects, e.g., its global distribution and relative abundance, remains surprisingly limited. Biological control still focuses almost exclusively on a few species of hymenopteran parasitoids. Although these can be remarkably effective, insecticides continue to form the basis of management; their inappropriate use disrupts parasitoids and has resulted in field resistance to all available products. Improved ecological understanding and the availability of a series of highly effective selective insecticides throughout the 1990s provided ...

Metarhizium spp., cosmopolitan insect-pathogenic fungi: mycological aspects.

Abstract: Publisher Summary The chapter focuses on mycological aspects of the genus Metarhizium . The genus includes several species, varieties within species, and individual isolates with broad ranges of physiological traits—including host range. The interactions of these fungi with their hosts, and the large literature on their use for pest control, largely define the scientific and popular concepts of Metarhizium spp. Fungi of the hyphomycete genus Metarhizium have been isolated from infected insects and soil. Although some isolates of these fungi have rather restricted host ranges, the group is better known for its ability to kill a wide spectrum of insects, including insects in at least seven orders. The common name for Metarhizium -induced disease is “green muscardine,” based on the encrustation of insect cadavers with green conidia. The rapid increase in research on Metarhizium , followed by sustained high scientific output, can be explained by several important worldwide attitude changes and the initiation of several promising Metarhizium -based pest-control and molecular-biology efforts.

The amazing potential of fungi: 50 ways we can exploit fungi industrially

Abstract: Fungi are an understudied, biotechnologically valuable group of organisms. Due to the immense range of habitats that fungi inhabit, and the consequent need to compete against a diverse array of other fungi, bacteria, and animals, fungi have developed numerous survival mechanisms. The unique attributes of fungi thus herald great promise for their application in biotechnology and industry. Moreover, fungi can be grown with relative ease, making production at scale viable. The search for fungal biodiversity, and the construction of a living fungi collection, both have incredible economic potential in locating organisms with novel industrial uses that will lead to novel products. This manuscript reviews fifty ways in which fungi can potentially be utilized as biotechnology. We provide notes and examples for each potential exploitation and give examples from our own work and the work of other notable researchers. We also provide a flow chart that can be used to convince funding bodies of the importance of fungi for biotechnological research and as potential products. Fungi have provided the world with penicillin, lovastatin, and other globally significant medicines, and they remain an untapped resource with enormous industrial potential.

Long-range seasonal migration in insects: mechanisms, evolutionary drivers and ecological consequences

Abstract: Myriad tiny insect species take to the air to engage in windborne migration, but entomology also has its ‘charismatic megafauna’ of butterflies, large moths, dragonflies and locusts. The spectacular migrations of large day-flying insects have long fascinated humankind, and since the advent of radar entomology much has been revealed about high-altitude night-time insect migrations. Over the last decade, there have been significant advances in insect migration research, which we review here. In particular, we highlight: (1) notable improvements in our understanding of lepidopteran navigation strategies, including the hitherto unsuspected capabilities of high-altitude migrants to select favourable winds and orientate adaptively, (2) progress in unravelling the neuronal mechanisms underlying sun compass orientation and in identifying the genetic complex underpinning key traits associated with migration behaviour and performance in the monarch butterfly, and (3) improvements in our knowledge of the multifaceted interactions between disease agents and insect migrants, in terms of direct effects on migration success and pathogen spread, and indirect effects on the evolution of migratory systems. We conclude by highlighting the progress that can be made through inter-phyla comparisons, and identify future research areas that will enhance our understanding of insect migration strategies within an eco-evolutionary perspective.