No abstract

Biocontrol agents and oviposition attractants are promising alternate tools/adjuncts for mosquito control. Using oviposition attractants, monitoring of vector populations, especially Aedes species, could be carried out so as to plan control measures, or to attract gravid females to lay eggs at chosen sites and kill the emerging larvae by combining a larvicide. Microorganisms inhabiting mosquitobreeding sites (Androsov et al. 1986) play a major role in the decomposition of detritus present in the habitats leading to the production of several metabolites. Some of these metabolites are likely to act as oviposition attractant and/ or stimulants for mosquitoes. Therefore, in the present study culture filtrates containing metabolites of a few bacteria were examined for oviposition attractancy and the results are presented hereunder. Cultivation of bacteria -Nutrient broth (NB) containing (wt/v %) glucose (0.5), beef extract (0.5), sodium chloride (0.5), and peptone (0.5) in distilled water at a pH 7.5 was used to grow P. (Yousten et al. 1980). And to grow B. sphaericus the medium NYSM without glucose was used. For the cultivation of A. brasilense a medium containing (wt/v %) yeast extract, 1.0 in distilled water, pH 7.5 was used. A loop full of bacterial growth from an agar slope was transferred to 10 ml of growth medium (in a boiling tube) and incubated for 8 h on a rotatory shaker at 250 rpm and 28 ± 2 o C. The culture was then transferred to 50 ml of growth medium (in 250 ml capacity Erlenmeyer flask) and incubated, as stated above, for 10 h. Five ml of this inoculum was transferred to 500 ml of production medium (in 2 l flask) and incubated for 48 h. Then, the cell-mass from the culture was harvested by spinning at 10,000 rpm for 10 min. The cell-mass was discarded and the cell-free supernatant was used as test material for oviposition attractancy tests. MATERIALS AND METHODS Bacterial strains -Determination of optimum concentration of bacterial culture filtrates for oviposition attractancy testThree-day-old Culex quinquefasciatus females, obtained from a colony maintained at VCRC, were fed on fowl blood and maintained for two days on raisins at 28 ± 2 o C and 70-80% RH. Gravid females were used for determination of oviposition attractancy of various compounds. Different concentrations (5-3000 ppm) of the test materials were prepared in tap water. Two hundred ml of each test preparation held in disposable cups (capacity, 250 ml) was placed in a mosquito cage (size, 55 x 55 x 55 cm). Tap water was used as a control. One hundred fully gravid female mosquitoes were released into the cage. For each test, one cage was used and at any given time, not more than five disposable cups were kept on the floor of the cage. Four cups with four different concentrations of the culture filtrate were on four corners and the fifth cup with tap water (control) was at the center of the cage. The cages were kept at 28 ± 2 o C and 70-80% RH. Experiments were set up

No abstract

Methanolic extracts of 20 medicinal plants were screened at 1-10 mg/ml for in vitro macrofilaricidal activity by worm motility assay against adult Setaria digitata, the cattle filarial worm. Four plant extracts showed macrofilaricidal activity by worm motility at concentrations below 4 mg/ml and an incubation period of 100 min. Complete inhibition of worm motility and subsequent mortality was observed at 3, 2, 1 and 1 mg/ml, respectively, for Centratherum anthelminticum, Cedrus deodara, Sphaeranthus indicus and Ricinus communis. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) reduction assay was carried out at 1 mg ml(-1) and 4-h incubation period, and the results showed that C. deodara, R. communis, S. indicus and C. anthelminticum exhibited 86.56, 72.39, 61.20 and 43.15% inhibition respectively in formazan formation compared to the control.