• Volume 96, Issue 6

      November 1987,   pages  647-725

    • Experimental studies on the hatching rhythm and larval release in Palaemonid and Atyid prawns

      R Ponnuchamy S Ravichandra Reddy Katre Shakuntala

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      The hatching behaviour and larval release ofMacrobrachium lanchesteri (de Man) (Palaemonidae) andCaridina weberi (de Man) (Atyidae) are described in relation to natural (LD nat) and altered laboratory (LL, DD and DL) illumination cycles. A clear nocturnal hatching rhythm is observed in femaleMacrobrachium lanchesteri, which releases the larvae in batches on successive nights till all the eggs held in the brood are hatched. Maximum number of larvae are released between 24 and 3 h. InCaridina weberi such a precise rhythm is loosely operative.

    • Population structure and breeding season inRattus rattus wroughtoni Hinton

      S Keshava Bhat A Sujatha R Advani A S Sukumaran

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      Observations were made from July 1982 to June 1985 on certain aspects of the population ecology ofRattus rattus wroughtoni Hinton. Altogether 2639 specimens of rats were collected. The male to female ratio was 0·87:1·0. Male rats were significantly heavier and bigger than the females. Pregnant female rats were encountered throughout the year with two peaks, one during early summer (February–March) and the other during monsoon (July–August). The incidence of pregnancy was lowest in May when the day temperature was maximum. The litter size ranged from 1–8. The pre-implantation loss was 0·75 ovum per female.

    • Feeding and extracellular digestive rhythms in some intertidal bivalve molluscs

      P Shahul Hameed A L Paulpandian

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      The tidal rhythms for changes in morphology, length, dry weight and protein content of the crystalline style are studied in two venerid clams,Meretrix meretrix andKatelysia opima and in a donacid clam,Donax cuneatus. In the two venerid clams the style is housed in a sac conjoined with midgut and there is a tidal rhythm of feeding and extracellular digestion involving a partial dissolution of the style in the ebb tide and reformation in flood tide. But in the donacid clam where the style sac is completely separated from midgut, no detectable changes in the style parameters are recorded during a tidal cycle. However, the rhythmicity in feeding activity is indicated, by the presence of ‘mudcap’ and food particles in the style during flood tide and their subsequent absence during ebb tide. Hence the tidal rhythm of feeding and digestion inDonax cuneatus may be without corresponding changes in the crystalline style. Also this study throws light on the mode of style dissolution.

    • Terminal velocity of the first instarEctropis excursaria (Guenee) (Lepidoptera: Geometridae)

      R Ramachandran

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      The terminal velocity of first instarEctropis excursaria, determined in a part mechanical part electrical apparatus, were 114±12 cm/s and 118±12·5 cm/s for two different heights. Terminal velocity decreased exponentially with increased silk lengths. For a given length of silk there wsa a significant difference in the terminal velocity of live and anaesthetised insects. The significance of these results to the understanding of the wind dispersal of first instar caterpillars is discussed.

    • Evaluation of brodifacoum against house murids of Garhwal Himalaya (India)

      C Sheikher N Ahmad S S Guraya

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      Brodifacoum (WBA 8119) was tested at various concentrations (0·02, 0·01, 0·005, 0·0025 and 0·00125%) by choice tests in laboratory against house murids vizRattus rattus gangutrianus Hinton andMus musculus Linnaeus of Garhwal Himalaya. It was fairly acceptable and produced 100% mortality of both the target species at all levels of its concentrations except at 0·00125% level causing 83·3% mortality inRattus rattus gangutrianus and 100% inMus musculus. The mean period of mortality is increased with the decrease in the concentration, the range being 3–17 days. In house trial a short exposure of 1-night of moist brodifacoum (0·0025%) bait after pre-baiting for 3-nights produced 100% murids mortality which was significantly (P<0·01) higher than that achieved in a similar trial with dry brodifacoum bait.

    • Qualitative and quantitative changes in lipids along the length of female reproductive system of the poultry nematodeAscaridia galli (Schrank 1788)

      D S Jitla V R Parshad S S Guraya

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      Qualitative and quantitative studies have been made of lipids along the length of the female reproductive system of the poultry nematode,Ascaridia galli. Adult specimens were collected in 0·9% saline from the intestines of naturally infected fowls. The quantitative studies have revealed significant (P=0·05) differences of total lipids, phospholipids, sterols, free fatty acids and glycerides and significantly (P<0·001) higher amounts of non polar than polar lipids in different regions of the reproductive system. The qualitative studies have showed that the germinal, growth and maturation regions of the ovary, oviduct and uterus contained 7, 7, 6, 6, 10 fractions respectively of polar and 12, 12, 12, 11, 10 fractions respectively of non polar lipids.

    • Stress induced alterations in the hemocyte population ofPeriplaneta americana (L.)

      N K More Y S Sonawane

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      Alterations in the hemocyte population ofPeriplaneta americana (L.) during starvation and desiccation were studied for 11 days. Total hemocyte count showed increasing trend throughout the starvation period. Changes in differential hemocyte count were evident. Plasmatocytes and granulocytes decreased marginally. Increase in coagulocyte count occurred from 6th day onwards. Two-fold increase in the total hemocyte and differential count was pronounced during subsequent days. During the combined stress period total hemocyte count was significantly higher. Differential hemocyte count was also altered. Degenerative changes set in during late phases of the experiment. The causal factors for such changes in hemocyte population under experimental stress are discussed.

    • Effect of cruciferous glucosinolates on probing pattern and feed uptake by mustard aphid,Lipaphis erysimi (Kaltenbach)

      V K Dilawari A S Atwal

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      The glucosinolate content of the 3 host plants, viz. yellowsarson, Brassica campestris L. var. yellowsarson, Chinese cabbage,Brassica campestris L. var.pekinensis andtaramira, Eruca sativa Lam. var. ITSA differed qualitatively as well as quantitatively mainly with respect to allyl-, methylthiobutyl-, pent-4-enyl-, methyl- and benzyl-glucosinolates. The mean number of total probes on feeding media incorporated with crude extracts containing glucosinolates from 0·25, 0·50 and 1·0 g green parts oftaramira per ml of feeding media was 5·8, 6·7 and 8·4, respectively. Such probes in case of yellowsarson and Chinese cabbage were 2·6, 2·2 and 1·5; and 2·6, 2·0 and 3·0, respectively. The mean number of probes on feeding media containing sinigrin (K+-allylglucosinolate) at the rate of 0·125, 0·25, 0·50 and 1·0% was 1·9, 3·3, 3·9 and 5·2, respectively. Uptake of feeding media incorporated with extracts containing glucosinolates fromtaramira, yellowsarson and Chinese cabbage varied from 4·05–9·40, 31·5–52·0 and 30·5–51·3%, respectively. Similarly, the uptake in the case of feeding media containing sinigrin (0·125–1%) varied from 1·6–44·95%).

    • Energy utilization in freshwater mullet,Rhinomugil corsula (Hamilton) under exercise

      N Sukumaran M N Kutty

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      Energy utilization in mullet,Rhinomugil corsula, exercised continuously for 5 h at different swimming speeds ranging between 20 and 77 cm s−1 was studied in a tunnel type apparatus. Oxygen consumption, carbon dioxide output and respiratory quotient decreased with increase in the duration of exercise. The initial (1st h) respiratory quotient, which was always above unity, increased with intensity of swimming speed, but the steady (5th h) respiratory quotient remained below unity, at about the same level irrespective of the increase in activity.

      Nitrogen (NH3 and total) excretion, ammonia quotient and nitrogen quotient increased with both duration and intensity of exercise, indicating the increased protein utilization during the later phase of exercise.

      An attempt has been made to estimate the relative energy derivation from different substrates with some assumptions for the entire 5 h of exercise at 20 and 77 cm s−1. At 20 cm s−1 the energy derived aerobically from proteins, carbohydrates and fats and that from anaerobic source (carbohydrate) were estimated as 13040·3, 1378·2, 2367·3 and 1048·5 J kg−1 fish, being 73·1, 7·7, 13·3 and 5·9% of a total of 17834·3 J kg−1 fish, whereas at a swimming speed of 77 cm s−1 it was estimated as 33587·9, 2841·4 and 1305·4 J kg−1 fish from proteins, fats and anaerobic source respectively, being 89·0, 7·5, 3·5% of a total of 37734·7 J kg−1 fish.

    • Wing microsculpturing in two arabian species of termite genusAmitermes (Termitidae, Amitermitinae)

      M L Roonwal N S Rathore

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      To understand the intra-generic variability of wing microsculpturing inAmitermes (hitherto known in a single species,Amitermes belli), two other species from Arabia (Amitermes messinae andAmitermes sp.) were studied. Microsculpturing consists of two elements—papillae and micrasters. There is an intra-generic range of complexity in micrasters, from the simple nonasteroids to the complex asteroids. The general pattern conforms to the condition in the subfamily Amitermitinae as a whole.

    • Haematological effects of sublethal concentration of formalin onSarotherodon mossambicus (Peters)

      M Razia Beevi S Radhakrishnan

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      Exposure of fishSarotherodon mossambicus (Peters) for 24 h to 80 ppm formalin induced lowering of total erythrocyte count and increase in haemoglobin and haematocrit. Erythrocyte constants and indices of exposed fish were higher than of the control fishes. The sum total of the effect of sublethal concentration of formalin on the peripheral blood ofSarotherodon mossambicus was macrocytosis and hyperchromia.

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