Nest architecture and colony composition in two populations of Ectatomma ruidum sp. 2 (E. ruidum species complex) in southwestern Colombia

Abstract

Nest architecture plays a fundamental role in the adaptation of ants to their habitat, favoring the action of economically important species. Ectatomma ruidum sp. 2 (ruidum species complex) is a biological control agent in Neotropical agroecosystems, exhibiting high bioturbation impact due to high nest densities. The architecture and composition of 152 nests were studied in two Andean populations of southwestern Colombia, 24 of them being cast using the paraffin wax technique. Nest entrance was a single, circular, 4 mm hole at ground level, without any special external structure, connected to a single vertical tunnel communicating with successive half ellipsoidal chambers. Nests were extremely shallow (depth range: 28.7–35.4 cm), with an average of six chambers and an overall volume of 92.2 cm3 per nest. The deeper the chamber, the smaller its volume. Nest building was independent of plants or roots, and no surface or underground physical connections were found between neighboring nests. Few nests possessed a queen, and neither ergatoids nor microgynes were recorded. Despite significant interactions between localities and the number of both males and workers, queen presence had an overall highly positive effect on the number of workers and larvae and a negative one on the number of gynes. Overall, the studied Colombian populations of E. ruidum sp. 2 retained the simple nest structure described for other species of this species complex and for colonies of the same species from other geographical areas, though they constrasted in their extreme shallowness. Our data suggest that E. ruidum sp. 2, at the local level, does not follow the usual monodomic pattern of this species with facultative polygyny but, rather, has a polydomic pattern with monogyny, perhaps related to the extreme shallowness of the nests due to soil structure, which could significantly enhance the queen’s reproductive inhibition previously reported for this species.

Construction of nest mound and preference for it during relocation in an Indian ant Diacamma indicum

“…In Ectatomma ruidum the nest depth and type of nesting (monodomic or polydomic) varies in different habitat conditions particularly the soil properties. The deeper the nest chambers, the lower is their volume and building is not dependent upon presence of plants or roots, whereas we saw D. indicum mounds getting supports from those structures in nature (Santamaría et al, 2022). While these studies were conducted in the natural habitat of the ants and gives information about the abiotic factors that affect them, they have the limitation of being influenced by a plethora of factors and not just water.…”

Feature-preserving synthesis of termite-mimetic spinodal nest morphology

“…Termites (Isoptera) form large colonies, archetypal of superorganisms, with amazing self-organizational features, 1 , 2 , 3 a form of extended phenotype. 4 , 5 Living underground and being blind, termites are considered soil engineers, famous for their complex nest constructions 6 and vibrational communication. 7 Their mounds i.e., the above ground nest, have attracted much attention.…”