Effect of Synergist Piperonyl Butoxide (PBO) on the Toxicity of Some Essential Oils Against Mosquito Larvae.

Effect of a known synergist piperonyl butoxide on the toxicity of steam distillate essential oils of Jamarosa (Cymbopogan nardus), Pacholli (Pogostemon pacholli), Basil (Ocimum basilicum), and Peppermint (Mentha pipreta) plant species against Anopheles stephensi larvae were evaluated. The purpose of the present study was to identify the insecticidal potential of these oils against mosquito larvae. The Piperonyl Butoxide (PBO) was used to enhance the activity of these oils with the aim of developing essential oil based formulations. The bioassays of these oils with and without PBO were performed against late 3rd instar larvae of An. stephensi. The LC values against An. 50 stephensi were 44.19 ppm for Ocimum basilicum oil, followed by, Mentha pipreta, Cymbopogan nardus, and Pogostemon pacholli oil which gave LC 50 values above 250 ppm. Thus in the present study the Ocimum basilicum oil was found to be most effective, whereas Pogostemon pacholli oil was found to least effective against mosquitoes for larvicidal action. The effect of synergist PBO led to the enhancement of toxicity of oils, the LC value 50 for Ocimum basilicum were reduced from 44.19 ppm to 23.87 ppm. Similarly the oil of Pogostemon pacholli showed most significant results where the LC value was >250 ppm it was reduced to 50 ppm with PBO.

Effect of Synergist Piperonyl Butoxide (PBO) on the Toxicity of Some Essential Oils against Mosquito Larvae.

Effect of a known synergist piperonyl butoxide on the toxicity of steam distillate essential oils of Jamarosa (Cymbopogan nardus), Pacholli (Pogostemon pacholli), Basil (Ocimum basilicum), and Peppermint (Mentha pipreta) plant species against Anopheles stephensi larvae were evaluated. The purpose of the present study was to identify the insecticidal potential of these oils against mosquito larvae. The Piperonyl Butoxide (PBO) was used to enhance the activity of these oils with the aim of developing essential oil based formulations. The bioassays of these oils with and without PBO were performed against late 3rd instar larvae of An. stephensi. The LC values against An. 50 stephensi were 44.19 ppm for Ocimum basilicum oil, followed by, Mentha pipreta, Cymbopogan nardus, and Pogostemon pacholli oil which gave LC 50 values above 250 ppm. Thus in the present study the Ocimum basilicum oil was found to be most effective, whereas Pogostemon pacholli oil was found to least effective against mosquitoes for larvicidal action. The effect of synergist PBO led to the enhancement of toxicity of oils, the LC value 50 for Ocimum basilicum were reduced from 44.19 ppm to 23.87 ppm. Similarly the oil of Pogostemon pacholli showed most significant results where the LC value was >250 ppm it was reduced to 50 ppm with PBO.

Effect of cybil on reproductive success of wild Drosophila melanogaster.

Cybil (a synthetic pyrethroid) was used to assess its impact on the reproductive success in F1 and F2 generations of wild Drosophila melanogaster. The LC50 has been estimated as 0.0267 microl/100 ml food. Reproductive success has been found to be affected in addition to fecundity and pupation following toxicity of cybil.

Normal vibrations and valence charge distribution in relation to bioactivity of gammexane.

Normal coordinate analysis has been made for gammexane using the Wilson's G-F matrix method with Urey-Bradley force field. Molecular orbital calculations using CNDO/2 method have also been carried out for the five isomers of hexachlorocyclohexane to give the valence charge densities on the atoms of the molecules. A toxicity parameter that takes into account a shape factor and the valence charge density on the atoms has been defined. On the toxicity scale so defined the gamma-isomer alone has a significant value.

Hydrolytic enzymes of rhesus placenta during Plasmodium cynomolgi infection: ultrastructural and biochemical studies.

Placenta in monkey demonstrated altered pathophysiology after P cynomolgi infection. The electronmicroscopic observations showed slight complete focal necrosis of the placental tissue, besides alterations in total protein, phosphatases and proteinases. These changes in cellular constituents of placenta during malaria infection may be responsible for malfunctioning of the organ and in turn, abnormal development of foetus.

Central hyperthermic effect of arsenic in rabbits.

Hyperthermic effect of arsenic was investigated in rabbits. Injections of arsenic trioxide (0.0001 to 0.1 micrograms) into a lateral cerebral ventricle of the rabbit evoked a dose-dependent hyperthermia, respiratory stimulation and peripheral vasodilatation. Heat loss through respiratory stimulation and peripheral vasodilatation appeared responsible for the long latent period and the slight hypothermia sometimes obtained during this period as these effects followed the same time course. These effects were centrally mediated as demonstrated by the lack of efficacy of the same doses by the intravenous route. The hyperthermic effect of arsenic was antagonized by the sulphydryl donator, dimercaprol, the a-adrenoceptor blocking agent-phenoxybenzamine and the PG-synthesis inhibitor-aspirin. Multiple sites, for antagonistic effects of these substances can be explained by the action of arsenic in inactivating sulphydryl containing enzymes which are many and catalyze diverse biochemical reactions.

Acetylcholine: a possible neurotransmitter in Setaria cervi.

The total and free acetylcholine (Ach) and cholinesterase (CHE) content of adult Setaria cervi were estimated. The Ach was estimated by bioassay on rectus abdominis muscle of frog and the CHE by measuring the drop in pH following incubation of worm homogenate with Ach chloride. The free and total Ach contents (4.0 +/- 0.57 and 6.0 +/- 0.48 microgram/g wet weight of worms respectively) were as high as found in mammalian brain cortex. The cholinesterase activity was found to be 5.57 +/- 0.6 units/g wet weight of worms. It is possible that there may exist a well developed system responsible for the synthesis, storage, release and destruction of Ach and that Ach may be acting as an excitatory neurohormone in S. cervi.

Effect of diethylcarbamazine on Setaria cervi in vitro.

Diethylcarbamazine (DEC) produced an initial stimulation followed by depression of the movements of the intact worm and nerve-muscle preparation of Setaria cervi. The effective concentration of DEC was reduced to one hundredth in the nerve-muscle preparation as compared to the whole worm, suggesting that the cuticular barrier is highly effective in preventing the penetration of the drugs. The depressant effect of DEC was concentration dependent and was not reversed even after repeated changes of the bath fluid. The worms consumed 7.7 mg +/- 0.2 glucose/g wet weight/hr. The consumption of glucose was directly proportional to its motor activity; it increased during the stimulant phase with low doses of DEC and decreased during the depressant phase.