• Volume 95, Issue 6

      December 1986,   pages  641-769

    • Prediction of assimilation efficiency of lepidopterans

      T J Pandian M Peter Marian

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      From 206 values reported for over 60 lepidopteran species, it was found that nitrogen content of food shows a significant (P<0·001) and a positive correlation (r=0·704) to assimilation efficiency with standard error of 10·33. Unlike in aquatic animals, water content of food influences assimilation efficiency in these terrestrial lepidopterans; however, the relation between leaf water and assimilation efficiency is also correlated, but the correlation is lower than that (r=0·529; SE=11·8) obtained for leaf nitrogen. Considering the individual effect of water on assimilation efficiency as well as its covarying relation with nitrogen, leaf water was included as a co-predictor. The inclusion of leaf water as a co-predictor of leaf nitrogen content improves the precision of prediction (r=0·868; SE=9·7). The role of digestive reducing substances (e.g. Tannins) on assimilation efficiency was considered as a second co-predictor. Realising the difficulties of considering the digestive reducing substances as a second co-predictor, and observing the closeness of the observed and predicted values in the present study, nitrogen and water contents of leaf are considered as adequate explanatory variables for the prediction of assimilation efficiency.

    • Further observations on the ultrastructure of the flank gland of the musk shrew,Suncus murinus viridescens (Blyth)

      M Balakrishnan V E Sokolov O A Basurmanova

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      The ultrastructure of the flank gland tissue of both sexes of the Indian musk shrew,Suncus murinus viridescens was investigated. The undifferentiated and differentiated sebaceous secretory cells in the glands of both sexes possess 1–8 mitochondrial dense osmophilic inclusions. A few inclusions of medium electron density, and clear vacuoles were also seen in the mitochondria. The muscle fibres in the glandular complex were devoid of these characteristic mitochondrial inclusions. Secretory activity of the well differentiated sebaceous cells was characterised by the presence of a number of large secretory granules. Mitochondria and polyribosomes were found in close association with the secretory granules. The flank gland tubules of the shrew were highly vascularised.

    • Effect of certain experimental regimens on mating behaviour and the impact of nutritional difference between copulating males and females on the reproductive programming inDysdercus koenigii (Fabr.) (Heteroptera: Pyrrhocoridae)

      K P Shahi S S Krishna

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      Male/female individuals of the red cotton bug,Dysdercus koenigii (Fabr.) in a given population, when provided equal mating opportunities, exhibit interesting variability in their mating trends with more coitions occurring between sexes comprising 3- and 5-day old adults. Mating between females ingesting cotton leaf and cotton seed-fed males is a futile sexual exercise in this bug’s reproductive programme yielding no output of fertile eggs. However, in a vice versa situation, the mateds deposit viable eggs the proportion of which, following a second mating with seed-fed males, gets appreciably augmented in the subsequent egg batch.

    • Occurrence of gastric absorption in the cichlid fish,Sarotherodon mossambicus

      M Narayanan S V Job

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      Absorption in the stomach region has been quantified in the freshwater fish,Sarotherodon mossambicus. When fish of different size groups were fed with wheat flour, irrespective of the size group, the maximum gastric absorption averaged to 26%. However, the time required to attain the maximum percentage of gastric absorption differs with size of the fish; in smaller individuals (3 g) it occurred within 90 min and in larger individuals (8 g) it took 60 min.

    • Effect of an insect growth regulator on the growth and development of the tobacco caterpillar,Spodoptera litura Fabricius

      G T Gujar K N Mehrotra

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      Effect of an insect growth regulator BASF LAB 153 959 I was studied on the various stages ofSpodoptera litura Fabr. BASF growth regulator of substituted urea type had a similar action as diflubenzuron and was effective against larval stages ofSpodoptera litura. It was ineffective against egg and pupal stages due to poor contact action. It affected adversely fecundity of female moth and fertility of eggs.

    • Heliothis species and their natural enemies, with their potential for biological control

      C S Pawar V S Bhatnagar D R Jadhav

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      Four egg and 24 larval parasitoids including one mermithid species have been identified fromHeliothis armigera collected at and around ICRISAT Center. Twenty one insect and five spider species have been recorded as predators ofHeliothis. The degree of parasitism varies according to the crop. Egg parasitism is absent on chickpea, and almost negligible on pigeonpea (0·3%). Most early larval parasitism occurs on pearl millet (50·7%), sorghum (49·5%), and chickpea (31·4%), whereas late larval parasitism occurs on pigeonpea (16·4%), and groundnut (11·5%).

      The egg parasitoids, mostlyTrichogramma chilonis Ishii, and the parasitoids of small larvae, mostlyCampoletis chlorideae Uchida, are the most abundant natural enemies ofHeliothis in the study area.

    • Testicular damage in rats fed on irradiated diets

      A K S Kushwaha S S Hasan

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      Feeding effect of irradiated diets was studied on the pups born to mother fed either on irradiated normal diet or irradiated low protein diet. The study indicated that pups born to mother fed on the irradiated normal diet and unirradiated low protein diet. Similarly, pups maintained on the irradiated low protein diet showed marked decrease in alkaline phosphatase and cholesterol contents in the testes rather than in the pups fed irradiated normal as well as unirradiated low protein diets. The irradiated low protein diet fed pups showed increased depletion and vacuolization of adrenocortical and medullary cells.

    • Changes in the haemolymph protein and copper in the crabOcypoda macrocera Milne Edwards (Crustacea: Brachyura)

      C A Nageswara Rao K Shyama Sundari K Hanumantha Rao

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      Wide fluctuations in the concentration of the haemolymph protein and its copper were observed during the moult cycle of the crabOcypoda macrocera. Blood protein and copper concentrations were more in the intermoult (C4) and premoult crabs (D1-D2) but decreased in the postmoult crabs (A1-B2). A direct relationship between the blood protein and copper concentration is observed during the moult cycle. More copper in the hepatopancreas is seen during the premoult stage (D1-D2) and its level increased further in the postmoult stages (A1-B2). Increase of hepatic copper with a decrease in haemolymph copper content during the post moult stages shows the transfer of copper liberated from the haemolymph to the hepatopancreas due to the breakdown of haemocyanin, the major blood protein, during starvation period of moult cycle.

    • Impact of phenthoate in continuous flow and static media on the respiratory enzymes of the murrel,Channa punctatus (Bloch)

      K R S Sambasiva Rao K V Ramana Rao

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      Channa punctatus, exposed to sublethal concentration of phenthoate showed a significant decrease of glycogen content under both static and continuous exposure systems. Further, succinate, malate and lactate dehydrogenases in the muscle, gill and liver tissues showed decreased activity. The inhibition of these enzyme systems was relatively more in continuous flow than in static media. Results indicate that phenthoate reduces the tissue oxidative status of the fish both in static and continuous flow systems. This impact is more conspicuous with the continuous flow system which may be attributed to the continuous availability of the pesticide whereas in the static media pesticide detoxification is possible with progress of time.

    • Blood glucose in a freshwater leech,Poecilobdella viridis (Blanchard): Neuroendocrine regulation

      G K Kulkarni A Bhaskar Rao C S K Anand

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      Hormonal involvement in the control of blood glucose level ofPoecilobdella viridis was tested by performing debraining, supra- and sub-oesophageal ganglionectomy, followed by injections of the extract of neuroendocrine tissues in operated leeches. Anatomically, the brain ring, through which the oesophagus passes, of this leech is composed of two separate ganglia, the supra-oesophageal and sub-oesophageal, connected to each other by circum-oesophageal connectives. In normal leeches blood glucose level was found to be 10·2 μg%. Removal of complete brain and only the supra-oesophageal portion of the brain produced after 24 h a significant (P<0·01) decrease in the blood glucose concentration. Sub-oesophageal ganglionectomy produced no effect. Injections of brain and supra-oesophageal ganglion extracts into 24 h debrained and supra-oesophageal and sub-oesophageal ganglionectomized leeches increased the blood glucose level significantly, but the injections of sub-oesophageal ganglion homogenates had no effect. These data indicate that supra-oesophageal ganglionic portion of the brain ofPoecilobdella ciridis may be the production site of hyperglycemic hormone.

    • Effects of ecological factors on the performance of rodenticides in sugar cane

      V R Parshad Nafis Ahmad G Chopra

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      The sugar cane fields located near river Sutlej at Ladhowal (Lat. 30° 56’N, Long. 75° 52’E) were found infested with 4 rodent species namely,Bandicota bengalensis, Rattus meltada, Tatera indica andMus spp. Of these,B. bengalensis was most predominant. Compared to the adjoining wheat, paddy and mung crops the sugar cane fields at growth and maturity stages harboured high rodent population due to frequent waves of rodent immigration as a result of heavy rainfall and flooding of paddy fields in August and September and agronomic operations related to paddy-wheat rotation in most of the fields. Multiple poison baiting of rodents with brodifacoum (0·005%) and zinc phosphide (2·4%) in different fields of sugar cane resulted in significant differences in their performance within and between the fields. With these poisons the rodent control success ranged from 23·0–45·6% in the months of August and September and 68·1–93·4% in October to December. Overall reduction in post-control activity of rodents ranged from 47·2–96·1% in different fields with different poison combinations. The rodent control success seemed to be related to the differences in rodent populations, post-control reinfestation rates, timings of poison baiting, stage of crop development, weather conditions and sowing and harvesting operations in the adjoining crop fields. The environmental factors particularly affected the post-control reinfestation of rodents which as compared to the reference fields (0·35 rodents/100 traps/day) was significantly higher in the treated fields (0·56–2·33 rodents/100 traps/day).

    • Characteristics of phenoloxidases in larval cuticle of the coconut pest,Oryctes rhinoceros

      R Jeyaraj T Thangaraj C A Vasuki M Aruchami

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      Characteristics of cuticular phenoloxidases of the coconut pest,Oryctes rhinoceros were studied biochemically with respect to substrate specificity, pH optima, thermostability and the behaviour of the enzyme in the presence of various chemicals. Biochemical studies indicate that the larval cuticle contains tyrosinase (EC, 1·10·3·1 Ortho diphenol: O2 oxidoreductase), and laccase type of enzymes (EC, 1·10·3·2. Para diphenol: O2 oxidoreductase). These enzymes showed similarity to enzyme types A and C with respect to the enzyme activity in the larval cuticle ofCalliphora vicina. In the electrophoretic study two fractions are discernable in the gel which confirms the occurrence of two enzymes namely tyrosinase and laccase types.

    • Pollination potential of thrips (Insecta: Thysanoptera) in some fabaceous plants

      R S Annadurai R Velayudhan

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      The vector role of thrips in pollinating several fabaceous flowers has been studied. The flowring phenology showed a coincidence with the life cycle of the thrips species. The population dynamics of the thrips, crop-weed dispersal, the pollen carrying efficiency and the percentage of pod set are discussed.

    • Discharge-time method. A new technique for sampling plankton in fluvial systems, with a note on the modified plankton sampling device

      Prakash Nautiyal A S Saklani H R Singh

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      A technique to sample plankton efficiently in the fluvial systems is being propounded along with a note on the need and design of the plankton sampling device suited to torrential reaches. The technique, christened as discharge-time method, has certain advantages. The requirements are minimum (detachable bucket of the conical plankton net with bolting silk cloth of required mesh size) and the efforts are nominal. In order to sample plankton the device has to be dipped into the river with its open end facing the current, for a pre-calculated period of time. The formula, ‘t’ seconds=x/4v was computed to calculate the time for which the device should remain submerged. It is thus, an efficient and time saving technique for large volumes can be filtered within seconds. The validity of this method has been assessed by employing ‘t’ test.

    • Factors affecting pollination activity ofMegachile lanata lepel

      D P Abrol R P Kapil

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      Foraging activity ofMegachile lanata onCrotalaria juncea L. flowers occurred only when minimum threshold of environmental factors was surpassed, while the cessation of activities was governed mainly by the fast decline in values of light intensity and solar radiation. Between the initiation and cessation of field activity, foraging population showed a positive correlation with air temperature, light intensity, solar radiation and nectar-sugar concentration fluctuations, but was negatively correlated with relative humidity, soil temperature and wind velocity. The path coefficient analysis revealed that direct effect of solar radiation and light intensity on foraging population were much pronounced and positive, while the effects of other factors were of very low magnitude, negative or negligible. However, their interrelationships caused accentuation of the overall effects of air temperature, relative humidity and nectar-sugar concentration. The resultant correlation with bee activity were strengthened through their favourable or unfavourable interaction with other factors.

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