Insecticide susceptibility status of malaria vectors in Himachal Pradesh, India

Background & objectives: The state of Himachal Pradesh is one of the hilly forested states of India. Warming of climate has been evidenced in the state due to the ongoing climate change which may cause the upsurge/introduction of mosquito-borne diseases. To curb disease transmission, an effective vector control strategy will be required. Methods: Insecticide susceptibility status of available malaria vectors was determined using the standard WHO method in six districts Kangra, Una, Mandi, Bilaspur, Solan and Mandi of the state. An. culicifacies and An. fluviatilis were tested against DDT (4%), malathion (5%) and deltamethrin (0.05%) using WHO insecticide susceptibility kits. Results: Overall, An. culicifacies was found resistant to DDT in all the six districts, susceptible to malathion in all districts except Bilaspur and Solan where it showed possible resistance. It was susceptible to deltamethrin in all the study districts. An. fluviatilis was resistant to DDT and susceptible to malathion and deltamethrin in Kangra and Una districts. Interpretation & conclusion: At present, indoor residual spraying (IRS) is not being undertaken in Himachal Pradesh. However, with the information generated through the present study, the state government can plan evidence-based IRS at least for focal spray in limited foci reporting malaria incidence.

Battling malaria iceberg incorporating strategic reforms in achieving Millennium Development Goals & malaria elimination in India.

Malaria control in India has occupied high priority in health sector consuming major resources of the Central and State governments. Several new initiatives were launched from time to time supported by foreign aids but malaria situation has remained static and worsened in years of good rainfall. At times malaria relented temporarily but returned with vengeance at the local, regional and national level, becoming more resilient by acquiring resistance in the vectors and the parasites. National developments to improve the economy, without health impact assessment, have had adverse consequences by providing enormous breeding grounds for the vectors that have become refractory to interventions. As a result, malaria prospers and its control is in dilemma, as finding additional resources is becoming difficult with the ongoing financial crisis. Endemic countries must contribute to make up the needed resources, if malaria is to be contained. Malaria control requires long term planning, one that will reduce receptivity and vulnerability, and uninterrupted financial support for sustained interventions. While this seems to be a far cry, the environment is becoming more receptive for vectors, and epidemics visit the country diverting major resources in their containment, e.g. malaria, dengue and dengue haemorrhagic fevers, and Chikungunya virus infection. In the last six decades malaria has taken deep roots and diversified into various ecotypes, the control of these ecotypes requires local knowledge about the vectors and the parasites. In this review we outline the historical account of malaria and methods of control that have lifted the national economy in many countries. While battles against malaria should continue at the local level, there is a need for large scale environmental improvement. Global Fund for AIDS, Tuberculosis and Malaria has provided huge funds for malaria control worldwide touching US$ 2 billion in 2011. Unfortunately it is likely to decline to US$ 1.5 billion in the coming years against the annual requirement of US$ 5 billion. While appreciating the foreign assistance, we wish to highlight the fact that unless we have internal strength of resources and manpower, sustained battles against malaria may face serious problems in achieving the final goal of malaria elimination.

Can Mosquito Magnet® substitute for human-landing catches to sample anopheline populations?

The efficiency of the Mosquito Magnet Liberty PlusTM (MMLP) trap was evaluated in comparison to human-landing catches (HLCs) to sample anopheline populations in Jabillal, state of Bolivar, southern Venezuela. The village comprised 37 houses and a population of 101; malaria in this village is primarily due to Plasmodium vivax and the Annual Parasite Index is 316.8 per 1,000 population. A longitudinal study was conducted between June 2008-January 2009 for three nights per month every two months between 17:30 pm-21:30 pm, a time when biting mosquitoes are most active. Anopheles darlingi and Anopheles nuneztovari were the most common species collected by both methods, whereas Anopheles marajoara was more abundant according to the HLC method. The MMLP trap was more efficient for collecting An. nuneztovari [63%, confidence interval (CI): 2.53] than for collecting An. darlingi (31%, CI: 1.57). There were significant correlations (p < 0.01) between the two methods for An. darlingi [Pearson correlation (R²) = 0.65] and An. nuneztovari (R² = 0.48). These preliminary results are encouraging for further investigations of the use of the MMLP trap for monitoring anopheline populations in remote malaria-endemic areas in the Amazon Basin.

Estacionalidad de la densidad larval del mosquito Anopheles aquasalis (Diptera: Culicidae) y otros insectos asociados a su hábitat en Sucre, Venezuela

Larval seasonality of the mosquito Anopheles aquasalis (Diptera: Culicidae) and other insects associated to its habitat in Sucre, Venezuela. Anopheles aquasalis Curry is considered the main vector of human malaria in Northern Venezuela. A longitudinal study was carried out in the coastal areas of the Paria Peninsula, Sucre state. The larval habitats of A. aquasalis were classified as: 1- Brackish mangrove, and 2- Freshwater herbaceous swamp. Field surveys of mosquito larvae and aquatic insects were carried out in the same breeding sites over a one-year period, between January and December 1999. At each site, 30 samples of Anopheles larvae and aquatic insects were taken monthly. Simultaneously with mosquito larvae sampling, five selected variables of water were measured: conductivity, salinity, dissolved oxygen, temperature and pH. Seasonal and temporal variations of A. aquasalis larvae and aquatic insects were determined in the two larval habitats. For the entire study period, the abundance of larvae was higher in the mangrove. Correspondence analysis showed a strong relation between some chemical factors of water and larval abundance. The abundance of A. aquasalis larvae in both seasons, was positively correlated with water salinity, pH and conductivity, and negatively with dissolved oxygen in the dry season. The presence of larvae was positively correlated with the presence of Avicenia germinans. In the mangrove there was a positive association between larvae abundance and Scirtidae family abundance and a negative correlation between larvae abundance and monthly precipitation (Spearman), as well as a significant negative correlation between Gerridae abundance and monthly precipitation. In the herbaceous swamp, there were not significant associations between A. aquasalis larvae abundance and abundance of others aquatic insects associated to habitat. Rev. Biol. Trop. 58 (2): 777-787. Epub 2010 June 02.

Anopheles aquasalis es considerado como el principal vector de malaria humana en el norte de Venezuela. El estudio longitudinal se llevó a cabo en áreas costeras de la Península de Paria, estado Sucre. El hábitat de las larvas de A. aquasalis fue clasificado como: manglar salobre y pantano herbáceo. Muestreos para recolectar larvas de mosquitos e insectos asociados se realizaron mensualmente en ambos criaderos desde enero hasta diciembre de 1999 (30 muestras). Simultáneamente se midieron cinco variables seleccionadas del agua: conductividad, salinidad, oxígeno disuelto, temperatura y pH. En ambos criaderos de determinaron las variaciones estacionales y temporales de las larvas de A. aquasalis e insectos acuáticos. Para el período de estudio, la abundancia de larvas fue mayor en el manglar. El análisis de correspondencia mostró una fuerte relación entre algunos factores químicos del agua y la abundancia de las larvas. La abundancia de las larvas de A. aquasalis en ambas épocas, se correlacionó positivamente con la salinidad del agua, pH y conductividad, y negativamente con el oxígeno disuelto, en la estación seca. La presencia de larvas se correlacionó positivamente con la presencia de Avicennia germinans. En el manglar existió una asociación positiva entre la abundancia de larvas y la abundancia de la familia Scirtidae y una correlación negativa entre la abundancia de larvas y la precipitación mensual (Spearman), así como una correlación negativa significativa entre la abundancia de Gerridae y la precipitación mensual. En el pantano herbáceo, no había asociaciones significativas entre la abundancia de las larvas de A. aquasalis y la abundancia de otros insectos acuáticos asociados al hábitat.

Morphological analysis of three populations of Anopheles (Nyssorhynchus) nuneztovari Gabaldón (Diptera: Culicidae) from Colombia

Based on the results of comparative analyses of 1,039 specimens of several progenies of Anopheles nuneztovarifrom three localities in Colombia, eight costal wing spot patterns were observed. Patterns I and III were the most frequent: 77.96 percent and 11.36 percent, respectively. Using the diagnostic characters ratio of the length of the basal dark area of hind tarsomere II/length of hind tarsomere II, ratio of the length of the humeral pale spot/length of the pre-humeral dark spot, and the ratio of the length of the subcostal pale spot/length of the distal sector dark spot (DS-III2/Ta-III2, HP/PHD, SCP/DSD) approximately 5 percent of the adult females were misidentified as a species of Nyssorhynchus, different from An. nuneztovari. Approximately 5 percent of the specimens showed DS-III2/Ta-III2 ratio less than 0.25 (range 0.21 - 0.24), and among them 3.34 percent shared a HP/PHD ratio less than 1.50. Consequently, 1.52 percent of An. nuneztovari individuals can be misidentified as Anopheles oswaldoi. In those specimens with the DS-III2/Ta-III2 ratios higher than 0.25, 34.45 percent displayed SCP/DSD values greater than 0.50 and of these, 3.65 percent displayed HP/PHD values greater than 1.8. This combination of characters could lead one to misidentify samples of An. nuneztovari as Anopheles rangeli. Similarly, 2.43 percent of the females could be identified erroneously as either Anopheles aquasalis or Anopheles benarrochi. Individuals with a HP/PHD ratio greater than 2.0, could be misidentified as Anopheles trinkae, Anopheles strodei or Anopheles evansae. A distinct combination of diagnostic characters for An. nuneztovari from Colombia is proposed.

Systematic notes on Anopheles Meigen (Diptera: Culicidae) species in the state of Amapá, Brazil

Identification of Anopheles nuneztovari Gabaldón and An. goeldii Rozeboom and Gabaldón based on the male genitalia traits is discussed. An. goeldii is in the synonymy of An. nuneztovari, however, characters of the aedeagus of male genitalia distinguish both species. We hypothesize that An. goeldii may be a valid species, however, further studies using molecular characters, especially ITS2 rDNA sequences will be necessary to elucidate the taxonomic status of the species. An. konderi Galvão and Damasceno and An. forattinii Wilkerson and Sallum are registered for the first time in the state of Amapá.

A population genetics study of Anopheles darlingi (Diptera: Culicidae) from Colombia based on random amplified polymorphic DNA-polymerase chain reaction and amplified fragment lenght polymorphism markers

The genetic variation and population structure of three populations of Anopheles darlingi from Colombia were studied using random amplified polymorphic markers (RAPDs) and amplified fragment length polymorphism markers (AFLPs). Six RAPD primers produced 46 polymorphic fragments, while two AFLP primer combinations produced 197 polymorphic fragments from 71 DNA samples. Both of the evaluated genetic markers showed the presence of gene flow, suggesting that Colombian An. darlingi populations are in panmixia. Average genetic diversity, estimated from observed heterozygosity, was 0.374 (RAPD) and 0.309 (AFLP). RAPD and AFLP markers showed little evidence of geographic separation between eastern and western populations; however, the F ST values showed high gene flow between the two western populations (RAPD: F ST = 0.029; Nm: 8.5; AFLP: F ST = 0.051; Nm: 4.7). According to molecular variance analysis (AMOVA), the genetic distance between populations was significant (RAPD:phiST = 0.084; AFLP:phiST = 0.229, P < 0.001). The F ST distances and AMOVAs using AFLP loci support the differentiation of the Guyana biogeographic province population from those of the Chocó-Magdalena. In this last region, Chocó and Córdoba populations showed the highest genetic flow.