Mitigation of emerging implications of climate change on food production systems.

The use of microbial tools to sustainably increase agricultural production has received significant attention from researchers, industries and policymakers. Over the past decade, the market access and development of microbial products have been accelerated by (i) the recent advances in plant-associated microbiome science, (ii) the pressure from consumers and policymakers for increasing crop productivity and reducing the use of agrochemicals, (iii) the rising threats of biotic and abiotic stresses, (iv) the loss of efficacy of some agrochemicals and plant breeding programs and (v) the calls for agriculture to contribute towards mitigating climate change. Although the sector is still in its infancy, the path towards effective microbial products is taking shape and the global market of these products has increased faster than that of agrochemicals. Promising results from using microbes either as biofertilizers or biopesticides have been continually reported, fuelling optimism and high expectations for the sector. However, some limitations, often related to low efficacy and inconsistent performance in field conditions, urgently need to be addressed to promote a wider use of microbial tools. We propose that advances in in situ microbiome manipulation approaches, such as the use of products containing synthetic microbial communities and novel prebiotics, have great potential to overcome some of these current constraints. Much more progress is expected in the development of microbial inoculants as areas such as synthetic biology and nano-biotechnology advance. If key technical, translational and regulatory issues are addressed, microbial tools will not only play an important role in sustainably boosting agricultural production over the next few decades but also contribute towards other sustainable development goals, including job creation and mitigation of the impacts of climate change.

https://sfamjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/1751-7915.13866

Realities and hopes in the application of microbial tools in agriculture.

Impact of genetically modified crops on rhizosphere microorganisms and processes: A review focusing on Bt cotton

Colorado potato beetle, CPB (Leptinotarsa decemlineata Say), is one of the most important pests of the potato globally. Larvae and adults can cause complete defoliation of potato plant leaves and can lead to a large yield loss. The insect has been successfully suppressed by insecticides; however, over time, has developed resistance to insecticides from various chemical groups, and its once successful control has diminished. The number of available active chemical control substances is decreasing with the process of testing, and registering new products on the market are time-consuming and expensive, with the possibility of resistance ever present. All of these concerns have led to the search for new methods to control CPB and efficient tools to assist with the detection of resistant variants and monitoring of resistant populations. Current strategies that may aid in slowing resistance include gene silencing by RNA interference (RNAi). RNAi, besides providing an efficient tool for gene functional studies, represents a safe, efficient, and eco-friendly strategy for CPB control. Genetically modified (GM) crops that produce the toxins of Bacillus thuringiensis (Bt) have many advantages over agro-technical, mechanical, biological, and chemical measures. However, pest resistance that may occur and public acceptance of GM modified food crops are the main problems associated with Bt crops. Recent developments in the speed, cost, and accuracy of next generation sequencing are revolutionizing the discovery of single nucleotide polymorphisms (SNPs) and field of population genomics. There is a need for effective resistance monitoring programs that are capable of the early detection of resistance and successful implementation of integrated resistance management (IRM). The main focus of this review is on new technologies for CPB control (RNAi) and tools (SNPs) for detection of resistant CPB populations.

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Modern Techniques in Colorado Potato Beetle ( Leptinotarsa decemlineata Say) Control and Resistance Management: History Review and Future Perspectives

Since the discovery of RNA interference (RNAi) in the nematode worm Caenorhabditis elegans in 1998 by Fire and Mello et al., strides have been made in exploiting RNAi for therapeutic applications and more recently for highly selective insect pest control. Although triggering mRNA degradation in insects through RNAi offers significant opportunities in crop protection, the application of environmental naked dsRNA is often ineffective in eliciting a RNAi response that results in pest lethality. There are many possible reasons for the failed or weak induction of RNAi, with predominant causes being the degradation of dsRNA in the formulated pesticide, in the field or in the insect once ingested, poor cuticular and oral uptake of the nucleic acid and sometimes the lack of an innate strong systemic RNAi response. Therefore, in the last 10 years significant research effort has focused on developing methods for the protection and delivery of environmental dsRNA to enable RNAi-induced insect control. This review focuses on the design and synthesis of vectors (vehicles that are capable of carrying and protecting dsRNA) that successfully enhance mRNA degradation via the RNAi machinery. The majority of solutions exploit the ability of charged polymers, both synthetic and natural, to complex with dsRNA, but alternative nanocarriers such as clay nanosheets and liposomal vesicles have also been developed, see Fig. 1. The various challenges of dsRNA delivery and the obstacles in the development of well-designed nanoparticles that act to protect the nucleic acid are highlighted. In addition, future research directions for improving the efficacy of RNA-mediated crop protection are anticipated with inspiration taken from polymeric architectures constructed for RNA-based therapeutic applications.

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Recent Advances in Engineered Nanoparticles for RNAi-Mediated Crop Protection Against Insect Pests

Bacillus thuringiensis (Bt) crops are plants genetically engineered (modified) to contain the endospore (or crystal) toxins of the bacterium, Bt to be resistant to certain insect pests. In 1995, the Environmental Protection Agency (EPA) in USA approved the commercial production and distribution of the Bt crops: corn, cotton, potato, and tobacco. Currently, the most common Bt crops are corn and cotton. The crystal, referred to as Cry toxins, is proteins formed during sporulation of some Bt strains and aggregate to form crystals. Such Cry toxins are toxic to specific species of insects belongs to orders: Lepidoptera, Coleoptera, Hymenoptera, Diptera, and Nematoda. In 2016, the total world area cultivated with genetically modified crops (GM crops) reached about 185 million ha. This review shows that there is a worldwide controversy about the safety of Bt crops to the environment and mammals. Some researchers support the cultivation of Bt crops depending upon the results of their laboratory and field studies on the safety of such crops. Others, however, are against Bt crops as they may cause risk to human.

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Genetically engineered (modified) crops (Bacillus thuringiensis crops) and the world controversy on their safety

Some laboratory studies revealed that predators can readily attack and consume virus-infected prey with no detrimental effects on their biological parameters. Most tested predacious species did not discriminate between healthy and virus-infected prey. In addition, such predators were found to excrete detectable amounts of polyhedral inclusion bodies for few days that might infect healthy prey. Field studies demonstrated that the population densities and dispersal of the predators were not affected in fields sprayed with entomopathogenic virus formulations. Some laboratory studies stated that egg and larval parasitoids did not discriminate between healthy and virus surface-contaminated or virus-infected hosts. However, some parasitoids did not lay or laid few eggs in virus-infected hosts. Parasitoid adults that laid eggs in virus-infected host larvae could transmit the virus to healthy hosts through the ovipositor. Also, adult parasitoids emerged from virus-infected hosts transmitted the virus to healthy hosts whereas other parasitoids did not transmit the virus.

/pdf/interactions-between-baculoviruses-and-entomophagous-insects-3gpb6fkqqv.pdf

Interactions between baculoviruses and entomophagous insects

The interactions between insect pathogens, parasitoids, and predators have been proposed as “intraguild predation (IGP).” It occurs when two species share a host or prey (and therefore may compete) or when they engage in a trophic interaction with each other (parasitism or predation). Laboratory studies revealed that many predacious species attack and consume Bacillus thuringiensis (Bt)-infected prey with no detrimental effects on the biological parameters of the predators. However, some studies indicated adverse impact of Bt on development and biology of the predators. As for parasitoids, some studies showed no detrimental effects on the biology of the parasitoids when reared on Bt-infected hosts and others revealed negative effects on their biological aspects. Such negative effects were found to be related to Bt concentration and timing of treatment (parasitism or infection). The biological parameters of the offspring of the adult parasitoids that had emerged from infected parasitized larvae were not affected. Also, ingestion of Bt by adult parasitoids did not affect the longevity or fecundity of such parasitoids. Concerning Bt crops, a recent published report in 2019 stated that over the past 20+ years, extensive experience and insight have been gained through laboratory and field studies of non-target effects of crops producing Cry proteins. Overall, the vast majority of the studies demonstrated that the insecticidal proteins developed today do not cause adverse effects on natural enemies (parasitoids and predators) of target pests.

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Mohamed Samir Tawfik Abbas

Papers

Genetically engineered (modified) crops (Bacillus thuringiensis crops) and the world controversy on their safety

Interactions between baculoviruses and entomophagous insects

Interactions between Bacillus thuringiensis and entomophagous insects