Over the years, extensive use of commercially available synthetic pesticides against phytophagous insects has led to their bioaccumulation in the environment causing increased resistance and reduction in soil biodiversity. Further, 90% of the applied pesticides enter the various environmental resources as a result of run-off, exposing the farmers as well as consumers of the agricultural produce to severe health issues. Therefore, growing attention has been given toward the development of alternate environmentally friendly pesticides/insecticides that would aid an efficient pest management system and also prevent chronic exposures leading to diseases. One such strategy is, the use of neem plant's (Binomial name: Azadirachta indica) active ingredients which exhibit agro-medicinal properties conferring insecticidal as well as immunomodulatory and anti-cancer properties. The most prominent constituent of neem is azadirachtin, which has been established as a pivotal insecticidal ingredient. It acts as an antifeedant, repellent, and repugnant agent and induces sterility in insects by preventing oviposition and interrupting sperm production in males. This review discusses, key neem pesticidal components, their active functional ingredients along with recent strategies on employing nanocarriers, to provide controlled release of the active ingredients and to improve their stability and sustainability.

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Progress on Azadirachta indica Based Biopesticides in Replacing Synthetic Toxic Pesticides.

Microbial control in integrated pest management (IPM) programs of coffee plantations is an important factor for the reduction of pest population densities. The use of selective pesticides can be associated with entomopathogens, increasing the efficiency of the control and reducing the use of required insecticides. The in vitro fungitoxic effect of insecticide formulations of Thiamethoxam, Cyfluthrin, Deltamethrin, Alpha-Cypermethrin, Triazophos, Chlorpyrifos, Fenpropathrin and Endosulfan and Beauveria bassiana (CG 425 strain) was evaluated at three concentrations (FR = average field recommendation; 0.5 ´ FR and 2 ´ FR). Effects of these products on conidia germination, vegetative growth and sporulation were compared. Only five insecticides, at the FR concentration, promoted conidia viability higher than 60%. Viability should be considered the most important factor to be evaluated since it is the first step of the infection process. The insecticide formulations of Alpha-Cypermethrin, Thiamethoxam and Cyfluthrin caused the lower inhibition level on conidia germination at the two lower concentrations, with no difference in relation to the control. With respect to vegetative growth analysis, Thiamethoxam at the two lower concentrations was not found to cause radial growth inhibition. Thiamethoxam caused the smallest inhibition level with regard to conidia production. The use of Alpha-Cypermethrin and Thiamethoxam formulations in coffee IPM programs for a B. bassiana inoculum conservation strategy are recommended, since these products were compatible with the entomopathogenic fungus Beauveria bassiana (CG 425), an important natural control agent of the coffee berry borer, Hypothenemus hampei.

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Compatibility between the entomopathogenic fungus Beauveria bassiana and insecticides used in coffee plantations

Entomopathogenic fungi (EPF) are microorganisms that cause fatal diseases of arthropods. The infection process involves several stages that consist of direct contact of the fungus with the surface of the cuticle of the attacked insect. The factors that determine the effectiveness of the infection process include lytic enzymes, secondary metabolites, and adhesins produced by EPF. Because of their high insecticidal effectiveness, these fungi are commonly used as biopesticides in organic farming. As the environment and farmlands are contaminated with many compounds of anthropogenic origin (e.g., pesticides), the effects of these toxic compounds on EPF and the mechanisms that affect their survival in such a toxic environment have been studied in recent years. This review presents information on the capacity of EPF to remove toxic contaminants, including alkylphenols, organotin compounds, synthetic estrogens, pesticides and hydrocarbons. Moreover, these fungi produce numerous secondary metabolites that can be potentially used in medicine or as antimicrobial agents. Despite their huge potential in biocontrol processes, the use of EPF has been underestimated due to a lack of knowledge on their abilities. In our work, we have presented the available data on the possibilities of the additional and unconventional use of these microorganisms.

https://link.springer.com/content/pdf/10.1007/s11157-020-09525-1.pdf

Entomopathogenic fungi: unconventional applications

Entomopathogenic fungi are microorganisms that specifically infect and often kill insects and other arthropods. Most are nonpathogenic to plants, and relatively non-toxic to humans and animals. Though fungus-infected insects can be commonly found in nature, and epizootics are observed impacting pest populations, mortality from fungal infection rarely occurs naturally at sufficiently high levels or early enough in a pest cycle to prevent economic loss. Despite their many advantages over other biological and chemical products, entomopathogenic fungi remain relatively underutilized. Experience has taught growers, pest managers, researchers and policy makers that rarely does one silver bullet solve a pest problem. A multi-faceted approach combining all available integrated pest management (IPM) tools into a comprehensive strategy has a better potential to suppress pests below economically damaging levels. With increased commercialization, entomopathogenic fungi are poised to become a significant component of IPM. This chapter reviews these promising microbial agents, and factors that contribute to their success and failure under field conditions. It also describes two agricultural scenarios where entomopathogenic fungi are or could become an integral component of IPM.

Role of Entomopathogenic Fungi in Integrated Pest Management

The compatibility of a commercial formula of emulsible neem oil (Azadirachta indica A. Juss.) and of aqueous extracts of neem seeds and leaves with Beauveria bassiana (Bals.) Vuill. was evaluated in vitro. Three experiments were conducted to evaluate the effect of each product on the fungus vegetative growth and on conidia production and viability. The products were incorporated to a culture medium (BDA+E) and distributed into petri dishes, in the following concentrations: 0.15%; 1.5% and 15% (leaf aqueous extract), 1%; 2% and 4% (seed aqueous extract) and 0.5%; 1% and 1.5% (emulsible oil). Vegetative growth and conidia production were the basis for characterization of the aqueous extracts of seeds and leaves and of the emulsible oil, using the T classification model for compatibility of products. Seed and leaf extracts were less harmful to B. bassiana than the emulsible oil. Under the tested concentrations, the oil was not compatible with B. bassiana, inhibiting conidia vegetative growth significantly and decreasing production and viability of conidia, particularly at higher concentrations. Neem seed and leaf extracts were compatible with the entomopathogen in all concentrations. The seed extracts reduced conidia vegetative growth and production, but it did not affect the viability of spores. Leaf extract at 15% had a small negative impact on vegetative growth, and on production and viability of conidia, but it was still compatible with the fungus B. bassiana, according to the T model.

http://www.scielo.br/pdf/ne/v34n4/25817.pdf

Compatibility of the fungus Beauveria Bassiana (Bals.) Vuill. (Deuteromycetes) with extracts of neem seeds and leaves and the emulsible oil

The in vitro fungitoxic effect of three biofertilizers, E.M.-4, Multibion O and Supermagro used in organic agriculture and the neem oil (Azadirachta indica A. Juss) on the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana was studied. These products were mixed in a medium where the two fungi were inoculated, and germination, vegetative growth and conidiogenesis were assessed. The biofertilizers Supermagro and E.M.- 4 showed to be less toxic for the two fungi whereas MultibionO caused major inhibition on M. anisopliae, with reductions in germination (-37.74%), colony diameter (-30.26%) and conidiogenesis (-42.62%). Neem oil promoted a larger negative effect on B. bassiana, inhibiting germination (-45.27%), colony diameter (-36.62%) and conidiogenesis (-84.93%).

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Cristiane H. Peralta

Papers

Effect of Biofertilizers and Neem Oil on the Entomopathogenic Fungi Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok