Mosquito Control Agent Research Articles

Assessing the Efficacy of Melia azedarach Leaf Extracts as a Mosquito Control Agent Against Aedes aegypti and Culex quinquefasciatus

Assessing the Efficacy of Melia azedarach Leaf Extracts as a Mosquito Control Agent Against Aedes aegypti and Culex quinquefasciatus

Stage‐by‐stage exploration of normal embryonic development in the Arabian killifish, Aphanius dispar

AbstractBackgroundArabian killifish, Aphanius dispar, lives in marine coastal areas of the Middle East, as well as in streams that experience a wide range of salinities and temperatures. It has been used as a mosquito control agent and for studying the toxicities of environmental pollutants. A. dispar's eggshell (chorion) and embryos are highly transparent and are suitable for high resolution microscopic observations, offering excellent visibility of live tissues.ResultsIn this study, the staging of normal embryonic development of A. dispar was described and investigated at different temperatures. Embryonic development was then examined under different thermal environments from 26 to 34°C. Our data suggest that temperature has a significant effect on embryonic development, with accelerated development at higher temperatures.ConclusionA. dispar exhibits broad thermal tolerance and extended independent feeding capabilities, making it a promising model organism for toxicology and pathogenesis studies conducted over an extended period of time (12 days post‐fertilization).

Larvicidal potency of four Egyptian herbs on Culex pipiens larvae: Phytochemical composition and molecular networking for most potent extracts

Utilizing synthetic insecticides to control mosquito populations has many adverse side effects as they can cause environmental pollution and insecticide resistance. Therefore, the search for eco-friendly and effective mosquito control agents has led to the exploration of plant extracts with larvicidal efficacy. In this study, we aimed to explore the larvicidal activity of four Egyptian plant extracts: Rosmarinus officinalis, Melissa officinalis, Cichorium intybus, and Beta vulgaris var. cicla against Culex pipiens and to identify the chemical constituents present in the active extracts. The methanolic extracts of the four plants were prepared and tested against the third instar larvae of C. pipiens using a standard method. The lethal concentrations (LC50 and LC90) were calculated using probit analysis. The active extracts were subjected to ultra-performance liquid chromatography-mass spectroscopy (UPLC-MS/MS) analysis and the data were processed using the global natural products social molecular networking (GNPS) platform to generate molecular networks and identify the compounds based on spectral similarity and database matching. The methanolic extracts of R. officinalis L. and M. officinalis L. had the highest larvicidal activity, where LC50 values were 9.795 and 26.505 μg/mL, respectively. Their exposure caused a high mortality rate and disrupted the biochemical and physiological parameters (total carbohydrates, total lipids, total protein, acetylcholinesterase (AChE), and glutathione S-transferase (GST) in the body of C. pipiens when compared with Cichorium intybus (Chicory) and Beta vulgaris var. cicla (Chard). The UPLC-MS/MS analysis with the aid of the GNPS platform, revealed the presence of 23 and 41 metabolites from R. officinalis L. and M. officinalis L., respectively. The identified metabolites may act as larvicidal agents by interfering with the physiological or biochemical processes of the mosquito larvae. Overall, the findings suggest that the methanolic extracts of R. officinalis and M. officinalis are potential sources of natural larvicides for mosquito control.

Synthesis, molecular modelling and evaluation of larvicidal efficacy of annulated Benzo[h]chromenes against Culex pipiens L. Larvae

A new series of substituted benzo[h]chromene, benzochromenopyrimidine, and benzochromenotriazolopyrimidine derivatives were synthesized via chemical transformations of iminonitrile, ethoxymethylene amino, and cyanomethylene functionalities. The chemical structures of the synthesized compounds were assured by spectroscopic data and elemental analysis. The larvicidal efficacy of these compounds against Culex pipiens L. larvae was investigated, revealing potent insecticidal activity, particularly for compounds 6, 10, and 16, exceeding that of the standard insecticide chlorpyrifos. The mode of action of these compounds was explored through molecular docking studies, indicating their potential as acetylcholine esterase (AChE) inhibitors and nicotinic acetylcholine receptors (nAChR) blockers. The structure–activity relationship analysis highlighted the influence of substituents and fused heterocyclic rings on larvicidal potency. These findings suggest that the synthesized compounds hold promise as potential candidates for developing novel and effective mosquito control agents.

Host-specific effects of a generalist parasite of mosquitoes

Microsporidians are obligate parasites of many animals, including mosquitoes. Some microsporidians have been proposed as potential agents for the biological control of mosquitoes and the diseases they transmit due to their detrimental impact on larval survival and adult lifespan. To get a more complete picture of their potential use as agents of biological control, we measured the impact of Vavraia culicis on several life-history traits of Aedes aegypti and Anopheles gambiae. We measured the infection dynamics and clearance rate for the two species, and we assessed sexual dimorphism in infection dynamics within each species. Our results show differences in infection dynamics, with Ae. aegypti life-history traits being more affected during its aquatic stage and exhibiting higher clearance of the infection as adults. In contrast, An. gambiae was unable to clear the infection. Additionally, we found evidence of sexual dimorphism in parasite infection in An. gambiae, with males having a higher average parasite load. These findings shed light and improve our knowledge of the infection dynamics of V. culicis, a microsporidian parasite previously recognized as a potential control agent of malaria.

Terminalia Arjuna (Roxb.) Wight & amp; Arn: Unveiling its Potential as a Mosquito Control Agent through Biosynthesized Nanomaterials and Computational Analysis against Aedes Aegypti and Aedes Albopictus

Terminalia Arjuna (Roxb.) Wight & amp; Arn: Unveiling its Potential as a Mosquito Control Agent through Biosynthesized Nanomaterials and Computational Analysis against Aedes Aegypti and Aedes Albopictus

Larvicidal activity of six Moroccan Artemisia essential oils and a correlation study of their major components against Culex pipiens

AbstractThe present study was carried out for the first time in Morocco to valorise plant species of the Artemisia genus. Its aim was to evaluate the larvicidal activity of essential oils from six Artemisia plants (A. herba alba, A. absinthium, A. campestris L., A. negrei, A. pontica, and A. arborescens) against Culex pipiens mosquitoes, which are recognised as potential vectors of West Nile virus. Bioinsecticides derived from EOs have shown promise as effective mosquito control agents. The EOs were analysed using GC–MS and GC‐FID and were obtained by hydrodistillation from the aerial parts of the plants. Besides, the experiment was carried out according to the standard WHO protocol. Thujone and camphor were identified as the predominant compounds in all six Artemisia plants. A. herba alba demonstrated the highest larvicidal activity with LC50 and LC90 values of 4.85 and 15.39 μg/mL, respectively. Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were employed to explore the correlation between major EO compounds and larvicidal efficacy. The results suggest that these findings could pave the way for the development of tailored biocides that specifically target important disease vectors.

Microencapsulation of pyriproxyfen using the particles from gas‐saturated solutions process as a controlled‐release system

AbstractThe purpose of this investigation was to determine whether pyriproxyfen (PPF), a synthetic juvenile hormone analog (JHA), could be encapsulated in supercritical carbon dioxide (scCO2) using the process particles from the gas‐saturated solutions (PGSS) for a controlled‐release system. The PGSS process represents a promising two‐step production system especially suited for the encapsulation and controlled‐release system (CRS). In contrast to traditional encapsulation methods that often involve the use of harsh organic solvents or high temperatures, the PGSS process offers a gentler approach employing scCO2 as an alternative. The solubility of scCO2 in polymer (poly‐ϵ‐caprolactone [PCL]) allowed for the formation of PPF microparticles, and the particle size distribution could be controlled by adjustment of operating pressure and temperature. The obtained particles had a mean particle size of 73.6 ± 2 μm and encapsulation efficiency of 78.8 ± 9% at 60°C and 10 MPa. Furthermore, the in vitro dissolution profiles of PPF–PCL particles showed a low‐level release pattern (42.5 ± 5 ppb/d) in water, followed by zero‐order kinetics indicating a high‐performance CRS. Finally, the in vivo bioassay using microparticles treated water exhibited 95%–100% emergence inhibition of mosquitoes, suggesting the effectiveness of PPF–PCL particles as a mosquito control agent.

Larvicidal Efficiency of Citrus maxima against Aedes aegypti and Aedes albopictus

Mosquitoes transmit serious human diseases, causing millions of deaths every year and developed resistance to chemical insecticides resulting in rebounding vectorial capacity. Plants are the alternative sources of mosquito control agents. In the present study, various concentrations of 10, 20, 30, 40, and 50 mg of Citrus maxima (Brunnich) Merr. were tested against the third instar larvae of Aedes aegypti (Linn) and Aedes albopictus (Skuse). The highest larval mortality was found in the extract of C. maxima against third-instar larvae with P value = 0.0287. This study concluded that the increase in concentration of C. maxima extract increased the mortality of Aedes aegypti and Aedes albopictus.

Assessing the possibility of using entomopathogenic fungi for mosquito control in Hawaii

Currently, the Hawaiian government uses chemical pesticides and Bti, a bacterial agent applied to larval pools, for mosquito control. These methods can pose a threat to the environment and be expensive. Additionally, mosquitoes usually develop a resistance toward these pesticides. An alternative agent for mosquito control is entomopathogenic fungi, which can kill or disable insects while they are non-pathogenic to plants and mammals. The purpose of this research is to investigate the use of entomopathogenic fungi as a more sustainable mosquito-control method. We isolated Metarhizium anisopliae from local soil samples in Honolulu, Hawaii. We hypothesized that this entomopathogenic fungus from Hawaii would effectively kill Culex quinquefasciatus mosquito larvae. We tested the fungus on the larvae of C. quinquefasciatus at concentrations of 1 x 104 and 1 x 105 conidia/mL. We found that the more concentrated fungal solution was more virulent to the larvae. Hence, this entomopathogenic fungus may offer a sustainable approach to mosquito control.

Investigating the Insecticidal Properties of Alangium salviifolium Root Extracts on Culex quinquefasciatus Mosquitoe

This study evaluated the effectiveness of successive hexane, chloroform, and methanol extracts of Alangium salviifolium roots in combating mosquito-borne diseases caused by Culex quinquefasciatus mosquitoe in India. The hexane extract showed the highest efficacy with LC50 values of 105.0 ppm (larvicidal activity), 108.0 ppm (pupicidal activity), and 65.6 ppm (ovicidal activity). The chloroform extract had LC50 values of 156.8 ppm (larvicidal), 376.0 ppm (pupicidal), and 20.0 ppm (ovicidal), while the methanol extract had LC50 values of 235.7 ppm (larvicidal), 441.8 ppm (pupicidal), and 30.4 ppm (ovicidal). The hexane extract of A. salviifolium roots shows potential as a mosquito control agent, specifically against Cx. quinquefasciatus mosquitoes. Further studies are needed to assess the safety and effectiveness of this extract. This research highlights the potential of plant extracts as alternative mosquito control agents for mitigating mosquito-borne diseases in India.

Predators as biocontrol agents of mosquito larvae in small and large habitats in Chiang Mai, Thailand.

Controlling mosquito-borne disease is a major global challenge due to the rise of insecticide-resistant mosquitoes. In response, we conducted a study in Chiang Mai Province, Thailand, which is one of the largest and the most popular cities for tourists in Southeast Asia, to explore the potential of local species as biological control agents for mosquito larvae. Mosquito larvae and aquatic predators were sampled from large and small habitats, while relevant physico-chemical parameters were measured. The study identified 560 predators and 1,572 mosquitoes, with most mosquito species belonging to the genus Culex. Additionally, the study identified 16 predator taxa, including four fish taxa and 12 taxa of predatory aquatic insects belonging to four orders: Coleoptera, Hemiptera, Odonata, and Diptera. The study found that several locally occurring predator species, namely Poecillia, Laccophilus, Lutzia, Toxorhynchites splendens, Agrionoptera, and Pseudarion, shared habitats with mosquitoes, indicating their potential as effective biological control agents for mosquito control. Conductivity, dissolved oxygen, and pH were the important physico-chemical parameters that affect both predators and mosquito larvae. Consequently, promoting native predators and reducing mosquito larvae through habitat management would be a sustainable and ecologically friendly approach in large habitats where it is not possible to remove mosquito oviposition sites. In smaller habitats, releasing local aquatic predators and removing oviposition sites may be a suitable strategy.

Assessing the trade-offs in more nature-friendly mosquito control in the Upper Rhine region

Recent studies show that the widely used mosquito control agent Bti has more negative effects on nature than previously expected. However, it is not yet clear whether people support a more nature-friendly mosquito control, as such an adaptation could potentially lead to higher nuisance. This study explores this question by assessing the willingness to pay for an adapted mosquito control strategy that reduces the use of Bti, while maintaining nuisance protection within settlements. For this purpose, a Contingent Valuation Study was conducted in the German Upper Rhine Valley. The results show that the majority of the surveyed population attaches a high value to a more nature-friendly mosquito control in terms of willingness to pay and is willing to accept a higher nuisance outside the villages. Policy makers should, thus, foster the development and implementation of such more nature-friendly mosquito control strategies to increase both environmental and societal benefits.

Larvicidal constituents from Poncirus trifoliata root extracts.

In the search for effective and environmentally friendly mosquito control agents, we have examined natural sources, such as microbes and plants, and the synthetic analogs of natural products. These plants and microbes have evolved in their ecological niches to produce defensive compounds against other competing organisms in their surroundings such as microbes, plants, and insects as a means to enhance their survival. Thus, some of these plants and microbes have bioactive compounds with insecticidal, fungicidal, and phytotoxic activities. In our previous research, we successfully isolated bioactive constituents from natural sources. We have carried out synthetic modifications and total synthesis of marginally active isolated compounds to achieve significantly higher active compounds. We have focused on plants in the Rutaceae family as the members of this family are known to possess bioactive compounds with algicidal, antifungal, insecticidal, and fungicidal activities. In this article, we report the isolation and structure elucidation of mosquito larvicidal constituents from Poncirus trifoliata (Rutaceae) root extract.

A meta-analysis reveals that dragonflies and damselflies can provide effective biological control of mosquitoes.

Dragonfly/damselfly naiads have the potential to control mosquitoes, and indirectly the diseases they carry, due to their extensive predation on mosquito larvae. Experimental studies have measured the effectiveness of individual dragonfly/damselfly naiads in controlling mosquitoes by introducing them to mosquito larvae and counting the number of larvae eaten in a given time period (i.e. predation success). Without a quantitative synthesis, however, such individual measures are unable to provide a generalized estimation about the effectiveness of dragonflies/damselflies as biological mosquito control agents. To achieve this, we assembled a database containing 485 effect sizes across 31 studies on predation successes of 47 species of commonly found dragonfly/damselfly naiads on nine species of mosquito larvae belonging to Aedes, Anopheles and Culex. These studies covered 14 countries across Asia, Africa and South and North America, where mosquitoes are the vectors of Chikungunya, Dengue, Japanese encephalitis, Lymphatic filariasis, Malaria, Rift Valley fever, West Nile fever, Yellow fever and Zika. Using this database, we conducted a meta-analysis to estimate the average predation success per day by a single individual dragonfly/damselfly naiad on these mosquito larvae as a generalized measure of the effectiveness of dragonflies/damselflies for mosquito control. We also built an interaction network for predator-dragonflies/damselflies and prey-mosquitoes and the diseases they vector to understand the functioning of this important predator-prey network. Our results showed that mosquito larvae were significantly reduced through predation by dragonfly/damselfly naiads. Within experimental containers, a single individual dragonfly/damselfly naiad can eat on average 40 (95% confidence intervals [CIs] = 20, 60) mosquito larvae per day, equivalent to a reduction of the mosquito larval population by 45% (95% CIs = 30%, 59%) per day. The average predation success did not significantly vary among Aedes, Anopheles and Culex mosquitoes or among the four (I-IV) mosquito larval stages. These results provide strong evidence that dragonflies/damselflies can be effective biological control agents of mosquitoes, and environmental planning to promote them could lower the risk of spreading mosquito-borne diseases in an environmentally friendly and cost-effective manner.

A Review on Vector Borne Diseases and Various Strategies to Control Mosquito Vectors

Mosquito vector transmit serious infectious diseases that include dengue, chikungunya, malaria, filariasis, leishmaniasis, Japanese encephalitis, west Nile fever, yellow fever and rift valley fever. Insecticides-based control measures have historically and currently been an important control approach against major mosquito-borne diseases. Chemical pesticides, on the other hand, are non-selective and can harm other beneficial organisms. Controlling mosquitoes with entomopathogenic bacteria is a convincing, ecologically acceptable alternative to chemical pesticides. Bacillus thuringiensis israelensis and Bacillus sphaericus are insecticidal microorganisms which are spore forming and these bacteria are the most extensively utilised alternative mosquito control agents, considering the rapid development of resistance, especially to B. sphaericus by the larvae of Culex spp. Under this circumstances, it is necessary to find an alternative biological control agents from natural resources. The present review focus mainly on the various strategies to control mosquito vectors.

Toxic Effects of Perilla frutescens (L.) Britt. Essential Oil and Its Main Component on Culex pipiens pallens (Diptera: Culicidae).

Sustainable control of mosquitoes, vectors of many pathogens and parasites, is a critical challenge. Chemical insecticides are gradually losing their effectiveness because of development of resistance, and plant metabolites are increasingly being recognized as potential alternatives to chemical insecticides. This study aimed to analyze the main components of Perilla frutescens essential oil (PE-EO), investigate the specific activity of PE-EO as a botanical insecticide and mosquito repellent, and explore whether its main constituents are potential candidates for further research. The larvicidal activity assay showed that LC50 of PE-EO and 2-hexanoylfuran was 45 and 25 mg/L, respectively. In the ovicidal activity assay, both 120 mg/L PE-EO and 80 mg/L 2-hexanoylfuran could achieve 98% egg mortality. Moreover, PE-EO and 2-hexanoylfuran showed repellency and oviposition deterrence effects. Notably, 10% PE-EO maintained a high rate of protection for 360 min. Although PE-EO and its main component had certain toxic effects on zebrafish, no significant harmful effects were detected in human embryonic kidney cells. Therefore, perilla essential oil is an effective agent for mosquito control at several life stages and that its main component, 2-hexanoylfuran, is a potential candidate for developing novel plant biopesticides.

Impact across ecosystem boundaries – Does Bti application change quality and composition of the diet of riparian spiders?

Emerging aquatic insects link aquatic and adjacent terrestrial food webs by subsidizing terrestrial predators with high-quality prey. One of the main constituents of aquatic subsidy, the non-biting midges (Chironomidae), showed altered emergence dynamics in response to the mosquito control agent Bacillus thuringiensis var. israelensis (Bti). As riparian spiders depend on aquatic subsidy, they may be affected by such changes in prey availability. Thus, we conducted a field study in twelve floodplain pond mesocosms (FPMs), six were treated with Bti (2.88 × 109 ITU/ha, VectoBac WDG) three times, to investigate if the Bti-induced shift in chironomid emergence dynamics is reflected in their nutritional value and in the diet of riparian spiders. We measured the content of proteins, lipids, glycogen, and carbohydrates in emerged Chironomidae, and determined the stable isotope ratios of female Tetragnatha extensa, a web-building spider living in the riparian vegetation of the FPMs. We analysed the proportion of aquatic prey in spiders' diet, niche size, and trophic position. While the content of nutrients and thus the prey quality was not significantly altered by Bti, effects on the spiders' diet were observed. The trophic position of T. extensa from Bti-treated FPMs was lower compared to the control while the aquatic proportion was only minimally reduced. We assume that spiders fed more on terrestrial prey but also on other aquatic organisms such as Baetidae, whose emergence was unaffected by Bti. In contrast to the partly predaceous Chironomidae, consumption of aquatic and terrestrial primary consumers potentially explains the observed lower trophic position of spiders from Bti-treated FPMs. As prey organisms vary in their quality the suggested dietary shift could transfer previously observed effects of Bti to riparian spiders conceivably affecting their populations. Our results further support that anthropogenic stressors in aquatic ecosystems may translate to terrestrial predators through aquatic subsidy.

Ovicidal toxicity of plant essential oils and their major constituents against two mosquito vectors and their non-target aquatic predators

Plant essential oil (EO) is a natural alternative to synthetic chemical insecticides for mosquito control. EOs from Citrus aurantium L., Cymbopogon citratus (Stapf.), and Cinnamomum verum (J. Presl.) were selected for topical assay of their ovicidal activity against Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse). Their efficacy was compared to that of 1% (w/w) temephos. In addition, their non-toxicity against aquatic mosquito predators, Poecilia latipinna and Poecilia reticulata, was tested. Found by GC–MS analysis, the major constituent of C. verum EO was trans-cinnamaldehyde, of C. aurantium EO was d-limonene, and of C. citratus EO was geranial. Both C. verum EO and trans-cinnamaldehyde at a high concentration (30,000 ppm) exhibited high ovicidal activity against Ae. aegypti and Ae. albopictus eggs after 48 h of incubation with an inhibition rate of 91.0–93.0% for C. verum EO and 96.7–95.2% for trans-cinnamaldehyde. The combination of C. verum EO + geranial exhibited the strongest synergistic inhibition activity (100%) against the two mosquito vectors and was five times more effective than temephos. Moreover, they were not toxic to the non-target fishes. As a safe ovicidal agent for mosquito egg control, the combination of C. verum EO + geranial has excellent potential.

Potential biological agents for control of mosquitoes

Potential biological agents for control of mosquitoes