A pinboard by
Rashmi Shanbhag

Scientist Indian Plywood Industries Research and Training Institute Bangalore


Ecosystem Services provided by termites in tropical forest system

Intensification of agriculture and related soil degradation has brought subject of soil management using soil biodiversity into limelight. Soil organisms play major role in the nutrient cycling, soil-water dynamics and productivity of the any system in tropics. Termite, major decomposer community play a key role on ecosystem functioning through their activities as litter decomposers and soil bioturbators. But studies pertaining to particular aspect is not much evident from tropics especially from India. Considering the lacuna in the field project aims to better understand the roles played by these organisms in forest and forest like ecosystem functioning in India. So that the generated knowledge can be utilized for the better natural resource management which are also the main ingredients in the agricultural landscapes.


The restoration of termite diversity in different reforestated forests

Abstract: In this study we compare the richness, abundance and guild composition between two different reforestations in the meridional part of the Amazon. We test the hypothesis that the termite community is affected by the identity of the tree species used in reforestation. More precisely, we test whether the reforestation of a native species of fig (Ficus sp) is more efficient in restoring biodiversity than reforestation of exotic teak trees (Tectona grandis). We sampled the termite community in these reforested areas and three other different “control” areas: active pastures, abandoned pastures (secondary forests) and mature pristine forest. We found that the distance of reforestation from the nearest primary forest had no effect on termite biodiversity, at the scale studied. But, as expected, richness and the abundance were higher in the mature forest, intermediate in reforestation areas, and lower in secondary forest and pastures. In fact, the only studied habitat with biodiversity comparable to the mature forest was the fig plantations. The guild composition in reforested areas was also similar to that of the mature forest. The diversity and abundance of humivorous termites was particularly pronounced in the reforestation areas compared with pasture or secondary forests. The humivorous guild provides important functional services, since its action makes nitrogen and other nutrients available to the plants along ecological succession. Our results show that reforestation is a valuable strategy in restoring termite diversity and recovering the ecosystem services they provide.

Pub.: 08 Oct '15, Pinned: 30 Jun '17

Farmers’ perception of the usefulness of vetiver grass for termite’ control on Ogbomoso Agricultural Zone farmlands, south-western Nigeria

Abstract: Publication date: Available online 9 January 2017 Source:Journal of King Saud University - Science Author(s): Esther Abosede Ewetola, Samuel Adelani Babarinde, Tolulope Omirin, David Olufemi Ojewole The study investigated farmers’ perception on the use of vetiver grass for termite’ control in Ogbomoso Agricultural Zone, south-western Nigeria. Respondents were selected using purposeful sampling technique from four out of the five local government areas (LGAs) that made up the agricultural zone. Sampling was restricted to the farmers that could identify vetiver, based on our preliminary informal investigation. Information was elicited from the respondents on damage caused by termites, termite’ control practices, awareness of the potentials of vetiver grass for termite’ control, perception of the usefulness of vetiver grass for termite’ control and reasons for adoption of vetiver. Sixty five validly filled questionnaires were analysed using descriptive statistics and chi-square. A larger proportion of the respondents (33.3%) were 40-49 years old and 81.5% of the respondents were married. A larger percentage of the respondents (35.4%) had no formal education, while 23.1% had primary education. The respondents were predominantly Christians (58.5%) while 38.50% practised Islam. Male gender formed the majority (72.3%) of the respondents. Respondents’ perception of the type of damage caused by termites on crops was significantly affected by their educational qualification (X 2=4.941, p=0.026), the majority (81.8%) who were illiterates agreed that termite reduced crop yield. The proportion of the respondents who used chemical method for control of termites was significantly affected by secondary occupation (X 2=4.740, p=0.029) with the civil servants (53.8%), those who have private businesses (63.9%) and the students (66.7%) being the predominant users of chemical termiticides. Respondents’ perception of the effectiveness of vetiver grass for the control of termites was significantly affected by their secondary occupation (X 2=3.853, p=0.050); the majority (77.8%) who were into private businesses strongly agreed on the effectiveness of vetiver grass for the control of termites. It is recommended that agricultural extension agents should educate farmers on the potentials of vetiver grass as a compatible strategy with chemical method for control of termites.

Pub.: 15 Jan '17, Pinned: 30 Jun '17

Social buffering in a eusocial invertebrate: termite soldiers reduce the lethal impact of competitor cues on workers.

Abstract: While the impact of predator-induced stress on prey has received considerable attention, there has been far less research into the effect of competitors. Cues from aggressive competitors should be particularly likely to evoke behavioral and/or physiological responses, since they may be indicative of both direct (interference) and indirect (exploitative) threats. The danger posed by such competitors, and the 'fear' they evoke, should be reduced at lower competitor densities and by the presence of individual conspecifics specialized for defense. We assessed how Reticulitermes flavipes termite workers and soldiers were affected by cues from conspecific nestmates, conspecific non-nestmates, and the heterospecific competitor R. virginicus. Competitor cues altered flavipes worker and soldier behavior, decreasing worker growth and increasing their mortality. The presence of flavipes soldiers largely ameliorated these negative impacts: adding even a single soldier (5% of flavipes individuals) decreased worker mortality by 50-80%. Although worker mortality increased with competitor density, increased soldier densities did not increase the benefit to workers. The small number of soldiers required to substantially alter cue-mediated interactions suggests that this caste, in addition to providing direct defense, also occupies a 'keystone role' by providing homeostatic feedback to workers functioning in stressful environments. This article is protected by copyright. All rights reserved.

Pub.: 26 Jan '17, Pinned: 30 Jun '17

Termite mounds harness diurnal temperature oscillations for ventilation

Abstract: Many species of millimetric fungus-harvesting termites collectively build uninhabited, massive mound structures enclosing a network of broad tunnels which protrude from the ground meters above their subterranean nests. It is widely accepted that the purpose of these mounds is to give the colony a controlled micro-climate in which to raise fungus and brood by managing heat, humidity, and respiratory gas exchange. While different hypotheses such as steady and fluctuating external wind and internal metabolic heating have been proposed for ventilating the mound, the absence of direct in-situ measurement of internal air flows has precluded a definitive mechanism for this critical physiological function. By measuring diurnal variations in flow through the surface conduits of the mounds of the species Odontotermes obesus, we show that a simple combination of geometry, heterogeneous thermal mass and porosity allows the mounds to use diurnal ambient temperature oscillations for ventilation. In particular, the thin outer flute-like conduits heat up rapidly during the day relative to the deeper chimneys, pushing air up the flutes and down the chimney in a closed convection cell, with the converse situation at night. These cyclic flows in the mound flush out $\text{CO}_2$ from the nest and ventilate the colony, in a novel example of deriving useful work from thermal oscillations.

Pub.: 19 Mar '17, Pinned: 30 Jun '17

Rainfall and soil properties influence termite mound abundance and height: A case study with Odontotermes obesus (Macrotermitinae) mounds in the Indian Western Ghats forests

Abstract: Publication date: Available online 5 December 2016 Source:Applied Soil Ecology Author(s): Rashmi Ramesh Shanbhag, Meyssoun Kabbaj, R. Sundararaj, Pascal Jouquet Several fungus-growing termite species build mounds, or termitaria, that are conspicuous features of African and Asian landscapes. Studies of the genus Macrotermes in Africa have established that their mounds provide an environment buffered against extremes of temperature and humidity, as well as protection from predators, and are correspondingly modified in composition. However, no studies are available in the specific context of the Asian continent where termite mounds are also abundant. Hence this study focused on the abundance and properties of mounds built by Odontotermes obesus in relation to rainfall and parent soil properties in southern Indian forests, in the Western Ghats area. Termite mound densities and sizes were measured in 18 forests along a rainfall gradient from 1160 to 3670mmyr−1. The C and clay contents were analyzed in soil samples collected from mounds and the surrounding topsoil. Mound numerical density was positively correlated with mound height and rainfall had a negative relationship with the abundance. Neither vegetation type nor or rainfall influenced the clay content in the mound walls but a positive linear relation was observed between the clay content in the termite mound wall and that in the surrounding topsoil environment, suggesting a rather low impact of termites on the clay content in the mound soil. The C content in mound walls depended mainly on how much clay the termites used. In conclusion, this study shows that the amount of rainfall affects the abundance of O. obesus mounds in India while the amount of clay in the surrounding topsoil determines mound soil properties.

Pub.: 05 Dec '16, Pinned: 08 Jun '17