Volume 93, Issue 1
January 1984, pages 1-76
pp 1-8 January 1984
The population trends of the planthoppers,Dichoptera hyalinata Fabricius (Dictyopharidae),Eurybrachys tomentosa Fabricius (Eurybrachidae), andRicania fenestrata Fabricius (Ricaniidae) were studied with reference to the abiotic factors like temperature, humidity and rainfall and biotic factors like two nymphal ectoparasites,Dryinus sp. (A)* andDryinus sp. (B)* (Dryinidae: Hymenoptera) and two egg parasites,Proleurocerus fulgoridis Ferriere (Encyrtidae: Hymenoptera) andTetrastichus sp. (Eulophidae: Hymenoptera).
pp 9-23 January 1984
Primary productivity at four representative stations in the Ashtamudi estuary has been presented. The average gross and net productivities in the surface water was maximum at Neendakara, the bar mouth zone and minimum at Kadapuzha, the riverine zone consistently exposed to pollution from paper mill effluents. Ashtamudi, the station directly on the gradient line and Kanjirakode, the station equidistant from Kadapuzha and Ashtamudi presented a transition phase with regard to the primary productivity. In the bottom water also productivity was minimum at the polluted zone. Generally productivity at sub-surface levels was higher than that at the surface. A seasonal pattern, independent of various environmental parameters, was discernible both in the gross and net productivity changes at surface and sub-surface levels. High concentrations of dissolved oxygen, silicate and nitrite helped to maintain higher productivities at Neendakara, Ashtamudi and Kanjirakode on several occasions during the year. The fact that productivity at the polluted Kadapuzha station was the lowest, indicates that the paper mill effluent has considerably disturbed the productivity mechanism of this otherwise healthy ecosystem.
pp 25-28 January 1984
The oviposition response and development ofCallosohruchus chinensis Linn was studied on twenty promising varieties of mothbean. Though the beetle oviposited on all varieties, the preference for oviposition was not related to the suitability of seeds for the development. The development of grub was also not dependent on the amount of food consumed. There was significant difference among the varieties in the amount of food consumed per grub and the loss of 100 seed weight. On the basis of food consumed per grub and loss of 100 seed weight as a combined criterion, the varieties are grouped into least susceptible, moderately susceptible and highly susceptible varieties.
pp 29-33 January 1984
Life fecundity tables were studied forSpodoptera litura (Fabricius) when reared on castor (Ricinus communis L.), groundnut (Arachis hypogea), okra (Abelmoschus esculentus L.) and sunflower (Helianthus annuus L.) under laboratory conditions at 26·8±2°C temperature. The net reproductive rate (R0), was calculated in each case.
pp 35-41 January 1984
InBarbatia obliquata the mantle edge is divided into three folds as in most other lamellibranchs. Two types of gland cells are noticed in the mantle; epithelial and sub-epithelial. The epithelial glands include mucous glands, mucoprotein glands and lipid glands. The epithelial mucous glands secrete metachromatic, alcianophilic sulphated mucopolysaccharides. The sub-epithelial mucous glands are classified into two categories, according to their histochemical reactions. Some of them secrete non-metachromatic, alcianophilic sulphated mucopolysaccharides and the others secrete mucosubstances which are carboxylated.
pp 43-47 January 1984
Desiccation engenders “super elevation” in the osmotic concentration of the body fluid which eventually provokes characteristic alterations in the functional activity of the ventral nerve cord-neurosecretory system. Enhancement in the number of deep stained cells and partial to acute depletion in association with interruption in axonal transport in moderately stained cells are some of the interesting features revealed in course of this investigation. The results indicate a correlation between the neurosecretory mechanism and ecophysiological bearing.
pp 49-54 January 1984
Initial dyadic social interactions of 13 rhesus monkeys were observed in a free-ranging group of 26 members. Each subject was observed for 900 intervals of 20 sec each by focal animal method. The obtained matrix of approach interactions was separately analyzed in relation to sex and dominance level of interacting animals. Dominance ranks were determined by approach-withdrawal scores and its validity was assessed with other submissive scores. Chi-square analysis revealed a significant preference for opposite sexed animals. High ranked animals initiated more social interactions than was expected; however, other animals approached less towards them. It is concluded that in free-ranging group situations, members do not interact at random, rather their interactions are patterned by individual characteristics, such as age, sex and relative dominance level in the group hierarchy.
pp 55-63 January 1984
Employing three different methods, 108 rice varieties were screened for resistance againstN. virescens andN. nigropictus. In mass screening test, 76 varieties suffered significantly less damage byN. virescens, whileN. nigropictus caused less damage to 72 varieties. Ten varietiesviz. Ptb 2, Ptb 18, Ptb 7, Khama 49/8, Ptb 21, DS 1, ARC 6049, Khama 49/2, ARC 10243 and Jhingasail were greatly detrimental to insect bionomics in the studies using first instar nymphs and newly emerged adults. Adult longevity test could be a good criterion to identify the high degree of resistance in the varieties. From an overall assessment, Ptb 18, Ptb 2 and Ptb 7 were identified as highly resistant to both the species.
pp 65-70 January 1984
Activity of arginase, GDH, AAT and ALAT have been studied in the liver and kidney of three amphibian species that differ in their habitat preferences ranging from aquatic, semiterrestrial to terrestrial modes of living. The enzyme levels in the liver tissue cannot be correlated to the habitat preferences of the species, but the kidney enzymes show some correlations, with aquatic species showing higher rates of enzyme activity. The kidney-to-liver ratio of enzyme activity is also high in aquatic species.
pp 71-76 January 1984
The olfactory communication signals in eleven individuals of sambar deer were studied. They marked the objects in the enclosure with the secretions of diverse specialized integumentary glands. The tendency to sniff the marked sites was more consistent among females than in males. Both sexes of this species of deer depend considerably on olfactory cues during various social interactions.