Natural UV protectants and humectants to improve the efficiency of Steinernema carpocapsae in controlling foliar pests

Authors: HA, BINGJUN - Nankai University; WEI, XIANQIN - Nankai University; LU, PEIYU - Nankai University; QING, HUI - Nankai University; GUO, JINXUAN - Nankai University; ZHANG, RENJIA - Nankai University; CHEN, LEI - Nankai University; LI, XINGYUE - Sichuan Agricultural University; HU, BIN - Institute Of Plant Protection - China; WANG, SHUAIYU - Institute Of Plant Protection - China; XU, YANG - Triumph Haofeng Agriculture Group Co, Ltd; FU, ZHEN - Van Andel Research Institute; Shapiro Ilan, David; RUAN, WEIBIN - Nankai University

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2024
Publication Date: 2/13/2025
Citation: Ha, B., Wei, X., Lu, P., Qing, H., Guo, J., Zhang, R., Chen, L., Li, X., Hu, B., Wang, S., Xu, Y., Fu, Z., Shapiro Ilan, D.I., Ruan, W. 2025. Natural UV protectants and humectants to improve the efficiency of Steinernema carpocapsae in controlling foliar pests. Pest Management Science. https://doi.org/10.1002/ps.8544.
DOI: https://doi.org/10.1002/ps.8544

Interpretive Summary: Entomopathogenic nematodes, also known as beneficial nematodes, are small round worms that are used as environmentally-friendly bio-pesticides. These nematodes are used to control a wide variety of economically important insects pests in various cropping systems such as pecan and peach. Generally, the nematodes are applied to a soil. Applications aboveground are hindered because the nematodes are sensitive to UV radiation and desiccation. Therefore, research to develop formulations that protect the nematodes against UV and desiccation is desirable. We tested a variety of materials to protect the nematodes during aboveground applications. In laboratory and field tests, we discovered that a combination of grape seed extract and fire blocking gel provided high levels of protection against UV and desiccation. Therefore, the newly discovered formulation may be extremely useful in expanding the use of beneficial nematodes for insect pest control, which could thereby significantly reduce the amount of chemicals used in agriculture.

Technical Abstract: BACKGROUND: Entomopathogenic nematodes (EPNs) are recognized as effective biocontrol agents against various soil dwelling pests. However, their efficacy in managing leaf pests is often constrained by factors such as ultraviolet (UV) radiation and desiccation. RESUTLS: We evaluated the protective effects of five plant derived substances, including grape seed extract, sodium copper chlorophyllin, vitamin C, ß-carotene, and lutein, on Steinernema carpocapsae upon exposure to three wavelengths of artificial ultraviolet radiation (UVA, UVB, UVC). The five protectants showed efficient protective effects. Notably, grape seed extract, sodium copper chlorophyllin, and vitamin C exhibited significant protective effects on infective juveniles (IJs) even after exposure to UVC for 4, 8, and 12 hours. Moreover, after 48 hours of infection with Galleria mellonella larvae, all three UV protectants demonstrated robust efficacy. Under natural light conditions, we combined these UV protectants with three humectants and evaluated their effects on IJ viability. Orthogonal experiments revealed that the combination treatment of 0.2% grape seed extract and 0.1% fire blocking gel yielded the highest IJ survival rate. This foliar formulation was tested in the field, leading to significantly higher mortality of Tuta absoluta compard with EPNs only. CONCLUSION: Our findings suggest that the formulation containing UV protectants and humectants effectively overcome the limitations encounted in the foliar application of EPNs, thereby enhancing their potential for pest management in agricultural contexts.