Effect of nanoparticles and combinations with Beauveria bassiana on controlling fall armyworm, spodoptera frugiperda

Abstract

The polyphagous pest known as the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is emerging as one of the main threats to agricultural crop production. It has about 80 host species that seriously harm crops of vegetables and cereals. In North and South America, it is a significant pest of maize. It was first discovered in Africa in 2016 and has since spread to other parts of the globe and become a significant invasive pest of maize. The fall armyworm is extremely challenging to manage because of its capacity for rapid reproduction, migration, and feeding on a variety of host plants. Nowadays, many of the registered chemical pesticides are neurotoxic, which means that their fundamental mode of action interferes with the insects’ nervous system and some of which may pose risks to mammals, environmental contamination, and bioaccumulation. Moreover, the use of Beauveria bassiana an important and widely used microbial agent, is an entomopathogenic fungus that is used to control numerous significant pests. This species has a long history of use and is widely used commercially. Additionally, they have been applied to a wide range of host arthropods and are utilized globally. B. bassiana is used in agriculture to control a variety of insect pests, but it has not yet met the requirements for commercialization, primarily because some isolates are weak in their natural state, have a narrow host range, and have a low mortality rate. Hence, the use of B. bassiana could be improved if their infection and killing infecting and killing ability is enhanced. Nanotechnology is currently accepted in the world of pesticides and pest management, and it has the potential to revolutionize agricultural pest control technology. Moreover, nanotechnology has the potential to provide effective solutions for a variety of agricultural issues. Recently, the efficacy of several nanoparticles against medically and economically significant arthropod pests has been investigated. Nanoparticle use combination with entomopathogens to control insect pest is limited and poor data. To address the expanding challenges of yield loss and food security, this research seeks to (i) select nanotechnology that is effective on the digestive system, reproductive system, and life cycle of S. frugiperda, and (ii) study the interactive effects of nanotechnology in combination with B. bassiana to control S. frugiperda. Nanotechnology is urgent as a highly attractive field for agricultural research geared toward developing new "insect pest control nanoparticles." The first study was to determine the effect of zinc oxide nanoparticles against S. frugiperda under laboratory conditions. The results showed that ZnO NPs were diluted into different concentrations (100–500 ppm) in which baby corn was dipped to feed the S. frugiperda larvae. The development of the insect feeding on food dipped in ZnO solution was significantly (p 0.05) affected, the number of days it took to complete its life cycle when compared to the control. When all concentrations of ZnO NPs were compared to the control, there was a significant difference in adult emergence, with over 90% of the eggs successfully completing the cycle until adult emergence. Several malformations were also observed throughout the insect's lifecycle. Female fecundity was also significantly affected. The findings of this study suggest that ZnO nanoparticles could be used not only to eradicate S. frugiperda but also to significantly reduce its population in the ecosystem through body deformations, reduced fecundity, reduced oviposition, and decreased egg hatchability. The last study show that copper nanoparticles were characterized by using a scanning electron microscope (SEM) and energy dispersive X-ray (EDaX) analysis. The EDaX analysis results clearly show that the synthesized copper nanoparticles contain copper as the main element, and the SEM analysis results show nanoparticle sizes ranging from 29 to 45 nm. The CuO NPs showed remarkable larvicidal activity (97%, 94%, and 81% were observed on the 3rd, 4th, and 5th instar larvae, respectively). The CuO NPs produced high antifeedant activity (98.25%, 98.01%, and 98.42%), which was observed on the 3rd, 4th, and 5th instar larvae, respectively. CuO NPs treatment significantly reduced larval hemocyte levels 24 h after treatment; hemocyte counts and sizes changed in the CuO NPs treatment compared to the control. After 24 h of treatment with CuO NPs, the larval acetylcholinesterase enzyme levels decreased with dose dependent activity. All of the results demonstrate the potential of nanoparticles and their combination with entomopathogens to control fall armyworm and their impact on nontarget organisms; it demonstrated new strategies to control fall armyworm, showed alternative methods for farmers in IPM programs, and provided a new data base for scientists.