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Laboratory Evaluation of Beauveria bassiana for Biological Control of the Elm Leaf Beetle, Pyrrhalta aenescens (Coleoptera: Chrysomelidae)
College of Forestry, Shenyang Agricultural University, Shenyang 110866, China
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Insects 2026, 17(6), 626; https://doi.org/10.3390/insects17060626 (registering DOI)
Submission received: 12 May 2026
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Revised: 9 June 2026
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Accepted: 12 June 2026
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Published: 14 June 2026
(This article belongs to the Section Insect Behavior and Pathology)
Simple Summary
This paper presents a laboratory study aimed at evaluating the efficacy of Beauveria bassiana against the elm leaf beetle, Pyrrhalta aenescens. The pathogenicity of B. bassiana spore suspensions against eggs, larvae of all instars, pupae, and adults of P. aenescens was determined using a dipping method. A leaf-disk choice assay revealed that the larvae significantly avoided leaf disks treated with B. bassiana, and this avoidance behavior was positively correlated with the spore concentration. The study further investigated the physiological and immunological impacts of B. bassiana infection on the host. Data indicated that the fungal infection significantly inhibited larval growth in terms of body length and weight gain. Regarding immune responses, the infection led to a significant decrease in the total hemocyte count and triggered intense melanization and nodulation reactions, with immune responses being more pronounced in early-instar larvae. This study confirmed that B. bassiana has significant direct lethal and various sublethal effects on P. aenescens, with the most pronounced efficacy observed against early-instar larvae. Beauveria bassiana demonstrates considerable application potential in the biological control of P. aenescens, providing a scientific basis for developing environmentally friendly control technologies based on this fungus.
Abstract
To identify novel field control strategies against Pyrrhalta aenescens (Coleoptera: Chrysomelidae) and provide scientific support for its biocontrol in urban tree management, this study investigated the virulence of Beauveria bassiana against this pest under laboratory conditions, as well as its physiological and biochemical effects. Bioassays using the dipping method showed that B. bassiana was pathogenic to all developmental stages of P. aenescens, with the highest virulence observed against early-instar larvae (1st and 2nd instars). For these stages, corrected mortality and mycosis rate were positively correlated with conidial concentration, and the median lethal time (LT50) was the shortest. In contrast, pupae and eggs exhibited the strongest resistance to fungal infection. In leaf-disk choice tests, larvae significantly preferred untreated leaves or those treated with low concentrations of B. bassiana, displaying a concentration-dependent repellent response to the fungus. Physiological measurements revealed that larval body length and weight gain were significantly inhibited following fungal exposure. Further analysis indicated that B. bassiana infection markedly reduced total hemocyte counts and triggered intense melanization and nodulation responses, particularly in younger larvae. Overall, these results suggest that B. bassiana has strong potential for the biological control of P. aenescens. Control measures targeting early-instar larvae are recommended for cost-effective management, providing a scientific basis for developing eco-friendly control technologies based on this entomopathogenic fungus.
