• Volume 98, Issue 4

      July 1989,   pages  223-289

    • Shell structure and shell strength in Cirripedes

      A A Karande M Udhayakumar

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      Compressive and adhesive strengths of 7 barnacles endemic to Bombay shore were ascertained by using Instron universal testing machine. The adhesive strengths of balanid species settled on man-made materials like bakelite, asbestos, perspex, rubber, glass and teflon were determined. The adhesion on teflon was found to be the poorest. Comments are made on the compressive strengths of barnacles and their shell macrostructures. A need for the adoption of uniform method of the preparation of shell samples as well as of instrumental technique has been suggested for computing fresh data for the representative species.

    • Differentiation of male reproductive system inOryctes rhinoceros (Coleoptera: Scarabaeidae)

      Mariamma Jacob

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      The male reproductive system of adultOryctes rhinoceros consists of a pair of testes with 6 follicles in each, connected to vasa deferentia by small vasa efferentia, a pair of accessory glands, a median ejaculatory duct and a chitinous intromittent organ. The differentiation of these structures in the successive instars is described in detail. In the first, second and early third (final) instar larvae the reproductive system is rudimentary consisting of a pair of testes (each testis is a rounded aggregate of 6 follicles held together in a connective tissue sheath), a pair of delicate ducts or the vasa deferentia connected to ‘genital disc’ at the mid-ventral aspect of the 9th abdominal sternite. A chitinous plate makes its appearance in the ‘genital disc’ of second instar and is discarded alongwith prepupal exuvium. In the pupa, each testicular follicle gets separated to independent disc shaped organ. The ejaculatory duct and accessory glands differentiate from the distal part of ‘genital disc’ whereas the proximal part gives rise to the intromittent organ. Definitive spermatogonia differentiate in the late third instar larval testis. Spermatocysts and meiotic figures are seen only in the pupal stage and spermiogenesis after adult emergence. Sperm bundles are noticed only in a 2–4-day old adult. Accessory glands release secretion in 10–14-day old adult. Gradual degeneration of testis and ducts is observed in the adults from the third month onwards.

    • Sclerotization of the periostracum of the marine bivalvePerna viridis (Linnaeus)

      M S Bharathi K Ramalingam

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      The enzyme phenoloxidase from the periostracum of the bivalvePerna viridis (Linnaeus 1758) was extracted and the substrate specificity was studied spectrophotometrically. The enzyme is solubilised by sodium dodecyl sulphate and is activated by trypsin. It shows high activity with the phenolic substrates pyrocatechol, dopamine (3–4 dihydroxyphenylethylamine) and dopa (3–4 dihydroxyphenylalanine). As the enzyme shows catalytic activity with many substrates, it may exist in a multiple form. A qualitative analysis of the phenols occurring in the mantle reveals the presence of dopa and dopamine which may play a role in the tanning of the periostracum. The nature and properties of the enzyme phenoloxidase from the periostracum ofPerna viridis differ from that occurring in its byssal gland.

    • Mitochondrial adenosine triphosphatase ofPenetrocephalus ganapatii (Cestoda: Pseudophyllidea) in relation to activators and inhibitors

      S Dhandayuthapani K Nellaiappan

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      The mitochondrial adenosine triphosphatase of the cestode parasite,Penetrocephalus ganapatii exists as a latent form and is activated by dinitrophenol or MgCl2. Irrespective of MgCl2 or dinitrophenol concentrations, the enzyme shows optimum activity at pH 8. Effects of inhibitors on Mg2+, dinitrophenol and Mg2++dinitrophenol activated ATPase reveal that ATPase is not highly sensitive towards oligomycin and the alteration of the redox state of the respiratory chain components by rotenone, antimycin A, azide and cyanide has little effect on ATPase activity. −SH groups of the enzyme seem to play a limited role in the hydrolysis of ATP, as the enzyme is only partially sensitive top-chloromercuribenzoic acid. Generally, cations inhibit Mg2+ stimulated ATPase and activate dinitrophenol stimulated ATPase but most of the anions are inhibitory to dinitrophenol or Mg2+ stimulated ATPase.

    • Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) as a parasite ofHelicoverpa armigera (Hub.) (Lepidoptera: Noctuidae) in southwest India

      C S Pawar V S Bhatnagar D R Jadhav

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      Campoletis chlorideae Uchida was the most common parasite emerging from the larvae ofHelicoverpa armigera (Hub.) collected during 1974–83 from almost all of its crop and weed hosts from Andhra Pradesh, Karnataka and Maharashtra. In most years, parasitism was highest in September and lowest in May. At ICRISAT Center, during 1977–83, the average percentage parasitism of first to third instar larvae, which are only parasitised byCampoletis chlorideae, was 44·2 on sorghum, 33·1 on chickpea, 32·6 on pearl millet, 7·1 on groundnut and 4·2 on pigeonpea. Parasitism in pesticide-treated crops was lower than in untreated crops. Ten species of hyperparasites were recorded from cocoons ofCampoletis chlorideae. Hyperparasitism was around 40% on cereals and 10% on legumes.

    • Relative development and voracity of six species of Aphidophagous syrphids in cruciferous crops

      B K Agarwala A K Bhaumik F S Gilbert

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      The development and voracity of 6 species of syrphid are described and contrasted.Eupeodes (Macrosyrphus) confrator was larger than the other species as an adult and as a larva, and had a greater daily voracity. Size contributed greatly towards variation in longevity and voracity. All species were similar in the time-course of feeding behaviour.

    • Role of soil fauna in decomposition of rice and sorghum straw

      Arun Lekha G Chopra S R Gupta

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      This study examines the mass loss patterns and meso-invertebrate populations during rice and sorghum straw decomposition, using litter-bag technique, in an agricultural system at Kurukshetra (29°58’N, 76°51’E, 250 m above mean sea level). The decomposition rates were influenced by litter quality, soil and litter moisture, leaching of water soluble substances, and colonization by the meso-invertebrates. During the cropping season, wet soil conditions favoured rapid decomposition rates. For the total sampling period of 285 days, the mass loss of rice and sorghum straw was 78·2 and 82% respectively. The single exponential model described the pattern of decomposition over time (r2=0·88,Ps0·001). Meso-invertebrate populations were higher during rapid phase of decomposition and influenced by soil and litter moisture. Maximum meso-invertebrate density per litter bag was 77·4±6·12, for rice straw and 78·4±3·05 for sorghum straw. Collembola and mites were the dominant groups of fauna in litter bags. Enchytraeids formed 2·45% of the total meso-invertebrates extracted from litter bags.

    • Mass loss and concentrations of nutrients in relation to microarthropod abundance, during needle decomposition in a pine plantation

      M Vikram Reddy

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      Mass loss and concentrations of N, P, Ca and Mg of needle litter in relation to microarthropod population abundance during decomposition were investigated by the litter-bag method in a pine (Pinus kesiya Royle) plantation in north-eastern India. Collembola and Acarina together constituted 97·5% of the total microarthropods. Nitrogen slowly increased in its concentration in litter as decomposition progressed. Concentrations of Ca and Mg increased while that of K decreased in the litter. The microarthropods showed significant positive correlation with mass loss of the litter, but did not show any relationship with the N and Ca concentrations. Acarina abundance showed significant positive correlation with Mg concentrations of litter. The microarthropods other than Collembola and Acarina, however, showed significant negative correlation with K concentration of litter although they were recorded in meagre numbers.

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