A note on the insecticide susceptibility status of secondary malaria vector An. annularis in Jharkhand state of India

Background & objectives: An. annularis van der Wulp (1884) is the secondary malaria vector of importance in India. In Jharkhand state it is present in almost all the districts abundantly and transmits malaria. The development of resistance to Dichlorodiphenyltrichloroethane (DDT) in An. annularis was reported from various parts of India. The main objective of this study was to generate information on insecticide susceptibility status of An. annularis to DDT, malathion, deltamethrin and permethrin in different districts of Jharkhand state. Methods: Adult An. annularis female mosquitoes were collected form villages of six tribal districts Simdega (Kurdeg and Simdega CHC), Khunti (Murhu and Khunti CHCs), Gumla (Bharno and Gumla CHCs), West Singhbhum (Chaibasa and Bada Jamda CHCs), Godda (Poraiyahat and Sunderpahari (CHCs) and Sahibganj (Borio and Rajmahal CHCs). Insecticide susceptibility status was determined by using WHO tube test method against prescribed discriminatory dosages of insecticides, DDT - 4.0%, malathion - 5.0%, deltamethrin - 0.05% and permethrin - 0.75%. Results: An. annularis was reported resistant to DDT in six districts, possible resistant to malathion in districts Gumla, Khuntiand Sahibganj and susceptible to deltamehrin (98% to100% mortality) and permethrin (100% mortality). Interpretation & conclusion: An. annularis, the secondary vector species is associated with the transmission of malaria reported resistant to DDT and susceptible to pyrerthroids deltamethrin and permethrin. In view of large-scale distribution of long-lasting insecticidal nets (LLINs) in all the districts, the response to synthetic pyrethroid needs to be periodically monitored to assess the effectiveness.

Shelf life of bioagents and longevity of biologically coated pigeonpea seed

Biological seed coating is a new technique of seed treatment through which biological agents are coated over the seed surface for effective control of seed and soil-borne pathogens. In this study, pigeonpea seed was biologically coated with Pseudomonas fluorescens, Rhizobium spp. and Phosphorus solubilizing bacteria (PSB) using biofriendly polymer and sugar syrup as adjuvants. The shelf life of bioagents and seed quality parameters was studied during six months of storage period. The colony units of Pseudomonas increased with biofriendly polymer either as individual or in consortia with biofertilizers. Six months after treatment, more colony units of Pseudomonas fluorescens were recorded on the surface of biologically coated seed of pigeonpea with biofriendly polymer as an adjuvant compared to sugar syrup. Seeds coated with Pseudomonas and PSB using biofriendly polymer recorded high seed germination and seedling vigour compared to sugar syrup. The observations reveal that there is a possibility of coating seed with biological agents using biofriendly polymer immediately after processing or before packaging without affecting the shelf life of bioagents and seed quality. Thus, the biologically coated pigeonpea seed in advance of cropping season can go a long way in minimizing risk associated with on farm seed treatment.

Spectrum of congenital malformations in newborns: in a medical college hospital in South India.

The study was carried out with the aim to determine the overall rate of congenital malformations, incidence in live births and stillbirths, as well as incidence affecting various organ systems, at a medical college hospital in Karnataka and compare them to previous studies Methods: All intramural deliveries between June 2012 and March 2014 were included in the study. All the new-borns were examined for congenital malformations soon after birth and every day during routine ward rounds. Relevant radiological, histo-hematological and genetic tests were carried out. Results: During the study period there were 3016 births out of which 2941 were live births and 75 were still born. 93 babies had one or more malformations. The overall incidence of malformations was 3.083%. Incidence of malformations among live births was 2.72% whereas it was 17.33% among still born babies. Musculoskeletal malformations accounted for 27.5% of all the malformations. This was followed by cutaneous 19.16%, genitourinary 15.83%, gastrointestinal 12.5%, neurological 10% and cardiac 5.83%. Conclusion: Congenital anomalies are a major cause of stillbirths and infant mortality. Musculoskeletal malformations were the commonest system involved. Still born babies had a significantly higher incidence of malformations and also had a higher incidence of multiple malformations.

Agenesis of the hemidiaphragm: A rare presentation in an adult.

Unilateral diaphragmatic agenesis is a rare finding in adult patients. We report a case of unilateral agenesis of diaphragm in a 22-year-old male patient to highlight the fact that a rare entity of agenesis of diaphragm can have a misleading presentation in adulthood due to both pulmonary and abdominal symptoms.

Field evaluation of lambda-cyhalothrin (ICON 10 CS) indoor residual spraying against Anopheles culicifacies in India.

Background & objectives: Field trials of lambda-cyhalothrin 10 CS (ICON 10 CS) in indoor residual spraying (IRS) with 25 mg a.i./m2 against Anopheles culicifacies was undertaken vs malathion IRS (25% WP–2 g a.i./ m2) in Tumkur district, Karnataka; vs deltamethrin IRS (2.5% WP–20 mg a.i./m2) in Dharmapuri district; and vs lambda-cyhalothrin (10 WP–25 mg a.i./m2) in Ramanathapuram district, Tamil Nadu, India. Methods: Spray operations in the experimental villages were done by the National Institute of Malaria Research (NIMR) and in the control villages by the respective State Health Department staff. Persistence of efficacy of insecticide sprayed in villages was assessed by contact bioassays against vector mosquitoes. Entomological indicators such as per structure density, parity rates of vector mosquitoes and sporozoite rates were measured in all the three study areas using standard procedures. Mass blood surveys and active fever case detections were carried out in experimental and control villages to study the impact of IRS on malaria transmission. Results: Persistence of effectiveness of ICON 10 CS was observed up to 2–3 months in all the three study areas. ICON 10 CS was found effective at par with or better than the insecticides used in the national programme in reducing the mosquito densities and in interrupting malaria transmission in the study villages. Vector density, parity rates and malaria cases considerably reduced in the ICON 10 CS-sprayed villages. Conclusion: Field trials at three sites have established that ICON 10 CS formulation was relatively more effective than malathion 25% WP, deltamethrin 2.5% WP and lambda-cyhalothrin 10% WP in some evaluation parameters like indoor resting mosquitoes, parity rates in vector mosquitoes and persistence of effectiveness. It can be used for IRS for malaria vector control with two rounds of spray at an interval of 3 months for curtailing the malaria transmission and an additional round is recommended in perennial malaria transmission areas.

Persistence of DDT, malathion & deltamethrin resistance in Anopheles culicifacies after their sequential withdrawal from indoor residual spraying in Surat district, India.

Background & objectives: Under the national antimalaria programme DDT was introduced in early 1950s for vector control and later hexachloro cyclohexane (HCH) followed by malathion and recently synthetic pyrethroids in 1990s to manage the insecticide resistance in Anopheles culicifacies. Subsequent replacement led to development of multiple resistances in An. culicifacies in Surat district in Gujarat State. Indoor residual spray (IRS) was completely withdrawn in southern villages in Surat in 2002. This study was undertaken in these areas to study the persistence of resistance to DDT, malathion and deltamethrin after sequential withdrawal of IRS with these insecticides at different times. Methods: Susceptibility tests on An. culicifacies were conducted using standard WHO methods and kits. Mortality, knockdown time and lethal times were calculated for An. culicifacies exposed to WHO prescribed diagnostic concentrations of different insecticide impregnated papers. Results: Persistence of DDT-resistance was observed even after 30 yr of its withdrawal from IRS. Similarly, persistence of malathion resistance was also observed after 9 yr of its withdrawal from IRS, while reversal of deltamethrin-resistance was observed very fast within 2-3 yr after its withdrawal from IRS in 2002. Interpretation & conclusion: Present data indicate that the quantum of reversion of insecticide resistance in a population is relative and depends on the genetic stability of the respective resistance genes in the mosquitoes. In the present study withdrawal of pyrethroid-IRS resulted in increased susceptibility against pyrethroids alone and was independent of existence of resistance to insecticides of other groups. This study emphasizes that appropriate rotation of different insecticides; including carbamates may prevent or delay the onset of resistance.

Evaluation of Larvicidal and Repellent Activity of Xanthium Strumarium (Asteraceae) Ethanol Extract agaist Mosquito Vectors.

Ethanol extract of leaf and seed of Xanthium strumarium was investigated for anti-mosquito potential, including larvicidal and repellent activities against Anopheles culicifacies, Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti. The ethanol-extracted Xanthium strumarium possessed larvicidal activity against fourth instar larvae of An. culicifacies, An. stephensi Cx. quinquefasciatus and Ae. aegypti. The LD 50 and LD values of ethanol-extracted of leaf were 0.19, 0.8, 0.27, 0.27% and 90 1.3, 1.3, 1.0, 1.8% and seed were 0.15, 0.9, 0.25, 0.23 and 1.5, 1.4, 1.7, 1.9% against An. culicifacies An. stephensi Cx. quinquefasciatus and Ae. aegypti respectively. It showed 100% repellency against An. culicifacies, An. stephensi and Culex quinquefasciatus in 0h 1h, 2h 4h and 1h 2h 6h, at 10% concentration respectively. It also provided biting protection time of 0h, 1h, 2h, 4h, and 6h when applied at a concentration of 2.5, 5, and 10 %. Against Deet- 2.5% An. culicifacies Giles species A 100% repellency in 1h, 2h, An. stephensi Liston 100% repellency in 2h, 4h, and Culex quinquefasciatus Say have shown 100% repellency in 4h. Xanthium strumarium, therefore, can be considered as a probable source of some biologically active compounds used in the development of mosquito control agents, particularly repellent and larvicidal products.

Laboratory studies on mosquito larvicidal efficacy of aqueous & hexane extracts of dried fruit of Solanum nigrum Linn.

Background & objectives: Aqueous and organic solvent extracts of plants/plant parts were effective in killing the mosquito larvae. Comparative efficacy of the aqueous and hexane extracts of dried fruit of Solanum nigrum was tested against five laboratory colonized strains of mosquito species, namely Anopheles culicifacies species A, An. culicifacies species C, An. stephensi, Culex quinquefasciatus and Aedes aegypti to assess the possibility for use of these extracts for their control. Methods: Concentrations of aqueous extract of dried fruit in the range of 62.5 to 2000 ppm and hexane extract of dried fruit in the range of 0.781 to 150 ppm were used in bioassays. The mortality data were subjected to log probit regression analysis to detertmine the median lethal concentrations (LC50 and LC90) to kill 50 and 90 per cent of the treated larvae of the respective species. Results: All the five species registered 100 per cent mortality in larval bioassays at 1000 ppm with aqueous extract and at 100 ppm with hexane extract of dried fruit. In bioassays with aqueous extract An. culicifacies species A registered the lowest LC50 of 208.5 ppm (range-208.5-359 ppm for different mosquito species) while with hexane extract, An. stephensi registered the lowest LC50 of 6.25 ppm (6.25- 17.63 ppm for different mosquito species). The LC50 of aqueous extract was 13-39 fold higher than the values of hexane extract of dried fruit for different species. The calculated LC90 for hexane extract of dried fruit for different species was in the range of 43.38-95.28 ppm. Interpretation & conclusion: Hexane extract showed good mosquito larvicidal efficacy than that of the aqueous extract. The calculated LC 90 for the extract for different species was below 100 ppm and could be effective for comprehensive control of disease vectors.

Temporal-scale spectral variability analysis of water quality parameters to realize seasonal behaviour of a tropical river system - River cauvery, India.

This paper describes the Time series analysis of river water quality with emphasis on variation in parameters as evidenced by statistical approach and mathematical models. The extensive study enabled to differentiate and realize the behaviour of river and catchment’s changes induced by human activities. The Time series analysis evaluation indicated trivial variation and movement in the water quality as reflected by the changes in the catchment characteristics. Although the observed trends showed an insignificant human contribution to basin hydrology and river water chemistry, noticeable human activities and unsustainable practices steadily contributed to change in water quality from the existing long term spectral signatures to short term spectral signatures. It is inferred that short term spectral signature exhibited on temporal scale by a monitoring program of this kind reflects an insalubrious river system and long term gradual changes in spectrum is an indication of healthy system. Monitoring and analyses of these decisive changes in water quality parameters over a period could be a powerful tool for assessing general river water quality and management plan.

Evaluation of Tribulus terrestris Linn (Zygophyllaceae) Acetone extract for Larvicidal and Repellence Activity against Mosquito Vectors.

Acetone extracts of leaves and seeds from the Tribulus terrestris (Zygophyllaceae) were tested against mature and immature different mosquito vectors under laboratory condition. The extract showed strong larvicidal, properties 100 per cent mortality in the 3rd-instar larvae was observed in the bioassays with An. culicifacies Giles species A, An. stephensi Liston , Culex quinquefasciatus Say and Aedes aegypti Linn ,against 200ppm of the leaf acetone extract and 100 ppm seed acetone extract. The LC values 50 of leaf acetone extract estimated for 3rd-instars An. culicifacies species A, An. stephensi, Cx. quinquefasciatus and Ae. aegypti after 24 hour of exposure were 117, 124, 168 and 185 ppm respectively. The LC values of seed 50 acetone extract estimated for 3rd-instars An. culicifacies species A, An. stephensi, Cx. quinquefasciatus and Ae. aegypti after 24 hour of exposure were 100, 72, 91 and 91 ppm respectively. It is confirmed from the LC values 50 that the seed acetone extract of T. terrestris is more effective compared to leaf extracts. A significant (P<0.004) higher concentration of acetone extract leaf was required to kill equal number of larvae i.e. against acetone extract of seed. The seed acetone extract showed strong repellent activity against adults mosquitoes. Per cent protection obtained against Anopheles culicifacies species A 100% repellency in 1h, 6h; Anopheles stephensi 100% repellency in 0h, 4h, 6h; and Culex quinquefasciatus 100% repellency in 0h, 2h, 4h, at 10% concentration respectively. Against Deet- 2.5% An. culicifacies Giles species A has shown 100% repellency in 1h,2h,6h , An. stephensi Liston 99% repellency in 4h , and Culex quinquefasciatus Say has shown 100% repellency in 1h,2h.

Biological control of mosquito populations through frogs: opportunities & constrains.

The use of frogs and tadpoles for disease vector control is still largely unexplored. Frogs are an important part of the ecosystem with a role for insect and pest control including mosquitoes. Available information suggests the existence of many direct and indirect factors affecting the growth and survival of both prey and predators. Other controphic species that have influence on this relationship also show considerable effect. Still, the associations of different prey and predator relationships in the environment to assess the feasibility of use of a species as biocontrol agent for vector control and management. However, frogs cannot be used as an independent intervention for disease vector control and more research is needed to use them effectively for mosquito control.

Impact of DDT spraying on malaria transmission in Bareilly District, Uttar Pradesh, India.

BACKGROUND & OBJECTIVES: Impact of indoor residual spraying of DDT on malaria transmission and vector density was evaluated in six villages of Shergarh PHC, Bareilly district, Uttar Pradesh under the operational condition of National Vector Borne Disease Control Programme (NVBDCP) from July 2001 to March 2002 (one transmission season only). METHODS: Two rounds of DDT (50% WDP) spraying @ 1 g/m2 were done both in the experimental and control villages by the state health authorities. The spraying in experimental villages was supervised by Malaria Research Centre (MRC) whereas the district health authorities supervised the operation in control villages. Mass blood surveys were made three times--before the first round, in between the first and second rounds and after the second round of spraying. The blood smears were examined by the trained microscopists of MRC, Haldwani. From the above examinations epidemiological indicators such as slide positivity rate (SPR), slide falciparum rate (SFR) and infant parasite rate (IPR) were calculated. All malaria positive cases were given radical treatment as per NVBDCP schedule. Entomological parameters such as per man hour mosquito density, parity rate, gonotrophic condition and adult susceptibility status of Anopheles culicifacies to diagnostic dosages of DDT (4%) were monitored as per the standard techniques. RESULTS: A total of 988.5 kg of DDT was consumed during two rounds of spray. The house coverage varied from 87 to 95.3%. Parasitological evaluation revealed significant reduction in malaria cases (p < 0.0005) and infant parasite rate declined from 2.9 to 0%. Entomological observations revealed considerable reduction in the density of malaria vector An. culicifacies despite of its 21.4% mortality against DDT test papers. INTERPRETATION & CONCLUSION: The overall results of the study revealed that DDT is still a viable insecticide in indoor residual spraying owing to its effectivity in well supervised spray operation and high excito-repellency factor.

Evaluation of bifenthrin treated mosquito nets against anopheline and culicine mosquitoes.

BACKGROUND AND OBJECTIVES: The main rural malaria vector Anopheles culicifacies has developed resistance to dichloro diphenyl trichloroethane (DDT), hexachloro cyclo hexane (HCH) and malathion in the state of Haryana in northern India. An alternative synthetic pyrethroid insecticide bifenthrin was therefore evaluated on mosquito nets against anopheline and culicine mosquitoes, in two villages Jagdishpur and Garh Mirakpur of Community Health Center (CHC) Badhkhalsa in district Sonipat, Haryana state. METHODS: Two formulations of bifenthrin, suspension concentrate (SC) and micro-emulsion (ME) were compared with micro-capsule suspension (CS) of lambdacyhalothrin. The impact of three doses of bifenthrin (10, 25 and 50 mg/m(2)) impregnated on mosquito nets was compared with lambdacyhalothrin (25 mg/m(2)) and untreated control. Quality assessment of treatment on treated nets was carried out by residue analysis and the persistence of the insecticide on nets was determined by contact bioassays. Efficacy of treated nets on mosquito density was assessed by calculating mosquito entry rate, immediate mortality, delayed mortality and excito-repellency to the insecticides. RESULTS: In susceptibility tests An. culicifacies was susceptible to bifenthrin (0.1% test papers) and to lambdacyhalothrin (0.05% test papers). Bioassays on treated nets against A. culicifacies recorded 100 per cent mortality up to tenth fortnight for all the doses of impregnation with bifenthrin (SC and ME) and lambdacyhalothrin (CS). Ring-net bioassays against An. culicifacies showed median knock-down time between 3.1 to 11.4 min. Behavioural indices were also studied for anopheline and culicine mosquitoes. The reduction in entry rates of anopheline and culicine mosquitoes into the rooms with treated nets compared to control indicated good efficacy with all the formulations and doses of the insecticides. INTERPRETAION AND CONCLUSION: Indoor (immediate) mortality of mosquitoes with bifenthrin ME formulation was relatively lower compared to SC fomulation of bifenthrin and based on delayed mortility and continued susceptibility in bioassays, bifenthrin ME at the rate of 10 mg/m(2) dose was found suitable for the impregnation of mosquito nets for phase III trial.