This study explores the food transport efficiency (E) in a termite tunnel consisting of a main tunnel and a 2-segment loop tunnel through a model simulation. Simulated termites navigate between the main and loop tunnels through branching nodes (a, b, c, d) with associated probabilities (P1, P2, P3, P4). The loop tunnel locations (δ) are considered: near the nest (δ = 1), at the center of the main tunnel (δ = 2), and close to the food site (δ = 3). The results reveal that for δ = 1, paths such as a → d → b → c and c → d → b → a exhibited high E values. Conversely, for δ = 2, P3 and P4 demonstrate elevated E values ranging from 0.4 to 0.6. For δ = 3, paths like c → d or c → b display high E values, emphasizing the significance of in-loop separation tunnels (characterized by P3 and P4) in alleviating traffic congestion. Partial rank correlation validates that P1 and P2 minimally influence E, while P3 and P4 significantly negatively impact E, regardless of δ. However, for δ = 2, the influence of P3 and P4 is notably reduced due to the positional symmetry of the loop tunnel. In the discussion, we address model limitations and propose strategies to overcome them. Additionally, we outline potential experimental validations to ensure a comprehensive understanding of the dynamics governing termite food transport within tunnels.

Termites are believed to have evolved in a way that optimizes their foraging efficiency, which involves both searching for food and transporting it efficiently. Although the search efficiency has been well-studied through tunnel pattern analysis, transport efficiency has received limited attention due to the challenges of directly observing behavior that is highly influenced by environmental conditions. In this study, we introduce an individual-based model to simulate transport behavior and examine transport efficiency (E) by considering the tunnel surface irregularities and curvature, which are critical environmental factors. The model is characterized by four control variables: tunnel curvature (k1), termite stopping time at irregularity sites (k2), irregularity distribution (k3), and irregularity density (k4). The simulation results indicate that as k1 increases, E decreases, while k3 has little impact on E. The impact of k4 on E is decisive; when k4 ≤ 6, an increase in k4 results in increased traffic jam frequency and a faster reduction in E. However, when k4 > 6, the jamming frequency is not significantly affected, reducing the decrease in E. k2 strongly contributes to reducing E without significantly affecting the frequency. In the discussion section, we explore potential mechanisms that termites use to maintain transport efficiency in heterogeneous soils, and discuss how to improve the model to better reflect real-termite systems.

The present research study has evaluated the roles of different naturally occurring compounds in termite mounds of Odontotermes longignathus (GenBank Id: MZ542727.1) which facilitate to promote higher population growth of termites and subsequent biodegradation. The study has also monitored the change in physicochemical parameters along with the trend of biodegradation of complex organic carbon-based compounds like lignin, polysaccharides etc. and nitrogenous compounds from two different types of termite mounds such as developing (T1) and developed (T2) mounds. The GC MS profiling of mound samples have revealed the occurrence of different humic acids like organic materials in both T1 and T2 mound samples. Both the termite mounds have demonstrated a high population density as T1 (23.67 ± 1.56) individuals and T2 (43.51 ± 2.36) individuals per 0.1 kg of mound materials. Such observations have prompted to undertake molecular docking experiments which revealed that different molecules interact at low binding affinity with hormone receptors involved in moulting, spermatogenesis and oogenesis of termite like Adamantane carboxylate (EcR: -7.6 Kcal/mol; BTB-KLHL10: -6.2 Kcal/mol; USP-LBD: -7.3 Kcal/mol; VgR: -6.8 Kcal/mol), Benzene dicarboxylic acid (EcR: -5.5 Kcal/mol; BTB-KLHL10: -5.1 Kcal/mol; USP-LBD: -5.4 Kcal/mol; VgR: -5.6 Kcal/mol), Hexadecanol (EcR: -6.0 Kcal/mol; BTB-KLHL10: -4.4 Kcal/mol; USP-LBD: -6.9 Kcal/mol; VgR: -6.0 Kcal/mol), oxirane (EcR: -5.3 Kcal/mol; BTB-KLHL10: -4.9 Kcal/mol; USP-LBD: -5.2 Kcal/mol; VgR: -5.3 Kcal/mol) and tocopherol (EcR: -8.0 Kcal/mol; BTB-KLHL10: -5.4 Kcal/mol; USP-LBD: -7.6 Kcal/mol; VgR: -7.0 Kcal/mol). Such spontaneous ligand binding phenomenon coupled with high population density of termites have established the significance of different bioactive xenobiotics in achieving high reproductive potential of termites which in turn facilitate the process of biodegradation and enhance the nutrient enrichment in the soils of tropical deciduous forest.

Sensilla on antennae of the workers and soldiers of Coptotermes formosanus Shiraki were examined by scanning electron microscopy in this study. As the two castes were allocated totally different tasks in the termite colony, we wondered if there was a big difference between their antennae which were recognized as the main sensory appendages of insects. Therefore, detailed information about the morphology, distribution and abundance of various types of sensilla was described in this report. However, our results showed no obvious caste dimorphism was observed. The morphology of antennae and sensilla as well as the general sensilla distribution pattern did not differ between the workers and soldiers of C. formosanus. In total, seven types of sensilla including sensilla chaetica (I, II, III), Böhm bristles, sensilla campaniformia (I, II, III), sensilla trichodea, sensilla basiconica, sensilla trichodea curvata and sensilla capitula were found on the antennae. Additionally, small apertures were found scattered randomly in the antennal cuticle. Functions of these sensilla or structures were proposed to be mechanoreceptors, chemo-receptors, thermo-hygroreceptors, co2-receptors etc. which probably play crucial roles in their various social behaviors.

Secondary reproductives develop primarily from nymphs. However, they have been rarely studied; in particular, the development of adultoid reproductives (AR) with floppy wings is still unclear. In this study, the change in juvenile hormone (JH) levels, vitellogenin gene expression, and oogenesis during the development of AR and brachypterous neotenic reproductives (BN) from the last instar nymphs of Reticulitermes labralis are investigated and compared. The results showed that the AR derived from the last instar nymphs by molting, and they were more similar to neotenic reproductives in morphology. In addition, the paired AR were not able to survive in the absence of workers. In R. labralis, the process of the last instar nymphs developing into AR and BN took an increase in JH level as a starting point. The JH level of the last instar nymphs molting into BN was approximately 1.5-fold higher than that of the AR. Additionally, The JHIII level of BN peaked on day 5, and that of AR peaked on day 10, which induced the onset of vitellogenesis in BN and AR, respectively. After molting, the vitellogenin gene expression levels of both BN and AR initially increased and then declined, and the expression levels in the BN were significantly higher than those in the AR. In addition, the oocytes of BN matured earlier than those of the AR, and the number of eggs laid by the BN was higher than the number laid by the AR. Our results demonstrate that, in R. labralis, the last instar nymphs can develop into AR, which are significantly different from BN in their development.