Dynamics of dimorphic workers of Constrictotermes cyphergaster (Blattodea: Termitidae) during nest repair

Abstract

Termite nest repairs are considered a defensive conduct as they reduce the colony's exposure to the external environment. Repair activities are carried out by worker castes that can be polymorphic, representing a relationship between polymorphism and divisions of functions that can enhance task completion. Repairs are influenced by the extent of damage, nest volume, and the population dynamics of the building species, which regulate the recruitment of individuals for this activity. Our objective was to verify the performances (recruitment for repair) of dimorphic workers of Constrictotermes cyphergaster (Silvestri, 1901) during the damage repair activities performed on the external walls of termite nests of different sizes. We found a significant difference in the presence of dimorphic workers that performed repairs, with greater recruitment of the small morphotype, and observed an alternation of morphotypes between initial and final repair activities, with no influence of morphotype on the replacement pattern. Our results also showed that the total number of recruited workers decreased with increasing nest volume. These results help to better understand the social organization of a Nasutitermitinae termite species and the strategies adopted to protect its colonies.

Keywords: behavior; defense; polyethism; termite.

Graphical Abstract

Fig. 1.

Location of the São João do Cariri Experimental Station (black dot), in the municipality of São João do Cariri, Paraíba, Brazil.

Fig. 2.

Schematic design of the fieldwork procedure to certify repair activity of the Constrictotermes cyphergaster. a) and b) Damage was done to 1/8 of the top surface of the nest. c) Collection of workers involved in the repair activity every 5 min for 1 h, making up a total of 12 sample units per nest.

Fig. 3.

The 2 sub-castes of Constrictotermes cyphergaster workers. a) Dorsal view of the minor worker, b) dorsal view of the major worker, c) lateral view of the minor worker, and d) lateral view of the major worker. Thin arrows indicate morphological differences in the head. Note the head capsule is larger and darker in major workers. Thick arrows indicate differences in the curvature of the abdomen. Note that the abdomen is more curved in minor workers.

Fig. 4.

The relationship between the proportion of workers recruited to the damaged surface (y) and the duration since the damage (x). The values in the plot were estimated via the model, hence each points represents the estimated marginal mean ± the standard error. The substantial interaction term between morphotype and time better describes the pattern of worker turnover at the damage. As time progressed, the originally bigger share of major workers dwindled, with minors accounting for nearly the entire workforce. The model equation is log (proportion of workers) = 0.754531 − 1.509062 × Morphotype:Minor − 0.044278 × Time + 0.088556 × Morphotype:Minor × Time.

Fig. 5.

The relation between the number of individuals in the damaged area (y), by morphotype, and the nest volume (x). The values in the plot were estimated via the model. Each points represents the estimated marginal mean ± the standard error. At the period of an hour, the amount of workers attending the damaged area decreases steadily, regardless of the size of the workers. The model equation is log(average number of individuals) = 1.4233760 − 0.0326675 × nest volume + 0.5634694 × Morphotype:Minor.