scholarly journals Microbial Toxins in Insect and Nematode Pest Biocontrol

2021 ◽  
Vol 22 (14) ◽  
pp. 7657
Author(s):  
Subbaiah Chalivendra

Invertebrate pests, such as insects and nematodes, not only cause or transmit human and livestock diseases but also impose serious crop losses by direct injury as well as vectoring pathogenic microbes. The damage is global but greater in developing countries, where human health and food security are more at risk. Although synthetic pesticides have been in use, biological control measures offer advantages via their biodegradability, environmental safety and precise targeting. This is amply demonstrated by the successful and widespread use of Bacillusthuringiensis to control mosquitos and many plant pests, the latter by the transgenic expression of insecticidal proteins from B. thuringiensis in crop plants. Here, I discuss the prospects of using bacterial and fungal toxins for pest control, including the molecular basis of their biocidal activity.

Author(s):  
Sean D. Moore

Thaumatotibia leucotreta, known as the false codling moth, is a pest of citrus and other crops in sub-Saharan Africa. As it is endemic to this region and as South Africa exports most of its citrus around the world, T. leucotreta has phytosanitary status for most markets. This means that there is zero tolerance for any infestation with live larvae in the market. Consequently, control measures prior to exporting must be exemplary. Certain markets require a standalone postharvest disinfestation treatment for T. leucotreta. However, the European Union accepts a systems approach, consisting of three measures and numerous components within these measures. Although effective preharvest control measures are important under all circumstances, they are most critical where a standalone postharvest disinfestation treatment is not applied, such as within a systems approach. Conventional wisdom may lead a belief that effective chemical control tools are imperative to achieve this end. However, we demonstrate that it is possible to effectively control T. leucotreta to a level acceptable for a phytosanitary market, using only biological control tools. This includes parasitoids, predators, microbial control, semiochemicals, and sterile insects. Simultaneously, on-farm and environmental safety is improved and compliance with the increasing stringency of chemical residue requirements imposed by markets is achieved.


Author(s):  
Yu-Lan Wang ◽  
Kuo-Sheng Fan ◽  
Hui-Ju Tsai ◽  
Chin-Yu Cheng ◽  
Chia-Kai Tang ◽  
...  

Background: A probable outbreak of respiratory disease in a nursing home serving exclusively patients in a persistent vegetative state (PVS) resulted in hospitalization of eight patients. Methods: Microbes from all PVS patients’ respiratory tracks and environments were surveyed by microbiological methods. Major pathogenic microbes were analyzed by pulsed-field gel electrophoresis (PFGE). Results: 24 PVS patients were investigated. Half were colonized with at least four different pathogenic microbes in their respiratory tracts. The most prevalent microbes were Pseudomonas aeruginosa in 15 patients (62.5%), Serratia marcescens in 14 (58.3%), Citrobacter koseri in nine (37.5%), Streptococcus pneumoniae in six (25%), and Proteus mirabilis in five (20.8%). By PFGE analysis, one major pulsotype each was identified for S. marcescens (92.9%, 13/14) and S. pneumoniae (100%, 6/6), whereas diverse pulsotypes were identified for P. aeruginosa, C. koseri, and P. mirabilis. Both major pulsotypes for S. marcescens and S. pneumoniae were also found in strains from patients outside the nursing home. No environmental reservoir was found for prevalent microbes. Conclusions: Clonal transmission of S. marcescens and S. pneumoniae among PVS patients in the nursing home was evident, indicating a need to enforce control measures to reduce threats to this type of facility.


2020 ◽  
Vol 33 (2) ◽  
pp. 328-335 ◽  
Author(s):  
Joram A. Dongus ◽  
Deepak D. Bhandari ◽  
Monika Patel ◽  
Lani Archer ◽  
Lucas Dijkgraaf ◽  
...  

Plants have evolved mechanisms to protect themselves against pathogenic microbes and insect pests. In Arabidopsis, the immune regulator PAD4 functions with its cognate partner EDS1 to limit pathogen growth. PAD4, independently of EDS1, reduces infestation by green peach aphid (GPA). How PAD4 regulates these defense outputs is unclear. By expressing the N-terminal PAD4 lipase-like domain (PAD4LLD) without its C-terminal EDS1-PAD4 (EP) domain, we interrogated PAD4 functions in plant defense. Here, we show that transgenic expression of PAD4LLD in Arabidopsis is sufficient for limiting GPA infestation but not for conferring basal and effector-triggered pathogen immunity. This suggests that the C-terminal PAD4 EP domain is necessary for EDS1-dependent immune functions but is dispensable for aphid resistance. Moreover, PAD4LLD is not sufficient to interact with EDS1, indicating the PAD4-EP domain is required for stable heterodimerization. These data provide molecular evidence that PAD4 has domain-specific functions.


2020 ◽  
Vol 7 ◽  
Author(s):  
Ângelo J. Mendes ◽  
Daniel T. Haydon ◽  
Emma McIntosh ◽  
Nick Hanley ◽  
Jo E. B. Halliday

This paper aims to illustrate the interdependencies between key epidemiological and economic factors that influence the control of many livestock infectious diseases. The factors considered here are (i) farmer heterogeneity (i.e., differences in how farmers respond to a perceived disease risk), (ii) off-farm effects of farmers' actions to control a disease (i.e., costs and benefits borne by agents that are external to the farm), and (iii) misalignment between privately and socially optimal control efforts (i.e., privately optimal behavior not conducive to a socially optimal outcome). Endemic chronic diseases cause a wide range of adverse social and economic impacts, particularly in low-income countries. The actions taken by farmers to control livestock diseases minimize some of these impacts, and heterogeneity in those actions leads to variation in prevalence at the farm level. While some farmers respond to perceived disease risks, others free-ride on the actions of these individuals, thereby compromising the potential benefits of collective, coordinated behavior. When evaluating a plausible range of disease cost to price of control ratios and assuming that farmers choose their privately optimal control effort, we demonstrate that achievement of a socially optimal disease control target is unlikely, occurring in <25% of all price-cost combinations. To achieve a socially optimal disease control outcome (reliant on farmers' voluntary actions), control policies must consider farmer heterogeneity, off-farm effects, and the predicted uptake of control measures under the assumption of optimized behavior.


Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2898
Author(s):  
Alberto Galisteo Pretel ◽  
Helena Pérez del Pulgar ◽  
Estela Guerrero de León ◽  
José Luis López-Pérez ◽  
A. Sonia Olmeda ◽  
...  

Currently, the use of synthetic pesticides is the main method of plant protection applied in agri- and horticulture. However, its excessive use leads to the development of pesticide resistance, a contamination of the environment, toxicity to non-target organisms, and risks for human health. With the ultimate aim of contributing to the develop of a more sustainable pest management, we used the natural product germacrone (compound 1), reported to possess significant insecticidal activity, as starting material for the generation of molecular diversity (2–24). Some of the generated derivatives are natural compounds, such as 1,10-epoxygermacrone (2), 4,5-epoxygermacrone (3), gajutsulactone A (7), germacrol (11), isogermacrone (14), 9-hydroxyeudesma-3,7(11)dien-6-one (19), eudesma-4,7(11),dien-8-one (20), eudesma-3,7(11)-dien-8-one (21) and eudesma-4(15),7(11)-dien-8-one (22). Compounds, 7,11-9,10-diepoxigermacr-4,5-en-8-ol (17), 7,11-epoxieudesma-4,7(11)-dien-8-one (23) and 7,11-epoxieudesma-3,7(11)-dien-8-one (24) are described for the first time. The biocidal activity of most of these compounds was assayed against the tick Hyalomma lusitanicum. The acaricidal effects of compound 24 were four times higher than that of germacrone (1). Compound 2 is an insect antifeedant a thousand times more potent than germacrone against Rhopalosiphum padi, which makes this substance a promising selective antifeedant against this cereal pest.


2012 ◽  
Vol 518-523 ◽  
pp. 1040-1044
Author(s):  
Jian Lin Xu ◽  
Guo Qiang Xi ◽  
Yong Bo Jiang ◽  
Jia Wang ◽  
Yu Fan Zhang ◽  
...  

With the continuous development of superfine powder industry and the application scope, the environmental safety of superfine powder preparation has been getting more and more attention. This article discusses the possible pollution source causing hazards to environmental safety and put forwards some corresponding control measures by analyzing the production factors in the process of super fine power preparation.


2012 ◽  
Author(s):  
Jessica Page ◽  
Paul Horne

Controlling Invertebrate Pests in Agriculture discusses the principles of pest management and relates this to historical methods as well as current and future directions. It describes current practice, the concept of agricultural ecosystems, the role of pesticides and cultural control options. A separate chapter covers biological control and the different ways in which this may be implemented. The book provides a detailed examination of the application of pesticides, the different types that are available and how they may be integrated into more holistic approaches. A summary of all available pest control measures is given to allow the reader to decide which approach is best to adopt. The authors clearly describe why the most ecologically sound methods are not always adopted, but also explain why they can be adopted with great success. Examples of successful implementation of Integrated Pest Management are highlighted, together with a discussion on what is required in the future to achieve successful control of pests in a sustainable manner.


2021 ◽  
Vol 24 (2) ◽  
pp. 192-196
Author(s):  
P. D Halle ◽  
M. A. Raji ◽  
N. D. G. Ibrahim

A ten-year (1986 - 1995) record of necropsy report on diagnosed livestock diseases in Zaria, Kaduna State is evaluated to determine the prevalence and seasonal occurrence of the major livestock diseases in the Northern part of Nigeria. A total 1093 animals comprising 132 cattle, 240 goat 318 shell, 20 horses, 47 pigs and 336dogs were examined at necropsy. Some diseases such as cowdriosis, Pneumonia, Ectoparasitism, and Haemonchosis showed seasonal fluctuation while others like Babesiosis, Trypanosomiasis and physical injuries were evenly distributed throughout the year. The major problem of livestock in Zaria was Pneunonia (247 cases) with a seasonal occurrence of 38.6% and 61.31% for the dry and rainy seasons respectively. During the rainy season, cowdriosis (17.42%) in cattle, Pneumonia (25.0%, 21.10% and 20.0%) in goats, sheep and horses; gastroenteritis (14.89%) and starvation/malnutrition (14.89%) in pigs and rabies (8.93%) in dogs were the major problems. Starvation/malnutrition (4.17%) in Goats and gastroenteritis (12.5%) were more prevalent during the dry season. The relevance during of this report to effective control measures for the livestock resources in Nigeria is also highlighted.


2020 ◽  
Author(s):  
Robin A. Choudhury ◽  
Neil McRoberts

AbstractCalifornia spinach growers struggle to manage spinach downy mildew disease. The disease is especially difficult in the organic crop, which currently relies on resistant varieties to maintain disease-free crop. Alternative control measures are available, but it is not clear how growers perceive the efficacy of these methods. It is also not clear who growers contact to find out information on spinach downy mildew disease management. In this study, we conducted an online survey of people involved in spinach production, asking about their beliefs in the efficacy of different control methods and who they contact frequently to discuss spinach downy mildew control. We found that respondents were most positive about the efficacy of resistant varieties and synthetic pesticides, with much lower perceived efficacy for the practices of disking diseased fields, roguing diseased plants, and organic pesticides. Growers most frequently contacted pest control advisors (PCAs) about management strategies for spinach downy mildew. These results suggest that respondents are most confident about the efficacy of resistant varieties and synthetic pesticides and may be hesitant to adopt new control strategies like organic pesticides. The results also suggest that future extension efforts can be focused on PCAs to reach the most stakeholders with up to date research on downy mildew control.


Insects ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 846
Author(s):  
Darka Hamel ◽  
Vlatka Rozman ◽  
Anita Liška

At a time when there is much talk of reducing pesticide use and the implementation of integrated pest management, mainly in fields and glass-houses, it is appropriate to consider how cereals in storage are handled and what measures are taken to protect them against insects and other pests. For decades, the use of various synthetic pesticides has been the basis for the proper and long-term storage of cereals, primarily free of insects and mites, but also fungi and their mycotoxins and rodents. However, due to the registered negative effects of synthetic pesticides, such as dichloro-diphenyl-trihloroethane (DDT) or methyl bromide, on human health and the environment, and the appearance of resistance to, e.g., malathion, researchers have been looking for new acceptable control measures. Due to the proven and published non-acceptable data regarding synthetic pesticide effects, a combination of physical, mechanical, and biological measures with the minimal use of synthetic pesticides, under the name of integrated pest management, have been promoted. These combinations include high and low temperatures; the removal of dockages; and the application of pheromones, diatomaceous earth, and natural compounds from various plants, as well as inert gases, predators, and parasites. A ban of any synthetic pesticide usage is currently being considered, which emphasizes the fact that protection should only be performed by measures that do not leave harmful residues. However, the facts show that the application of physical, mechanical, and/or biological measures, besides the fact that they are not necessarily efficient, is very demanding because more knowledge and experience is required, as well as better equipment, greater financial investment, and awareness raising not only for agricultural producers and storage keepers, but also for consumers. In order to use these measures, which are less hazardous to humans and the environment, it is necessary to adapt regulations not only to speed up the registration protocols of low-risk pesticides, but also to prescribe criteria for placing agricultural products on the market, as well as quality standards, i.e., the permitted number of present insects, in addition to their parts in certain types of food. Additionally, we should be aware of control measures for protecting novel food and other non-traditional foods. It is important to continue to combine different protection measures, namely integrated pest management, until all of the other new procedures that must be carried out during the period of storing cereals and other products are clear, in order to ensure the best quality of final products for consumers.


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