Urbanization alters the spatiotemporal dynamics of plant-pollinator networks in a tropical megacity.

Urbanization is a major driver of biodiversity change but how it interacts with spatial and temporal gradients to influence the dynamics of plant-pollinator networks is poorly understood, especially in tropical urbanization hotspots. Here, we analysed the drivers of environmental, spatial and temporal turnover of plant-pollinator interactions (interaction ß-diversity) along an urbanization gradient in Bengaluru, a South Indian megacity. The compositional turnover of plant-pollinator interactions differed more between seasons and with local urbanization intensity than with spatial distance, suggesting that seasonality and environmental filtering were more important than dispersal limitation for explaining plant-pollinator interaction ß-diversity. Furthermore, urbanization amplified the seasonal dynamics of plant-pollinator interactions, with stronger temporal turnover in urban compared to rural sites, driven by greater turnover of native non-crop plant species (not managed by people). Our study demonstrates that environmental, spatial and temporal gradients interact to shape the dynamics of plant-pollinator networks and urbanization can strongly amplify these dynamics.

Protocol for establishing a model for integrated influenza surveillance in Tamil Nadu, India.

The potential for influenza viruses to cause public health emergencies is great. The World Health Organisation (WHO) in 2005 concluded that the world was unprepared to respond to an influenza pandemic. Available surveillance guidelines for pandemic influenza lack the specificity that would enable many countries to establish operational surveillance plans. A well-designed epidemiological and virological surveillance is required to strengthen a country's capacity for seasonal, novel, and pandemic influenza detection and prevention. Here, we describe the protocol to establish a novel mechanism for influenza and SARS-CoV-2 surveillance in the four identified districts of Tamil Nadu, India. This project will be carried out as an implementation research. Each district will identify one medical college and two primary health centres (PHCs) as sentinel sites for collecting severe acute respiratory infections (SARI) and influenza like illness (ILI) related information, respectively. For virological testing, 15 ILI and 10 SARI cases will be sampled and tested for influenza A, influenza B, and SARS-CoV-2 every week. Situation analysis using the WHO situation analysis tool will be done to identify the gaps and needs in the existing surveillance systems. Training for staff involved in disease surveillance will be given periodically. To enhance the reporting of ILI/SARI for sentinel surveillance, trained project staff will collect information from all ILI/SARI patients attending the sentinel sites using pre-tested tools. Using time, place, and person analysis, alerts for abnormal increases in cases will be generated and communicated to health authorities to initiate response activities. Advanced epidemiological analysis will be used to model influenza trends over time. Integrating virological and epidemiological surveillance data with advanced analysis and timely communication can enhance local preparedness for public health emergencies. Good quality surveillance data will facilitate an understanding outbreak severity and disease seasonality. Real-time data will help provide early warning signals for prevention and control of influenza and COVID-19 outbreaks. The implementation strategies found to be effective in this project can be scaled up to other parts of the country for replication and integration.

Functional diversity of farmland bees across rural-urban landscapes in a tropical megacity.

Urbanization poses a major threat to biodiversity and food security, as expanding cities, especially in the Global South, increasingly compete with natural and agricultural lands. However, the impact of urban expansion on agricultural biodiversity in tropical regions is overlooked. Here we assess how urbanization affects the functional response of farmland bees, the most important pollinators for crop production. We sampled bees across three seasons in 36 conventional vegetable-producing farms spread along an urbanization gradient in Bengaluru, an Indian megacity. We investigated how landscape and local environmental drivers affected different functional traits (sociality, nesting behavior, body size, and specialization) and functional diversity (functional dispersion) of bee communities. We found that the functional responses to urbanization were trait specific with more positive than negative effects of gray area (sealed surfaces and buildings) on species richness, functional diversity, and abundance of most functional groups. As expected, larger, solitary, cavity-nesting, and, surprisingly, specialist bees benefited from urbanization. In contrast to temperate cities, the abundance of ground nesters increased in urban areas, presumably because larger patches of bare soil were still available beside roads and buildings. However, overall bee abundance and the abundance of social bees (85% of all bees) decreased with urbanization, threatening crop pollination. Crop diversity promotes taxonomic and functional diversity of bee communities. Locally, flower resources promote the abundance of all functional groups, and natural vegetation can maintain diverse pollinator communities throughout the year, especially during the noncropping season. However, exotic plants decrease functional diversity and bee specialization. To safeguard bees and their pollination services in urban farms, we recommend (1) preserving seminatural vegetation (hedges) around cropping fields to provide nesting opportunities for aboveground nesters, (2) promoting farm-level crop diversification of beneficial crops (e.g., pulses, vegetables, and spices), (3) maintaining native natural vegetation along field margins, and (4) controlling and removing invasive exotic plants that disrupt native plant-pollinator interactions. Overall, our results suggest that urban agriculture can maintain functionally diverse bee communities and, if managed in a sustainable manner, be used to develop win-win solutions for biodiversity conservation of pollinators and food security in and around cities.

Determinants of transmission hotspots and filarial infection in households after eight rounds of mass drug administration in India.

OBJECTIVES: Lymphatic filariasis (LF) elimination through mass drug administration (MDA) of DEC and albendazole have resulted in very low levels of infection in most endemic districts in India. But small pockets with residual microfilaraemia in the community and antigeneamia in children ('hotspots') are a cause of concern. We aimed to identify the determinants of such transmission hotspots and filarial infection in households using data from 33 communities. METHODS: The filariasis vector Culex quinquefasciatus was collected from 627 randomly selected households using gravid traps. Parallel data on environmental, entomological, demographical, socio-economical and behavioural factors were analysed to identify the determinants of hotspots and household-level infection. RESULTS: Hotspots and non-hotspots did not differ significantly in terms of socio-economical and behavioural aspects, but did differ in terms of demographical and environmental factors. Logistic regression revealed that tiled and concrete houses increased the risk of an area being a hotspot by 2.0 and 2.9 times respectively. Presence of Culex breeding habitats was significantly associated with elevated risk of being a hotspot. Proximity of U-drains to a house increased the risk of filarial infection 5.8 times. CONCLUSIONS: An environment suitable to Culex breeding influences continued transmission despite eight rounds of MDA, particularly in hotspots. Proximity to U-drains increases the risk of infection in households. Implementing localised vector control measures may help interrupt low-level transmission, thereby reducing the risk of resurgence in the absence of MDA.

Hyper-Expression of PD-1 Is Associated with the Levels of Exhausted and Dysfunctional Phenotypes of Circulating CD161++TCR iVα7.2+ Mucosal-Associated Invariant T Cells in Chronic Hepatitis B Virus Infection.

Mucosal-associated invariant T (MAIT) cells, defined as CD161++TCR iVα7.2+ T cells, play an important role in the innate defense against bacterial infections, and their functionality is impaired in chronic viral infections. Here, we investigated the frequency and functional role of MAIT cells in chronic hepatitis B virus (HBV) infection. The peripheral CD3+CD161++TCR iVα7.2+ MAIT cells in chronic HBV-infected patients and healthy controls were phenotypically characterized based on CD57, PD-1, TIM-3, and CTLA-4, as well as HLA-DR and CD38 expression. The frequency of MAIT cells was significantly decreased among chronic HBV-infected individuals as compared to controls. Expression of CD57, PD-1, CTLA-4, as well as HLA-DR and CD38 on MAIT cells was significantly elevated in chronic HBV-infected individuals relative to controls. The percentage of T cell receptor (TCR) iVα7.2+ CD161+ MAIT cells did not correlate with HBV viral load but inversely with HLA-DR on CD4+ T cells and MAIT cells and with CD57 on CD8+ T cells suggesting that decrease of MAIT cells may not be attributed to direct infection by HBV but driven by HBV-induced chronic immune activation. The percentage and expression levels of PD-1 as well as CTLA-4 on MAIT cells inversely correlated with plasma HBV-DNA levels, which may suggest either a role for MAIT cells in the control of HBV infection or the effect of HBV replication in the liver on MAIT cell phenotype. We report that decrease of TCR iVα7.2+ MAIT cells in the peripheral blood and their functions were seemingly impaired in chronic HBV-infected patients likely because of the increased expression of PD-1.

A new species of the genus Discoelius Latreille, 1809 (Hymenoptera: Vespidae: Eumeninae) from India.

Discoelius vasukii Pannure & Carpenter, sp. nov. is described and illustrated from Tamil Nadu, India.        Discoelius Latreille, 1809 is a small genus of solitary wasp with ten species and one subspecies described, of which D. aurantiacus Nguyen, D. emeishanensus Zhou & Li, D. esakii Yasumatsu, D. longinodus Yamane, D. nigriclypeus Zhou & Li, D. turneri (Meade-Waldo), D. wangi Yamane and D. zonalis (Panzer) are recorded from Oriental Region (Zhou et al. 2013; Nguyen 2016). Only a single species, D. turneri described from Shillong (Meghalaya) (Meade-Waldo, 1910) and later recorded from Sikkim (Giordani Soika 1960) has been previously known from India. In this study, we describe a new species of Discoelius from India based on a single female specimen collected at Valparai (Tamil Nadu), India.

Taxonomic studies on potter wasps (Hymenoptera: Vespidae: Eumeninae) of south India.

The family Vespidae is represented in India by four subfamilies: Vespinae, Polistinae, Stenogastrinae, and Eumeninae. The subfamily Eumeninae is the most species rich among the Vespidae. The potter wasps of south India are reviewed for the first time to comprise 31 valid genera. The genera Discoelius Latreille, 1809, Coeleumenes van der Vecht, 1963, Euodynerus Dalla torre, 1904, and Pseudonortonia Giordani Soika, 1936 are newly reported from south India. Diagnoses and a key to south Indian eumenine genera are given. A total of 72 species and subspecies are listed, 15 of them are newly reported from Karnataka and two species from Kerala.

Filamentation temperature-sensitive protein Z (FtsZ) of Wolbachia, endosymbiont of Wuchereria bancrofti: a potential target for anti-filarial chemotherapy.

Lymphatic filariasis (LF) is a leading cause of morbidity in the tropical world. It is caused by the filarial parasites Wuchereria bancrofti, Brugia malayi and Brugia timori and transmitted by vector mosquitoes. Currently a programme for the elimination of LF, Global programme for Elimination of Lymphatic Filariasis (GPELF), is underway with the strategy of mass administration of single dose of diethylcarbamazine or ivermectin, in combination with an anthelmintic drug, albendazole. However, antifilarial drugs used in the programme are only microfilaricidal but not or only partially macrofilaricidal. Hence, there is a need to identify new targets for developing antifilarial drugs. Filarial parasites harbor rickettsial endosymbionts, Wolbachia sp., which play an important role in their biology and hence are considered as potential targets for antifilarial chemotherapy development. In this study, one of the cell division proteins of Wolbachia of the major lymphatic filarial parasite, W. bancrofti, viz., filamentation temperature-sensitive protein Z (FtsZ), was explored as a drug target. The gene coding for FtsZ protein was amplified from the genomic DNA of W. bancrofti, cloned and sequenced. The derived amino acid sequence of the gene revealed that FtsZ protein is 396 amino acids long and contained the tubulin motif (GGGTGTG) involved in GTP binding and the GTP hydrolyzing motif (NLDFAD). The FtsZ gene of endosymbiont showed limited sequence homology, but exhibited functional homology with ß-tubulin of its host, W. bancrofti, as it had both the functional motifs and conserved amino acids that are critical for enzymatic activity. ß-tubulin is the target for the anti-helminthic activity of albendazole and since FtsZ shares functional homology with, ß-tubulin it may also be sensitive to albendazole. Therefore, the effect of albendazole was tested against Wolbachia occurring in mosquitoes instead of filarial parasites as the drug has lethal effect on the latter. Third instar larvae of Culex quinquefasciatus were treated with 0.25mg/ml of albendazole (test) or tetracycline (positive control) in the rearing medium for different intervals and tested for the presence of Wolbachia by FtsZ PCR. All the treated larvae were negative for the presence of the FtsZ band, whereas all the control larvae were positive. The findings of the study, thus indicated that FtsZ is sensitive to albendazole. In view of this albendazole appears to have dual targets; FtsZ in Wolbachia and ß-tubulin in W. bancrofti. Further, the functional domain of the gene was assessed for polymorphism among recombinant clones representing 120 W. bancrofti parasites, prevalent across wide geographic areas of India and found to be highly conserved among them. Since it is highly conserved and plays an important role in Wolbachia cell division it appears to be a potential target for anti-filarial chemotherapy development.

Molecular and functional characterization of macrophage migration inhibitory factor (MIF) homolog of human from lymphatic filarial parasite Wuchereria bancrofti.

The ability of nematode parasites to survive in a highly complex immune system involves diverse strategies including production of a variety of host immune modulators. Various parasite-associated surface antigens or excretory and secretory products may possibly play a role in the host-parasite interactions and successful survival of parasite in their respective host. One among these molecules is a human cytokine homolog, macrophage migration inhibitory factor-1 (MIF-1) in various parasites. We identified a homolog of this cytokine from human lymphatic filarial parasite, Wuchereria bancrofti, expression cloned and investigated its molecular characteristics and catalytic properties. We also assessed the humoral reactivity of the recombinant MIF-1 of W. bancrofti (rWb-MIF-1) against sera belonging to different categories of individuals viz. microfilaremic, chronic patients, endemic normal, and non-endemic normal. Our results showed that the complete coding sequence of W. bancrofti is 1,078 bp, comprising two introns and three exons: first and second introns being 577 and 153 bp long, while the three exons I, II, and III being 108, 173, and 67 bp long, respectively. The rWb-MIF-1 was overexpressed in a salt-inducible host, Escherichia coli GJ 1158, and its functional activity was determined by dopachrome tautomerase and insulin reduction assays. The results of both the assays showed that the purified protein is functionally active and hence folded appropriately. The rWb-MIF-1 protein did not show elevation of specific IgG4 antibodies in microfilaremic cases, a hallmark in case of lymphatic filariasis, while it showed IgE reactivity in some of these cases (five out of ten).

Use of a simple DNA extraction method for high-throughput detection of filarial parasite Wuchereria bancrofti in the vector mosquitoes.

Molecular xenomonitoring of filariasis is the detection of filarial DNA in mosquitoes by PCR and a useful tool for monitoring transmission. DNA extraction coupled with PCR allows rapid detection of the presence or absence of the filarial parasite in vector mosquitoes compared to traditional method of manual dissection of the mosquito and observation for parasite under a microscope. A Tris-EDTA (TE) buffer-based boiling method of DNA extraction developed earlier by us was employed and explored for its suitability in the detection of Wuchereria bancrofti DNA in pools of Culex quinquefasciatus mosquitoes in real-time PCR assay. In this preliminary study, 1,000 laboratory-reared C. quinquefasciatus were made into 40 pools, each containing 25 mosquitoes spiked with 2mf. DNA from the first 20 pools was extracted using Qiagen DNeasy blood and tissue kit as standard, and the other 20 pools were subjected to TE buffer-based boiling method of DNA extraction. When the results (Ct values) obtained for DNA samples extracted by TE buffer-based boiling method were compared with that of the DNA samples extracted by the standard Qiagen method, they were found to be highly concordant without any significant difference (P = 0.9). Besides being cost- and time-effective, this protocol was found useful in extracting filarial DNA from two other mosquito genus Aedes and Anopheles, species of which have been reported as important vectors of W. bancrofti in other endemic regions of the world. Thus, TE buffer-based boiling method of DNA extraction is useful for the high-throughput detection of W. bancrofti in vector mosquitoes.

RT-PCR assay for the detection of infective (L3) larvae of lymphatic filarial parasite, Wuchereria bancrofti, in vector mosquito Culex quinquefasciatus.

BACKGROUND & OBJECTIVES: Periodic monitoring of vector population for infection and infectivity rates is central to the evaluation of the filariasis elimination strategies in endemic areas to monitor the success of MDA and also to establish endpoints for intervention. The main objective of this study was to develop a RT-PCR assay, based on L3 stage-specific primers to detect the presence of infective stage larvae of filarial parasite, Wuchereria bancrofti in the vector Culex quinquefasciatus. MATERIAL & METHODS: Subtracted probe development technique was employed for the identification of infective stage (L3) specific genes. The subtracted cDNA was labeled by non-radioisotopic method and used for screening cDNA library of L3 stage larvae of W. bancrofti constructed in UniZap XR. Recombinants were probed and identified from the library. The inserts of the recombinant clones were purified and sequenced. Primers were designed based on the sequence information of three recombinant clones for detecting L3 larvae of W. bancrofti in the vector by RT-PCR assay. Preliminary laboratory evaluation was carried out to assess the sensitivity and specificity of WbL31 RT-PCR assay. RESULTS: cDNA library of L3 stage of W. bancrofti constructed in UniZap XR vector, constituted 5 x 10(5) phages with 80-90% recombinant phages and the size of inserts varied from 0.1 to 1.0 kb. When subtracted cDNA was random prime labeled and used for screening cDNA library of L3 stage of W. bancrofti constructed in UniZap XR, 18 clones were identified from the library. Three genes were found up-regulated in the L3 stage, out of which WbL31 (cuticular collagen) was found to be useful in detecting L3 larvae of W. bancrofti in the vector by RT-PCR assay with high specificity and sensitivity (98-100%). CONCLUSION: Present paper marks first report on the development of an infective stage-specific RT-PCR assay (WbL31 RT-PCR assay) to detect L3 stage W. bancrofti in the vector. This assay will have potential application in assessing the transmission of infection and hence in decision-making related to elimination programme.

A simple and rapid DNA extraction method for the detection of Wuchereria bancrofti infection in the vector mosquito, Culex quinquefasciatus by Ssp I PCR assay.

A simple, rapid and inexpensive method for the extraction of DNA from filarial vector, Culex quinquefasciatus, useful in Ssp I PCR assay for xenomonitoring of infection with Wuchereria bancrofti is presented. The DNA extracted by this method was found suitable for PCR detection of W. bancrofti infection in pools of 10-30 mosquitoes. The PCR assay employing the simplified DNA extraction method was evaluated for its sensitivity on field caught Cx. quinquefasciatus, in comparison with the conventional dissection and microscopy technique. When assayed on dissection washings of vector mosquitoes the PCR assay detected 45 pools out of 49 dissection positive pools as positive for infection and hence found to be less sensitive than the conventional technique. The reason for detecting four dissection positive pools as negatives by the PCR assay may be due to the loss of a few numbers of parasites (1-3) present in these pools during the transfer of washings of dissected mosquitoes. The PCR assay detected ten out of 72 dissection negative pools as positives, while it did not detect any of the 62 known negative (laboratory reared, uninfected) mosquito pools as positives. When 38 pools (10 mosquitoes/pool) of intact mosquitoes were assessed for infection by each method, the infection rates obtained by the two methods were almost similar (3.35 and 3.01%, respectively, for conventional method and PCR assay). The results thus show that the DNA extraction method, which is simple, rapid, safe and inexpensive, is efficient to generate DNA from vector mosquitoes useful in PCR assay and hence has potential application in xenomonitoring.

Development and standardization of a rapid, PCR-based method for the detection of Wuchereria bancrofti in mosquitoes, for xenomonitoring the human prevalence of bancroftian filariasis.

PCR has recently been studied as a promising tool for monitoring the progress of efforts to eliminate lymphatic filariasis. PCR can be used to test concurrently at least 30 pools, with as many as 40 mosquitoes in each pool, for the presence of filarial larvae. The SspI PCR assay for the detection of Wuchereria bancrofti DNA in pools of mosquitoes has been used since 1994 in a variety of laboratories worldwide. During that time, the original assay has been modified in these different laboratories and no standardized assay currently exists. In an effort to standardize and improve the assay, a meeting was held on 15-16 November 2001, at Emory University in Atlanta, with representatives from most of the laboratories currently using the assay. The first round of testing was designed to test the four most promising methods for DNA extraction from pools of mosquitoes. Two of the four methods stood out as clearly the best and these will be now optimised and evaluated in two further rounds of testing.

A rapid and simplified method of DNA extraction for the detection of Brugia malayi infection in mosquitoes by PCR assay.

Currently used protocols for the extraction of filarial parasite DNA from mosquito samples are tedious and involve extensive use of expensive and hazardous chemicals. Therefore, in order to arrive at a simple procedure, four different methods (A, B, C and D) were tried for the extraction of DNA from mosquitoes infected with filarial parasite, Brugia malayi. Method D was found to be as efficient as the current procedure for the extraction of DNA from a single microfilaria in pools of 25 mosquitoes and the DNA was suitable for polymerase chain reaction (PCR) amplification, yielding a band of 322 base pairs with primers specific for B. malayi. Method D involved drying and crushing the mosquitoes to a powder, which was homogenized in 100 microl TE buffer, vortexed, boiled for 10 min, centrifuged at 14000 r.p.m. for 10 min, and the supernatant used for the PCR assay. Dot-blot hybridization confirmed the specificity of the PCR amplified fragment. The DNA extracted by this method was stable for about 1 year. When comparing with the standard method, the cost of a single PCR reaction, inclusive of DNA extraction, was reduced by 50% and the hands on time was minimized fivefold. Hence, this simple TE-based method is rapid, safe and also cost-effective in assessing the B. malayi infection in pools of vector mosquitoes.

Detection of Brugia malayi in laboratory and wild-caught Mansonioides mosquitoes (Diptera: Culicidae) using Hha I PCR assay.

An Hha 1 based polymerase chain reaction (PCR) assay developed for the detection of Brugia malayi, the causative agent of Brugian lymphatic filariasis, was evaluated for its sensitivity in the laboratory and for its usefulness in measuring changes in transmission of the disease in the field. Laboratory studies showed that the new assay was highly sensitive in comparison with the standard dissection and microscopy technique. The assay can detect as little as 4 pg of parasite DNA or a single microfilaria in pools of up to 100 mosquitoes. The optimum pool size for convenience was found to be 50 mosquitoes per pool. The efficacy of PCR assay was evaluated in filariasis control programmes in operation in endemic areas of Kerala State, South India. The infection rates obtained by the Hha I PCR assay and the conventional dissection and microscopy technique were 1.2% and 1.7% respectively in operational areas and 8.3% and 4.4% respectively, in check areas, which were not significantly different (P < 0.05). Thus, the Hha I PCR assay was found to be as sensitive as the conventional technique and hence it can be used as a new epidemiological tool for assessing parasite infection in field-collected mosquitoes.

Laboratory evaluation of Ssp I PCR assay for the detection of Wuchereria bancrofti infection in Culex quinquefasciatus.

BACKGROUND & OBJECTIVES: There is a need to delimit the areas of filariasis transmission in view of the Filariasis Elimination Programme launched in India. Infection rate in vectors is an important parameter in determining transmission and it is conventionally assessed by dissection and microscopy. A PCR assay based on Ssp I repeats of Wuchereria bancrofti has shown potential in the detection of infection in vectors. The aim of the present study was to evaluate the specificity and sensitivity of this assay on W. bancrofti and its vector, Culex quinquefasciatus, prevalent in India. METHODS: The DNA from pools of C. quinquefasciatus to which W. bancrofti microfilariae (mf) were added, was extracted by lysing with 0.1 M NaOH and 0.2 per cent sodium dodecyl sulphate (SDS), followed by silica absorption in the presence of guanidinium thiocyanate. The PCR assay of the DNA samples was carried out using NV-1 and NV-2 primers and the species specific SspI band was visualized on agarose gels stained with ethidium bromide. RESULTS: The Ssp I PCR assay was found to be highly species specific, as it did not detect the DNA of a closely related filarial parasite, Brugia malayi. The assay detected as little as 0.04 pg of W. bancrarofti DNA. Minimum number of parasite detectable in pools of mosquitoes was 1 mf. A pool size of 50 mosquitoes was found to be optimum for the PCR assay. INTERPRETATION & CONCLUSION: The Ssp I PCR assay was found to be highly specific and sensitive in detecting filarial parasite in pools of mosquitoes and therefore has potential application in rapid assessment of transmission of filariasis.

Influence of IGR treatment on oviposition of three species of vector mosquitos at sublethal concentrations.

Sublethal effect of hexaflumuron, an insect growth regulator (IGR), on the oviposition of three species of vector mosquitos. Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi was studied. Significant reduction in oviposition was observed in the females of the above three species derived from fourth instar larvae and pupae exposed to sublethal (EI5 and EI50) doses. The reduction in egg laying is proportional to the dose of exposure and was found to be about twice higher in females of three species exposed to EI50 dose than those exposed to EI5 dose. Among the three species exposed at larval and pupal stages, Ae. aegypti showed maximum reduction in egg laying (29.3-46.6%). Blood feeding was also reduced in females exposed to EI50 dose at larval stage and a positive correlation was demonstrated between the quantity of blood meal taken and the proportion of eggs laid. Significant reduction in the quantum of blood ingested by the treated females may be responsible for the reduced egg laying.

Insecticidal activity of some new synthetic compounds against different mosquito species.

Insecticidal activity of an organosilane (HOE 84498, OMS 3055), Organophosphorous (MAT 9460, OMS 3052) and a synthetic pyrethroid compound (Trebon, OMS 3002) was evaluated against adult and larval stages of eight species of mosquitoes. Insecticidal activity of these compounds was limited to larval stages only. Highest activity of HOE 84498 was found against both Cx. tritaeniorhynchus and Anopheles culicifacies (LC50-0.0065 mg/I), MAT 9460 against Armigeres subalbatus (LC50-0.00043 mg/I) and Trebon against Cx. quinuefasciatus (LC50-0.00579 mg/I). Adulticidal effect was observed at higher dosages of 25-100 ug/cm2 of MAT 9460 and HOE 84498 against all the species with LT50 ranging from 22.15-33.76 min. No appreciable residual effect was evident for the three compounds on the surfaces treated at the rate of 1-100 mg/m2 against any mosquito species.

Use of hexaflumuron, an insect growth regulator in the control of Aedes albopictus (Skuse).

An attempt was made to assess the control potency of an insect growth regulator (IGR), hexaflumuron, against Aedes albopictus, a potent dengue vector, both in the laboratory and under field conditions. Emergence inhibition activity of this IGR against laboratory reared and field collected larvae of Ae. albopictus showed EI50 values of 1.9 x 10(-4) and 1.80 x 10(-4) mg(ai)/l respectively. Under field conditions, no appreciable reduction in immature density occurred at the lowest application rate of 0.001 mg(ai)/l whereas at the rate of 0.01 mg(ai)/l 100% reduction could be seen in earthern pots placed in a garden for 9 days. A reduction of 100% in pupal density was observed for 21 and 18 days at an application rate of 0.1 mg(ai)/l in pots and tyres respectively. Considering that this IGR was effective for about three weeks, it can be used successfully at the rate of 0.1 mg(ai)/l for controlling Ae. albopictus breeding in container habitats.