Volume 99, Issue 5
September 1990, pages 353-418
pp 353-362 September 1990
Studies were conducted on the endoparasiteApanteles machaeralis Wilkinson (Hymenoptera: Braconidae) to determine its biology whenDiaphania indica (Lepidoptera: Pyralidae) is its host. Eggs were deposited in host larvae and increased greatly in size before hatching. The first instar larva was very active with functional mandibles, whereas the second stage larva was quiescent. The third instar larva spins its cocoon outside the body of the dead host. Mean development time from egg to adult was 12·63 days at 29·25 ± 1·82°C and 59-66% RH. There is no preoviposition period. The sex ratio was 1:1·22 (males/females). Mean adult longevity was not significantly different for males (9·31 days) and females (11·68 days).
pp 363-368 September 1990
Histological observations were made on the digestive gland of infected and uninfected freshwater snails,Lymnaea auricularia, and the varying degree of histopathogenesis of echinostome cercaria,Cercaria itoi, as well as strigeoid metacercaria,Tetracotyle lymnaei, along withCercaria itoi (double infection) in the digestive gland have been observed. Basically 3 types of lesions, L1, L2 and L3 were found and were associated with the types and size of trematode larvae as well as with the degree of parasitemia. In the early stage of larval development or in mild infection, type I lesions (L1) were commonly observed in which degenerative changes were confined to individual digestive gland tubules, and neighbouring tubules mostly remained healthy or unaffected. The type II lesions (L2) were associated with severe infection and were less common than L1 lesions and large areas of parasitised digestive gland tubules were revealed to be necrotic. Type III lesions (L3) were also associated with severe infection in which digestive gland tubules appeared as rudimentary tubules located between trematode rediae. In the present study, in addition to a description of the different types of lesions, the various alterations of cellular structures of the digestive gland ofLymnaea auricularia due to single or double infections (Cercaria itoi + Tetracotyle lymnaei) are also discussed.
pp 369-375 September 1990
The total free amino acid levels declined from the early-fourth instar to the mid-fifth instar and were elevated during the late-fifth instar in the metamorphosing silkworm,Bombyx mori. The activity levels of aspartate and alanine aminotransferases showed an increase in the silk gland while they decreased in the central nervous system, muscle and hemolymph. The molting period was, however, characterized by low activity levels in all the tissues studied. The total and soluble protein levels increased continuously during metamorphosis. The results are correlated with active protein synthesis and silk production in the developingBombyx mori.
pp 377-386 September 1990
We studied by autoradiography the replication and transcription patterns of polytene X chromosomes in different segmental aneuploid and hyperploid conditions in a constant diploid autosomal background. In all karyotypes, the patterns of X chromosome compaction and DNA synthesis were observed to be set strictly either at a “male-level” or a “female-level”. Addition of X-fragments to 1X progeny exceeding a certain limit (62% with proximal duplication) changed the pattern of chromatin compaction and replication of X chromosomes from male to female level, while similar additional X-fragments had no comparable effect on 2X hyperdiploids. In contrast, different levels of X-transcription per segment were observed in these aneuploids with variable X-load and in consequence, an equivalent amount of total X-transcription (relative to autosomal transcription) was visualized. These findings while favour a positive correlation between the state of chromosome compaction and replication patterns, are at odds with the idea that for an altered level of transcription, a modulation in the state of chromosome compaction and replication is an obligatory pre-requisite.
pp 387-390 September 1990
Assay of amylase activity carried out in 3 species of carps viz.Cyprinus carpio, Catla calla andHypothalmichthys molitrix, when fed with 3 formulated feeds viz. protein, lipid and carbohydrate rich diets, showed an increase in the enzyme activity discernible after 15 days of feeding. The activity decreased during the starvation period. Protein rich diet ensured better growth in fishes than the lipid and carbohydrate rich diets.
pp 391-395 September 1990
Tetrastichus pantnagarensis Khan (Hymenoptera: Eulophidae) was recorded as a hyperparasite ofDiaphania indica (Saunders) (Lepidoptera: Pyralidae) throughApanteles taragamae Viereck (Hymenoptera: Braconidae). Studies were conducted on its biology. This solitary endoparasite oviposited in the host pupa within the host cocoon and the larva passes through 3 instars. Mean development time from egg to adult is 12–18 days at 26–43±2–53°C. After a preoviposition period of 1–2 days oviposition continued for 7–10 days. Mean adult longevity for males was 8·51 days and for females 11·41 days.
pp 397-400 September 1990
Moulting is the predominent feature of crustaceans. Cyclic cuticle deposition and resorption of calcium from old cuticle occur in relation to the crustacean moult cycle. Prolonged exposure of the prawn,Caridina rajadhari to media containing sublethal doses (0·015, 0·020, 0·025 and 0·040 ppm) of tributyltin oxide led to an apparent increase in dry weight of exuvia as well as an increase in the total quantity of calcium. The increase in weight and calcium content of exuvia was not significant in the initial two moults whereas it was significant (P<0·05) in the third moult when exposed to minimum (0·015 ppm) dose. However significant (P<0·01) rise in both exuvial weight and calcium quantity in the first two moults and highly significant (P<0·001) in the third moult exuvia were observed when exposed to maximum (0·040 ppm) dose. The observed changes in exuvia from prawns exposed to tributyltin oxide might be due to a decrease in the resorption of the old cuticle and/or due to the inhibition of chitinolytic enzymes.
pp 401-409 September 1990
Juveniles ofPenaeus indiens were fed with different concentrations of protein diet (0–60% of dry weight of diet) with purified lipid free casein as protein source. During the experimental period of 30 days, survival was only 27% in the group fed with protein free diet. Survival (75%) and protein efficiency ratio (3·7) were maximum at 40 and 30% protein level, respectively; specific food consumption (4·3–6·7%) and food conversion ratio (1·3–1·4) were lowest at 30 and 40% protein level, respectively. Another experiment conducted to precisely quantify the near optimum protein requirement for maximum growth ofPenaeus indiens revealed significantly higher growth and protein efficiency ratio in the groups receiving 35–37·5% protein than the other groups.
pp 411-418 September 1990
The acute toxicity of heavy metal salts onDaphnia similis Claus is studied in terms of LC50. Copper is found to be the most toxic and zinc the least. Toxicity of the heavy metals is studied by observing changes in the longevity, body length, fecundity and moulting frequency of the animal. The decreasing order of toxicity of heavy metals on the longevity, body length and fecundity is indicated by Zn>Pb>Cu>Hg, Cu>Zn>Hg>Pb and Pb>Cu>Zn>Hg respectively. The average number of instars increased with the increase of the concentration of metals in the medium. The order of accumulation pattern is Zn>Pb>Cu for 24 h and Zn>Cu>Pb for 48 h. On doubling the concentration of metal to whichDaphnia similis is exposed and fed to the fishSaratherodon mossambicus, the biomagnification increases for copper and zinc while it decreases for lead.