The genetics of green thorax, a new larval colour mutant, non-linked with ruby-eye locus in the malaria mosquito, Anopheles stephensi Liston

Background & objectives: Anopheles stephensi, an important vector of malaria continues to be distributed widely in the Indian subcontinent. The natural vigour of the species combined with its new tolerance, indeed resistance to insecticides has made it obligatory that we look for control methods involving genetic manipulation. Hence, there is an immediate need for greater understanding of the genetics of this vector species. One of the requirements for such genetic studies is the establishment of naturally occurring mutants, establishment of the genetic basis for the same and use of such mutants in the genetic transformation studies and other genetic control programme(s). This paper describes the isolation and genetic studies of a larval colour mutant, green thorax (gt), and linkage studies involving another autosomal recessive mutant ruby-eye (ru) in An. stephensi. Methods: After the initial discovery, the mutant green thorax was crossed inter se and pure homozygous stock of the mutant was established. The stock of the mutant ruby-eye, which has been maintained as a pure stock in the laboratory. Crosses were made between the wild type and mutant, green thorax to determine the mode of inheritance of green thorax. For linkage studies, crosses were made between the mutant green thorax and another autosomal recessive mutant ruby-eye. The percentage cross-over was calculated for the genes linkage relationship for gt and gt ru. Results: Results of crosses between mutant and wild type showed that the inheritance of green thorax (gt) in An. stephensi is monofactorial in nature. The gt allele is recessive to wild type and is autosomal. The linkage studies showed no linkage between ru and gt. Interpretation & conclusion: The mutant gt represents an excellent marker for An. stephensi as it is expressed in late III instar stage of larvae and is prominent in IV instar and pupal stages with complete penetrance and high viability. The said mutant could be easily identified without the aid of a microscope. This mutant can be used extensively to conduct basic and applied research. The mutant has been maintained in two large cages in our laboratory

Genetic Study of Propoxur Resistance—A Carbamate Insecticide in the Malaria Mosquito, Anopheles stephensi Liston

Anopheles stephensi Liston (Diptera: Culicidae) is the urban vector of malaria in the Indian subcontinent and several countries of the Middle East. The genetics of propoxur resistance (pr) in An. stephensi larvae was studied to determine its mode of inheritance. A diagnostic dose of 0.01 mg/L as recommended by WHO was used to establish homozygous resistant and susceptible strains. Reciprocal crosses between the resistant and susceptible strains showed an F1 generation of incomplete dominance. The progenies of backcrosses to susceptible parents were in 1 : 1 ratio of the same phenotypes as the parents and hybrids involved. The dosage mortality (d-m) lines were constructed for each one of the crosses, and the degree of dominance was calculated. It is concluded that propoxur resistance in An. stephensi larvae is due to monofactorial inheritance with incomplete dominance and is autosomal in nature

Insecticide susceptibility status in three medically important species of mosquitoes, Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus, from Bruhat Bengaluru Mahanagara Palike, Karnataka, India

Background: Development of resistance among mosquito vectors of diseases is of growing concern in many countries of the subtropics, including much of India. The distributions of susceptibility/resistance to insecticides are scarcely recorded and are unknown in many parts of India. This manuscript reports the susceptibility status among strains of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus collected from different geographical areas of Bruhat Bengaluru Mahanagara Palike (BBMP), Karnataka, to six conventionally used insecticides. Results: An. stephensi, Ae. aegypti and Cx. quinquefasciatus from different geographic areas showed susceptibility towards temephos. However, susceptibility was meagre for most of the other insecticides used in the study. Strong resistance to propoxur was reported in Ullala (RR90 = 467.1) and Bannerghatta (RR90 = 12 265) populations of An. stephensi and Ae. aegypti respectively. RR90 â 12 830 was recorded as higher in the Yelahanka (YLK) population of Cx. quinquefasciatus to neem. Significant differences at LC50 and LC90 concentrations were observed against various insecticides in different mosquito populations. Resistance was observed against some of the larvicides for the diagnostic dose recommended by WHO. Conclusion: The results form baseline data on the susceptibility status of three medically important mosquito vectors of diseases to commonly used insecticides in the field at present emphasise the importance of carrying out more effective and planned vector control measures. © 2012 Society of Chemical Industry

Differential Expression of Glutathione s-Transferase Enzyme in Different Life Stages of Various Insecticide-Resistant Strains of Anopheles Stephensi: A Malaria Vector

Background & objectives: Interest in insect glutathione s-transferases (GSTs) has primarily focused on their role in insecticide resistance. These play an important role in biotransformation and detoxification of many different xenobiotic and endogenous substances including insecticides. The GST activity among 10 laboratory selected insecticide resistant and susceptible/control strains of Anopheles stephensi was compared using the substrates 1-chloro-2,4-dinitrobenzene (CDNB). The difference in the GST activities of different life stages of diverse insecticide resistant strains was compared and presented.Methods: About 100 larvae, pupae, adult males, adult females and eggs (100 μg in total weight) were collected and used for the experiment. The extracts were prepared from each of the insecticide-resistant strains and control. Protein contents of the enzyme homogenate and GST activities were determined.Results: Deltamethrin and cyfluthrin-resistant strains of An. stephensi showed significantly higher GST activity. Larvae and pupae of DDT-resistant strain showed peak GST activity followed by the propoxur-resistant strain. On contrary, the GST activity was found in reduced quantity in alphamethrin, bifenthrin, carbofuran and chloropyrifos resistant strains. Adults of either sexes showed higher GST activity in mosquito strain resistant to organophosphate group of insecticides namely, temephos and chloropyrifos. Interpretation & conclusion: The GST activity was closely associated with almost all of the insecticides used in the study, strengthening the fact that one of the mechanisms associated with resistance includes an increase of GST activity. This comparative data on GST activity in An. stephensi can be useful database to identify possible underlying mechanisms governing insecticide-resistance by GSTs

Bibliography: Diseases, Parasites and Toxicology of Perna viridis,Crassostrea madrasensis and Villorita cyprinoids (Mollusca: Pelecypoda) of India

A proper understanding of the hazards associated with the fishery products on national basis has been the primary objective of the AP Cess Funded National Network Project on National Risk Assessment Programme for Fish and Fish Products for Domestic and International Markets. In this connection, the bibliography is prepared with the sole aim to compile all the available literature on this subject to produce a ready source of reference material for future investigators. In spite of the meticulous task and completeness, the authors express their regrets for any errors or omissions

Some Consequences of Dark Energy Density varying Exponentially with Scale Factor

In this paper we have explored the consequences of a model of dark energy with its energy density varying exponentially with the scale factor. We first consider the model with $\rho_{\phi} \propto e^{\kappa a}$, where $\kappa$ is a constant. This is a kind of generalisation of the cosmological constant model with $\kappa = 0$. We show that such an exponentially varying dark energy density with the scale factor naturally leads to an equivalent phantom field. We also consider a model with $\rho_{\phi} \propto e^{\kappa /a}$ and we show that this also naturally leads to an equivalent phantom field.Comment: 22 pages, 6 figure

A note on perfect scalar fields

We derive a condition on the Lagrangian density describing a generic, single, non-canonical scalar field, by demanding that the intrinsic, non-adiabatic pressure perturbation associated with the scalar field vanishes identically. Based on the analogy with perfect fluids, we refer to such fields as perfect scalar fields. It is common knowledge that models that depend only on the kinetic energy of the scalar field (often referred to as pure kinetic models) possess no non-adiabatic pressure perturbation. While we are able to construct models that seemingly depend on the scalar field and also do not contain any non-adiabatic pressure perturbation, we find that all such models that we construct allow a redefinition of the field under which they reduce to pure kinetic models. We show that, if a perfect scalar field drives inflation, then, in such situations, the first slow roll parameter will always be a monotonically decreasing function of time. We point out that this behavior implies that these scalar fields can not lead to features in the inflationary, scalar perturbation spectrum.Comment: v1: 11 pages; v2: 11 pages, minor changes, journal versio

Evaluation of oil of Cedrus deodara and benzyl benzoate in sarcoptic mange in sheep

Two commonly used acaricidal drugs in India containing oil Cedrus deodara (OCD) and benzyl benzoate (BB), respectively, were used in 24 lambs (3–6 months) naturally infected with Sarcoptes mites. The lambs were divided in three equal groups. Two groups were kept as treated groups and a third as control. Drugs were applied locally on affected parts on alternate days and recovery changes in skin lesions were observed regularly at the time of application. Blood samples from each group were collected and analysed for total erythrocytes, leukocytes, and haemoglobin concentration every 10 d Post treatment (PT). The two treated groups responded to the treatment but recovery in the C. deodara group (CDG) was faster and lesions were free from mites after 5 applications (tenth day) as compared to the seventh application (fourteenth day) in the benzyl benzoate group (BBG). Erythrocyte and leukocyte counts were significantly different in treated groups as compared to control. Animals treated with OCD had significantly more erythrocyte and leukocyte counts compared to control; however, haemoglobin did not show significant difference. Oil of C. deodara was found more efficacious in controlling sarcoptic mange in sheep

Mouthpart morphology of phyllosoma of the tropical spiny lobster Panulirus homarus (Linnaeus, 1758)

Mouthpart morphology of Panulirus homarus phyllosoma larva was studied under scanning electron microscope in order to analyse the developmental changes during growth. Phyllosoma larvae have six pairs of mouthparts (mandibles, maxillule, maxilla, maxillipeds I, II, and III), labrum, and paired paragnaths. Increased length of second and third maxillipeds in late stage phyllosoma resulted in the increase of oral field, thus increasing its ability to catch prey. Labrum and paired paragnaths form a semienclosed oral chamber where mastication by the mandibles occurs. The improved threshing and tearing efficiency in late instars (stage VI-VIII) is facilitated by morphological changes in the mouthparts viz., increase in oral field, increased robustness and number of spinose setations of maxillule, and lengthy maxillipeds, indicating that the late instar larvae can process fleshier prey as compared to the early instar counterparts