Trichoderma harzianum Outperforms Chemical Alternatives in Controlling Okra Jassid in Nepal’s Mid-Hills

A new two-year field study from the Institute of Agriculture and Animal Science (IAAS), Tribhuvan University, has demonstrated that the fungus Trichoderma harzianum can effectively control the okra jassid (Amrasca biguttula biguttula), a major pest responsible for severe yield losses in okra production across Nepal’s mid-hill regions.

Researchers experimented over two Kharif seasons (2023 and 2024), comparing four biopesticide treatments — Trichoderma harzianum, Beauveria bassiana, neem oil (1% EC), and the traditional organic mix Jholmal — against an untreated control. The study used a randomized complete block design with four replications at IAAS Lamjung’s research farm.

Key Findings:

T. harzianum achieved the highest mortality rates of okra jassid — 76.72% in 2023 and 77.26% in 2024 — significantly higher than other biopesticides.
Neem oil also showed comparable early-season efficacy but fell behind in later applications.
T. harzianum treatment boosted okra yields to 18.73 t/ha in 2023 and 21.25 t/ha in 2024, compared to just 8.75 t/ha and 8.00 t/ha in the untreated control.
Both Trichoderma and neem oil significantly outperformed the locally made Jholmal and Beauveria bassiana.

The study highlights T. harzianum not only as an entomopathogenic fungus capable of infecting and killing sucking insects but also as a biofertilizer that enhances soil health and plant growth. The authors noted that the use of chemical pesticides in Nepal has risen to 681 tons annually, posing risks to the environment and human health, making biopesticides a necessary sustainable alternative.

Among the tested biopesticides, Trichoderma harzianum was the most effective in reducing jassid populations and enhancing okra yield under mid-hill conditions.

The research suggests that T. harzianum could be integrated into Nepal’s pest management programs as a cost-effective and environmentally safe option for smallholder farmers seeking to reduce chemical dependence and improve okra productivity.

Reference

Saud, D., Dawadi, B., & Bhatta, K. (2025). Efficacy of Trichoderma harzianum against okra jassid (Amrasca biguttula biguttula) (Hemiptera: Cicadellidae): a two-year comparative study of biopesticides. Egyptian Journal of Biological Pest Control, 35(1), 36. https://doi.org/10.1186/s41938-025-00870-3