Volume 95, Issue 4
July 1986, pages 371-485
pp 371-378 July 1986
An experiment was conducted to study the effect of artificial aeration on the growth and survival ofCatla catla (Ham.),Labeo rohita (Ham.) andCirrhinus mrigala (Ham.). Aeration was effected by means of an air-lift system, which sucks water from the bottom and splashes the oxygenated water at the surface, thus facilitating circulation and aeration. All the 3 species of fish recorded slightly better growth in aerated cisterns when compared to the controls. However, the difference observed was marginal and statistically not significant due to the shorter duration of the experiment. Rohu and mrigal exhibited higher survival in aerated cisterns, while catla did not show much variation between the two sets. The overall computed fish production and the average rate of survival were significantly higher in the aerated cisterns when compared to the control.
pp 379-385 July 1986
Final (3rd) instar larvae of the coconut rhinoceros beetleOryctes rhinoceros were found to undergo precocious metamorphosis when subjected to starvation; the beetles produced as a result were subnormal in size. However, the larva showed this kind of response to starvation only after attaining a certain critical stage of development; otherwise they died after surviving for a varying period, depending on their age. Topical application of the juvenile hormone analogue ‘Kinoprene’ (ZR 777) in sufficient doses at definite periods caused significant delay in the onset of precocious metamorphosis thus suggesting an endocrine involvement. Evidently, starvation might have caused a decrease in JH-titre which in its turn, triggered a chain of events leading to precocious metamorphosis.
pp 387-395 July 1986
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.
pp 397-401 July 1986
Thirteen leaves, 4 oilcake extracts and 4 root exudates were tested against rootknot nematode,Meloidogyne incognita to study their effect on egg hatch and larval mortality. Aqueous leaf extracts ofDatura stramonium, Parthenium hysterophorus andTagetes erecta and oilcake extracts of karanj and neem were the most potent treatments and they not only inhibited egg hatch but also killed the larvae significantly. The root exudates ofBrassica campestris andTagetes erecta also killed the second stage larvae ofMeloidogyne incognita.
pp 403-410 July 1986
Energy requirement ofCalotes versicolor, as judged by the rate of oxygen consumption by whole body, liver and muscle, was recorded to be minimum during hibernation (quiescent phase) and maximum during breeding phase. Kidney metabolic rate was comparatively high during hibernation and post-hibernation. Statistically significant circannual rhythms were detected in the rate of oxygen consumption of whole body, liver, muscle and kidney but not in that of brain. However, significant but transient increase in the rate of brain oxygen uptake was recorded during February (arousal), May (initiation of breeding) and November (entry into hibernation). It seems that the annual changes in metabolic rate are reflections of energy requirements of the lizard and its tissues during different phases of the annual activity cycle. Further, climatic factors seem to affect the oxidative metabolism ofCalotes acting through the endocrine glands.
pp 411-416 July 1986
Activity of tail, gut and muscle acid phosphatase ofRana tigrina tadpoles in relation to metamorphic index and temperature was studied. Optimum pH of the enzyme was between 4·0 and 4·5.Km for the muscle phosphatase was low, indicating its greater affinity to the substrate. With advancing stage of metamorphosis or increasing temperature, activity of the enzyme increased. At metamorphic climax the activity was low. Tail acid phosphatase displayed higher activity than the gut or muscle phosphatase, indicating the role of the enzyme in autolysis of the tail during metamorphosis.
pp 417-421 July 1986
SinceRattus gleadowi replacesMeriones hurrianae andTatera indica after a control operation, studies were planned on the bait preferences of this minor pest species. Results tend to reveal that bajra (Pennisetum typhoides) whole grain, bajra flour and wheat grain +2% arachis oil may be used as effective poison carriers for this sand coloured rat. Additives like sugar and salt did not improve the palatability of the candidate bait material. Average energy requirement of experimental rodents ranges from 70·9 Kj/100 g body wt/24 hr in multiple choice tests to 72·6 Kj/100 g body wt/24 hr in single choice tests.
pp 423-427 July 1986
The length-weight relationship was computed independently for males and females ofMacrognathus aculeatus. The analysis of covariance revealed no significant difference (p=0·05) between the length-weight relationship of males and females. Hence, a common logarithmic equation (log W=−5·6934+3·1234 log L) was fitted for the species. The regression coefficient of logarithm of weight on logarithm of length was found to depart significantly (p=0·05) from the cubic value.
pp 429-436 July 1986
Studies on the feeding ecology of large grey babblerTurdoides malcolmi (Sykes) were carried out during August 1981 to July 1982 at Ludhiana. Observations on feeding behaviour and feeding association with other bird species were recorded throughout the season. Gut contents of 125 adults and 20 nestlings revealed that this species is mainly insectivorous and annual percentage of animal matter in the diet was found to be 62 and 93 respectively.
pp 437-445 July 1986
Twentynine species of crabs encountered along the shores of the Pulicat lake have been surveyed with special reference to their vertical distribution, zonation of discrete patches, seasonal variation in population densities and the extent of their penetration into the lake. Specific association between vertical range and moisture content of the soil, zonation of discrete patches and composition of the substratum and reduction in number or total disappearance of crabs and lowering of salinity caused by monsoonal floods were discussed.
pp 447-456 July 1986
Eggs of Triatominae and Echtrichodiinae, though identical, present distinct ultrastructural diversities in respect of collar rim, follicular pattern, position and distribution of the aero-micropylar system and the operculum, facilitating easy identification of the eggs of the species of the subfamilies. Possessing as they do, a continuous endochorionic aerostatic layer for supplying ambient oxygen to the developing embryos, they simulate other reduviid eggs. While the eggs of Triatominae are comparatively simple, being laid in exposed habitats, those of Echtrichodiinae possess additional opercular respiratory structures in view of their oviposition in specialised habitats.
pp 457-462 July 1986
Specific growth rate and protein efficiency ratio were highest inClarias batrachus (Linn.) fed with Halver’s diet followed by fish fed with fishmeal, dried silkworm pupae, meatmeal and groundnut oilcake in decreasing order. Protein synthesis in liver was maximum in fish fed with standard test diet followed by those fed with silkworm pupae, fishmeal, meatmeal and oilcake fed fish. Intestinal protease activity was unaltered in all fishes except those on oilcake diet. Level of total serum protein of different groups of test fishes were comparable. Growth of fish and serum Ca:P ratio were positively correlated (P<0·05). The results suggest that animal protein component is a better source of protein in the diet ofClarias batrachus for satisfactory growth and that fishmeal and silkworm pupae can be incorporated in the operational diet with advantage.
pp 463-468 July 1986
Changes in the haematological indices like haemoglobin, mean corpuscular haemoglobin, colour index, iron, total red blood corpuscles, white blood corpuscles and blood glucose in albino rats duringTrypanosoma evansi infection and the influence of some hormones like hydrocortisone, insulin and thyroxine on these changes have been investigated.
pp 469-473 July 1986
Six strains of amoebae belonging to two species, vizAcunthamoeba culbertsoni andAcanthamoeba rhysodes, were isolated during the 3 prominent seasonal periods of premonsoon, monsoon and postmonsoon from the south of Sagar Island facing Bay of Bengal (21°56′ to 21°88′ N and 88°08′ to 88°16′E). The actual sampling sites were the lowest low tide belt areas. They were co-cultured in pairs, for respective seasonal periods, in 20‰ saline distilled water agar medium with their habitat associated microbiota as food. Dominance of all the seasonal isolates ofAcanthamoeba culbertsoni over the corresponding strains ofAcanthamoeba rhysodes arising out of competitive growth has been observed. Thus in laboratory maintained cultural conditions, strains ofAcanthamoeba culbertsoni show remarkable adaptive superiority over those ofAcanthamoeba rhysodes.
pp 475-485 July 1986
A study relating to seasonal prevalence and host visitation ofMansonia mosquitoes in Trivandrum city was carried out between August 1984 and July 1985. The area chosen was the one which is a perennial breeding source forMansonia mosquitoes. OnlyMansonia uniformis andMansonia annulifera were prevalent in this area of which the former was found to be the predominant species. Decrease in the number ofMansonia annulifera from the survey conducted during the previous year may be due to the disappearance ofPistia stratiotes and its replacement bySalvinia auriculata. Rainfall and temperature are the two important environmental factors which influence the number ofMansonia mosquitoes visiting the host. The maximum number of adults ofMansonia uniformis was collected during February to June 1985. No swarm ofMansonia uniformis was encountered during the present study, however, males were found to wait and mate with the resting as well as blood fed females in the vicinity of the host. Both sexes ofMansonia mosquitoes were parasitized byArrenurus and limnesiid species of water mites. Maximum parasitization was seen during July 1985.