Population dynamics of the Teak defoliator (Hyblaea puera Cramer) in Nilambur teak plantations using Randomly Amplified Gene Encoding Primers (RAGEP)

BACKGROUND: The Teak defoliator (Hyblaea puera) is a pest moth of teak woodlands in India and other tropical regions (e.g. Thailand) and is of major economic significance. This pest is of major concern as it is involved in complete defoliation of trees during the early part of the growing season. Defoliation does not kill teak trees, but it results in huge amount of timber loss. Teak defoliator outbreaks are a regular annual feature in most teak plantations in India and it is extremely difficult to predict the exact time and place of occurrence of these outbreaks. Evidence from the study of the population dynamics of H. puera indicated habitual, short range movements of emerging moth populations, suggesting that these populations have spread to larger areas, generation after generation, affecting the entire teak plantations. We were therefore interested in investigating the temporal and spatial relationship among various population groups in Nilambur, Kerala (India) and address the cause of outbreak at the landscape level. RESULTS: The populations were classified into 'endemic', 'epicenter' and 'epidemic' populations based on the time of occurrence and size of infestation. We devised a novel method of screening nuclear and mitochondrial DNA polymorphisms using Randomly Amplified Gene Encoding Primers (RAGEP). We have used this method extensively to evaluate the species specificity, reproducibility and to discriminate among the three different characterised populations of teak defoliator. CONCLUSIONS: This method also allowed us to comment with some certainty that the endemic teak defoliator, H. puera do not play a major role in contributing to large-scale infestations. With respect to the hypotheses put forward regarding the origin of outbreaks of the moth, this study confirms the role of migration in outbreak causation, while negating the belief that endemic populations aggregate to cause an epidemic

Experimental Study on the Impact of Seasonal Sound Speed Variability on Signal Detection Range in Arabian Sea

Temporal variability of Signal Detection Range (SDR) with respect to measured noise level and sound speed is examined. An N x 2D acoustic model which included bathymetric variations, was used to study detection ranges for an area in Arabian Sea. Azimuthal and seasonal SDR at octave bands within 500 Hz were determined at different receiver depths. Study shows that seasonal change in sound speed profile resulted in high SDR and noise level in winter at the location. Study also confirms the significant seasonal difference in detection range corresponds to the cut off frequency at 160 Hz. Detection range for a receiver at a depth 40 m is observed to be high across the azimuth and seasons of study

Evolution mechanism of contrasting phases of consecutive IOD events from 1994 to 1998

The Dipole Mode Index (DMI), an Index used to represent the Indian Ocean Dipole (IOD), shows a back to back occurrence of positive and negative IOD events during the period 1994 to 1998. The year 1994 was a strong positive IOD year and was followed by a strong negative IOD in 1996. The positive IOD in 1997 and negative IOD in 1998 were co-occurred with the strong El-Nino and strong La-Nina, respectively. In the present study, we have looked into the evolution of consecutive IOD events during the period 1994 to 1998 and analyzed the differences in their formation, features and association with Indian Summer Monsoon Rainfall (ISMR) for various homogenous regions of the Indian subcontinent. We have found that the El-Nino and La-Nina enhances the IOD-induced positive SST anomalies in the western and eastern parts of the Indian Ocean during the co-occurred years, respectively. The evolution of positive IOD in 1997 is driven by the strong easterly wind anomalies associated with strong El-Nino. The positive anomalies of SST in the western equatorial Indian Ocean is maintained by the El-Nino which results in the long life span of positive IOD in the year 1997 than that of pure positive IOD year 1994. The westward propagating Rossby wave generated due to PIOD is maintained by strong El-Nino in the year 1997. The vertical dynamics, represented by D20, showed minor differences during the pure and co-occurred IOD events. The positive IOD years with El-Nino had good correlation with the Peninsular India and Central North East India regions rainfall. Since we have used only limited samples or cases under the different categories, our present results are preliminary in nature

Evolution mechanism of contrasting phases of consecutive IOD events from 1994 to 1998

521-532The Dipole Mode Index (DMI), an Index used to represent the Indian Ocean Dipole (IOD), shows a back to back occurrence of positive and negative IOD events during the period 1994 to 1998. The year 1994 was a strong positive IOD year and was followed by a strong negative IOD in 1996. The positive IOD in 1997 and negative IOD in 1998 were co-occurred with the strong El-Nino and strong La-Nina, respectively. In the present study, we have looked into the evolution of consecutive IOD events during the period 1994 to 1998 and analyzed the differences in their formation, features and association with Indian Summer Monsoon Rainfall (ISMR) for various homogenous regions of the Indian subcontinent. We have found that the El-Nino and La-Nina enhances the IOD-induced positive SST anomalies in the western and eastern parts of the Indian Ocean during the co-occurred years, respectively. The evolution of positive IOD in 1997 is driven by the strong easterly wind anomalies associated with strong El-Nino. The positive anomalies of SST in the western equatorial Indian Ocean is maintained by the El-Nino which results in the long life span of positive IOD in the year 1997 than that of pure positive IOD year 1994. The westward propagating Rossby wave generated due to PIOD is maintained by strong El-Nino in the year 1997. The vertical dynamics, represented by D20, showed minor differences during the pure and co-occurred IOD events. The positive IOD years with El-Nino had good correlation with the Peninsular India and Central North East India regions rainfall. Since we have used only limited samples or cases under the different categories, our present results are preliminary in nature

Multiphoton localization and propagating quantum gap solitons in a frequency gap medium

The many-particle spectrum of an isotropic frequency gap medium doped with impurity resonance atoms is studied using the Bethe ansatz technique. The spectrum is shown to contain pairs of quantum correlated ``gap excitations'' and their heavy bound complexes (``gap solitons''), enabling the propagation of quantum information within the classically forbidden gap. In addition, multiparticle localization of the radiation and the medium polarization occurs when such a gap soliton is pinned to the impurity atom.Comment: 8 pages, RevTEX, to appear in Phys. Rev. Let

Radiating dipoles in photonic crystals

The radiation dynamics of a dipole antenna embedded in a Photonic Crystal are modeled by an initially excited harmonic oscillator coupled to a non--Markovian bath of harmonic oscillators representing the colored electromagnetic vacuum within the crystal. Realistic coupling constants based on the natural modes of the Photonic Crystal, i.e., Bloch waves and their associated dispersion relation, are derived. For simple model systems, well-known results such as decay times and emission spectra are reproduced. This approach enables direct incorporation of realistic band structure computations into studies of radiative emission from atoms and molecules within photonic crystals. We therefore provide a predictive and interpretative tool for experiments in both the microwave and optical regimes.Comment: Phys. Rev. E, accepte

Cu based Metal Organic Framework (Cu-MOF) for electrocatalytic hydrogen evolution reaction

Hydrogen production using novel catalysts is regarded as one of the most needed technology for the future economic needs and water splitting to give H2 gas, which is a challenging task for large-scale production. This work reports the synthesis of Meso-Cu-BTC metal organic framework and further used for understanding its role in electrochemical hydrogen evolution reaction (HER) in 1 M NaOH solution. Meso-Cu-BTC electrocatalyst showed a less overpotential of 89.32 mV and an onset potential of 25 mV with an appreciable current density. Results show a low Tafel slope of 33.41 mVdec−1 and long-term durability. Thus, the overall results show that Meso-Cu-BTC acted as a good candidate for electrocatalysis towards hydrogen evolution

Prawn fauna (Crustacea: Decapoda) of India - An annotated checklist of the Penaeoid, Sergestoid, Stenopodid and Caridean prawns

Twenty four species of Pandalid shrimps reported from the Indian waters, of which six genera (Chlorotocella, Chlorotocus, Chlorocurtis, Dorodotes, Heterocarpoides and Stylopandalus) are represented by single species each. The genera, Plesionika and Heterocarpus are represented by eleven and seven species respectively. Plesionika adensameri (Balss, 1914) a deep-sea shrimp hitherto unreported from Indian waters is recorded from west coast of India. Information on some biological aspects of few Pandalid shrimps from Indian waters is also reported in the present paper