The larvicidal activity of hydrodistillate extracts from Mentha piperita L. Ocimum basilicum L. Curcuma longa L. and Zingiber officinale L. were investigated against the dengue vector Aedes aegypti L. (Diptera: Culicidae).The results indicated that the mortality rates at 80, 100, 200 and 400 ppm of M. piperita, Z. officinale, C. longa and O. basilicum concentrations were highest amongst all concentrations of the crude extracts tested against all the larval instars and pupae of A. aegypti. Result of log probit analysis (at 95% confidence level) revealed that lethal concentration LC₅₀ and LC₉₀ values were 47.54 and 86.54 ppm for M. piperita, 40.5 and 85.53 ppm for Z. officinale, 115.6 and 193.3 ppm for C. longa and 148.5 and 325.7 ppm for O. basilicum, respectively. All of the tested oils proved to have strong larvicidal activity (doses from 5 to 350 ppm) against A. aegypti fourth instars, with the most potent oil being M. piperita extract, followed by Z. officinale, C. longa and O. basilicum. In general, early instars were more susceptible than the late instars and pupae. The results achieved suggest that, in addition to their medicinal activities, Lamiaceae and Zingiberaceae plant extracts may also serve as a natural larvicidal agent.

The present study investigated the effect of the aqueous extract of Helicteres isora L. (Sterculiaceae) bark on oxidative stress in the heart of rats during diabetes. The aqueous extract of Helicteres isora bark (100 mg, 200 mg/kg body weight, b.w.) was screened for its antioxidant effect in streptozotocin (STZ) induced diabetic rats. An appreciable decrease in peroxidation products, thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD), and hydroperoxides (HP) was observed in the heart tissues of Helicteres isora (HI) treated diabetic rats. The decreased activities of key antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-tranferase (GST) and glutathione (GSH) in diabetic rats were brought back to near normal range upon HI treatment. Tolbutamide was used as the standard reference drug. These results suggest that HI possesses promising antioxidative activity in STZ diabetic rats.

This study reports the results on induced meiotic diploid gynogenesis and female homogametic nature in the Indian cat¢sh, Heteropneustes fossilis. The eggs of H. fossilis were inseminated with conspe-ci¢c sperm. The sperm suspension was diluted to 1 Â 10 7 sperm mL À 1 in Hanks balanced salt solution. Sperm were irradiated under UV light, with the exposure time ranging from 15 to 360 s (7500 ergs mm À 2 for 60 s). The genetic inactivation of paternal chromosomes was con¢rmed by chromosome counting from the larval cells and the larvae also had a characteristic haploid syndrome. A typical 'Hertwig e¡ect' in the yield of hatched larvae was observed with doses of UV exposure 475 s (9375 ergs mm 2 ). Larvae resulting from sperm UV irradiated above 120 s (15000 ergs mm 2 ) were 100% haploids. Application of heat shock to the activated eggs was e¡ective in suppressing the release of the second polar body (meiotic gynogenesis) and resulted in diploid gynogenetic larvae morphologically identical to those of the control. The best yield of diploid gynogens (49.3% with respect to the control) was found to be at 6 min after egg activation and the heat shock at 41 1C for a 1-min duration, at an ambient water temperature of 27 1C. A total of 113 diploid gynogenetic fry from seven di¡erent female ¢sh were reared and subjected to sexing. All gynogenetic ¢sh were female in contrast to the control, which had a mean sex ratio of 56.7% females (which was not signi¢cantly di¡erent from 50% female). From these results, the sex determination mechanism in H. fossilis was presumed to be female homogamety.

The present investigation shows the antihyperglycaemic activity of aqueous extract of bark of Helicteres isora L. (100, 200 mg/kg b.w./p.o.) in streptozotocin (STZ) induced diabetic rats. Blood glucose levels, body weight, food and liquid intake were measured on every 5 th day over a period of 14 days. A single injection of STZ at a dose of 60 mg/kg b.w./i.p. elevated the glucose levels >240mg/dl after 5 days. Administration of H. isora at a dose of 100, 200 mg/kg/p.o. resulted in a significant (p<0.05) reduction in blood glucose levels. Body weights were significantly (p<0.05) reduced in STZ-induced diabetic rats when compared to normal rats while the extract significantly (p<0.05) prevented a decrease in body weight in the H. isora treated animals. The study also evaluated the antioxidant potential of H. isora in STZ-induced diabetic rats. Decreased levels of thiobarbituric acid reactive substances (TBARS), increased levels of reduced glutathione (GSH) and the activities of superoxide dismutase (SOD) and catalase (CAT) resulted in the reduction of free radical formation in various tissues such as liver, kidney, and brain of the diabetic rats. Tolbutamide was used as a standard reference drug. The results clearly indicate that the aqueous extract of bark of H. isora exhibits significant antihyperglycaemic and in vivo antioxidant activity in STZinduced diabetic rats and the results were found to be dose dependent.

Aeromonas hydrophila, an opportunistic fish pathogen, which causes several major diseases including skin ulcer and haemorrhagic septicemia, contributes considerably to the lethality in aquaculture. Chemical and antibiotic treatment employed against A. hydrophila for disease management are expensive and consequently prompted the advent of drug resistance among the pathogens. To overcome these draw backs, alternative aquatic disease control methods using conventional plant-based medicines are focussed. Our present study aimed to augment the fish non-specific immune system with the implementation of methanolic crude extracts of Andrographis paniculata to Labeo rohita, for evaluating their efficacy against A. hydrophila. Histology of major organs of A. hydrophila-infected fish such as the gills and liver displayed severe tissue damage. A. paniculata extracts exhibited the strong antibacterial activity against A. hydrophila even at lower concentrations (50 μl). The extracts also altered the haematological profile of treated infected fishes by increasing the levels of haemoglobin and total erythrocyte-leucocyte counts, along with the phagocytic index. The extracts also had a significant impact on modifying the anatomy and swimming pattern of infected fish, post treatment with the extracts. Also, A. paniculata treated infected fishes in all the plant extract administration methods, viz. injection, oral feeding and diffusion, and reduced the cumulative mortality rate to less than 30%. Even lower concentrations of A. paniculata extracts (50 μl) resulted in maximum relative percentage survival of treated fishes. Therefore, our findings suggest that A. paniculata was effective against A. hydrophila infection in aquaculture, thereby maintaining a healthy status of these fishes in aquaculture.

The larvicidal activity of extracellular metabolites of keratinophilic fungus Trichophyton mentagrophytes against Aedes aegypti larvae was determined. T. mentagrophytes was isolated from soil by the feather baiting technique. Culture filtrates (10-100 microL/mL) were found to be entomotoxic to 3rd instars larvae of A. aegypti (L3), LC(50) and LC(90) being 110 +/- 11.5 and 200 +/- 20.7 microL/mL, respectively, after 2 d. Extracellular metabolites are proteinaceous in nature and more specific to chitin of mosquito larvae. They degraded cock feather causing an average of 20.0 +/- 2.6 % loss in feather mass. Culture filtrate at 100 microL/mL produced 90 % mortality against L3 after 3 d; mortality was increased in dose- and time-dependent manner. These extracellular metabolites of T. mentagrophytes could be regarded as alternatives to synthetic insecticides.

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