Adult Aedes Aegypti Research Articles

A Native Bacillus Thuringiensis Strain with Higher Insecticidal Activity Against Adult Aedes Aegypti Than the Larvae

Mosquitoes of several species cause the deaths of millions of people annually, making them the major disease vectors. Bioinsecticide formulations derived from Bacillus thuringiensis are widely acknowledged as highly efficient, sustainable, environmentally friendly, and safe means of controlling insect pests. In this study, a strain of B. thuringiensis exhibiting significant efficacy in controlling Aedes aegypti was isolated from the local environment, identified, and physiologically characterized. The isolated B. thuringiensis strain exhibited positive insecticidal activity against the larvae and adult Aedes aegypti, causing mortality of the insect larvae at a rate of 3.33% and adult at 53.33 – 93.33% in 48 hours. Experiments conducted in a controlled laboratory setting showed that B. thuringiensis toxin exhibited higher levels of activity against the adult mosquito than the larvae. This study demonstrates that bioinsecticide formulation using B. thuringiensis as the active agent has the potential to effectively and sustainably manage larvae and adult Aedes aegypti.

Mating of unfed, engorged, and partially to fully gravid Aedes aegypti (Diptera: Culicidae) female mosquitoes in producing viable eggs

BackgroundUnderstanding the relationship between blood-feeding and mating is important in effectively managing the most well-adapted vector insect, Aedes aegypti (Linnaeus). Although extensive studies have investigated the behavioural aspects of Aedes such as blood-feeding, mating, and their relationship, several knowledge gaps still exist. Therefore, the present study was undertaken to determine the possibility of successful mating by unfed, engorged, and partially to fully gravid (up to 5 days after blood-feeding with fully developed eggs) female Ae. aegypti mosquitoes and production of viable eggs.MethodsMating of sexually mature adult Aedes aegypti was allowed in three different ways. In control 1, the females were allowed to mate before taking blood meal, and in control 2, the females were not at all allowed to mate. In the experiment, the females were separated into six categories, viz. D-0 to D-5. In D-0, the females were allowed to mate immediately after the bloodmeal and, in D-1, the females were allowed to mate on the first day of blood feeding, likewise, the females of D-2, D-3, D-4 and D-5 were allowed to mate on 2nd, 3rd, 4th and 5th day of blood feeding. Ovitrap was uniformly kept on the 4th day of blood feeding for the cages D-0 to D-3 for 1 h and then removed and for the cages D-4, and D-5, the ovitrap was kept on 4th and 5th day of blood feeding for 1h immediately after mating. The total number of eggs and the total number of hatching were counted. In the subsequent days, the entire experiment was replicated two times with different cohorts of mosquitoes, and the mean value of three experiments was used to draw Excel bars with 5% error bars and also for the statistical analysis.ResultsIt was found that mating just before oviposition was sufficient to produce 1581 eggs (70% compared with control) and fertilize 1369 eggs (85% compared with total eggs laid), which is far higher than the 676 non-hatching (unfertilized) eggs (30%) laid by unmated females. Although mating is not essential for producing eggs, our study shows that even brief exposure to the semen and seminal fluids greatly enhances the oviposition and hatching efficiency, even if the mating occurs just before oviposition. However, those females mating before blood-feeding and those mating after blood-feeding produced 2266 and 2128 eggs, with hatching rates of 96.78% and 95.54%, respectively. Hence, the retention time of seminal fluid in the female seems to influence the number of eggs laid and the number of eggs hatched.ConclusionsIn general, mating is possible in Ae. aegypti even minutes before oviposition and is sufficient to produce a greater number of viable eggs.Graphical

Roles of a newly lethal cuticular structural protein, AaCPR100A, and its upstream interaction protein, G12-like, in Aedes aegypti

Mosquitoes form a vital group of vector insects, which can transmit various diseases and filarial worms. The cuticle is a critical structure that protects mosquitoes from adverse environmental conditions and penetration resistance. Thus, cuticle proteins can be used as potential targets for controlling the mosquito population. In the present study, we found that AaCPR100A is a structural protein in the soft cuticle, which has flexibility and elasticity allowing insects to move or fly freely, of Aedes aegypti. RNA interference (RNAi) of AaCPR100A caused high mortality in Aedes aegypti larvae and adults and significantly decreased the egg hatching rate. Transmission electron microscopy (TEM) analysis revealed that the larval microstructure had no recognizable endocuticle in AaCPR100A-deficient mosquitoes. A yeast two-hybrid assay was performed to screen proteins interacting with AaCPR100A. We verified that the G12-like protein had the strongest interaction with AaCPR100A using yeast two-hybrid and GST pull-down assays. Knockdown of G12-like transcription resulted in high mortality in Ae. aegypti larvae, but not in adults. Interestingly, RNAi of G12-like rescued the high mortality of adults caused by decreased AaCPR100A expression. Additionally, adults treated with G12-like dsRNA were found to be sensitive to low temperature, and their eggshell formation and hatching were decreased. Overall, our results demonstrated that G12-like may interacts with AaCPR100A, and both G12-like and AaCPR100A are involved in Ae. aegypti cuticle development and eggshell formation. AaCPR100A and G12-like can thus be considered newly potential targets for controlling the Ae. aegypti mosquito.

Stage-specific insecticide susceptibility and life-table analysis of the dengue vector mosquitoes <em>Aedes aegypti</em> and <em>Ae. albopictus</em>

Vector resistance to insecticides is a significant challenge in the control of mosquito-borne diseases such as dengue. Analysis of the growth rate and survivorship of the immature stages of larvae has been important in formulating effective vector control strategies. The present study aimed to assess insecticide resistance in both larvae and adults of Aedes aegypti and Ae. albopictus, and the life tables of their immature stages.Mosquito eggs collected from Kurunegala and Colombo districts of Sri Lanka from January to March 2023 were reared under laboratory conditions. Larval bioassays were carried out with temephos (0.0125 ppm, 0.0625ppm and 0.125ppm) and, the adult bioassays were with pyrethroids (0.03% deltamethrin, 0.05% and 0.08% lambdacyhalothrin, 0.04% permethrin) and malathion (1%and 5%). Biochemical assays were used to evaluate the activity of insecticide-detoxifying enzymes and the insensitivity of the organophosphate target site acetylcholinesterase. Survivorship of immature stages under laboratory conditions and semi-field conditions i.e., bamboo stumps, tyres and clay pots, were studied using Kaplan-Meier survival analysis.Larvae and adults of both species from Kurunegala were susceptible to all the insecticides tested, whereas Colombo populations were resistant. Acetylcholinesterases were largely sensitive in all vector populations. Higher activities of esterases, glutathione s-transferases and monooxygenases were found in Colombo populations. Results indicated that Ae. aegypti larvae were more resistant to insecticides than Ae. albopictus larvae. Also, the mechanisms of insecticide resistance were well developed in adults than in larvae.Aedes aegypti larval development time (5 days) was significantly shorter than that of Ae. albopictus (9 days) under laboratory conditions. Survival probabilities of them were 76-80%. Egg hatching to adult emergence period was 8 days for Ae. aegypti and 13 days for Ae. albopictus. This period, under semifield conditions were; bamboo stumps 7-7.2 days, tyres 10-11.3 days, and clay pots 13.8-14 days with survival rates varied from 28.8 to 63% for both species. This study highlights stage specific response of dengue vectors to insecticides and survivorship of their immature stages in different habitats. This knowledge can be effectively used in future dengue vector control programmes.

Pesticide Efficiency of Environment-Friendly Transition Metal-Doped Magnetite Nanoparticles.

This study explored the potential of Fe3O4, SnFe2O4, and CoFe2O4 nanoparticles as larvicidal and adulticidal agents against Aedes aegypti (A. aegypti) larvae and adults, which are vectors for various diseases. This research involved the synthesis of these nanoparticles using the coprecipitate method. The results indicate that CoFe2O4 nanoparticles are the most effective in both larvicidal and adulticidal activities, with complete mortality achieved after 96 h of exposure. SnFe2O4 nanoparticles also showed some larvicidal and adulticidal efficacy, although to a lesser extent than the CoFe2O4 nanoparticles. Fe3O4 nanoparticles exhibited minimal larvicidal and adulticidal effects at low concentrations but showed increased efficacy at higher concentrations. The study also revealed the superparamagnetic nature of these nanoparticles, making them potentially suitable for applications in aquatic environments, where A. aegypti larvae often thrive. Additionally, the nanoparticles induced observable damage to the gut structure of the mosquitoes and larvae, which could contribute to their mortality. Overall, this research suggests that CoFe2O4 nanoparticles, in particular, hold promise as environment-friendly and effective agents for controlling A. aegypti mosquitoes, which are responsible for the transmission of diseases such as dengue fever, Zika virus, and Chikungunya. Further studies and field trials are needed to validate their practical use in mosquito control programs.

Differential expression of brummer and levels of TAG in different developmental stages Aedes aegypti (Diptera: Culicidae), including fasted adults.

Lipid storage in the form of triacylglycerol (TAG)is essential for insect life, as it enables flight, development, and reproduction. The activity of the lipase brummer (bmm) has been shown to be essential to insects' homeostasis. The objective of this study was to evaluate how bmm expression occurs in Aedes aegypti larvae and adults, and to observe TAG levels during fasting in adult females. The bmm sequence was identified in A. aegypti and exhibited a patatin-like phospholipase domain reinforced by the presence of a catalytic dyad with serine and aspartate residues, revealing a high degree of similarity with other organisms. Bmm expression was differentiated in the larvae and adult fat body (FB)following TAG reserve dynamics. Bmm was expressed three times in larval stages L3, L4, and pupae compared with L1 and L2, which could indicate its role in the maturation of these insects. In the postemergence (PE)and post-blood meal (PBM)FB of adult insects, bmm expression varied over several days. PE adults showed a pronounced bmm increase from the third day onward compared with those not subjected to fasting. This was accompanied by a decrease in TAG from the third day onward, suggesting the participation of bmm. Six hours after blood feeding, TAG levels increased in mosquitos reared in the absence of sucrose, suggesting lipid accumulation to guarantee reproduction. Bmm responded positively to fasting, followed by TAG mobilization in adult FB. During the previtellogenic period, bmm levels responded to low TAG levels, unlike the PBM period.

Arbovirus Detection of Adult Female <i>Aedes aegypti</i> for Dengue Surveillance: a Cohort Study in Bandung City, Indonesia

Dengue surveillance is an important activity to prevent dengue outbreaks. This activity becomes a significant challenge for the region with limited logistic capabilities. Developing a simple mathematical model to predict the possibility of dengue incidence provides a reliable early warning system. This study compared the correlation between vector (adult female Aedes aegypti) and arbovirus detection on a vector to dengue incidence, which generalized linear mixed models tested. The incidence of adult female Aedes aegypti and dengue fever cases were interpolated through third-power inverse distance weighting (IDW). A spatial correlation between female Aedes aegypti incidence and dengue incidence was obtained from polynomial regression. Collection sites were 16 villages in Bandung city, one of the significant dengue endemic areas in January–December 2017. A total of 8,402 mosquitoes of Aedes aegypti, Aedes albopictus, and Culex sp., with 17% belonging to Aedes aegypti as the subject of the dengue virus (DENV) infection test. Data analysis only showed a weak correlation between the numbers of adult female Aedes aegypti and dengue incidence. On the other hand, there is no correlation between positive dengue infection of vector and dengue incidence. This study highlights the importance of constant arbovirus surveillance and integrated surveillance methods on all possible dengue vectors to develop an early warning system for dengue incidence.

Effects of different diets on Aedes aegypti adults: improving rearing techniques for sterile insect technique.

The aim was to evaluate the effect of different energy diets available in adulthood on the longevity, dispersal capacity and sexual performance of Aedes aegypti produced under a mass-rearing system. To evaluate the effects of diets in relation to the survival of the adult male insects of Ae. aegypti, six treatments were used: sucrose at a concentration of 10%, as a positive control (sack10); starvation, as a negative control (starvation); sucrose at a concentration of 20% associated with 1 g/l of ascorbic acid (sac20vitC); wild honey in a concentration of 10% (honey10); demerara sugar in a 10% concentration (demerara10); and sucrose at a concentration of 20% associated with 1 g/l of ascorbic acid and 0.5 g/l of amino acid proline (sac20vitCPr). Each treatment had 16 cages containing 50 adult males. For the tests of flight ability and propensity to copulation, five treatments were used (saca10; sac20vitC; mel10; demerara10; and sac20vitCPr), with males each for flight ability and females copulated by a single male for copulation propensity. The diet composed of sucrose at a concentration of 20% associated with ascorbic acid, as an antioxidant, improved the survival, flight ability and propensity to copulate in Ae. aegypti males under mass-rearing conditions, and may be useful to enhance the performance of sterile males, thus improving the success of sterile insect technique programmes.

Protein Profiling of Aedes aegypti Treated with Streptomyces sp. KSF103 Ethyl Acetate Extract Reveals Potential Insecticidal Targets and Metabolic Pathways.

The insecticidal activity of Streptomyces sp. KSF103 ethyl acetate (EA) extract against mosquitoes is known; however, the underlying mechanism behind this activity remains elusive. In this study, liquid chromatography with tandem mass spectrometry (LC-MS/MS) was employed to investigate changes in the protein profile of Aedes aegypti larvae and adults treated with lethal concentrations of 50 (LC50) EA extract. By comparing the treated and untreated mosquitoes, this study aimed to identify proteins or pathways that exhibit alterations, potentially serving as targets for future insecticide development. Treatment with a lethal concentration of EA extract upregulated 15 proteins in larvae, while in adults, 16 proteins were upregulated, and two proteins were downregulated. These proteins were associated with metabolism, protein regulation/degradation, energy production, cellular organization and structure, enzyme activity, and catalysis, as well as calcium ion transport and homeostasis. Notably, ATP synthase, fructose-bisphosphate aldolase (FBA), and ATP citrate synthase were significantly expressed in both groups. Gene ontology analysis indicated a focus on energy metabolic processes. Molecular docking revealed a strong interaction between dodemorph, selagine (compounds from the EA extract), and FBA, suggesting FBA as a potential protein target for insecticide development. Further studies such as Western blot and transcriptomic analyses are warranted to validate the findings.

Potentialities of iodine-enhanced micro-CT imaging in the morphological study of adult Aedes (Stegomyia) aegypti (Linnaeus, 1762) mosquitoes

X-ray micro-computed tomography (CT) produces three-dimensional images of samples on a micrometer scale. This technique has several advantages, such as its nondestructive character and low measurement time, compared with other techniques. However, when applied to biological samples of soft tissue, the low attenuation and low effective contrast between structures pose difficulties in creating appropriate images for morphological studies. Diffusible iodine-based contrast-enhanced CT (DICE-CT), which uses iodine solutions to enhance contrast, is a viable alternative for addressing the aforementioned challenges. Given the variety of biological samples, an appropriate methodology must be adapted depending on the dimensions and morphological characteristics of the investigated object. A specimen that has not been morphologically studied by micro-CT and is of high sanitary importance is the adult Aedes aegypti mosquito. This study investigated the stage of iodine staining in the treatment of the A. aegypti mosquito to determine the most suitable staining time for the morphological study of this mosquito in adulthood. After determining the appropriate staining time, we discuss the potential of applying DICE-CT and methodology to mosquito studies. Seven A. aegypti females were treated using fixation steps with Bouin's solution, dehydration in a graded ethanol series, staining with iodine solution (1%), and washing in absolute ethanol. Only the staining step was different between samples. Each mosquito spent a varying amount of time (6–72 h) in the iodine solution (1%). For comparison, one of the mosquitoes was not stained. After treatment, the samples were scanned using the Bruker SkyScan 1172 micro-CT scanner. The reconstructed volumes and histograms were compared to determine the most suitable time. In addition, a quantitative analysis was performed based on a comparison of the attenuation profiles of the mosquito brains. Thereafter, the most suitable treatment process was selected, and two other samples were scanned after applying the selected process. Although fewer than 18 h was insufficient for an effective increase in attenuation and effective contrast, surpassing 24 h proved unnecessary and resulted in saturating the gray tones visualized through the histograms, leading to information loss. Therefore, a time of approximately 24 h was the most suitable staining time for studying adult A. aegypti. It was possible to isolate the organs of the digestive and reproductive systems of the mosquito stained for 24 h. Thus, micro-CT was confirmed to be an excellent technique in studies of individual structures of adult A. aegypti mosquitoes.

Developing methods for chilling, compacting, and sterilizing adult Aedes aegypti (Diptera: Culicidae) and comparing mating competitiveness between males sterilized as adults versus pupae for sterile male release.

The yellow fever mosquito, Aedes aegypti L., can transmit several pathogens responsible for human diseases. With insecticide resistance development becoming a concern, alternative control strategies are needed for Ae. aegypti. Sterile insect technique (SIT) is an increasingly popular option being explored. However, logistical issues in mass production and sterilization make it difficult to maintain a SIT program. Male mosquitoes are typically irradiated as pupae because this is the earliest developmental point at which females can be separated from males, but asynchrony in pupation and high variability in pupal responses to irradiation based on pupal age make it difficult to sterilize mass quantities of pupae on a regular schedule in a rearing facility. Young adult mosquitoes have wider windows for irradiation sterilization than pupae, which can allow facilities to have fixed schedules for irradiation. We produced a workflow for adult Ae. aegypti irradiation in a mosquito control district with an operational SIT program that currently irradiates pupae. The impacts of chilling, compaction, and radiation dose on survival were all assessed before combining them into a complete adult irradiation protocol. Males chilled up to 16 h prior to compaction and compacted to 100 males/cm3 during radiation resulted in low mortality. Males irradiated as adults had increased longevity and similar sterility compared to males irradiated as pupae. Additionally, males sterilized as adults were more sexually competitive than males sterilized as pupae. Thus, we have shown that irradiating adult males can be a viable option to increase the efficiency of this operational mosquito SIT program.

Comparative efficacy trials with alcohol added d-phenothrin formulations against Aedes aegypti under open-field condition.

Evaporation inhibition of water-based space spray insecticides is necessary to prevent the drifting away of fog droplets and the release of insecticidal actives and to prolong suspension time. To address this problem, hygroscopic alcohols, namely propylene glycol and glycerol, were included as adjuvants in water-based d-phenothrin formulations. The performances of glycerol-added formulation (D1) and propylene glycol-added formulation (D2) in terms of droplet size and efficacy against larvae, pupae and adult Aedes aegypti in an open-field environment were examined and compared to the performance of a formulation without adjuvant (negative control). No significant difference in droplet size was observed between the formulations and fogging methods. The efficacy of cold fogs was significantly higher than thermal fogs for all formulations. D2 was found to be most effective against adult Ae. aegypti, followed by D1 and the negative control. D1 and D2 provided complete knockdown and mortality in adult Ae. aegypti at 10 and 25 m for cold and thermal fogging, respectively. However, all d-phenothrin formulations possessed minimal efficacy on immature Ae. aegypti. The incorporation of non-toxic alcohols as adjuvants in water-based space spray insecticides increased efficacy against adult Ae. aegypti, a major vector for dengue. Propylene glycol was discovered to induce higher adulticidal efficacy than glycerol. © 2023 Society of Chemical Industry.

Behavior of Adult Aedes aegypti and Aedes albopictus in Kinshasa, DRC, and the Implications for Control

Yellow fever and chikungunya outbreaks-and a few dengue cases-have been reported in the Democratic Republic of the Congo (DRC) in recent years. However, little is known about the ecology and behavior of the adult disease vector species, Aedes aegypti and Aedes albopictus, in DRC. Preliminary studies showed important differences in Aedes behavior in DRC and Latin-American sites. Therefore, this study aimed to assess the host-seeking and resting behaviors of female Ae. aegypti and Ae. albopictus, and their densities in four communes of Kinshasa (Kalamu, Lingwala, Mont Ngafula and Ndjili). Two cross-sectional surveys were carried out, one in the dry season (July 2019) and one in the rainy season (February 2020). We used three different adult vector collection methods: BG-Sentinel 2, BG-GAT, and prokopack. Both Aedes species were clearly exophagic, exophilic, and sought breeding sites outdoors. The adult house index for Ae. aegypti exceeded 55% in all communes except Lingwala, where it was only 27%. The Adult Breteau Index (ABI) for Ae. aegypti was 190.77 mosquitoes per 100 houses inspected in the rainy season and 6.03 in the dry season. For Ae. albopictus, the ABI was 11.79 and 3.52 in the rainy and dry seasons, respectively. Aedes aegypti showed unimodal host-seeking activity between 6 h and 21 h. The exophagic and exophilic behaviors of both species point to the need to target adult mosquitoes outdoors when implementing vector control.

Entomopathogenic fungi for the control of larvae and adults of Aedes aegypti (Diptera: Culicidae) vector of dengue, chikungunya and Zika viruses in Mexico

Objective. To assess larvicide and adulticide activity of different native strains of fungi on Aedes aegypti. Materials and methods. Third instar larvae were exposed for 72 h at a concentration of 1x108 conidia/ml of 15 fungi; only fungi that significantly affected the larvae were evaluated against the adult phase at a concentration of 2x1010 conidia/ml. Mortality readings were performed at 24, 48, and 72 h for larvae, and every day to 30 days for adults. Results. Trichoderma longibrachiatum, Aspergillus aculeatus, and Metarhizium anisopliae had the best larvicidal activity at 24 h of exposure (p<0.05), causing mortalities of 100, 72, and 62%, respectively. Adult mosquitoes were more affected by Gliocladium virens (45% mortality), M. anisopliae (30% mortality), and T. longibrachiatum (23.33% mortality). Conclusion. The larval stage of Ae. aegypti was more susceptible than the adult phase to the pathogenic action of native fungi, with T. longibrachiatum being with the highest virulence.

Peruvian plant resources as potential natural controllers of adult Aedes aegypti

Aedes aegypti is an important vector of tropical diseases like Dengue, Zika, Chikungunya, and Yellow Fever and affects mainly countries located in tropical and subtropical zones, including Peru. Synthetic insecticides are used to control this vector, but they also cause a residual effect on the environment, whereas the vector has developed resistance to these compounds, so there is a current need to search for new control alternatives, such as the use of abundant natural resources. Therefore, this work aimed to evaluate the biocidal activity of extracts and oils from Cymbopogum citratus, Rosmarinus officinalis, and Minthostachys mollis on adult Aedes aegypti, as well as to evaluate their quality parameters. Furthermore, the chemical profile of the three species was assessed by ultra-high-performance liquid chromatography coupled with mass spectrometry (LC-MS/MS). The results showed that the aqueous/ethanolic extracts and the essential oils from the three evaluated species presented a biocidal effect on adult A. aegypti. Regarding the analysis of the chemical profile, 15 compounds were identified in R. officinalis, while 29 compounds were identified from C. citratus and 30 compounds from M. mollis. Moreover, the extracts and oils presented quality parameters according to standards. In conclusion, the biocidal potential of the C. citratus, R. officinalis, and M. mollis on A. aegypti adults was reported so that they can be seen as a real natural alternative for the control of tropical diseases transmitted by this vector so that plant products are more eco-friendly and subject to lower resistance by target organisms.

Sugar Bait Composition Containing Ivermectin Affect Engorgement and Mortality of the Mosquito Aedes aegypti (Diptera: Culicidae).

Toxins and attractants have been studied and used in sugar baits for mosquitoes. However, little importance has been given to the combination of sugar concentration, bait composition, and their relationship with mosquito engorgement and mortality. Therefore, the present study evaluated the effects of three concentrations of sucrose on baits with and without an attractant (concentrated guava juice), on engorgement and mortality rates of adult Aedes aegypti (Linnaeus, Diptera: Culicidae). Toxic sugar baits (TSB) and attractant toxic sugar baits (ATSB) containing 10, 50, and 70% sucrose and 100 ppm ivermectin (IVM) were prepared to assess engorgement and mortality rates. Subsequently, different concentrations of IVM (0.312-100 ppm) in TSB and ATSB were prepared with sucrose concentrations of 10 and 70% to determine the lethal concentrations (LC50 and LC90) values. Engorgement on the baits was observed under a stereomicroscope, and mortality was followed up to 48 h after feeding. In general, more mosquitoes engorged on TSB regardless of the sugar concentration, while higher concentrations of sugar in ATSBs resulted in higher numbers of mosquitoes engorging. A large increase in the LC90 of IVM was observed for females feeding on ATSBs and TSBs with 70% sucrose relative to those feeding on baits with lower sugar concentrations. No such effect was observed for males.

Effect of short-chain alcohols on the physicochemical properties of d-phenothrin emulsions and their insecticidal activity against Aedes aegypti

Oil-in-water (o/w) emulsion is utilized as an insecticide delivery system for mosquito control. However, evaporation inhibition adjuvant is needed to prevent fog drift, inhibit release of insecticidal actives and prolong suspension time. In the current study, we evaluated the effect of different short-chain alcohols, namely, propylene glycol, 1,3-propanediol, glycerol and crude glycerol, as adjuvants on the physicochemical properties of d-phenothrin o/w emulsion system. The bioactivity of optimized formulations containing 20 wt% glycerol (D1), 20 wt% propylene glycol (D2) and without added alcohol (negative control) were tested against larvae, pupae and adult Aedes aegypti (Ae. aegypti). It was found that propylene glycol produced smaller droplets at lower concentrations but poor long-term stability at higher concentrations, whereas glycerol had an appreciable effect on initial droplet size and stability with increasing concentration. According to the dose-response bioassays and room size chamber testing, the highest larvicidal, pupicidal and adulticidal activities were observed with D2, followed by D1 and negative control. Overall, the above study demonstrated improved emulsion stabilities and potency against Ae. aegypti larvae, pupae and adults using glycerol as adjuvant for effective mosquito control.

Susceptibility of the Dengue Vector Aedes aegypti to Various Insecticides in Lahore, Pakistan

Objective: Present studies were carried out to examine the susceptibility of larvae and adults of Aedes aegypti (Ae. aegypti) from laboratory and field populations of Lahore city against four major groups of commonly used insecticides; Imidacloprid 5% SC, phenyl-pyrazoles* (fipronil 2.5% EC), pyrethroids (Deltamethrin 2.5% SC) and organophosphates (DDVP 50% EC) world health organization standard procedures were observed.
 Methods: For laboratory strain, adults and larvae were collected from the Insectary of the National Institute of Malaria Research and Training (NIMRT), Lahore, Pakistan. Insecticides of four major groups. Larval bioassays were conducted according to the World Health Organization procedure with minor modifications. Larval mortality was finalized after 48 hours for Deltamethrine, Imidacloprid, DDVP, and 72 hours for Fipronil.
 Results: Larval and adult toxicity results were different for wild and laboratory strains exposed to different groups of insecticides. Regression analysis showed non-significant trends in mortality. Imidacloprid proved to be the most toxic to wild larval strains of Ae.aegypti collected from different localities of Lahore while Fipronil was also active for wild larval samples.
 Conclusion: Deltamethrin showed the least activity against both adults and larval strains. The susceptibility of the field strains was lower than laboratory strains; the ratio varies from insecticide to insecticide.

Entomopathogenic Fungi from South Sumatra (Indonesia) Pathogenicity to Egg, Larvae, and Adult of Aedes aegypti

Fungi from South Sumatra (Indonesia) were identified morphologically and molecularly, and their pathogenicity to egg, larvae, and adult Aedes aegypti was evaluated. The fungal isolates used for bioassay were 11 isolates from this study and 4 isolates from the laboratory collection. Fifteen isolates of five fungal species (Metarhizium anisopliae, Penicillium citrinum, Talaromyces diversus, Beauveria bassiana, and Purpureocillium lilacinum) from South Sumatra, Indonesia, were pathogenic to the egg, larvae, and adult of Ae. aegypti. Egg mortality caused by M. anisopliae isolate MSwTp3 was the highest (38.31%). A novel finding of this study was that the eggs exposed to the fungus not only killed the eggs but could continue to kill the emerging larvae, pupae, and adults. The five fungal species induced larval mortality between 52.22−94.44% and adult mortality between 50.00−92.22%. Fungal strains belonging to M. anisopliae, P. citrinum, T. diversus, and B. bassiana from South Sumatra seem to possess remarkable ovicidal, larvicidal and adulticidal activity against Ae. aegypti. M. anisopliae, P. citrinum, T. diversus, and B. bassiana had the potential as entomopathogens to be developed into ovicides, larvicides, and adulticides for controlling Ae. aegypti.

Aedes aegypti (L.) and Anopheles stephensi Liston (Diptera: Culicidae) Susceptibility and Response to Different Experimental Formulations of a Sodium Ascorbate Toxic Sugar Bait.

Attractive toxic sugar baits (ATSBs) require target insects to locate, orient toward, and feed on an insecticidal sugar solution to control populations. Formulating these baits with different attractants and phagostimulants can increase their efficacy by causing insects to choose the ATSB over competing natural sugar sources, and to ingest more of the bait solution. We tested formulations of a 20% sodium ascorbate (SA) ATSB solution using different sugars, adenosine triphosphate (ATP), gallic acid, and six plant volatile compounds to determine their effect on adult Aedes aegypti (L.) and Anopheles stephensi Liston mortality. Baits formulated with fructose or sucrose had no effect on either species, neither did the addition of ATP. Gallic acid increased the survival of Ae. aegypti. Four of the six volatile compounds increased mortality in at least one species. We also examined An. stephensi response to baits formulated with each of the six volatile compounds. Anisaldehyde significantly increased the number of mosquitoes responding toward the SA-ATSB, but increasing the amount had no effect. Addition of anisaldehyde also significantly increased An. stephensi feeding rates on the SA-ATSB, though mosquitoes will avoid the toxic bait if a nontoxic sugar source is available. Formulation of SA-ATSBs with synthetic blends of attractive compounds can increase bait efficacy and consistency, though further research is needed to assess their performance in the field in the presence of natural sugar sources.