Sarayut Pittarate,Vivekanandhan Perumal,Swathy Kannan,Supamit Mekchay,Malee Thungrabeab,Piyawan Suttiprapan,Senthil-Nathan Sengottayan,Patcharin Krutmuang
Insecticidal efficacy of nanoparticles against Spodoptera frugiperda (J.E. Smith) larvae and their impact in the soil
Botanical toxicity,Nanotechnology,Insecticide,Spodoptera frugiperda (J.E. Smith),Insect pest management,Entomopathogenic fungi
The present study aims to evaluate the different nanoparticles (Cu NPs, KI NPs, Ag NPs, Bd NPs, and Gv NPs) against 4th instar Spodoptera frugiperda larvae as well as the microbial toxicity, phytotoxicity, and soil pH. Nanoparticles were tested at three concentrations (1000, 10000, and 100000 ppm) using two methods (food dip and larvae dip) against S. frugiperda larvae. Results (from the larval dip method) showed that among the nanoparticles, the KI NPs caused 63%, 98%, and 98% mortality within 5 days in the treatment of 1000, 10000, and 100000 ppm, respectively. After 24 h post treatment, a 1000 ppm concentration showed 95%, 54%, and 94% germination rates in Metarhizium anisopliae, Beauveria bassiana, and Trichoderma harzianum, respectively. The phytotoxicity evaluation clearly showed that NPs did not affect the morphology of the corn plants after the treatment. The soil nutrient analysis results showed that no effect was observed in soil pH or soil nutrients compared to control treatments. The study clearly showed that nanoparticles are caused toxic effect against S. frugiperda larvae.
Insecticidal efficacy of nanoparticles against Spodoptera frugiperda (J.E. Smith) larvae and their impact in the soil

The present study aims to evaluate the different nanoparticles (Cu NPs, KI NPs, Ag NPs, Bd NPs, and Gv NPs) against 4th instar Spodoptera frugiperda larvae as well as the microbial toxicity, phytotoxicity, and soil pH. Nanoparticles were tested at three concentrations (1000, 10000, and 100000 ppm) using two methods (food dip and larvae dip) against S. frugiperda larvae. Results (from the larval dip method) showed that among the nanoparticles, the KI NPs caused 63%, 98%, and 98% mortality within 5 days in the treatment of 1000, 10000, and 100000 ppm, respectively. After 24 h post treatment, a 1000 ppm concentration showed 95%, 54%, and 94% germination rates in Metarhizium anisopliae, Beauveria bassiana, and Trichoderma harzianum, respectively. The phytotoxicity evaluation clearly showed that NPs did not affect the morphology of the corn plants after the treatment. The soil nutrient analysis results showed that no effect was observed in soil pH or soil nutrients compared to control treatments. The study clearly showed that nanoparticles are caused toxic effect against S. frugiperda larvae.

Pest damage to agricultural food grains and cereals has been getting worse over the last few decades, which has raised concerns about the level of production. Fall armyworm (FAW) (Spodoptera frugiperda, J. E. Smith, 1797) is a serious insect pest in recent years, causing damage to more than 350 plant species in different families and with yield losses of up to 70% in maize fields [[1], [2], [3], [4], [5], [6], [7], [8]]. The insect has been reported as an invasive pest in many parts of Africa and Asia, and it is one of Thailand's most dangerous pests on many agricultural crops. More recently, this insect has been causing most of its damage to economically important cultivated cereals. It is likely to become endemic because of climate change and the large number of suitable host plants that allow the pest to have multiple generations in one season [9,10]. The FAW is the major pest of maize in Brazil, causing annual losses of US $400 million [11,12]. This pest has recently invaded and spread rapidly in many countries, including on the African continent, and has become a serious pest, causing severe damage to maize crops and other graminaceous crops [9], threatening the food security of millions of people. FAW is a polyphagous Lepidopteran pest from Brazil with a host range of 353 plant species from 76 plant families, including the Poaceae, Asteraceae, and Fabaceae [11]. Over 30 countries, including island nations, have identified the pest within their borders. Maize yield losses ranged from 8.3 million to 20.6 million metric tonnes per year across 12 maize-producing countries. The fall armyworm attacks maize crops from emergence through tasseling, silking, and cob formation. This pest can reduce corn grain yield by up to 34% and is estimated to cost Brazil $400 million per year [7,8]. Abrahamset al. [13] reported that FAW can cause corn, rice, and sorghum crop losses of up to US $13 billion per annum. Despite the fact that there are numerous available alternative methods, insect pest control is still largely based on the use of chemical pesticides, in the sense of organic chemical-based ingredients that are on crop fields [14,15]. Chemical pesticides have been the most commonly used weapons for insect pest control in plants since 1940 because they are the most effective, providing relatively quick and uncomplicated application and good effects. But using the same or different types of chemical pesticides over and over again has a number of unintended effects on non-target species, such as humans, who store the chemicals in food chains and make it possible for insect pests to become resistant to insecticides [16]. The majority of these issues have arisen as a result of excessive pesticide use. In the case of S. frugiperda, the larvae are “protected” by the plant's inner leaves, which are usually covered with larval excrement, making contact with the insecticide or pesticide problematic. As a result, farmers must apply the pesticide early in the planting season, almost directly on the ground or with granules directly on the plant bud. S. frugiperda resistance has developed as a result of the frequent overuse of chemical substances in these management tactics. When compared to vulnerable insects, Carvalho et al. [17] discovered S. frugiperda strains in Brazil that were 18- to 28-fold resistant to organophosphate and pyrethroid pesticides. Because of this, the repeated usage of different types of chemicals has increased in day by day, resulting in insecticide resistance to chemicals such as DDT, cyclodiene organophosphates, carbamates, and pyrethroids [[18], [19], [20]]. Many of the registered chemical pesticides used today are neurotoxic and cause skin allergies. This means that their main way of working is to mess with the nervous systems of insects. Some of these pesticides may be harmful to mammals, pollute the environment, and build up in the food chain [21]. Nanotechnology (NPs): Metal ions are reduced into nanoparticles with the help of biologically derived chemical constituents or chemical elements. As a results of the novel pest-resistive concepts and high-tech insect pest management strategies, new insect pest control strategies are required. Baruah and Dutta [22] say that the only way to deal with limited land, water resources, weather conditions, and pests in agriculture is to use modern technology to boost productivity. Nanoparticles are characterised based on their size, shape, and surface area of under 100 nm [21,23]. Many studies have looked into the effectiveness of various nanoparticles against medically, publicly, and economically significant arthropod pests, such as the dipterans Aedes aegypti and Hippobosca maculata [[24], [25], [26]]. Coleopterans: Tribolium castaneum, Sitophilus oryzae [27,28], Lepidopterans: Plutella xylostella, Spodoptera litura [[29], [30], [31], [32], [33]] and other Arthropods: Haemaphysalis bispinosa [24]. Nanoparticles are being employed as fertilisers, plant growth stimulants, insecticides, antibacterial agents, pesticides, and pesticide transporters. Because of the possible negative impacts of employing nanoparticles in agriculture, the phytotoxicity of nanoparticles is relatively low. Although nanosensors and nanoparticles that mediate gene transfer in plants are being studied for agricultural applications. The vast majority of nano-formulations are employed in the control of various insect pests. Nano-formulations are various formulations containing nanometer-sized components such as organic polymers or inorganic metal oxides [34]. The primary goals of nano-pesticide formulations are: (a) increasing the solubility of poorly soluble active ingredients (a.i.) or (b) achieving gradual, targeted release of the a.i. and/or protecting the a.i. from premature degradation [35]. Metals, metal oxides, nonmetal oxides, carbon, silicates, ceramics, clays, layered double hydroxides, polymers, lipids, dendrimers, proteins, and other natural or synthetic particles are utilized in the production of nanoparticles [36]. Polymeric nanoparticles are used in the formulation of controlled-release nanostructured systems [37]. Recently, they have been employed for pesticide delivery when the active chemicals are loaded with polymers in the nano range of 1–100 nm [38]. Nano-emulsions, nanoparticles, and nano capsules are the most popular nano-based insecticides and currently used in integrated pest management. Other common nano systems in insect pest management include nanogel, nanosphere, and nanosuspension. “Nano-encapsulation” refers to the coating of various compounds within another material at varying sizes in the nano-range, through which a chemical is slowly yet efficiently released [39]. Individual particles or droplets of solid or liquid core material are encircled or covered by a continuous coating of polymeric material during the nanoencapsulation process. This ensures that the pesticide is only released in the desired environment, such as at a specific pH (e.g., in the stomach or inside a cell), temperature, wetness, external ultrasonic frequency, or the presence of other chemicals [40]. Guan et al. [41] say that nano-capsules have a higher release rate than microcapsules because smaller materials have larger surface areas that are exposed to the environment. This is the most important way to protect plants from insect infestations and a very effective way to get rid of insect pests. Entomopathogens are parasitic microorganisms, such as fungi, that may infect and kill arthropods. Metarhizium sp., Beauveria sp., Isaria sp., Ophiocordyceps sp., Cordyceps sp., Torubiella sp., Pochonia sp., Hirsutella sp., Paecilomyces sp., Trichoderma sp., and Lecanicillium are the taxa that have been studied the most and are used most often in agriculture [7,25]. Several previous studies clearly showed that nanoparticles have a strong insecticidal, fungicidal, bactericidal, anti-feeding, and fecundity-inhibitory effect on a variety of insect species [42]. The present studies aim to (1) examine the efficiency of nanoparticles against larvae of Spodoptera frugiperda. And (2) the nanoparticles toxic efficacy was evaluated on corn plants, beneficial fungi, and soil.

This study was conducted in the Laboratory of Insect Pathology, Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai, Thailand. This area is mostly plain, with an altitude of 311 m above sea level at a longitude of 98.97°E and a latitude of 18.77°N.

The FAW colony used in this experiment was taken from a corn field at the Mae-Hia Agricultural Training and Research Center, Faculty of Agriculture, Chiang Mai University, Thailand (98.97°E, 18.77°N). This colony has been maintained in laboratory conditions for more than five generations. In this experiment, larvae were fed fresh corn (microbial infection-free) and reared in the laboratory condition at a temperature of 26 ± 1 °C. A relative humidity of 70%, and a photoperiod of 12:12 h (dark: light) were maintained.

Pure nanoparticles (Table 1, Cu = copper nanoparticles, KI = potassium nanoparticles, Ag = silver nanoparticles, Bd, betadine nanoparticles and Gv = Gentian violet nanoparticles) were purchased from the Chiang Mai University, Thailand, and analysed in the laboratory of the Central Laboratory, Faculty of Agriculture, Chiang Mai University, Chiang Mai, Thailand. Describe the particle size completely through a scanning electron microscope (SEM) (unpublished research). The two nanoparticles Bd and Gv are popular and strong inhibitors of bacterial and fungal growth.

The effects of commercial NPs were investigated for insecticidal activity against the fourth instar larvae of FAW. The larvae were transferred into a plastic container containing one piece of baby corn (1 × 1 cm). Then three different concentrations of NPs solutions (1000, 10000, and 100000 ppm) were prepared in 1% dimethyl sulfoxide (DMSO) solution for the larvicidal efficacy test. Thirty larvae were used for each concentration, with each concentration having three replications. Food baby corn was dipped into the various concentrations of nanoparticles (Cu, KI, Ag, Bd, and Gv) until it was uniformly covered. Dipping food and changing it every day. The insect larvae were dipped in nanoparticle solution for 3 s. Every day, dip insects in the nanoparticle solutions. The negative control groups were dipped in distilled water (nanoparticle-free). The results were recorded at 1, 3, 5 and 7 days post treatment.

In phytotoxicity assays, there are no particular test criteria for nanotoxicity. As a result, EPA48 or OECD49 chemical testing directives from the United States are now employed for this phytotoxicity assay. Phytotoxicity studies are performed on young maize plants (2–3-month-old) in greenhouse conditions with a potting soil ratio of part peat moss, part perlite, and parts vermicompost (1:1:2). The various nanoparticles (Cu, KI, Ag, Bd, and Gv) were sprayed on the corn plant in 50 mL at different concentrations (1000, 10000, and 100000 ppm). The negative control was achieved by spraying nanoparticle-free distilled water. Each treatment was replicated three times. After 30 days of treatment, the phytotoxic effects were evaluated. The negative control and nanoparticle-treated corn plant soil debris (0–1 cm) were removed, and rhizosphere soil samples (1 kg) were collected for analysis of the soil pH and chemical constituent analysis.

Beauveria bassiana, Metarhizium anisopliae, and Trichoderma harzianum were obtained from Rajamangala University of Technology, Thailand. All of the fungus isolates were originally obtained from soil or insect cadavers in the northern part of Thailand. Stock cultures were maintained at 25 ± 1 °C in test tubes on slants of potato dextrose agar supplemented with 1 gL-1 yeast extract (PDAY) and adjusted to pH 6.9 for 15 days with a photoperiod of 12:12 h (dark light).

Prepare the solutions of NPs with different concentrations (1000, 10000, and 100000 ppm) with pure distilled water, then mix them with 500 conidia per mL of fungus at different times of incubation (0 min, 30 min, 2 h, and 24 h) in a test tube. The negative control was distilled water with fungal conidia (nanoparticle-free). Petri dishes (90 mm in diameter) containing 15 mL MEA (malt extract 4%, soybean peptone 1%, and agar 1.5%) after solidification were inoculated in the centre of the plate with a droplet of 5 μl conidia suspension, smear and incubated under dark conditions at 25 ± 1 °C. After 72 h, the fungi spores inhibitions percentages were counted under the light microscope Assays were set up in a completely randomised design with three replicates.

After 30 days of phytotoxicity application on corn plants, soil pH and nutrient variations were evaluated with the negative control (distilled water treated soil) and more potent nanoparticles Cu, KI, and Gv treated (1000, 10000, 100000 ppm) corn plant rhizosphere soil sampling in the potted plant from 0 to 10 cm. In the present studies, we evaluated the nanoparticles' effects on the corn plant rhizosphere soil and calculated the levels of soil pH, copper, and potassium in the nanoparticle-treated corn plant rhizosphere soil. The pH of soil was detected by a pH/conductometer, Metrohm, and MS Scientific Instrument Co., Ltd. The exchangeable potassium and available copper were analysed by Atomic Absorption Spectrophotometer, Analytik Jena, ContrAA 800, Germany.

The cumulative insect mortality of FAW after treating with different concentrations of NPs was corrected for control mortality according to Abbott [43]. And, the percentage of conidial inhibition for each isolate was converted to a percentage relative to the germination rate of the control (in medium with no NPs). Standard procedures were followed to record the data [43]; According to the Tukey test at p < 0.05, statistical values that are separated by the same letter are not substantially different (two-way ANOVA). The statistical analyses were carried out using SPSS version 23.0 (IBM Corp., Armonk, NY, USA, 2015). and statistics version 8.0.

The larvicidal activity results showed that among the nanoparticle treatments, the KI NPs are highly toxic to 4th instar larvae of S. frugiperda in both the dip food and dip larval methods. The KI NPs caused high insect larvicidal activity, with a range of 31–83% mortality in the dip food methods and dip larval method caused mortality range from 11 to 90% mortality within three-day post treatment. KI NPs caused 71–100% mortality in the dip food method on the 7th day, and larval dip methods showed 98–100% mortality (Table 2; Fig. 1). In Fig. 1, pictures b to f show the malformed larvae cadaver after treatment with different kinds of nanoparticles compared to the untreated larvae in picture a (see Table 3). Cu NPs-caused mortality ranges from 6 to 93% in the dip food methods and 58–70% in the dip larval method within three days of treatment. Cu NPs caused 15–100% mortality in the dip food method on the 7th day, and larval dip methods showed 75–100% mortality. Ag NPs-caused mortality ranges from 10 to 33% in the dip food methods and 25–28% in the dip larval method within three days of treatment. Ag NPs caused 10–33% mortality in the dip food method on the 7th day, and larval dip methods showed 40–56% mortality (Table 2; Fig. 1). At three days of treatment, Bd NPs-caused mortality ranges from 0 to 51% in the dip food methods and 38–56% in the dip larval method. Bd NPs caused 11–100% mortality in the dip food method on the 7th day, and larval dip methods showed 58–100% mortality. Gv NPs-caused mortality ranges from 0 to 20% in the dip food methods and 45–84% in the dip larval method within three days of treatment. Gv NPs caused 5–65% mortality in the dip food method on the 7th day, and larval dip methods showed 100–100% mortality (Table 2; Fig. 1).

The nanoparticles are not affecting the beneficial entomopathogenic fungi in lower and medium concentrations (Table 4). The higher concentrations affect the germination rates of entomopathogenic fungi. In the KI NPs treatment with 10000 ppm concentration at 2 h of incubation, it did not affect the fungal germination and showed 100% germination rates in 2 h of incubation in KI NPs with M. anisopliae, 93% in B. bassiana, and 100% in T. harzianum (Table 4). In the Cu NPs treatment with a 10000-ppm concentration at 2 h of incubation, it did not affect the fungal germination and showed 90% germination rates in 2 h of incubation in Cu NPs with M. anisopliae, 100% in B. bassiana, and 100% in T. harzianum (Table 4). In the Ag NPs treatment with 10000 ppm concentration at 2 h of incubation, it affected the fungal germination and showed 96% germination rates in 2 h of incubation in Ag NPs with M. anisopliae, 83% in B. bassiana, and 91% in T. harzianum (Table 4). In the Bd NPs treatment with 10000 ppm concentration at 2 h of incubation, it did not affect the fungal germination and showed 89% germination rates in 2 h of incubation in Bd NPs with M. anisopliae, 78% in B. bassiana, and 85% in T. harzianum (Table 4). In the Gv NPs treatment with 10000 ppm concentration at 2 h of incubation, it did not affect the fungal germination and showed 75% germination rates in 2 h of incubation in Gv NPs with M. anisopliae, 97% in B. bassiana, and 93% in T. harzianum (Table 4). Our results clearly showed that the lower concentrations of the nanoparticles do not affect the growth and development of entomopathogenic fungi.

Following a 14-day treatment, our phytotoxicity test revealed that there were no adverse effects on the morphology of the corn plants in the greenhouse experiments. Based on what we've seen, it's clear that the nanoparticles don't have any effect on the morphology of the corn plants (Fig. 2). The phytotoxicity data make it abundantly evident that the nanoparticles were applied to the young corn plant did not suffer any significant morphological damage as a result of the nanoparticles. The KI NPS treatment has resulted in the appearance of a little dot on the upper surface of the leaves, but it has not had a significant morphological effect on the plants. As a result of our research, we came to the conclusion that the commercial nanoparticles that were evaluated do not pose a threat to morphology of the corn plant (Fig. 2).

The various commercially available nanoparticles' soil toxicity was evaluated after 14 days post-treatment. The treatment results clearly showed that the nanoparticles do not affect the soil pH or the levels of macro- and micronutrients. KI NPs before and after pH range is 7.14–7.45 and before treatment the exchangeable potassium and copper range is 248.15 mg/kg and 1.82 mg/kg and after treatment 260.75 mg/kg and 1.65 mg/kg (Table 5). The Cu NPs before and after pH range is 7.52 to 7.51, and before treatment, the exchangeable potassium and copper range is 166.90 mg/kg and 3.78 mg/kg, respectively, and after treatment, 207.68 mg/kg and 1.88 mg/kg (Table 5). Gv NPs before and after pH range is 7.89 to 7.39 and before treatment the exchangeable potassium and copper range is 186.28 mg/kg and 3.37 mg/kg and after treatment 276.75 mg/kg and 1.65 mg/kg (Table 5). Water treatment before and after pH ranges are 7.53 to 7.42, and before treatment the exchangeable potassium and copper ranges are 246.15 mg/kg and 1.36 mg/kg, respectively, and after treatment they are 184.73 mg/kg and 1.35 mg/kg (Table 5). Control treatment before and after pH range is 8.02 to 7.19 and before treatment the exchangeable potassium and copper range is 141.25 mg/kg and 1.99 mg/kg and after treatment 182.25 mg/kg and 1.68 mg/kg (Table 5).

The use of nanotechnology in agricultural insect pest management might be a potential biological alternative to synthetic chemical pesticides [44]. Recently, nanoparticles and nanomaterials-based formulations have been investigated as fungicides or insecticides for the efficient control of several insect pests and plant diseases [[45], [46], [47], [48], [49], [50]]. Previously, entomopathogenic fungi-derived copper nanoparticles treatment resulted in 80–98% mortality against medicinal and stored grain insect pests [7,8]. This present study describes that the use of various commercially available nanoparticles was evaluated against the 4th instar larvae of S. frugiperda with two different treatment methods (larval dip and food dip methods). This study showed that 4th instar S. frugiperda larvae were highly susceptible in KI NPs in both treatment methods (food dip and larval dip methods), within three days post treatment caused good insect larvicidal activity, in the dip larval methods 11–90% mortality and dip food methods 31–83% mortality was observed. After 7 days post treatment showed 98–100% mortality in larval dip methods and 71–100% mortality dip food methods. Among the nanoparticles tested (Cu, KI, Ag, Bd, and Gv), the KI NPs are highly effective against 4th instar larvae of S. frugiperda, an insect pest. Previously, similar studies reported that chemically synthesized zinc nanoparticles showed better insect larvicidal activity against S. frugiperda under laboratory conditions [8]. Previous research by Kalaimurugan et al. [26] found that Pseudomonas fluorescens bacterial-derived silver nanoparticles had high larvicidal activity against three major disease-transmitting mosquito vectors, Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus, 24 h after treatment. Similar to the current investigation, silver nanoparticles produced from the entomopathogenic fungus Fusarium oxysporum have significant mosquito larvicidal action against Ae. aegypti, An. stephensi, and Cx. quinquefasciatus at low concentrations [25]. Banu and Balasubramanian [51] discovered that, Ae. aegypti 2nd instar larvae had a decreased LC50 value of 0.79 ppm when treated with B. bassiana Ag NPs. In the present study, we find new information about insect molting. Among the two methods of treatment (insect dip and food dip methods), the food dip methods are highly toxic to the larvae of S. frugiperda, showing 100% mortality rates within five days. In the larval dip methods, S. frugiperda larvae were molting, which is why the larval mortality rates were reduced compared to the dip food methods, but the treatment of KI NPs showed high larvicidal activity that showed 98% mortality rates within five days (see Table 2). Previous research found that M. robertsii-mediated CuNPs are extremely toxic to the targeted insect pests (An. stephensi, Aedes aegypti, Cx. quinquefasciatus, and T. molitor), but less toxic to non-target organisms (A. salina, A. nauplii, E. eugeniae, and E. andrei) [7]. Silver nanoparticles derived from the entomopathogenic fungi F. oxysporum showed 80–90% mortality rates against disease-carrying mosquitoes [25]. According to Kalaimurugan et al. [26], nano-silver treatment resulted in high insecticidal activity against three major mosquito larvae. The metal nanoparticles inhibit substrate migration across the cell membrane, basic metabolism of electron transfer systems, and respiration of insect pests. Similarly, Yashkamal et al. [51,52] reported that the nanoparticles are highly effective against medical and agricultural insect pests, and nanoparticles offer chances to avoid the development of insecticide resistance in the insect pests. Previously, several researchers reported that chemical and biological synthesis nanoparticles offered in several industries, like pharmacology, cosmetics, insecticides, and medicine, showed outstanding performances [[53], [54], [55], [56], [57], [58], [59], [60], [61]]. Similar to our present studies, the KI NPs showed high insect larvicidal activity against larvae of S. frugiperda under laboratory evaluation. In the incubation process, the nanoparticles were exposed to the conidia of three different species of entomopathogenic fungi: M. anisopliae, B. bassiana, and T. harzianum. According to the findings, using lower and medium quantities of nanoparticles that are commercially accessible has no effect on germination of beneficial fungus, but using higher concentrations produces or influences the germination of fungi. This is the first study of entomopathogenic fungus to make use of nanoparticles as a research tool. In these tests, we observed action that was depending on the dosage. At lower concentrations and shorter incubation durations, it was discovered that fungal germination occurred at a rate of one hundred percent. On the young corn plant, a variety of various nanoparticles that are now available on the market were evaluated and assessed for their phytotoxicity. These nanoparticles include Cu, KI, Ag, Bd, and Gv. The results of our phytotoxicity test, which was conducted after a treatment that lasted for 30 days, showed that the maize plants were morphologically not affected. Based on what we've seen, it's clear that the nanoparticles have no effect on morphology of young maize plants (Fig. 2). The phytotoxicity studies clearly showed that the nanoparticles do not cause a toxic effect or pathogenicity on the corn plant at 30 days post-treatment in pot plants. According to the data nanoparticle soil toxicity studies, the soil's pH and the concentrations of macro and micronutrients are unaffected by the nanoparticles. Changes in exchangeable potassium and copper from 248.15 mg/kg and 1.82 mg/kg before treatment to 260.75 mg/kg and 1.65 mg/kg after treatment was characterize the pH range is 7.14–7.45 after treatment of KI NPs there is no significant differences were observed. The pre- and post-treatment pH range for Cu NPs is 7.52 and 7.51, respectively, while the pre-treatment and post-treatment exchangeable potassium and copper ranges are 166.90 mg/kg and 3.78 mg/kg. The pH of Gv NPs is between 7.89 and 7.39 before and after treatment, and the amounts of exchangeable potassium and copper are between 186.2 and 3.37 mg per kilogram and 1.65 mg per kilogram, respectively. The pH before and after water treatment ranges from 7.53 to 7.42, and the exchangeable potassium and copper levels drop from 246.15 mg/kg and 1.36 mg/kg, respectively, to 184.73 mg/kg and 1.35 mg/kg. Before and after the control treatment, the amount of exchangeable potassium and copper ranges from 141.25 to 1.99 mg/kg and 1.68 mg/kg. Similar to the present research Kitherian [62], reported that biological and chemical synthesized the nanoparticles showed high toxic effect against the different types of medical and agricultural pest control programme. Similarly, the Si NPs caused better insect mortality against various insect pest and cause significant effects on the insect cuticles and gut tissues [63].

In summary, this study evaluated the bio-insecticidal activity of various commercially available nanoparticles against the larvae of S. frugiperda and evaluated the nanoparticles for phytotoxicity and effects on soils. From this present study, we conclude that among the nanoparticles, the KI NPs showed high insect larvicidal activity within three days post-treatment. Among the nanoparticles tested, the KI NPs more toxic to S. frugiperda larvae in both insect dip and food dip methods. The nanoparticle treatments showed that there is no effect on the germination rates of entomopathogenic fungi M. anisopliae, B. bassiana, and T. harzianum with a medium concentration at 24 h of treatment. From the phytotoxicity evaluation, we concluded that NPs did not affect or damage the morphology of the corn plant after the two-week treatment. The soil analysis showed that the nanoparticles does not affect the soil pH values and the soil nutrients. Finally, these present studies showed that nanoparticles are caused toxic effect against larvae of S. frugiperda. Further, we will plan to conduct nanoparticle stability, microbial diversity, non-target bioassay and field studies of the NPs.

Sarayut Pittarate, Malee Thungrabeab, Supamit Mekchay, and Patcharin Krutmuang: Conceived and designed the experiments. Sarayut Pittarate, Malee Thungrabeab: Performed the experiments. Malee Thungrabeab, Vivekanandhan Perumal, Swathy Kannan, Sarayut Pittarate, Supamit Mekchay, Piyawan Suttiprapan, Senthil-Nathan Sengottayan and Patcharin Krutmuang: Analyzed and interpreted the data, contributed reagents, materials, analysis tools or data, wrote the paper.

Data will be made available on request.

No additional information is available for this paper.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.