Eur. J. Entomol. 122: 323-329, 2025 | DOI: 10.14411/eje.2025.036

Extrafloral nectaries on leaf margins and their ant visitors in bitter gourd, Momordica charantia (Cucurbitaceae): A case of facultative mutualismOriginal article

Rakhi VERMA ORCID...1, Raina Nivedita SAMUEL ORCID...1, Joy Nivedita SAMUEL ORCID...2, *
1 Department of Zoology, St. Andrew's College, Gorakhpur 273001, U.P., India; e-mails: rakhivermagkp1991@gmail.com, Raina.samuel@gmail.com
2 Department of Zoology, St John's College Agra, 282002, U.P., India; e-mail: joy.samuel17@gmail.com

Extrafloral nectaries (EFNs) are nectar-secreting structures found on various plants that attract insects, especially ants, which may in turn provide indirect defense against herbivores. This study investigates the presence, morphology, and ecological role of EFNs in Momordica charantia (bitter gourd) and documents the diversity and spatial behavior of its ant visitors. Field observations and scanning electron microscopy revealed button-shaped EFNs located along the adaxial leaf margin, which first appeared at the flowering stage and peaked during the early fruiting stage before declining. Six facultative ant species - Tapinoma melanocephalum, Crematogaster subnuda, Camponotus compressus, Camponotus sericeus, Tetraponera rufonigra, and Lepto­genys sp. - were recorded visiting the EFNs. All species spent significantly more time on the leaf margins than on other plant parts, with T. melanocephalum being the only species to show a strong preference for flowers. The findings highlight a stage-dependent EFN production in M. charantia and a preferential ant visitation pattern centered around EFNs, suggesting a potential role for these glands in ant-mediated plant defense. This study underscores the need for further experimental research to assess the defensive benefits of EFN-visiting ants in crop protection.

Keywords: Spatial visiting pattern, plant stage, pre-flowering, flowering, early-fruiting, late-fruiting, insect-plant relations

Received: July 16, 2025; Revised: October 14, 2025; Accepted: October 14, 2025; Published online: November 18, 2025  Show citation

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VERMA, R., SAMUEL, R.N., & SAMUEL, J.N. (2025). Extrafloral nectaries on leaf margins and their ant visitors in bitter gourd, Momordica charantia (Cucurbitaceae): A case of facultative mutualism. EJE, 122, Article 323-329. https://doi.org/10.14411/eje.2025.036
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