Mosquito-larvicidal Binary (BinA/B) proteins for mosquito control programs —advancements, challenges, and possibilities

Florida lies within a subtropical region where the climate allows diverse mosquito species including invasive species to thrive year-round. As of 2021, there are currently 66 state-approved Florida Mosquito Control Districts, which are major stakeholders for Florida public universities engaged in mosquito research. Florida is one of the few states with extensive organized mosquito control programs. The Florida State Government and Florida Mosquito Control Districts have long histories of collaboration with research institutions. During fall 2020, we carried out a survey to collect baseline data on the current control priorities from Florida Mosquito Control Districts relating to (1) priority control species, (2) common adult and larval control methods, and (3) major research questions to address that will improve their control and surveillance programs. The survey data showed that a total of 17 distinct mosquito species were considered to be priority control targets, with many of these species being understudied. The most common control approaches included truck-mounted ultra-low-volume adulticiding and biopesticide-based larviciding. The districts held interest in diverse research questions, with many prioritizing studies on basic science questions to help develop evidence-based control strategies. Our data highlight the fact that mosquito control approaches and priorities differ greatly between districts and provide an important point of comparison for other regions investing in mosquito control, particularly those with similar ecological settings, and great diversity of potential mosquito vectors, such as in Florida. Our findings highlight a need for greater alignment of research priorities between mosquito control and mosquito research. In particular, we note a need to prioritize filling knowledge gaps relating to understudied mosquito species that have been implicated in arbovirus transmission.

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Permethrin Resistance in Aedes aegypti Affects Aspects of Vectorial Capacity

Insects ◽

10.3390/insects12010071 ◽

2021 ◽

Vol 12 (1) ◽

pp. 71

Author(s):

Tse-Yu Chen ◽

Chelsea T. Smartt ◽

Dongyoung Shin

Keyword(s):

Aedes Aegypti ◽

Sodium Channel ◽

Mosquito Control ◽

Vector Competence ◽

Vectorial Capacity ◽

Parental Population ◽

Control Programs ◽

Channel Gene ◽

Sodium Channel Gene ◽

Specific Pcr

Aedes aegypti, as one of the vectors transmitting several arboviruses, is the main target in mosquito control programs. Permethrin is used to control mosquitoes and Aedes aegypti get exposed due to its overuse and are now resistant. The increasing percentage of permethrin resistant Aedes aegypti has become an important issue around the world and the potential influence on vectorial capacity needs to be studied. Here we selected a permethrin resistant (p-s) Aedes aegypti population from a wild Florida population and confirmed the resistance ratio to its parental population. We used allele-specific PCR genotyping of the V1016I and F1534C sites in the sodium channel gene to map mutations responsible for the resistance. Two important factors, survival rate and vector competence, that impact vectorial capacity were checked. Results indicated the p-s population had 20 times more resistance to permethrin based on LD50 compared to the parental population. In the genotyping study, the p-s population had more homozygous mutations in both mutant sites of the sodium channel gene. The p-s adults survived longer and had a higher dissemination rate for dengue virus than the parental population. These results suggest that highly permethrin resistant Aedes aegypti populations might affect the vectorial capacity, moreover, resistance increased the survival time and vector competence, which should be of concern in areas where permethrin is applied.

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Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance

Toxins ◽

10.3390/toxins13080523 ◽

2021 ◽

Vol 13 (8) ◽

pp. 523

Author(s):

Maria Helena Neves Lobo Silva-Filha ◽

Tatiany Patricia Romão ◽

Tatiana Maria Teodoro Rezende ◽

Karine da Silva Carvalho ◽

Heverly Suzany Gouveia de Menezes ◽

...

Keyword(s):

Mode Of Action ◽

Mosquito Control ◽

Binary Toxin ◽

Lysinibacillus Sphaericus ◽

Control Programs ◽

Resistance Selection ◽

Single Receptor ◽

Combined Use ◽

Environmentally Safe ◽

Medical Importance

Larvicides based on the bacteria Bacillus thuringiensis svar. israelensis (Bti) and Lysinibacillus sphaericus are effective and environmentally safe compounds for the control of dipteran insects of medical importance. They produce crystals that display specific and potent insecticidal activity against larvae. Bti crystals are composed of multiple protoxins: three from the three-domain Cry type family, which bind to different cell receptors in the midgut, and one cytolytic (Cyt1Aa) protoxin that can insert itself into the cell membrane and act as surrogate receptor of the Cry toxins. Together, those toxins display a complex mode of action that shows a low risk of resistance selection. L. sphaericus crystals contain one major binary toxin that display an outstanding persistence in field conditions, which is superior to Bti. However, the action of the Bin toxin based on its interaction with a single receptor is vulnerable for resistance selection in insects. In this review we present the most recent data on the mode of action and synergism of these toxins, resistance issues, and examples of their use worldwide. Data reported in recent years improved our understanding of the mechanism of action of these toxins, showed that their combined use can enhance their activity and counteract resistance, and reinforced their relevance for mosquito control programs in the future years.

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Investigating Male Aedes aegypti (Diptera: Culicidae) Attraction to Different Oviposition Containers Using Various Configurations of the Sound Gravid Aedes Trap

Journal of Medical Entomology ◽

10.1093/jme/tjz229 ◽

2019 ◽

Vol 57 (3) ◽

pp. 957-961

Author(s):

Kyran M Staunton ◽

Barukh B Rohde ◽

Michael Townsend ◽

Jianyi Liu ◽

Mark Desnoyer ◽

...

Keyword(s):

Aedes Aegypti ◽

Zika Virus ◽

Disease Transmission ◽

Urban Landscape ◽

Mosquito Control ◽

Transmission Risk ◽

Northern Australia ◽

Control Programs ◽

Male Dispersal ◽

Olfactory Attractant

Abstract Aedes aegypti (Linnaeus), the primary vectors of the arboviruses dengue virus and Zika virus, continue to expand their global distributions. In efforts to better control such species, several mosquito control programs are investigating the efficacy of rearing and releasing millions of altered male Aedes throughout landscapes to reduce populations and disease transmission risk. Unfortunately, little is known about Ae. aegypti, especially male, dispersal behaviors within urban habitats. We deployed Sound-producing Gravid Aedes Traps (SGATs) in Cairns, northern Australia, to investigate male Ae. aegypti attraction to various oviposition container configurations. The traps were arranged to include: 1) water only, 2) organically infused water, 3) infused water and L3 larvae, 4) infused water and a human-scented lure, and lastly 5) no water or olfactory attractant (dry). Our data suggest that males were more attracted to SGATs representing active larval sites than potential larval sites, but were equally attracted to dry SGATs relative to those containing water and/or infusion. Additionally, we found that female Ae. aegypti were equally attracted to wet SGATs, with or without infusion, but not dry ones. These results suggest that male Ae. aegypti within northern Australia are more attracted to active larval sites and equally attracted to dry containers as wet or infused ones. Additionally, female Ae. aegypti are unlikely to enter dry containers. Such findings contribute to our understanding of potentially attractive features for local and released Ae. aegypti throughout the northern Australian urban landscape.

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Comparison of mosquito control programs in seven urban sites in Africa, the Middle East, and the Americas

Health Policy ◽

10.1016/j.healthpol.2007.01.009 ◽

2007 ◽

Vol 83 (2-3) ◽

pp. 196-212 ◽

Cited By ~ 31

Author(s):

Daniel E. Impoinvil ◽

Sajjad Ahmad ◽

Adriana Troyo ◽

Joseph Keating ◽

Andrew K. Githeko ◽

...

Keyword(s):

Middle East ◽

Mosquito Control ◽

Control Programs ◽

Urban Sites

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Susceptibility Status of Aedes aegypti L. Against Different Classes of Insecticides in New Delhi, India to Formulate Mosquito Control Strategy in Fields

The Open Parasitology Journal ◽

10.2174/1874421401806010052 ◽

2018 ◽

Vol 6 (1) ◽

pp. 52-62 ◽

Cited By ~ 1

Author(s):

Roopa Rani Samal ◽

Sarita Kumar

Keyword(s):

Secondary Metabolites ◽

Aedes Aegypti ◽

Control Strategy ◽

Mosquito Control ◽

Current Status ◽

New Delhi ◽

Probit Regression ◽

Statistical Parameters ◽

Insecticide Susceptibility ◽

Control Programs

Background: Mosquito control is a major concern throughout the world because of rising cases of mosquito-borne diseases. The outbreak of Zika, Dengue and Chikungunya has caused grave situations raising urgent need to control Aedes aegypti. Moreover, extensive use of synthetic insecticides in mosquito control programs has resulted in high levels of insecticide resistance leading to the use of magnified concentrations, impacting human health and environment adversely. The knowledge about current status of the insecticide susceptibility against Ae. aegypti could help to devise mosquito control strategy. Objective: Present study evaluates the larvicidal potential of thirteen insecticides belonging to seven different classes; organochlorines, organophosphates, carbamates, pyrethroids, neonicotinoids, avermectins and secondary metabolites; against early fourth instars of Ae. aegypti. Materials and Methods: The insecticide susceptibility was evaluated as per WHO protocol. Fatality counts were made after 24h of exposure; and the LC50, LC90 and other statistical parameters were computed by probit-regression analysis. Results: The data reveals the maximum efficacy of pyrethroids and fenitrothion, with lethal values less than 0.001 ppm. Avermectins, organochlorines and carbamates were moderately toxic, while neonicotinoid posed appreciable toxicity. In contrast, berberine, a secondary plant metabolite was found inefficient. The larvicidal efficacy of tested insecticides against Ae. aegypti was found in the decreasing order of pyrethroids > organophosphates > avermectins > organochlorines > carbamates > neonicotinoids > secondary metabolites. Conclusion: Present investigations explore various toxicants as Dengue vector control agents in order to devise a suitable control strategy for mosquito control in fields.

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Discovery of Novel Entomopathogenic Fungi for Mosquito-Borne Disease Control

Frontiers in Fungal Biology ◽

10.3389/ffunb.2021.637234 ◽

2021 ◽

Vol 2 ◽

Author(s):

Anastasia Accoti ◽

Cecilia Springer Engdahl ◽

George Dimopoulos

Keyword(s):

Entomopathogenic Fungi ◽

Mosquito Control ◽

Control Strategies ◽

Pathogenic Fungi ◽

Suitable Alternative ◽

Control Programs ◽

Wide Range ◽

Outdoor Environments ◽

Environmentally Safe ◽

Emergence Of Resistance

The increased application of chemical control programs has led to the emergence and spread of insecticide resistance in mosquitoes. Novel environmentally safe control strategies are currently needed for the control of disease vectors. The use of entomopathogenic fungi could be a suitable alternative to chemical insecticides. Currently, Beauveria spp. and Metarhizium spp. are the most widely used entomopathogenic fungi for mosquito control, but increasing the arsenal with additional fungi is necessary to mitigate the emergence of resistance. Entomopathogenic fungi are distributed in a wide range of habitats. We have performed a comprehensive screen for candidate mosquitocidal fungi from diverse outdoor environments in Maryland and Puerto Rico. An initial screening of 22 fungi involving exposure of adult Anopheles gambiae to 2-weeks-old fungal cultures identified five potent pathogenic fungi, one of which is unidentified and the remaining four belonging to the three genera Galactomyces sp., Isaria sp. and Mucor sp. These fungi were then screened against Aedes aegypti, revealing Isaria sp. as a potent mosquito killer. The entomopathogenic effects were confirmed through spore-dipping assays. We also probed further into the killing mechanisms of these fungi and investigated whether the mosquitocidal activities were the result of potential toxic fungus-produced metabolites. Preliminary assays involving the exposure of mosquitoes to sterile filtered fungal liquid cultures showed that Galactomyces sp., Isaria sp. and the unidentified isolate 1 were the strongest producers of factors showing lethality against An. gambiae. We have identified five fungi that was pathogenic for An. gambiae and one for Ae. aegypti, among these fungi, four of them (two strains of Galactomyces sp., Mucor sp., and the unidentified isolate 1) have never previously been described as lethal to insects. Further characterization of these entomopathogenic fungi and their metabolites needs to be done to confirm their potential use in biologic control against mosquitoes.

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Trap Location and Premises Condition Influences on Aedes aegypti (Diptera: Culicidae) Catches Using Biogents Sentinel Traps During a ‘Rear and Release’ Program: Implications for Designing Surveillance Programs

Journal of Medical Entomology ◽

10.1093/jme/tjz018 ◽

2019 ◽

Vol 56 (4) ◽

pp. 1102-1111 ◽

Cited By ~ 7

Author(s):

Kyran M Staunton ◽

Peter Yeeles ◽

Michael Townsend ◽

Somayeh Nowrouzi ◽

Christopher J Paton ◽

...

Keyword(s):

Aedes Aegypti ◽

Building Materials ◽

Mosquito Control ◽

Male And Female ◽

Spatial Stability ◽

Control Programs ◽

Surveillance Programs ◽

Trap Location ◽

Release Program ◽

Trap Catches

AbstractAs the incidence of arboviral diseases such as dengue, Zika, chikungunya, and yellow fever increases globally, controlling their primary vector, Aedes aegypti (L.) (Diptera: Culicidae), is of greater importance than ever before. Mosquito control programs rely heavily on effective adult surveillance to ensure methodological efficacy. The Biogents Sentinel (BGS) trap is the gold standard for surveilling adult Aedes mosquitoes and is commonly deployed worldwide, including during modern ‘rear and release’ programs. Despite its extensive use, few studies have directly assessed environmental characteristics that affect BGS trap catches, let alone how these influences change during ‘rear and release’ programs. We assessed male and female Ae. aegypti spatial stability, as well as premises condition and trap location influences on BGS trap catches, as part of Debug Innisfail ‘rear and release’ program in northern Australia. We found similar trends in spatial stability of male and female mosquitoes at both weekly and monthly resolutions. From surveillance in locations where no males were released, reduced catches were found at premises that contained somewhat damaged houses and unscreened properties. In addition, when traps were located in areas that were unsheltered, more than 10 m from commonly used sitting areas or more visually complex catches were also negatively affected. In locations where males were released, we found that traps in treatment sites, relative to control sites, displayed increased catches in heavily shaded premises and were inconsistently influenced by differences in house sets and building materials. Such findings have valuable implications for a range of Ae. aegypti surveillance programs.

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Evaluation of Effectiveness and Persistence of three Slow Release Formulations against Aedes Aegypti (L) (Diptera: Culicidae) under Laboratory Conditions

Biosciences Biotechnology Research Asia ◽

10.13005/bbra/2693 ◽

2018 ◽

Vol 15 (4) ◽

pp. 841-849

Author(s):

Abbas Mohamed Al-Azab ◽

Essam Abdel-salam Shaalan

Keyword(s):

Slow Release ◽

Mosquito Control ◽

Larval Mortality ◽

Laboratory Evaluation ◽

Continuous Control ◽

Delayed Effects ◽

Control Programs ◽

Slow Release Formulations ◽

Pupal Mortality ◽

Plastic Containers

A laboratory evaluation of three slow-release formulations (SRFs) of spinosad tablets, sumilarv granules and du-dim tablets was carried out in 20 liters plastic containers. The tested formulations were applied according to recommended doses to evaluate their efficacy and longevity against Ae. aegypti. The results revealed that the tested SRFs achieved complete inhibition of adult stages emergence of Ae. aegypti in the first four weeks and gave continuous effective with 50-100% for 98, 86 and 78 days post -treatment by using spinosad tablets, sumilarv granules and du-dim tablets respectively. The highest larval mortality was observed for spinosad followed by sumilarv and du-dim, it gave 1.3 folds than sumilarv and 1.1 folds with du-dium, whereas sumilarv and du-dium were more effective on pupal mortality than spinosad. On the other hand, morphological abnormalities were observed in larval and pupal stages of Ae. aegypti as delayed effects by tested formulations. This study highlighted that these SRFs could be used as potential larvicidal compounds in mosquito control programs as a single treatment and provide satisfactory results and continuous control against the dengue vector Ae. aegypti for several weeks.

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Integrating Vector and Nuisance Mosquito Control for Severe Weather Response

Journal of the American Mosquito Control Association ◽

10.2987/19-6879.1 ◽

2020 ◽

Vol 36 (2s) ◽

pp. 41-48

Author(s):

Heather M. Ward ◽

Whitney A. Qualls

Keyword(s):

Public Health ◽

Vector Control ◽

Mosquito Control ◽

Mosquito Species ◽

Severe Weather ◽

Health Concern ◽

Control Plan ◽

Control Programs ◽

Nuisance Species ◽

Mosquito Management

ABSTRACT Ideally, all mosquito control programs would have public health–driven and nuisance population–focused components in their mosquito control plan. However, due to resource limitations many mosquito control programs focus attention on one specific component of integrated mosquito control, i.e., adulticiding only. Programs run by public health departments with limited resources are frequently heavily focused on vector control, targeting a few mosquito species that are locally medically relevant in human and animal disease cycles. Focusing their mosquito management on these specific vector species can result in inefficiencies after hurricanes and severe flooding events that create a need for nuisance mosquito control. Floodwater nuisance species that emerge are not routinely a public health threat, but hinder operations related to response efforts and can negatively affect the lives of people in areas recovering from these disaster events. Staff, training, equipment, and facilities, when aimed at public health vector control, may not have the experience, knowledge, or tools to effectively respond to postdisaster, floodwater mosquito populations. As such, all mosquito management programs should have plans in place to handle not only known vectors of public health concern in response to mosquito-borne disease, but also to manage floodwater mosquito populations after natural disasters to safeguard public health and facilitate recovery operations. The current paper discusses the severe weather events in South Texas in 2018 and the resulting integrated nuisance floodwater mosquito control guidance developed by the Texas Department of State Health Services.

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