Resident competitor ants in China to resist the fire ant invasion: natural strategies including novel insecticidal alkaloids from the Chinese pavement ant, Tetramorium smithi

Description

This dataset includes files supplementary to a published manuscript at the journal Entomologia Generalis (2025). These include images, videos and raw (i.e. original proprietary) files of chromatograms of the analysed insects and their toxins. A general outline of the research follows, below. The manuscript deals with the ecological strategies employed by few native-dwelling ants in China to resist territory usurpation by the implacable invasive fire ant Solenopsis invicta. Four species of Chinese ants nesting within urban crop&ornamental plant nurseries were selected for analysis, from observing they maintained high nest- and foraging densities even under pressure by the arrival of invasive fire ants into their grounds. One of the species -- a pavement ant, Tetramorium smithi -- proved particularly effective in rivalling the fire ants in direct confrontation, and was thus analysed with greater attention. The pavement ant is demonstrated to produce a venom alkaloid which is dramatically toxic against the invasive fire ants, so that one worker can defeat several larger invasive foes. File S1 Aerial map of the three plant nursery plots investigated. File S2 The raw chromatogram data files of the whole-body wash extracts of Solenopsis invicta workers and the venom of Tetramorium smithi workers. Video S1 Representative recording of an interspecific aggression test confronting workers of the invasive fire ant Solenopsis invicta against workers of three ant species native to China, Tetramorium smithi, Pheidole noda, and Camponotus pseudoirritans. Video S2 Representative recording of interspecific aggression of the resident ant Tetramorium smithi against other three ant species: the invasive fire ant Solenopsis invicta, the native Pheidole noda, and the native Camponotus pseudoirritans. Video S3 Representative recording of intraspecific aggressiveness tests confronting sub-colonies of the same size but different site locations from four ant species obtained from a plant nursery field in China: the invasive fire ant Solenopsis invicta, and the resident native species Tetramorium smithi, Pheidole noda, and Camponotus pseudoirritans. Video S4 Representative recording of an agression test by confronting a single worker of the native ant Tetramorium smithi against ten workers of the invasive fire ant Solenopsis invicta. Other confrontation proportions were also tested, as well as against different castes of the fire ant. Video S5 Representative recording of an aggression behavioral test of a single worker of the native ant Tetramorium smithi worker against a single worker of the invasive fire ant Solenopsis invicta worker. Other fire ant worker sizes and castes were likewise tested. Video S6 Representative recording of an aggression behavioral test of workers of the native ant Tetramorium smithi facing a single queen, sexual alate female (gyne), or a male of the invasive fire ant Solenopsis invicta. Fire ants of different worker sizes were likewise tested.

Steps to reproduce

- The nursery plots were mapped using a drone, in Tianhe district of Guangzhou, Guangdong, China. Ant nests were visually located and demarked with coloured flags, so that new and disappearing nests could be kept track of. - The most abundant ants were determined by relative nest densities, and their foraging area manually depicted from the maps based on estimations described in previous papers. - Confrontations between the different competing species were done using workers of controled sizes (see full manuscript for details) on Petri Dish arenas, from which dead workers were counted and collected for later inspection and potential chemical analyses. In short, groups of ten or individual workers were confronted. Further details on the test designs, whether of inter- or intraspecific confrontations, refer to the full manuscript. - The GC-MS analyses were carried out in a gas chromatograph as detailed in the appended raw datafiles. Either whole-body or venom extracts were tested, diluted in hexane organic solvent. In general, Samples of either venom pool or body wash extracts were injected (2 μL; n = 3) into a gas chromatograph spectrometer (GC-MS, Agilent 8890 - 5977B). Chromatograms provided the retention index (RI) for each detected peak based on an external standard injection of saturated alkanes (C8–C40). Tentative identifications of compounds spectra were made using Agilent MassHunter Qualitative Analysis (v.10.0; Agilent ) library search results in NIST17, and also qualitatively compared with published spectra and calculated RIs.

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