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C. N. Rao ¹, V. J. Shivankar ¹

Affiliations
1 National Research Centre for Citrus, Amaravati Road, Nagpur 440 010, Maharashtra, IN

Abstract

A study was carried out on the population dynamics and predatory potential of Cheilomenes sexmaculata (F.) on various citrus insect pests at National Research Centre for Citrus, Nagpur, during 2006-10. Visual observation of 3-5 minutes/tree during 2006-08 showed that the population of C. sexmaculata was significicantly higher in February (3.5/tree) and January (2.8/tree) than other month. The population of C. sexmaculata was significantly negatively correlated with wind velocity. Predatory potential studies revealed that each larva of C. sexmaculata consumed a total of 186.1 blackfly (Aleurocanthus woglumi Ashby) nymphs; 208.9 psylla (Diaphosis citri Kuwayama) nymphs and 252.8 aphids (Aphis spiraecola Patch) during 2008; a total of 189.0 blackfly nymphs/206.7. citri nymphs and 242.0 aphids during 2009 and a total of 184.8 A. nymphs/ 198.5 psylla nymphs and 260.2 aphids during 2010. Similarly, each adult of C. sexmaculata consumed a total of 540.5 blackfly nymphs: 660.2 psylla nymphs; 720.6 aphids and 210.3 leaf miner (Phyllocnistis citrella Stainton) pupae during 2008; a total of 538.3 blackfly nymphs, 651.8 psylla nymphs, 708.4 aphids and 216.1 leaf miner pupae during 2009 and a total of 519.5 blackfly numphs, 634.1 psylla nymphs, 695.7 aphids and 201.2 leaf miner pupae during preference of C. sexmaculata larvae and adults to A. spiraecola to other insect pests.

Keywords

Cheilomenes sexmaculata, Coccinellidae, Predatory Potential and Citrus Insect Pests.

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C. N. Rao ¹, V. J. Shivankar ¹, Sandnya Deole ¹, V. N. Dhengre ¹

Affiliations
1 National Research Centre for Citrus, Amaravati Road, Nagpur, Maharashtra 440 010, IN

Abstract

Studies on field evaluation of various stages and doses (eggs @ 2, 4 and 6/shoot, early instar larvae @ 2 and 4 /shoot, adults @ 1 and 2 pairs/shoot) of a chrysopid predator, Mallada desjardinsi (Navas) (Neuroptera: Chrysopidae) along with foliar application of malathion (0.06%) were conducted in Nagpur mandarin (Citrus reticulata Blanco) orchard with Asian citrus psyllid (Diaphorina citri Kuwayama) infestation during spring 2010, 11 and 12. Two releases of each treatment were made at an interval of 2-weeks. The observations on D. citri nymphal population were recorded at weekly intervals before and after the release of the predator. D. citri nymphal population was significantly less in malathion. Among the M. desjardinsi release stages and doses, early instar larvae @ 4/shoot, adults @ 2 pairs/shoot followed by eggs@ 6/shoot were found effective in reducing the D. citri population.

Keywords

Chrysopid Predator, Mallada desjardinsi, Field Evaluation, Asian citrus psyllid.

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Kailas Dilli ¹, C. N. Rao ¹

Affiliations
1 Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721302, IN

Abstract

A thick (770m) pelitic section ranging in age from Quaternary to Middle Miocene encountered at the DSDP site 218 in the Bengal Fan has been investigated for the burial diagenesis of clay minerals based on x-ray diffractometry and partial chemical analysis. The clay minerals are dominated by illite, with minor amounts of montmorillonite, chlorite and kaolinite. All the clay minerals are descrete and detrital derived from the Himalayan hinterland. The clay mineral transformations are largely confined to compaction attendant on the escape of pore water and adsorption of K and Mg in the interlayer positions resulting in better organised illite, montmorillonite-illite and montmorillonite-chlorite mixed layers at depth. The sediments are considered to be in the early diagenetic stage of Dunoyer de Segonzac (1970).

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C. N. Rao ¹, K. Srinivasan ², Amit Roychowdhuri ³

Affiliations
1 Department of Geology and Geophysics, I.I.T., Kharagpur, IN
2 Knoxville, Tenesse, US
3 Oil and Natural Gas Commission, Agartala, IN

Abstract

Phyllites from the Cumbum Formation are exclusively made up of 2 M polymorph of illite. The 2 M polymorph, the most stable phase in the temperature range of 200-300°C, is comidered to be due to its heritage from the source area, having been derived from high-grade metamorphic Eastern Ghat and Dharwarian provenances. The Illite Crystallinity Jndex shows progressive improvement with depth as well as nearness to the Pb-Zn mineralised zone. The crystallinity Index averaging 0.4°2θ is consistent with anchizone of metamorphism. The progressive increase in the crystallinity and size with depth and in the proximity of the mineralized zone suggest that the mineral suffered post-depositional recrystallisation effected by the depth of burial, uplift and folding in the eastern margin of the Cuddapah basin and subsequent hydrothermal activity concomitant with the Pb-Zn mineralisation at Bandlamotu.

Keywords

Illite, Cumbum Formation, Cuddapah, Andhra Pradesh.

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Haile Michael Fentaw ¹, C. N. Rao ², D. K. Sengupta ²

Affiliations
1 Ethiopian Institute of Geological Survey, Addis Ababa, ET
2 Department of Geology and Geophysics, I.I.T., Khargpur, W. B, IN

Abstract

The clay deposits at Malti in Purulia District, West Bengal have formed on phyllites of probable Precambrian age.

X-ray diffraction, differential thermal and Infra-red spectral studies suggest that these clay deposits contain kaolinite as the predominant clay mineral. The kaolinite shows two distinct varieties of crystal perfection-one the highly crystalline with Hinckley Indices of well over 0.8 (8 samples) and the other of comparatively low crystallinity with Hinckley Indices of less than 0.8.

The poorly crystalline samples show strong low temperature endothermic peaks at 200°C in DTA curves suggesting the presence of some inter-layer water. The presence of hydrated halloysite has, however, not been conclusively established.

Keywords

Clay Minerals, Kaolinite, Malti, Purulia Dist, West Bengal.

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Siddhartha Sankar das ¹, C. N. Rao ¹

Affiliations
1 Department of Geology and Geophysics, I.I.T., Kharagpur-721 302, IN

Abstract

The Channuria limestone is characterized by grey-black colour, bedding structure, fine grain size and authigenic pyrite cubes. Petrographically a minimicrite, the rock exhibits a texture composed of dark crinkled and light coloured laminae of lime mud. Pyrite has discordant relationship with laminae, whereas silt-sized terrigenous particles are present in the interlaminar areas. Mineralogically the limestone is made up of low Mg-calcite and quartz. Trace element distribution tndicates that the original mineralogy at the time of deposition was calcitic in nature and its distribution in the rock was controlled by the depositional/diagenetic conditions as well as the detrital clastics supplied into the basin. The depositional environment of the limestone is interpreted as shallow marine lagoonal condition and the site of deposition was very near to shore. The dysaerobic to anaerobic condition which is attributable to the restricted circulation of water and the concomitant slow sedimentation rate were responsible for the development of authigenic pyrite and grey-black colour of the limestone.

Keywords

Sedimentary Petrology, Geochemistry. Proterozoic, Chhattisgarh Basin, Madhya Pradesh.

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I. K. Kaul ¹, C. N. Rao ¹, T. Sanyal ¹

Affiliations
1 Department of Geology and Geophysics, I.I.T., Kharagpur 721302, IN

Abstract

A new technique to determine the homogenization temperatures of fluid inclusions is described. The technique is based on the principle of optical density and involves no ambiguity in recording homogenization temperatures unlike in the standard heating stage method where because of problems of visual clarity of liquid phase disappearance, accurate measurement of homogenization temperatures becomes difficult and unreliable. A comparison of the two methods shows that the present technique gives somewhat higher values than those based on heating stage method.

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Kailas Dilli ¹, C. N. Rao ¹

Affiliations
1 Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur, 721 302, West Bengal, IN

Abstract

Drill core samples of DSDP sites 241 and 250 in the Somali and Mozambique Basins respectively have been examined to understand the nature and extent of burial diagenesis in the deep-sea pelitic sediments of the western Indian Ocean based on X-ray diffractometry and partial chemical analysis. The clay mineral suite is almost identical in both the basins with montmorillonite being the dominant mineral. Illite and kaolinite are present in minor amounts white chlorite is present only in traces. The sediments are in early diagenetic stage. The apparent breakdown of kaolinite and illite and the adsorption of K by the clay minerals has resulted in montmorilloniteillite mixed layers being the only phase present at depth. The mineral trends observed suggest that diagenesis is indeed initiated at much shallower depths as proposed by Matter.

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C. N. Rao ¹, Anjitha George ¹, A. R. Prasad ², Hafeez Ur Rehman ², Rathod Aravind Kumar ², A. Suman Kumar ², Sonali Ghike ¹, V. N. Dhengre ¹

Affiliations
1 ICAR-Central Citrus Research Institute, Nagpur 440 033, IN
2 Centre for Semiochemicals Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Hyderabad 500 007, IN

Abstract

The objective of this study was to determine the optimum height and dose of the indigenously synthesized sex pheromone of citrus leaf miner, Phyllocnistis citrella Stainton for the management of citrus groves under central Indian conditions. The influence of pheromone dose (5 and 8 mg) and trap height (canopy and mid-canopy height) on the capture of P. citrella males was evaluated. The dose of 5 mg of synthetic sex pheromone placed at mid-canopy (1.55 m) height attracted the highest number of P. citrella males (667.15 ± 9.84 adults/trap/week) in <5 year-old Citrus aurantifolia (Christm) Swingle (acid lime) groves of ICAR-CCRI, Nagpur experimental farm. Further evaluation of the pheromone baited traps @ 10, 15 and 20 mg/lure in <5-year-old orchards of acid lime recorded significant maximum trap catch in orchards with 20 mg lure (4 traps/0.3 ha) with mean trap catch/month from 4, 3 and 2 traps/0.3 ha of 1659.76 ± 36.67, 950.19 ± 17.91 and 668.44 ± 8.78 adults in 2014–15 and 1400.17 ± 36.67, 873.64 ± 17.91, 446.91 ± 8.78 adults in 2015–16 respectively.

Keywords

Citrus Groves, Optimum Height and Dose, Phyllocnistis citrella, Sex Pheromone, Semiochemicals.

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Anjitha George ¹, C. N. Rao ¹, V. N. Dhengre ¹

Affiliations
1 ICAR-Central Citrus Research Institute, Nagpur (M.S.), IN

Abstract

Currently, India ranks third amongst the citrus producing countries with a production of 100 lakh tons from 9.85 lakh hectare and a productivity 12.8 tons/ha at national level. The productivity and quality of citrus is severely affected by several factors; insect pests being one of them. As many as 250 insect species have been reported attacking citrus of which a dozen of them are of economic importance. Management of these sucking insect pests at the right stage drastically helps to reduce the overload of insecticidal sprays thereby assists in sustaining the productivity of the orchard. Sucking insect pests like citrus psylla, blackfly/ whitefly, aphids, thrips and leaf miner are among the important pests of three flushing seasons in citrus viz., Ambia (February-March), Mrig (June-July) and Hasta (October-November). Identification of insect pest, incidence and damage symptoms are critical for implementing appropriate control measures.

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Anjitha George ¹, C. N. Rao ¹

Affiliations
1 Division of Entomology, ICAR-Central Citrus Research Institute, Nagpur (M.S.), IN

Abstract

Introduction: Mites (Acari) are arthropods, a group that includes insects, spiders and among them, different mite species cause considerable damage in citrus. There are major four mite families relevant to citrus viz., Tetranychidae, Tenuipalpidae, Tarsonemidae and Eriophyidae. It is a serious pest of citrus in Vidarbha region, especially during Ambia (February-March) and Hasta (October-November) seasons. Citrus mites are more active on new growth of citrus plants, especially in the late spring and early fall. Populations will also be higher during summer due to the higher temperatures and humidity.

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