Researchers examined 243 vines collected from separate host trees in secondary forests, forest edges and forest paths across central and eastern Thailand. Nearly all the vines contained naturally hollow stems, but the ants themselves did not appear to excavate these spaces. Cladomyrma sirindhornae occupied 223 vines, or 91.8 percent, while 11 vines housed other ant species and nine were unoccupied. This exceptionally high occupation rate indicates a close association between the ant and S. pentandra, which is currently the only known host of C. sirindhornae.

The partnership unfolds on an impressive architectural scale. The sampled vines averaged 16.9 metres in length and carried an average of 97 small, elliptical entrance holes. C. sirindhornae colonies occupied cavities from the base of the stem to the canopy, using a network of pre-existing chambers rather than digging its own tunnels. Major workers defended many entrances by blocking them with their heads, a defensive behaviour known as phragmosis. Dealate queens were usually found in swollen portions of the stem, between three and 12 metres above the base.

Inside the domatia, the researchers also found soft, light-orange, gel-like food bodies distributed throughout the cavities. Workers repeatedly carried these structures, indicating that they are an active food resource, although no extrafloral nectaries were found in the plant. Colonies also cohabited with pseudococcid scale insects, which produce honeydew. Both resources could help sustain the ants when external prey is scarce, although honeydew alone is relatively nitrogen-poor and may require complementary food sources to support colony growth.

To determine whether this sheltered lifestyle protected colonies from the dry season, researchers dissected 20 mature nests, with ten collected during each season. These colonies averaged about 5,349 workers and had a notable division of labour. Major workers, distinguished by their broad heads, made up roughly 30 percent of the workforce, while smaller minor workers formed the majority. Major workers ranged from 0.91 to 1.00 millimetres in head width, comparable to alate queens, whereas minor workers measured only 0.60 to 0.70 millimetres. Their smaller heads allowed them to pass through entrances that major workers could seal from outside, suggesting a precisely coordinated defence system.

Colony size did not vary significantly between wet and dry seasons. A Poisson generalized linear mixed model found no statistically significant effect of season on the number of workers, while host-plant length was also not a significant predictor. Total major and minor workers numbered 5,164 on average in the wet season and 5,283 in the dry season. The relative abundance of worker pupae, larvae and scale insects also did not differ significantly between seasons. In the dry-season colonies studied alongside these plant ants, researchers observed that many ground-dwelling ants had little or no brood, emphasizing how unusual it was for the protected Cladomyrma colonies to remain so active.

Seasonal differences emerged in reproduction rather than basic colony growth. Colonies produced both workers and sexual offspring in each season, but reproductive pupae and the combined number of alate queens and males were more abundant in the wet season. The relative number of reproductive pupae differed significantly between seasons, as did the combined reproductive-adult count. By contrast, separate comparisons of alate queens and males did not reach statistical significance, indicating that the clearest pattern emerged when the two sexes were considered together. These results suggest that resource demand for sexual development and dispersal rises when environmental conditions are less favorable.

The seasonal timing was also visible during colony founding. Newly established nests were encountered more frequently in the wet season. A founding queen chewed into a young stem just below a node, creating a small “primary hole” that she then blocked with her head. Continued growth of the plant eventually closed the opening, while the affected node became swollen. These early colonies generally contained a single dealate queen, a small quantity of brood and nanitic workers. Because winged reproductives must leave the host to mate and establish new nests, moderate temperatures, high humidity and other favorable outdoor conditions may be more important for dispersal than for the day-to-day persistence of mature colonies.

Queen physiology offers a possible explanation for the scale of these colonies. Thirteen queenright nests were examined, revealing highly physogastric queens with an average of 32 ovarioles, dense yellow bodies and numerous developing oocytes. The number of developing oocytes did not differ significantly between seasons, and major and minor workers each possessed only two ovarioles. Although roughly 32 ovarioles may appear modest for a colony capable of housing thousands of workers, the queens’ enlarged reproductive bodies and abundant mature eggs suggest substantial fecundity. Seven dissected colonies lacked a dealate queen, but workers in queenright and queenless nests did not differ significantly in number; the researchers noted that a queen might escape when a lower stem section was cut during collection.

Taken together, the findings portray S. pentandra as an oasis within the seasonally harsh forest floor. Its hollow stems offer buffered humidity, while food bodies, scale-insect honeydew and potentially other internal resources reduce dependence on exposed foraging. C. sirindhornae in turn may benefit its pioneer host by discouraging herbivores, limiting plant competitors or contributing nutrients through accumulated waste, although those benefits remain to be measured directly. The ants’ high occupation of the vine, coupled with the stable size of mature colonies, suggests a highly specialized mutualism in which the plant’s architecture protects a resident insect population. The central seasonal signal is not a boom-and-bust in colony size, but a shift in reproductive strategy: growth continues year-round inside the host, while mating and new colony establishment are concentrated in the wet season.

Subject of Research: Seasonal colony dynamics and reproductive behavior of the plant ant Cladomyrma sirindhornae in its Thai host plant Sphenodesme pentandra.

Article Title: Ant-plants as oases: Colonies of Cladomyrma sirindhornae ( Hymenoptera , Formicidae ) thrive in their host plants Sphenodesme pentandra in both the wet and dry seasons

Article References: Khachonpisitsak, S., Jaitrong, W., Jeenthong, T., Wongkunanusorn, C., Laedprathom, K., Chaianunporn, T., Khalife, A., Aupanun, S., & Ito, F. (2025). Ant-plants as oases: Colonies of Cladomyrma sirindhornae (Hymenoptera, Formicidae) thrive in their host plants Sphenodesme pentandra in both the wet and dry seasons. Journal of Hymenoptera Research, 98, 559-577. https://doi.org/10.3897/jhr.98.144518

Image Credits: AI Generated

DOI: 10.3897/jhr.98.144518

Keywords: Cladomyrma sirindhornae, Sphenodesme pentandra, ant-plant mutualism, myrmecophytes, seasonal ecology, Thailand, colony reproduction, scale insects, dry-season refuge, Ant-plants, oases, Colonies

The team used inter-simple sequence repeat markers, known as ISSR markers, to probe the genomes of the collected trees. ISSR markers target short repeated DNA sequences scattered throughout the genome, amplifying the stretches between them to produce a fingerprint of bands that can be compared across individuals. Because these microsatellite-flanking regions mutate relatively quickly, ISSR markers are sensitive tools for detecting variation even among closely related cultivars of the same crop. In this study, 14 ISSR primers generated 214 scorable bands across the 93 cultivars, and a striking 184 of those bands, or 85.98 percent, were polymorphic, meaning they differed among at least some of the trees sampled.

Those numbers translate into exceptionally high genetic diversity for a cultivated fruit tree. The researchers calculated a resolving power of 8.00 for their marker set, a Nei’s gene diversity index of 0.34, a polymorphism information content of 0.52, and a Shannon information index of 0.34. Each of these metrics describes a different facet of variation, from how well the markers distinguish individual genotypes to how much uncertainty remains when guessing the genetic makeup of a randomly chosen tree. A PIC value above 0.5 is generally considered highly informative, indicating that the ISSR system captured substantial discriminating power across the Moroccan fig collection.

Perhaps the most consequential finding came from the analysis of molecular variance, or AMOVA, a statistical framework that partitions genetic variation into components within and between groups. The results showed that 89 percent of the total genetic variation resided within groups of cultivars, while only 11 percent was found between groups. In practical terms, this means that a farmer’s orchard in one valley may contain nearly as much hidden genetic variation as an entire region hundreds of kilometers away. Traditional agroecosystems, where multiple varieties are grown side by side and exchanged informally among neighbors, appear to be incubators of diversity rather than mere repositories of it.

Cluster analysis reinforced this picture of diffuse, locally rich diversity. Using UPGMA, a hierarchical clustering method that groups genotypes according to overall band-sharing similarity, the researchers organized the 93 cultivars into five main groups. The edible female figs from the Beni Mellal-Khenifra region showed particularly high genetic dispersion, scattering across the clustering diagram rather than gathering into a tight regional cluster. That dispersion suggests extensive exchange of planting material, seedling selection by farmers, and possibly multiple historical introductions of fig germplasm into the region, which historically served as a crossroads for trans-Saharan trade routes.

The caprifigs told a very different story. Caprifigs are the male, inedible figs that produce pollen and host the tiny fig wasp, Blastophaga psenes, which pollinates female fig flowers in a symbiosis so ancient and so intimate that neither partner can reproduce without the other. In the study, caprifigs formed a distinct and homogeneous cluster regardless of where they had been collected, separating cleanly from the edible female cultivars. This clear genetic split mirrors the gynodioecious breeding system of Ficus carica, in which male and female functional forms are genetically differentiated, and it validates the use of molecular markers to distinguish caprifig germplasm for breeding and pollination management.

The significance of this work extends well beyond Morocco’s borders. The fig is one of the oldest domesticated fruit trees in the world, and its center of diversity lies in the Middle East and Mediterranean basin, with Morocco recognized as a rich secondary reservoir. Earlier studies using microsatellite and other marker systems have documented diversity in Turkish, Tunisian, Algerian, and Jordanian fig germplasm, and Moroccan collections have been characterized morphologically and with SSR markers in previous work. What this new study adds is a broad, marker-based survey that explicitly spans both the mountain agroecosystems of the Atlas and the desert oases of the south, two environments that impose very different pressures on the trees growing in them.

That environmental breadth matters for conservation planning. Oases are fragile systems threatened by water scarcity, salinization, and rural depopulation, while mountain terraces face their own pressures from land abandonment and climate shifts. When genetic variation is distributed mostly within rather than between sites, losing any single site erodes a meaningful slice of the species’ total diversity. The authors argue that their results underline the value of ISSR markers for conservation and breeding programs, providing a cost-effective way to identify unique genotypes, avoid duplicating accessions in germplasm collections, and select parents for crosses that maximize genetic gain in fruit quality, drought tolerance, or disease resistance.

The study also fits into a growing body of work by the same research group at Sultan Moulay Slimane University, which has applied ISSR markers to Moroccan walnuts, plums, apples, and the endemic resin spurge Euphorbia resinifera. Together with companion studies by Mardoume and colleagues on the sugar profiles, organic acids, antioxidant activity, and phenotypic variability of Moroccan figs, the molecular data sketch a crop that is not only genetically rich but also chemically and morphologically diverse. For breeders seeking climate-resilient cultivars, such multidimensional diversity is raw material that cannot be recreated once lost.

For now, the message from the oases and mountains of Morocco is a hopeful one: centuries of traditional farming have quietly assembled one of the most genetically diverse fig populations ever surveyed with molecular markers. The challenge ahead is to document and conserve that diversity before the agroecosystems that sustain it disappear. With 85.98 percent of their marker bands polymorphic and nearly nine-tenths of the variation locked within local groups, Moroccan figs demonstrate that the future of food security under global change may depend as much on the smallholdings of traditional farmers as on any high-tech gene bank.

Subject of Research: Genetic diversity of fig tree (Ficus carica) cultivars and caprifigs in Moroccan oases and Atlas regions assessed with ISSR molecular markers

Article Title: Genetic diversity of Caprifigs and female fig (Ficus carica) from Moroccan oases and Atlas Regions revealed by ISSR markers

Article References: Mardoume, I., Bouda, S., Khachtib, Y., Zaggoumi, H., Neg, I., Ait Bella, Y., & Haddioui, A. (2026). Genetic diversity of Caprifigs and female fig (Ficus carica) from Moroccan oases and Atlas Regions revealed by ISSR markers. Plant Biosystems, 160(4), Article 216. https://doi.org/10.1007/s44473-026-00221-6

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00221-6

Keywords: Ficus carica, genetic diversity, ISSR markers, Morocco, caprifigs, oases, Atlas Mountains, AMOVA, agroecosystems, germplasm conservation, plant breeding, molecular markers