• T J Pandian

      Articles written in Proceedings – Animal Sciences

    • Ecological energetics of the grasshopperPoecilocerus pictus in Bangalore fields

      M R Delvi T J Pandian

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      The structure and biomass ofPoecilocerus pictus population in four fields in Bangalore were estimated by direct observation method. Results on the density ofP. pictus, the survivorship curve of the grasshopper and the growth of the population are reported.

      The data on feeding rates, assimilation and conversion obtained in the laboratory were applied to the size and structure of theP. pictus populations in the different fields to estimate the rate and efficiency of energy flow through the population. The results indicate the defensive mechanism developed by the plant against predation. Efficiencies of exploitation, assimilation and production by the populations averaged 3·4, 34 and 15% respectively. Factors like predation, food and space do not appear to regulate the size of the population. Probably it is controlled by intrinsic population factors.

    • Effect of steroid injection on food utilization inChanna striatus

      A R C Nirmala T J Pandian

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      Synthetic anabolic sex steroid hormones such as methyltestosterone (MT), testosterone (T), testosterone propionate (TP), estroid (ED), diethylstilbesterol (DES), diethylstilbesterol dipropionate (DES dipro) and docabolin (DN) were tested separately for their effect on food utilization inChanna striatus. Injection of low dosages of DES, DES dipro and TP acts as appetite depressors and Dn, MT, Ed and T as stimulators. MT, Ed and Dn induced not only increased feeding but also increased conversion. T promoted growth along with food consumption. Though DES and DES dipro suppressed feeding; individuals receiving these hormones showed increased growth with increasing dosage.

    • Prediction of bioenergetics components of lepidopterous larva

      J Muthukrishnan T J Pandian

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      Using the bioenergetics data for the final instarAchaea Janata larva exposed to a wide range of ration levels and temperatures, a linear regression model to predict the bioenergetics components of lepidopterous larva has been developed. From the dry weight of faeces egested (F) it is possible to estimate the consumption (C), production (P) and metabolism (R). Validity of the proposed model has been tested using the data reported in literature.

    • Incubation, hatching and yolk utilization in the eggs of the orb weaving spiderCyrtophora cicatrosa (Araneae; Araneidae)

      S Palanichamy T J Pandian

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      Cyrtophora cicatrosa Stoliczka was reared from hatching to death at 4 different temperatures i.e. 22, 27, 32 and 37° C. A significant correlation is obtained between initial water content and hatchabiiity of the eggs. During embryonic development energy density and fat decreased but the water content increased. Fat was the main energy source for embryonic development. Of 0.34 gcal energy present in an egg, 29% is utilized on embryonic metabolism, 21% on postemergent activities.

    • Food utilization in the fishChauna striatus exposed to sublethal concentrations of DDT and methyl parathion

      T J Pandian R Bhaskaran

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      Sublethal concentrations of DDT and methyl parathion (MP) in the medium significantly affected the rates of feeding, absorption and conversion inChanna striatus. Fish exposed to 250 ppb DDT or MP consumed 23 or 50% less food than those exposed to pesticide-free water. Correspondingly, absorption rate also decreased from 120 cal/g live fish/day in the control to 88 and 59 cal/g/day in those exposed to 250 ppb DDT and MP. Efficiency to convert the absorbed food into body substance dropped from 30% in the control to 6 and 12% in the 250 ppb DDT and MP groups. Metabolic rate of the control averaged to 84 cal/g/day; whereas exposure to DDT did not significantly affect the metabolic rate, a concentration of 250 ppb MP depressed the rate to 52 cal/g/day.

    • Interactions of feeding frequency and density on food utilization in air-breathing murrel,Channa striatus

      K Sampath T J Pandian

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      In a factorial design of experiment, effects of feeding frequency on food utilization were studied inChanna striatus. Feeding frequency is positively related, whereas density is negatively related to the tested energetics components; absorption efficiency remains independent of both feeding frequency and density. Based on the minimum water requirement, a fish pond with an average depth of 1·5 m and an area of 1 ha could be stocked with 1·15 million fry ofC. striatus, of size 3 g. There is a significant interaction between feeding frequency and density suggesting that adverse effects of density could be compensated by increasing the frequency of feeding.

    • Effect of administering different doses of 17α-methyltestosterone inHeteropneustes fossilis

      S Sindhu T J Pandian

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      Heteropneustes fossilis were injected 0, 2·5, 5, 10, 20, 40, 60 or 80 mg 17α-methyltestosterone/kg fish. They were fedad libitum on choppedLepidocephalichthys thermalis and reared for 21 days. The steroid acts as an appetite stimulant and consequently both feeding and growth rates increased 2 to 3 times, when given the optimum dosage of 40mg/kg. It also doubles the growth efficiency. 17α-methy!testosterone is recognized as an appetite stimulant and an anabolic steroid.

    • Behavioural energetics of some insects

      T J Pandian

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      Foraging behaviour of insects includes the following energy-requiring processes: (i) location and (ii) gathering. Some insects do incur additional energy cost on transporting and storing food. Energy cost of foraging ranges from 2 to 5 % of the energy gained in bees and wasps. Initiation of flight, in large and insulated insects obligatorily requires ‘warming-up’ of muscle temperature and maintenance of endothermy by over 20°C above the ambient. Over-heating is avoided by pumping the cooler abdominal blood into the hot thorax. Pollinating insects include (i) hovering high-energy foragers, which expend more energy and visit more flowers per unit time and (ii) walking low-energy foragers, which expend less energy and visit few flowers per unit time. Decreasing of “wing loading” is another strategy adopted by saturniids, which do not feed as adults. Most bees forage, when flowers are just blooming, and when they have maximum nectar reward to offer. From the model study on energy cost of oviposition, it has been shown thatSceliphron violaceum makes greater and greater effort to complete the process of food provisioning and sealing the larval nest, when it has invested more and more energy on foraging and provisioning spiders to the larviposited young ones.

    • Production and utilization of frogs: an ecological view

      T J Pandian M Peter Marian

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      The frog producing area in India has been doubled (23–51 million ha) during the last 30 years, while the frog harvest has also been consistently increased by the biology education (3–18 million frogs) and export (17–60 million frogs) sectors. The carrying capacity of the irrigated land is in the range of 28 frogs/ha and a 7% harvest of the population may represent the optimal utilization. Frogs do control agricultural pests but not vectors like mosquitoes. A ban on the frog export from India would mean the loss of not only a revenue of 10 million US dollars/annum but also the jobs for 0–16 million villagers. The need for development of mass culturing techniques of tadpoles, juvenile frogs and ranching of frogs is emphasized.

    • Prediction of absorption efficiency from food nitrogen in amphibians

      T J Pandian M Peter Marian

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      Gravimetric estimation of absorption efficiency in amphibians is a timeconsuming process and still subject to technical errors. The need for the application of indirect methods requiring no quantitative recovery of feces is indicated. From 41 values reported for 11 amphibian species, it is observed that nitrogen content of food is significantly (P<0·001) and positively correlated (>0·9) with absorption efficiency. From the obtained regression equation (absorption efficiency=49·615+4·596 nitrogen), the per cent efficiency can be predicted with 3·748 standard error.

    • Prediction of assimilation efficiency of lepidopterans

      T J Pandian M Peter Marian

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      From 206 values reported for over 60 lepidopteran species, it was found that nitrogen content of food shows a significant (P<0·001) and a positive correlation (r=0·704) to assimilation efficiency with standard error of 10·33. Unlike in aquatic animals, water content of food influences assimilation efficiency in these terrestrial lepidopterans; however, the relation between leaf water and assimilation efficiency is also correlated, but the correlation is lower than that (r=0·529; SE=11·8) obtained for leaf nitrogen. Considering the individual effect of water on assimilation efficiency as well as its covarying relation with nitrogen, leaf water was included as a co-predictor. The inclusion of leaf water as a co-predictor of leaf nitrogen content improves the precision of prediction (r=0·868; SE=9·7). The role of digestive reducing substances (e.g. Tannins) on assimilation efficiency was considered as a second co-predictor. Realising the difficulties of considering the digestive reducing substances as a second co-predictor, and observing the closeness of the observed and predicted values in the present study, nitrogen and water contents of leaf are considered as adequate explanatory variables for the prediction of assimilation efficiency.

    • Relation between feeding and egg production in some insects

      J Muthukrishnan T J Pandian

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      Food consumption and fecundity of insects vary with life style and feeding pattern. In general, species which feed during the larval and adult stages and maintain a smaller biomass, allocate a higher percentage of the ingested energy to egg production (e.g.Oryzaephilus surinamensis; 34.4%). Species which grow larger but feed at lower rates and pass through extended adult life span display very low egg production efficiency (e.g.Poecilocerus pictus: 0·7%). A few others feed at faster rates during the larval period, shorten the adult phase and allocate fairly a high percentage of the ingested energy to egg production (e.g.Bombyx mori; 5·8%). Food quality regulates food consumption and thereby significantly influences egg production in several polyphagous insects. Prey density influences food consumption and fecundity of predators. Regression of fecundity on blood meal ingested for two hemipterans and two dipterans revealed that the dipterans are autogenous and are relatively independent on adult blood meal for oviposition in comparison with the hemipterans.

    • Faecal weight as an index of development rate and energy content of imago of lepidopterous insects

      J Muthukrishnan T J Pandian

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      Statistically significant correlation coefficients were obtained for the relation between defecation rate and development rate as well as energy contents of pupa and imago of the noctuid mothAchaea janata. Using simple regression equations, the dependent variables development rate, pupa and imago were predicted against values of defecation rate obtained in a factorial design of experiment. The predicted and observed values did not significantly differ from each other indicating the possibility of predicting these parameters from easily estimatable faecal weight. The validity of the concept was tested using the data available in literature.

    • Induction of allotriploids in the hybrids ofOreochromis mossambicus female × red tilapia male

      K Varadaraj T J Pandian

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      Cent percent allotriploids were induced by heat shocking (42°C for 3 min) of 2·5 min old (post-fertilization)Oreochromis mossambicus eggs fertilized with (homozygous) red tilapia milt. Control diploid hybrids were red (orange) in colour. A few triploid hybrids displayed more patches of black pigmentation. Hence red and black colours are regarded as co-dominants. Survival of the allotriploids was higher than that ofOreochromis mossambicus autotriploids.

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