• Volume 97, Issue 4

      July 1988,   pages  289-377

    • Electron microscopic studies on the follicle epithelial cell—oocyte cortex interface inArrhenothrips ramakrishnae Hood (Insecta: Thysanoptera)

      T N Ananthakrishnan

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      Observations relating to nuclear and perinuclear-cytoplasmic changes in the follicular epithelial cells as well as changes at the follicle epithelial cell-oocyte cortex interface inArrhenothrips ramakrishnae Hood, based on transmission electron microscopy are presented. The significance of increased pinocytosis during the later stages of the growth phase of follicle epithelial cells, the appearance of refractile bodies, as well as the apposition of numerous mitochondria of varied configuration to the rough endoplasmic reticulum are discussed.

    • Trophic structure and diversity in some litter inhabiting microarthropods of monoculture and natural forest ecosystems

      R S Annadurai S S Chandrasekar A Balu

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      Temporal changes in species composition of litter insect communities of Shevroys, as well as their trophic diversity involving mycophagous and predatory species are examined with reference to natural forest as well as monoculture systems.

    • Earthworm population dynamics in different jhum fallows developed after slash and burn agriculture in north-eastern India

      Keshab C Mishra P S Ramakrishnan

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      The population dynamics of earthworms in 3 successional fallows developed after slash and burn agriculture (jhum) at an elevation of 960 m of Meghalaya was analysed While 0- and 15-yr old fallows had only one species in the soil ecosystem, 5-yr fallow had one additional species apart from those found in the other two fallows. Monthly population fluctuation was related to soil temperature, moisture and litterfall pattern. The rate of mortality in the population was high with a generally low mature population fraction compared with juvenile and immature ones. Different species had different patterns for population fluctuation; this was particularly true in 5-yr old fallow where 3 species coexisted. The significance of these results are discussed.

    • Population, biomass and secondary net production of aboveground insects in a temperate grassland

      B R Kaushal P C Joshi

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      Population, biomass and secondary net production of aboveground insects were studied in a temperate grassland from February 1986 to january 1987. The live shoot biomass varied from 12·4±0·67 to 84·8 g m−2 and the aboveground net primary production was 190·3 g m−2 yr−1. A total of 65 species belonging to 33 families of 10 insect orders were collected. Herbivores (77·6%) were the most dominant insects followed by Omnivores (12%), Predators (5%), Saprophages (5%) and Parasites (0·4%). Maximum population density and biomass were 9·8 m−2 and 254 mg m−2, respectively. Cumulative secondary net production was 1·144 g m−2.

    • The subcellular morphology of avian adrenal medulla

      A Ghosh B Guha

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      The electron microscopic study of the avian adrenal medulla have shown that in most birds, the epinephrine and norepinephrine cells can be differentiated based on the morphology, size, opacity and the fine structures of their granules. However, the functional characterization of some medullary cells, other than epinephrine and norepinephrine remains unresolved to this date. Among the avian adrenals studied, it is only in the domestic fowl that the separate cellular origin of epinephrine and norepinephrine cells have been established.

      Earlier studies on the manner of release of secretory granules from the adrenal catecholamine storing cells in birds have led one to infer that exocytosis is only mode of discharge of granules. Surprisingly this is not apparent in some of the reports obtained in recent years. Hence the release mechanism of the adrenomedullary hormones need to be further explored ultrastructurally.

    • Functional response ofEocanthecona furcellata (Wolff.) (Heteroptera: Pentatomidae) in relation to prey density and defence with reference to its preyLatoia lepida (Cramer) (Lepidoptera: Lemacodidae)

      R Senrayan

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      The functional responses ofEocanthecona furcellata (Wolff.) that predates on its caterpillar prey,Latoia lepida (Cramer), a sporadic pest of many agricultural crop plants are presented using Holling’s ‘disc’ equation. The results indicate the importance of prey density and defence in influencing the attack response of the predator. Further, the phytophagous habits of this predatory bug and its ability to derive nourishment from plant sources during periods of prey absence are also discussed.

    • Role of endocrines in water balance in the coconut palm beetleOryctes rhinoceros—Ultrastructural and electrophoretic studies

      S Kannan

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      Ultrastructural observations on the brain median neurosecretory cells of the hydrated larvae (third instar) ofOryctes rhinoceros showed a well developed granulated endoplasmic reticulum and golgi bodies, indicating active state. The dehydrated animal on the other hand revealed inactive brain median neurosecretory cells with broken and swollen endoplasmic reticulum and underdeveloped golgi bodies. The axonal endings of the median neurosecretory cells in the corpus cardiacum of the dehydrated animal showed retention of secretory granules. Polyacrylamide gel electrophoretic studies also showed accumulation of neurosecretory materials in corpus cardiacum and brain samples of the dehydrated animal than those of the hydrated animal. The above results provide additional evidence that the brain median neurosecretory cells are involved in the regulation of water balance by secreting a diuretic hormone in response to hydration stress.

    • Population structure of earthworms in woodlands of Karnataka

      R V Krishnamoorthy S Ramachandra

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      Woodlands in karnataka differ with respect to earthworm species and their densities.Lampito mauriii Kinberg,Pontoscolex corethrurus Fr. Mull., andPheretima (now,Polypheretima)elongata E Perrier are the most dominant species. Significant positive correlations were obtained between the species number, diversity and population density on one hand, and plant species number, abundance, diversity, cover and biomass on the other. A major factor for the variations in the richness of worms was accounted through vegetation-related factors. Soil organic matter had a strong influence on the worm diversity.

    • Effects of varying dietary protein level on the blood parameters ofCyprinus carpio

      M Sakthivel

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      Effects of varying dietary protein levels, 14, 28, 38, 48 and 58%, on the blood parameters of juvenileCyprinus carpio were studied. It was found that the various blood cells and related parameters respond differently to the variation in the dietary protein. Fishes fed with low (14%) and high (58%) level protein showed lesser values of red blood cells, haemoglobin content, haematocrit, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, total leucocyte count (TLC), differential leucocyte count (DLC) and coagulation time when compared with optimum protein level (38%). On the other hand, immature red blood cells, erythrocyte sedimentation rate (ESR) and mean corpuscular volume values of fishes fed with low (14%) and high (58%) level proteins were higher than that of the fish fed with optimum (38%) protein level.

    • Laboratory studies on the life span, growth, fecundity and embryonic development ofDaphnia cephalata King (Crustacea: Daphniidae)

      N Murugan R K Moorthy

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      Studies onDaphnia cephalata, relating to its longevity, instar duration, growth and fecundity have been made. Fifteen of the 22 individuals reared became primiparous at the fourth instar, the remaining at fifth. During growth, the total length, carapace length and carapace height increased by 2·95, 2·20 and 1·79 mm respectively and the growth curves for the 3 morphometric dimensions are of the same shape. About 200 eggs were produced during the life span of 52 days when the animals were reared at 27±2°C. The early embryogeny resembles other tropical daphnids but for differences in the developmental period in the brood chamber.

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