Insecticidal application of essential oils loaded polymeric nanoparticles to control German cockroach: Design, characterization and lethal/sublethal effects

Gelatin Nanoparticles can Improve Pesticide Delivery Performance to Plants

Nanomaterials associated with plant growth and crop cultivation revolutionize traditional concepts of agriculture. However, the poor reiterability of these materials in agricultural applications necessitates the development of environmentally-friendly approaches. To address this, biocompatible gelatin nanoparticles (GNPs) as nanofertilizers with a small size (≈150 nm) and a positively charged surface (≈30 mV) that serve as a versatile tool in agricultural practices is designed. GNPs load agrochemical agents to improve maintenance and delivery. The biocompatible nature and small size of GNPs ensure unrestricted nutrient absorption on root surfaces. Furthermore, when combined with pesticides, GNPs demonstrate remarkable enhancements in insecticidal (≈15%) and weed-killing effects (≈20%) while preserving the efficacy of the pesticide. That GNPs have great potential for use in sustainable agriculture, particularly in inducing plant growth, specifically plant root growth, without fertilization and in enhancing the functions of agrochemical agents is proposed. It is suggested conceptual applications of GNPs in real-world agricultural practices.

Development and characterization of nanoemulsions loaded with essential oil and β-cypermethrin and their bioefficacy on insect pest of economic and medical importance

BACKGROUND

The development of novel and ecofriendly tools plays an important role in insect pest management. Nanoemulsions (NEs) based on essential oils (EOs) offer a safer alternative for human health and the environment. This study aimed to elaborate and evaluate the toxicological effects of NEs containing peppermint or palmarosa EOs combined with β-cypermethrin (β-CP) using ultrasound technique.

RESULTS

The optimized ratio of active ingredients to surfactant was 1:2. The NEs containing peppermint EO combined with β-CP (NEs peppermint/β-CP) were polydisperse with two peaks at 12.77 nm (33.4% intensity) and 299.1 nm (66.6% intensity). However, the NEs containing palmarosa EO combined with β-CP (NEs palmarosa/β-CP) were monodisperse with a size of 104.5 nm. Both NEs were transparent and stable for 2 months. The insecticidal effect of NEs was evaluated against Tribolium castaneum and Sitophilus oryzae adults, as well as Culex pipiens pipiens larvae. On all these insects, NEs peppermint/β-CP enhanced pyrethroid bioactivity from 4.22- to 16-folds while NEs palmarosa/β-CP, from 3.90- to 10.6-folds. Moreover, both NEs maintained high insecticidal activities against all insects for 2 months, although a slight increase of the particle size was detected.

CONCLUSION

The NEs elaborated in this work can be considered as highly promising formulations for the development of new insecticides. © 2023 Society of Chemical Industry.

Essential oils loaded on polymeric nanoparticles: bioefficacy against economic and medical insect pests and risk evaluation on terrestrial and aquatic non-target organisms

This paper introduces the lethal, sublethal, and ecotoxic effects of peppermint and palmarosa essential oils (EOs) and their polymeric nanoparticles (PNs). The physicochemical analyses indicated that peppermint PNs were polydisperse (PDI > 0.4) with sizes of 381 nm and loading efficiency (LE) of 70.3%, whereas palmarosa PNs were monodisperse (PDI < 0.25) with sizes of 191 nm and LE of 89.7%. EOs and their PNs were evaluated on the adults of rice weevil (Sitophilus oryzae L.) and cigarette beetle (Lasioderma serricorne F.) and the larvae of Culex pipiens pipiens Say. On S. oryzae and L. serricorne, PNs increased EOs' lethal activity, extended repellent effects for 84 h, and also modified behavioral variables during 24 h. Moreover, EOs and PNs generated toxic effects against C. pipiens pipiens. On the other hand, peppermint and palmarosa EOs and their PNs were not toxic to terrestrial non-target organisms, larvae of mealworm (Tenebrio molitor L.), and nymphs of orange-spotted cockroach (Blaptica dubia S.). In addition, PNs were slightly toxic to aquatic non-target organisms, such as brine shrimp (Artemia salina L.). Therefore, these results show that PNs are a novel and eco-friendly formulation to control insect pests.

Direct synthesis of lemongrass (Cymbopogon citratus L.) essential oil-silver nanoparticles (EO-AgNPs) as biopesticides and application for lichen inhibition on stones

Lemongrass essential oil (Cymbopogon citratus L.) is used directly to kill lichens and has many disadvantages such as being less effective, volatile, and inefficient. Lichens are a type of microbe that grows in rocks and cause biodeteriorations of rock material because they are highly erosive. Therefore, this research aims to investigate the direct synthesis of lemongrass (Cymbopogon citratus L.) essential oil-silver nanoparticles (EO-AgNPs) as biopesticides and application for lichens inhibition on stones. This was carried out in order to improve the performance and effectiveness of biopesticides which is excellent in killing lichens on stone surfaces. However, it has several disadvantages, such as not being economical, slow performance, and high volatility. The EO-AgNPs nanoparticles were produced by adding AgNO₃ powder directly to lemongrass essential oil. They were then observed to know the effect of variations in storage time on material stability and AgNO₃ concentration. The synthesized material was characterized by UV-Vis Spectrophotometer, FTIR, particle size analyzer (PSA), and SEM-EDX before being tested for its effectiveness in killing lichens directly on stones and inhibition activity. The results showed that the EO-AgNPs had been successfully synthesized as indicated by the color of the clear dark brown solution in the wavelength range of 430 nm. Furthermore, after it was analyzed using PSA and SEM-EDX, EO-AgNPs had a particle size of 332 nm and were spherical with Ag, C, O content of 27.28, 57.98, and 14.74%, respectively. The antifungal activity for killing lichens based on the diameter of inhibition zone (DIZ) using EO and EO-AgNO₃ was 14.7 mm and 20.3 mm, respectively. This shows that EO-AgNPs nanoparticles are capable of killing lichens on rock surfaces and also have a better inhibition activity than EO.

Nanotechnology-Based Bioactive Antifeedant for Plant Protection

The productivity of vegetable crops is constrained by insect pests. The search for alternative insect pest control is becoming increasingly important and is including the use of plant-derived pesticides. Plant-derived pesticides are reported as effective in controlling various insect pests through natural mechanisms, with biodegradable organic materials, diverse bioactivity, and low toxicity to non-target organisms. An antifeedant approach for insect control in crop management has been comprehensively studied by many researchers, though it has only been restricted to plant-based compounds and to the laboratory level at least. Nano-delivery formulations of biopesticides offer a wide variety of benefits, including increased effectiveness and efficiency (well-dispersion, wettability, and target delivery) with the improved properties of the antifeedant. This review paper evaluates the role of the nano-delivery system in antifeedant obtained from various plant extracts. The evaluation includes the research progress of antifeedant-based nano-delivery systems and the bioactivity performances of different types of nano-carrier formulations against various insect pests. An antifeedant nano-delivery system can increase their bioactivities, such as increasing sublethal bioactivity or reducing toxicity levels in both crude extracts/essential oils (EOs) and pure compounds. However, the plant-based antifeedant requires nanotechnological development to improve the nano-delivery systems regarding properties related to the bioactive functionality and the target site of insect pests. It is highlighted that the formulation of plant extracts creates a forthcoming insight for a field-scale application of this nano-delivery antifeedant due to the possible economic production process.