Volume 88, Issue 3
June 1979, pages 163-239
pp 163-169 June 1979
Rodent population is mostly related to the ecological conditions in rural dwellings. Each dwelling has its own ecosystem. Mainly population size depends on the varied habitats, food sources and status of sanitation existing in the premises. A methodology has been described to quantitate the above data. The parameters so fixed are not only useful for the assessment of populations, but also for evolving a strategy for effective and successful rodent control.
pp 171-178 June 1979
A detailed study on aspects of feeding behaviour of the Indian musk shrew,Suncus murinus viridescens, was made. The first solid food intake commenced on the 14th day and weaning occurred on the 20th day after birth. Olfaction was the primary sense involved in food searching. Prey killing was effected by a characteristic neck-bite. Death-shake could be seen when the shrews predate on earthworm or on rodents such as rats. Shrews hoard food when a large number of insects as food was offered. A thorough mastication of the food was observed before swallowing.
pp 179-185 June 1979
Studies on food deficit drives of the Indian musk shrew,Suncus murinus viridescens, have been made. The time taken by shrews experimentally subjected to definite periods of food deprivation to reach the food steadily decreased upto 4 hr of deficit, and thereafter a zig-zag pattern was discernible. The duration of eating bouts increased after shrews were motivated for food for a period of upto 36 hr. The amount of food intake by shrews steadily increased when subjected to differential food deficit drives upto 12 hr and subsequently declined. No significant sexual dimorphism was observed in the differential food deficit drives inSuncus murinus viridescens.
pp 187-192 June 1979
The chromosomes of the male scorpionPalamnaeus sp. has been analysed making use of the Colchicine-hypotonic-suspension technique. The diploid number has been found to be 62. The presence of clear constrictions on the spermatogonial metaphase chromosomes is noticed. The occurrence of diplotene-diakinesis, chiasmata and translocations have been encountered. The nature of the kinetochore is discussed. It is opined that the chromosomes of this scorpion are apparently monocentric (represented by constrictions on chromosomes) but behaving as holocentric.
pp 193-204 June 1979
Population fluctuations of various species ofDrosophila in the 5 localities of Bababudangiri and Kemmangundi Hill ranges (Western Ghats) were analysed with reference to the seasons of the year. The radical changes in the environmental factors caused by the alterations of seasons were found to influence greatly the size ofDrosophila populations. The quantitative differences in the monthly collections ofDrosophila species such asD. giriensis, D. takahashii, D. mysorensis, D. nasuta andD. immigrans were found to be closely related to the climatic variations. The differential magnitude of the population peaks and their asynchronous formation by different species as observed in the present study were found to be a reflection of differential responses of these species to the ambient and changing ecological factors. The cyclical changes in the size ofDrosophila populations under study appears to be regulated by the seasonal rainfall and the related changes in the environment (extrinsic factors) coupled with genetic and physiological factors (intrinsic factors) generated within the populations.
pp 205-208 June 1979
Influence of starvation has been observed on the total cholesterol levels of the brain and liver of the cat-fish,H. fossilis (Bloch). The cholesterol level decreased with starvation in liver but in brain, after registering an initial fall, it showed a distinct rise. The variations in the cholesterol level of fish observed during starvation have been attributed to the changes in the rate of cholesterol synthesis and metabolism.
pp 209-216 June 1979
A comparative study of the growth rates of three Indian major carp hybrids, namely, catla-rohu, mrigal-catla and mrigal-rohu, was made. The results showed that the growth of catla-rohu hybrid was the fastest followed by mrigal-catla while mrigal-rohu hybrid exhibited the poorest growth rate. Compared to the growth of mrigal-rohu hybrid, the increases in weight of catla-rohu and mrigal-catla hybrids were respectively 257·58% and 110·90% more. On statistical analysis of the growth data it was seen that the growth rates of the three hybrids studied differed significantly from one another.
pp 217-221 June 1979
The possibility of utilisation of a low priced catfish known as freshwater shark (Wallago attu) for the production of cheap and widely acceptable form of protein concentrate (FPC) has been studied. The fish could be converted into a product having good dispersible and better functional qualities of protein by solvent-extraction and other process techniques. Conventional processing was found to be improved by washing the fish in brine and initial steaming operation. Both steaming and use of brine during blending gave good appearance of the product. Slight hydrolysis with enzyme pepsin produced better foaming and required dispersion. The treatment with acetic acid resulted in a good swelling effect of the FPC.
pp 223-227 June 1979
The torus longitudinalis is highly developed inLabeo rohita, prominent inHeteropneustes fossilis and poorly developed inChanna punctatus. It shows some correlation with the development of optic lobes as observed inL. rohita.
pp 229-239 June 1979
The effect of temperature and starvation on the consumption, digestion and utilisation of food inPoecilocerus pictus Fabr. was investigated. Adult male when supplied with fresh leaves ofCalotropis procera R. Br., after 0, 6, 12, 18, 24 hr of starvation, attained maximum weights of 446±14 to 613±29 mg at all temperature under present study, while in female the maximum weights were 999±6 to 1726±3 mg. With increasing temperature the rates of consumption, digestion and utilisation increased; however, the insects died at 39° C. Feeding rates which did not differ significantly in males and females, varied from 20±4 to 1801±116 mg g−1 day−1. Assimilation efficiency increased from 51·6±1% at 15° C to 84·2±4·8% at 30°C and then decreased to 47·9% from 33°C to 36°C. Conversion efficiency varied from 8·0±7% to 41·8±9% at different temperatures. Ecological growth efficiency was maximum at 27° C.