Biological Forum-An International Journal

3

Authors: R.J. Andrew*, Payal Verma** and M.K. Rathodi***

ABSTRACT : The ultrastructure of the egg chorion of the dragonfly, Pantala flavescens (Fabricius) is described using the light and scanning electron microscope. The egg of Pantala flavescens is oval and the chorion is distinctly divided into an outer exochorion and an inner endochorion. The egg measures about 720 ± 20 × 530 ± 10 µm in unwetted condition. The endochorion is light yellow, but turns brown within a few hours in water. The exochorion which envelopes the endochorion as a thin covering which expands into a transparent thick, sticky, jelly-like structure when it comes in contact with water and therefore, the egg in wet condition bloats and measures 870 ± 20 × 550 ± 20 µm. The apically placed micropylar apparatus is nipple shaped, formed of a small sperm storage chamber (atrium) and a median projecting micropylar stalk. The stalk is of 'concave cone' type and possesses a pair of subterminal orifices. A circular groove demarcates the exochorion and the micropylar apparatus.

3

Authors: Gaurav Sharma* and R. Sundararaj**

ABSTRACT : Mutualism between individuals of two species is increasingly recognized as a common and important ecological interaction. Interactions between ants and honeydew-producing hemipteran insects are abundant and widespread in arthropod food webs, though their ecological consequences are not well understood. Ant-hemipteran interactions have potentially broad ecological effects, because the presence of honeydew-producing hemipterans dramatically alters the abundance and predatory behaviour of ants on plants. In this paper we present an account of the ants and Hemiptera that were observed in association in Bangalore provenance of sandal. Different ants were found associated with five species of coccids viz., Cardiococcus bivalvata Green (Coccidae), Ceroplastes actiniformis Green (Coccidae), Nipaecoccus viridis (Newstead) (Pseudococcidae), Parasaissetia nigra (Nietner) (Coccidae) and Saissetia coffeae Targioni-Tozzetti (Coccidae) and three species of membracids viz., Leptocentrus longispinus Dist., Otinotus oneratus Walk. and Oxyrachis tarandus Fabr. Ants were known for protecting hemipterans from predators and parasitoids, their association may accelerate the growth and impact of honeydew-producing hemipterans on sandal plants and these findings were discussed in this paper.

4

Authors: Khaidem Binky*, M. Shomorendra** and Devashish Kar*

ABSTRACT : Six hundred and sixty-nine fish belonging to eight different species, from Karbhala wetland in Silchar, Assam were examined for nematode infections. Thirteen nematode species were recovered of which, two species were unidentified. Monopterus cuchia (20%) and Channa orientalis (20%) showed the highest prevalence percentage. Colisa fasciatus showed the highest mean intensity (6.86) and mean abundance (0.92). Contracaecum sp. was found to be infected in two fish hosts (Lepidocephalichthys guntea and Mystus bleekeri). The present communication also attempts to show the relative higher prevalence and mean intensity of the fishes of Karbhala wetland.

4

Authors: Jini Deshmane* and S.G. Nanaware**

ABSTRACT : In order to elucidate the effects of toxin form the fruit extract of Sapindus laurifolius on the mortality of fresh water snail, Bellamya bengalensis, the present investigation was undertaken. The LC50 values of this toxin were determined for the 24 hrs., 48 hrs., 72 hrs. and 96 hrs. by using Probit analysis method (Finney, 1971). The LC50 value was found to be 376.6, 215.3, 163.1 and 136.9 ppm for 24 hrs., 48 hrs., 72 hrs. and 96 hrs., respectively. The results indicated that the mortality of Bellamya bengalensis when exposed to the above mention plant toxin was dose and time dependent. As the concentration of the toxin was increased, the time to kill 5o per cent snails was decreased and vice-versa. Similarly, if the exposure period increased in the particular concentration of the toxin the rate of mortality was also increased with advancing the exposure period. Such dose and time dependent mortality responses of the snail are interpreted in relation to the toxicity of active principles in the fruit extract of Sapindus laurifolius.

5

Authors: Sangeetha G. Kaimal and N. Ramani

ABSTRACT : Feeding characteristics and damage induced by the spider mite, Oligonychus biharensis (Hirst) on the detached leaves of cassava Manihot esculenta L. were evaluated in the laboratory at 30 + 2°C and 70 + 5% RH. Cultivation of mite-infested (M+) and mite-free (M–) host plants was done by constructing block design plots and replicated. Live cultures of different stages of mites were also maintained in the laboratory using leaf flotation technique. The results showed that O. biharensis colonized on both surfaces of the leaf lamina of mature leaves and the petioles showed high population densities. Initial symptoms of damage were numerous white spots at the points of feeding on the leaf surface. Prolonged feeding encompassed the formation of dark brown patches, crinkling and subsequent drying and defoliation of affected leaves. Attack by these mites affected the growth and vigour of cassava plants. Analysis of damage symptoms revealed extensive bleaching and chlorosis of the leaves. Protein profile of M. esculenta leaves revealed 5 prominent bands each, both in M+ and M– host samples. However, M– samples invariably showed higher protein concentration than the M+ samples. Per cent loss in chlorophyll 'a' and 'b' recorded 86.40 + 1.6 % and 81.03 + 1.2 % respectively. Chlorophyll loss was significant at 1% levels. Increase in total phenol content of M+ plants ranged from 11.67 + 0.17 mg phenol/gm plant material.

8

Authors: B. Deepa and O.K. Remadevi

ABSTRACT : The larvicidal and ovicidal activity of the extracts of the seeds and leaves of Acacia concinna (Willd.) DC. and seeds and flowers of Butea monosperma (Lam.) Taub, prepared from the organic solvents, viz. petroleum ether, chloroform, methanol, ethyl alcohol, ethyl acetate, acetone and water were evaluated against the teak defoliator, Hyblaea puera Cramer. The result showed that the methanol and ethyl acetate extract of the seeds of A. concinna and the ethyl acetate extract of the leaves of A. concinna were the most effective among all the extracts causing 100% larval mortality even with least concentration (0.25%). All the extracts of the seeds of A. concinna showed 100% egg hatch inhibition at lowest concentration (0.5%), whereas all the extracts of the leaves of A. concinna were ineffective as ovicides except petroleum ether extract which exhibited 40% egg hatch inhibition at highest concentration (2%). The ethyl acetate extract of the seeds of B. monosperma, was the most effective among all the extracts causing 100% larval mortality even with least concentration (0.25%). Highest egg hatch inhibition (80%) was recorded at highest concentration (2%) for the chloroform extract of the seeds of B. monosperma. All the organic solvent extracts of the flowers of B. monosperma did not show any larvicidal and ovicidal activity.

10

Authors: R.K. Verma and K.S. Kapoor

ABSTRACT : A study was conducted to understand the plant diversity along an altitudinal gradient with elevations varying from 3000m to 5000m above msl in Ropa- Giavung valley falling in cold desert area of Pooh sub division of district Kinnaur, Himachal Pradesh during 2008. The total number of plant species was 160 belonging to 51 families and 119 genera. The dominant families were Asteraceae, Polygonaceae, Rosaceae and Ranunculaceae. The number of tree species at 3000-3500m was 12 with the dominance of Pinus gerardiana. The number of shrub species were 20 and 15 in the elevations of 3000-3500m and 3500-4000m respectively. Rosa webbiana and Juniperus indica taking shape of the dominant shrub at 3000-3500m and 3500-4000m elevations respectively. The number of herb species were 83, 46, 44 and 30 at 3000-3500m, 3500-4000m, 4000-4500m and 4500-5000m elevational ranges respectively. On the basis of Importance Value Index (IVI), Ephedra gerardiana, Artemisia brevifolia, Bistorta affinis and Potentilla argyrophylla were the dominant herbs dotting different elevational ranges and distribution pattern of plant species was mostly contiguous in all the altitudes. Index of diversity for herb species in different elevational ranges was 3.97, 3.54, 3.16 and 2.98. Index of similarity for herb species between different altitudes was low indicating more dissimilarity of species between different altitudes.