What question did this study set out to answer?

The aim is to identify and characterize multifunctional lysozymes from Sycanus bifidus and understand their roles in prey capture.

June 23, 2026Pest Management Science0 citations

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Multifunctional lysozymes from the assassin bug Sycanus bifidus : Insecticidal proteins with anticoagulant and melanization inhibition properties

YLYuhan LiuChinese University of Hong Kong, Shenzhen WLWenkai LiangSouthwest Forestry University YWYi WangShihezi University

Key Points

The aim is to identify and characterize multifunctional lysozymes from Sycanus bifidus and understand their roles in prey capture.
Identified four lysozyme genes (one i-type and three c-type) through genomic analysis.
Conducted transcriptomic and qPCR analyses to assess expression levels in venom glands.
Performed functional assays to evaluate antibacterial, anticoagulant, and insecticidal activities.
SbLyzc1 and SbLyzc2 exhibited antibacterial activity against Pseudomonas aeruginosa and Enterococcus faecalis.
SbLyzc1 showed the highest anticoagulant potency with IC50 = 0.036 ± 0.003 μg μL–1.
All lysozymes led to >80% mortality in yellow mealworm pupae at a dose of 6 μg, with SbLyzc1 having the highest potency (LD50 = 4.25 ± 0.51 μg g–1).

Abstract

Abstract BACKGROUND Predatory hemipterans deploy complex venom cocktails to immobilize preys, yet the specific roles of many individual venom components remain poorly understood. RESULTS Four lysozyme genes were identified from the genome of the predatory assassin bug Sycanus bifidus (Hemiptera: Reduviidae), comprising one i‐type ( SbLyzi ) and three c‐type lysozyme genes ( SbLyzc1 – 3 ). Transcriptomic and quantitative (q)PCR analyses revealed that these lysozymes were expressed at different levels in various venom glands. Of them, SbLyzc1–3 with signal peptides displayed significant transcriptions in the venom glands, implicating these lysozymes as venom constituents. Functional assays found that SbLyzc1 and SbLyzc2 showed antibacterial activity against Pseudomonas aeruginosa and Enterococcus faecalis . Three lysozymes (SbLyzi, SbLyzc1 and SbLyzc3) suppressed thrombin‐induced fibrin clot formation, indicating anticoagulant activity, with SbLyzc1 exhibiting the greatest potency half‐maximal inhibitory concentration (IC 50 ) = 0.036 ± 0.003 μg μL –1 . SbLyzi and SbLyzc1 inhibited phenoloxidase activity in the hemolymph of the yellow mealworm Tenebrio molitor pupae, thereby suppressing its hemolymph melanization, with maximal inhibition rates of 78.4% and 74.3%, respectively. All four lysozymes exhibited insecticidal effects, causing >80% mortality in yellow mealworm pupae following injection of 6 μg per individual, with SbLyzc1 showing the highest insecticidal potency half‐maximal lethal dose (LD 50 ) = 4.25 ± 0.51 μg g –1 . CONCLUSION These findings demonstrate that lysozymes from S. bifidus possess multifunctional biological activities and SbLyzc1–3 act as significant venom components involved in capturing prey, providing new insights into the functional diversity of lysozymes in predatory bugs and their potential application in biological control strategies. © 2026 Society of Chemical Industry.

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Multifunctional lysozymes from the assassin bug Sycanus bifidus : Insecticidal proteins with anticoagulant and melanization inhibition properties

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