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This study focuses on the impact of methyl jasmonate on the populations of sucking pests and their natural predators in common beans.

January 18, 2026Open Access

Methyl jasmonate reduces sucking pest populations and increases predator abundance on common bean

Key Points

This study focuses on the impact of methyl jasmonate on the populations of sucking pests and their natural predators in common beans.
Field experiments conducted in Bolu, Türkiye in 2024 and 2025.
Common beans treated with four doses of methyl jasmonate (0.5, 1.5, 2.5, and 3.5 mM) at two growth stages.
Insect populations monitored using sticky traps, visual inspections, and sweep-net sampling.
Generalized linear mixed model analyses performed on collected data.
3.5 mM methyl jasmonate significantly reduced sucking pest populations, with apterous aphids down by 68.5% in 2025.
Significant increases in predator populations, such as coccinellids (3.62-fold) and syrphids (3.20-fold) at the 3.5 mM dose.
Overall pest reduction and enhanced predator abundance suggest improved ecological balance in pest management.

Abstract

Abstract The exogenous application of natural plant defense elicitors represents a promising strategy for alternative pest management. Such treatments enhance plant resistance to herbivores and influences interactions with natural enemies. Methyl jasmonate (MeJA), a key signaling molecule, is known to trigger plant defense mechanisms. In this study, the effects of MeJA on pest and predator populations associated with common bean were evaluated in field experiments conducted in Bolu, Türkiye in 2024 and 2025 using a randomized complete block design, where plants were treated with four MeJA doses (0.5, 1.5, 2.5, and 3.5 mM) at two plant growth stages. Insect populations were monitored weekly using sticky traps, visual inspection, and sweep-net sampling. A total of 14 insect species were recorded including five pests and nine predators. Generalized linear mixed model analysis revealed significant effects of MeJA dose and plant growth stage on pest abundances. The 3.5 mM MeJA dose significantly reduced the abundance of sucking pests across both 2024 and 2025 compared to the control group. In 2024, the strongest reductions were observed in apterous aphid populations (57.3%) and Empoasca decipiens Paoli (Hemiptera: Cicadellidae) (35.5%), followed by Thrips tabaci Lindeman (Thysanoptera: Thripidae) (27.0%) and alate aphids (26.1%). In 2025, the suppressive effects were generally more pronounced, with reductions reaching 68.5% in apterous aphids and 62.3% in T. tabaci , alongside significant decreases in alate aphids 50.9% and E. decipiens (47.8%). Additionally, MeJA had a positive influence on predator abundance. Syrphid and coccinellid numbers were significantly higher at the 3.5 mM dose across the entire sampling period, with Coccinellid abundances increasing 3.62-fold in 2024 and 3.17-fold in 2025, and Syrphid abundances increasing 1.66-fold in 2024 and 3.20-fold in 2025 compared to the control group. Chrysoperla carnea Stephens (Neuroptera: Chrysopidae) populations were not affected by MeJA concentration. Overall, these findings demonstrate the deterrent effects of MeJA-treated common bean plants on sucking insect pests while enhancing certain predator abundances, emphasizing their potential as a sustainable tool in integrated pest management.

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