Preventive residual insecticide applications successfully controlled aedes aegypti in yucatan, mexico

ABSTRACT Insecticide-based approaches remain a key pillar for _Aedes_-borne virus (ABV, dengue, chikungunya, Zika) control, yet they are challenged by the limited effect of traditional

outdoor insecticide campaigns responding to reported arboviral cases and by the emergence of insecticide resistance in mosquitoes. A three-arm Phase II unblinded entomological cluster

randomized trial was conducted in Merida, Yucatan State, Mexico, to quantify the entomological impact of targeted indoor residual spraying (TIRS, application of residual insecticides in _Ae.

aegypti_ indoor resting sites) applied preventively 2 months before the beginning of the arbovirus transmission season. Trial arms involved the use of two insecticides with unrelated modes

of action (Actellic 300CS, pirimiphos-methyl, and SumiShield 50WG, clothianidin) and a control arm where TIRS was not applied. Entomological impact was quantified by Prokopack adult

collections performed indoors during 10 min per house. Regardless of the insecticide, conducting a preventive TIRS application led to significant reductions in indoor _Ae. aegypti_

densities, which were maintained at the same levels as in the low arbovirus transmission period (Actellic 300CS reduced _Ae. aegypti_ density up to 8 months, whereas SumiShield 50WG up to 6 

months). The proportional reduction in _Ae. aegypti_ abundance in treatment houses compared to control houses was 50–70% for Actellic 300CS and 43–63% for SumiShield 50WG. Total operational

costs including insecticide ranged from US$4.2 to US$10.5 per house, depending on the insecticide cost. Conducting preventive residual insecticide applications can maintain _Ae. aegypti_

densities at low levels year-round with important implications for preventing ABVs in the Americas and beyond. SIMILAR CONTENT BEING VIEWED BY OTHERS A NONINFERIORITY CLUSTER RANDOMISED

EVALUATION OF A BROFLANILIDE INDOOR RESIDUAL SPRAYING INSECTICIDE, VECTRON T500, FOR MALARIA VECTOR CONTROL IN TANZANIA Article Open access 29 April 2025 EFFICACY OF PARTIAL SPRAYING OF

SUMISHIELD, FLUDORA FUSION AND ACTELLIC AGAINST WILD POPULATIONS OF _ANOPHELES GAMBIAE_ S.L. IN EXPERIMENTAL HUTS IN TIASSALÉ, CÔTE D'IVOIRE Article Open access 13 July 2023 TARGETED

INDOOR RESIDUAL INSECTICIDE APPLICATIONS SHIFT _AEDES AEGYPTI_ AGE STRUCTURE AND ARBOVIRUS TRANSMISSION POTENTIAL Article Open access 02 December 2023 INTRODUCTION The rapid propagation of

dengue and other _Aedes_-borne viruses (ABVs; e.g., chikungunya, Zika) throughout the Americas, particularly in cities with well-established and adapted _Aedes aegypti_ populations1, has

evidenced the difficulties in responding and preventing arbovirus outbreaks. A myriad of factors have explained this rapid arboviral range expansion and increased transmission intensity,

including _Aedes aegypti_ mosquito expansion2, rapid and unplanned urbanization3, the disproportionate contribution of inapparent infections to transmission4,5 and human mobility patterns6.

An additional challenge for effective ABV control stems from the remarkable paucity of evidence about the epidemiological impact of current vector control methods7,8. The World Health

Organization (WHO) guidelines for dengue prevention and control9, operationalized in the Americas by the Pan-American Health Organization (PAHO), emphasize the need for integrated vector

management (IVM) approaches to control _Ae. aegypti_10 and prevent ABV outbreaks. IVM centers in the integration of tools to attack multiple risk factors of human-mosquito contact.

Traditional methods such as environmental management (reduction or elimination of potential larval habitats such as plastic containers and unused yard debris or fixing large water-holding

containers) and chemical control (e.g., use of chemicals to kill larvae such as insect growth regulators or Bti, and application of ultra-low volume or thermal fogging of insecticides to

kill adult mosquitoes) have been and continue to be key pillars of the plan10,11. In most countries, the operationalization of IVM has encountered multiple roadblocks, including saturated

and under-resourced health services12, the emergence of insecticide resistance13, and limited practical guidance on how and when to deploy vector control interventions in different

epidemiological settings11. The Global Vector Control Response 2017–2030 from the WHO, which provides a new strategy to strengthen vector control worldwide, now emphasizes the need for

locally adapted vector control as a paradigm for incorporating existing and novel approaches within IVM plans11,14. Results from recent clinical trials evaluating _Wolbachia_ releases15 or

house screening16 and from mathematical models17,18 shown the important public health gains of conducting interventions that impact _Ae. aegypti_ continuously and preventively, rather than

reactively to increases in transmission intensity. The impressive success of perifocal spraying of DDT to eradicate _Ae. aegypti_ from the Americas relied on long-lasting residual

insecticides19. Similarly, the application of indoor residual spraying (IRS, the broadcast application of long-lasting insecticides indoors, primarily on walls, ceiling, and other surfaces)

against malaria vectors also led to a significant reduction in dengue burden both in British Guyana and Cayman Islands20,21,22. Despite this promising evidence, preventive _Ae. aegypti_

control is not yet considered as an integral part of any IVM program in the Americas, likely due to the limited existing evidence about its cost and efficacy compared to reactive

interventions. An improvement to IRS, that takes into consideration the known preferential resting of _Ae. aegypti_ indoors at heights lower than 1.5 m23 (termed targeted indoor residual

spraying, TIRS), consists of the selective application of residual insecticides on exposed low walls [< 1.5 m], under furniture and on dark surfaces24. TIRS is considered a rational

alternative to IRS, given it reduces the time and amount of insecticide used to spray a premise with no apparent loss in efficacy24,25. In Cairns, Australia, TIRS using alpha-cypermethrin

and deployed in premises identified by contact tracing as potential exposure sites during an outbreak reduced the probability of future DENV transmission by 86–96% as compared to unsprayed

premises26, whereas entomological cluster-randomized control trials (CRCT) conducted in Mexico showed sustained reductions in _Ae. aegypti_ abundance of up to 70% when the carbamate

insecticide bendiocarb was used27. The recent availability of new insecticide molecules with long-lasting residual power (> 6 months) with alternative modes of action that counter the

emergence of pyrethroid resistance28, could lead to a change in the implementation of TIRS. Modeling studies predict that, when insecticide residual power lasts at least 5 months, TIRS

epidemiological efficacy is highest if interventions are conducted prior to the beginning of the transmission season17,18,29. Preventive TIRS applications (i.e., pre-season intervention

delivery) may offset the low coverage that may be achieved if intervention is implemented reactively to symptomatic reported cases18 potentially leading to increases in coverage,

intervention efficiency and entomological impact. Here we present results from a three-arm unblinded entomological CRCT evaluating the efficacy of preventive TIRS application of two

long-lasting insecticides on _Ae. aegypti_, provide information about costs of the method when implemented by public health agencies, and describe the community response to the pre-season

insecticide application. METHODS TRIAL DESIGN An unblinded three-arm CRCT in which entire city blocks were used as clusters (14 blocks per arm, 42 blocks in total) and were randomly assigned

to receive TIRS or not (reactive space spraying by the MOH, considered as the control) was conducted in the city of Merida, Yucatan, Mexico. Merida is endemic for _Ae. aegypti_ and ABVs30

and the Collaborative Unit of Entomological Bioassays dependent of the Autonomous University of Yucatan (UCBE-UADY) has established a reputable infrastructure for conducting trials

evaluating vector control tools16,25,27. The study occurred in an area identified as a hotspot of ABV transmission within Merida30. Clusters had between 19 and 23 houses and were separated

by at least one city block (Fig. 1). The three arms for the trial involved: a) control (no insecticide applied by the research team but reactive peridomestic malathion spraying by the MOH in

response to symptomatic ABVs); b) Actellic 300CS (active ingredient, a.i., pirimiphos-methyl, Syngenta); c) SumiShield 50WG (a.i., clothianidin, Sumitomo Chemical Co. Ltd.). These two

next-generation residual insecticides have proven efficacy against _Anopheles_ spp.31,32 and were efficacious against _Ae. aegypti_ on Phase II using WHO cone bioassays on different treated

surfaces33. The study was carried out during 2018–2019 and included preventive TIRS applied before the typical ABV transmission season (which spans from July to December1). A

pre-intervention entomological survey (2 months prior to TIRS, April 10–16 2018) was followed by pre-season TIRS (June 16–29 2018) and monthly entomological surveys for 8 months post-TIRS to

cover the typical transmission season (July-December 2018) and 2 months after the arbovirus season (January–February 2019). We conducted the baseline 2 months prior to spraying to determine

whether our study arms were balanced with regard to _Ae. aegypti_ density (2 months gave us enough time to enroll new houses should arms be unbalanced). Since both arms were balanced, we

did not require any further enrollment. Additionally, we did not use any information from the baseline to inform any analysis of preventive TIRS. Entomological surveys were conducted using

Prokopack aspirators34 indoors on a random sub-sample of 10 houses per cluster to quantify indoor _Ae. aegypti_ density and presence27. Briefly, each house was visited by two field

collectors, one in charge of interviewing householders and the other of conducting Prokopack aspirations. Prokopack collections lasted for a total of 10-min per house and involved the

systematic collection of mosquitoes in all available rooms in the house (closed rooms were excluded), including bedrooms, bathrooms, living rooms and kitchens. On each room, the collector

walked with the Prokopack aspirator turned on, waving the device in dark areas below 1.5 m where _Ae. aegypti_ is known to rest23 (under beds, furniture, near dark objects, clothing or other

apparel used by people). Any flying insects detected by the collector (using a headlamp) were also collected by aiming the aspirators at them. A timer was used to make sure collections

ended at the 10-min mark. Collection cups, individualized by house, were placed in a cooler and taken to the entomological laboratory at UCBE-UADY at the end of the collection day for

species identification, sorting of bloodfed _Ae. aegypti_ females, and data entry. Table S1 shows the timing of each date with regards to the ABV season in Merida. Three months after

spraying (July 2018), a survey to assess community concerns and acceptance of TIRS was applied to 150 households, split between intervention arms. ETHICS STATEMENT All methods were carried

out in accordance with relevant guidelines and regulations. All study protocols were approved by Emory University Institutional Review Board (IRB00110234) as well as the Servicios de Salud

de Yucatan. Written informed consent was obtained from the household owner and houses who did not consent to the intervention were noted and not sprayed or visited in post-intervention

entomological surveys. Since this was an entomological CRCT (non-clinical), no registration on ClinicalTrials.gov or WHO trials databases was pursued. TIRS INTERVENTION Insecticides had

different presentations. Sumishield 50 WG was formulated as 150 g sachets containing 50% w/w clothianidin in a water dispersible granule. Actellic 300CS was formulated as 833 ml bottles of

capsule suspension containing 28.2% pirimiphos-methyl. We followed WHO/PAHO guidelines for TIRS implementation24. Briefly, both insecticides were mixed in 7.5 L of water and applied with a

manual compression sprayer IK-Vector Control Super (Goizper Group, Antzuola, Spain) with a 8002EVP nozzle and a Goizper low-pressure control flow valve (output pressure 1.5 bar) to provide a

flow rate of 580 ml per minute (± 5%), and a target dose of 300 and 1000 mg a.i./m2 for SumiShield 50WG and Actellic 300CS, respectively. From June 17 to 26 a total of 500 houses (248 for

Actellic 300CS: 252 for SumiShield 50WG) were intervened. Six teams with 3 persons each were assigned different clusters for conducting participant and household enrollment (including

informed consent), community engagement, and spraying. World Health Organization cone bioassays were conducted monthly up to 8 months post-intervention on ten houses receiving each

insecticide using laboratory-reared susceptible _Ae. aegypti_ females (Rockefeller strain) and estimating acute (2 h after exposure) and delayed (1 day to 7 days after exposure) mortality.

Susceptible females were used because the goal of the bioassays was to quantify insecticide residual activity, not the impact of insecticides on field populations. A total of 20 females were

placed on each cone, with four replicate cones conducted per house per month. Standard _Ae. aegypti_ ovitraps35 were placed in the front door of 10 houses in treatment clusters and ninety

female _Ae. aegypti_ mosquitos derived from the collected eggs were used to tested for susceptibility to different a.i. using the CDC bottle bioassay at the recommended diagnostic dose

(permethrin = 15 µg/bottle; deltamethrin = 10 µg/bottle; chlorpyrifos 50 µg/bottle) and assessed for knock-down and 24 h mortality. A total of 30 females were place per bottle, and three

replicate bottles were used per insecticide. At the time of the study, no diagnostic doses were established for pirimiphos-methyl or clothianidin in _Ae. aegypti_. We used chlorpyrifos as an

a.i. with potential cross-resistance with pirimiphos-methyl, since both are organophosphates and chlorpyrifos was used by the MOH to control _Ae. aegypti_ at the time of the study. ANALYSIS

PLAN The two endpoints for the trial were the density (number of _Ae. aegypti_) per house after a 10-min Prokopack aspiration indoors and number of bloodfed female _Ae. aegypti_ (a closer

proxy to transmission risk than adult mosquito density) per house. Generalized linear mixed models (GLMM) with a negative-binomial function were applied to quantify the efficacy of each

treatment compared to the control arm on each sampling date. We ran an overall model, including all post-intervention surveys, which included a random intercept for the survey month and

another for the cluster ID. The finding of a significant overall model provided the opportunity to evaluate the efficacy of each intervention by survey date, in which case only cluster ID

was used as a random intercept to nest house sub-samples to the cluster level. The overall and per-survey date intervention efficacy in reducing _Ae. aegypti_ density was calculated as _E_ =

 _1-IRR_, where IRR is the Incidence Risk Ratio calculated from the negative-binomial GLMM27. Costs of each component (provided by Yucatan MOH) were used to estimate the per-house cost of

TIRS implementation. Since SumiShield 50WG is not commercialized in Mexico, we used the price of Actellic 300CS to the MOH as a reference, and then considered an alternative costing scenario

considering the insecticide prices for global malaria control programs. RESULTS TIRS averaged 9.4 ± 4.8 min per house and 1083 ± 709 ml of insecticide per house (Table S2). Kitchens and

bathrooms were not treated, leading to lower number of rooms treated than available (Table S2). A total 3780 house entomological surveys were conducted throughout the study. The average (± 

Standard Deviation) number of _Ae. aegypti_ per house during the 8-months post-TIRS was 3.13 (3.62) in the control arm, versus 1.59 (2.09) for Actellic 300CS and 2.06 (2.80) SumiShield 50WG.

Adult _Ae. aegypti_ density in the control arm increased rapidly as the ABV transmission season progressed, peaking at an average (± 95%CI) of 4.5 ± 3.5–5.5 adults per house on July (1 

month post-intervention, MPI). Both pre-season TIRS treatments showed a dramatic reduction in adult _Ae. aegypti_ density per house compared to the control (Fig. 2). Interestingly, adult

_Ae. aegypti_ density was maintained at levels lower than the pre-season density for up to 5 MPI (past the seasonal ABV transmission peak) in both TIRS arms (Fig. 2). A similar temporal

trend was observed for the density of bloodfed females (Fig. S1). Only 18 dengue cases were reported in the south of Merida in 2018, none of them within any of the treatment clusters (Fig.

S2). The low number of cases led the MOH to deploy space spraying within a radius of 1 city block from the block where each case occurred, which means such application likely had a

negligible impact on the entomological measures in our study (Fig. S2). An overall (throughout the 8-month evaluation) statistically significant reduction in _Ae. aegypti_ density compared

to the control after pre-season TIRS was quantified for both TIRS arms (Table S3). When broken-down by MPI, Actellic 300CS significantly reduced _Ae. aegypti_ density up to 8 months, whereas

SumiShield 50WG up to 5 months (Table S3). The overall (throughout the 8-month evaluation) estimated intervention efficacy in reducing _Ae. aegypti_ density was 50% (95%CI, 44–55%) for

Actellic 300CS and 35% (28–41%) for SumiShield 50WG (Fig. 3). If only considering the period of peak ABV transmission (August-November) efficacy increased to 56.2% (46.8–63.9%) and 43.3

(31.4–52.9%), respectively. Broken down by MPI, there was no significant difference in efficacy between Actellic 300CS and SumiShield 50WG (Fig. 3). A similar trend in efficacy was

quantified for density of bloodfed females (Table S4). WHO cone bioassays confirmed the entomological residual impact of both insecticides (Fig. 4). Actellic 300CS showed strong acute

mortality (> 80%) up to 5 MPI, and up to 7 MPI when delayed mortality was assessed (Fig. 4). For SumiShield 50WG, acute mortality was very low (< 40%) throughout the evaluation, but

when delayed mortality was factored in, mortality was higher than 80% only during the first month post-spraying (Fig. 4). Knock-down values after exposure to different active ingredients in

CDC bottle bioassays were 72%, 94% for the pyrethroids permethrin and deltamethrin, and 100% for the organophosphate chlorpyrifos (Fig. S3). Over 98% of participants interviewed at 3 MPI

mentioned they would recommend TIRS with either insecticide (Table 1). While there were no reported concerns with the mode of application (duration, presence of personnel), respondents

identified that Actellic 300CS had more smell than SumiShield 50WG (39.5% vs 4.3%) and left more stains in walls (8.6% vs 1.5%) (Table 1). Staining of walls with Actellic 300CS led 6.2% of

respondents to clean the treated surfaces with a washcloth. Overall, 94–99% of respondents indicated no health impacts in them or a member of their family after insecticide application (the

few health effects of the insecticide indicated transient effects such as headache, sneezing or eye irritation). More than half respondents perceived a reduction in mosquitoes indoors after

the application (Table 1). Insecticides represented approximately 82.8% of total costs per house of TIRS, considering the amount Mexico’s MOH pays for Actellic 300CS (US$54/bottle) (Table

2). Under this costing scenario, preventively treating a house and protecting it throughout the ABV transmission season with TIRS would cost $10.5 (Table 2). We additionally considered a

scenario using the price of insecticides paid by the Global Fund for malaria control (US$15 per bottle or sachet)36. Under such scenario, insecticides constituted 57.3% of total costs and

cost of preventive TIRS per house was reduced to US$4.2 (Table 2). DISCUSSION Conducting a single TIRS application, averaging ~ 9 min per house (compared to ~ 25 min per house for classic

IRS), led to sustained and significant reductions in _Ae. aegypti_ that extended throughout the entire ABV transmission season. Compared to reactive peridomestic application of ephemeral ULV

space spraying, preventive TIRS has multiple entomological benefits. Since a large number of _Ae. aegypti_ rest indoors and in specific locations within the house23, TIRS maximized

insecticidal impact. Moreover, the long residual duration quantified for both insecticides (up to 5–7 months) provided full-season protection by maintaining _Ae. aegypti_ densities to levels

comparable to the low ABV transmission season in the evaluated year. While TIRS may appear intrusive to the community, the benefits seen by householders make it desirable and worth

recommending others. Costs per house were primarily driven by the cost of insecticides, which could provide an opportunity for significant cost-savings if prices were similar to those for

malaria control. The implementation of long-lasting interventions to prevent vector-borne pathogen transmission has been a common practice in the Americas and worldwide37, with periodic

traditional IRS routinely used to control Chagas’ disease and Leishmaniasis37 and traditional IRS plus long-lasting insecticide-treated nets to prevent malaria transmission38. While

contemporary _Ae. aegypti_ control has relied heavily on peridomestic space spraying either in reaction to cases or preventively in response to increased numbers of _Ae. aegypti_, early

efforts to control yellow fever relied on residual perifocal spraying19. The large extension and complexity of urban areas has led country ABV control agencies to focus efforts on the

prevention of explosive epidemics by implementing peridomestic spraying (either thermal fogging or ULV)9,39. Extensive evidence shows such approach has limited entomological and

epidemiological impact40,41. Indoor space spraying has shown higher entomological and epidemiological impact than peridomestic spraying41,42, yet its effect is short-lived. Capitalizing on

_Ae. aegypti_ behavior and the seasonality of ABV transmission, preventive TIRS may be incorporated into IVM plans as a complementary approach to mosquito space spraying and source

reduction43. In most of the tropics, and particularly in the Americas, ABVs are transmitted seasonally, coinciding with the rainy season44. Vector control activities tend to also be

concentrated during the same period. Thus, conducting preventive (pre-season) TIRS would not compete with other vector control activities and would provide an efficient approach for

intervention delivery. A recent WHO-PAHO manual was developed to aid MOHs in incorporating TIRS within their IVM plans24. Another component that can be incorporated to efficiently deploy

TIRS involves capitalizing on the high spatial heterogeneity in ABV transmission within cities, in which some neighborhoods concentrate a high burden of disease compared to the entire

city26,30. The PAHO has taken such evidence and turned it into a new IVM framework that utilizes spatial analysis and public health information to stratify urban areas based on arbovirus

transmission risk45. Risk stratification under this novel IVM PAHO framework is based on the application of spatial clustering tests (Getis Gi* hotspot analysis) to the number of cases per

urban census tract to identify tracts with significantly higher cases than predicted by chance1 By stratifying urban areas according to their risk of ABV transmission, preventive

interventions such as TIRS could be implemented in ‘high risk’ areas to reduce transmission while optimizing limited human and economic resources. Insecticide resistance is a major threat to

the efficacy of existing _Ae. aegypti_ control efforts13,27. Pyrethroid resistance is dominant in the Americas13 and, while results from CDC bottle bioassays may not always imply that a

specific pyrethroid formulation will not be efficacious in field conditions, there is a need for the development of insecticides to which mosquitoes are fully susceptible. Efforts to

mitigate insecticide resistance in malaria vectors has led to next generation insecticide formulations such as Actellic 300CS and SumiShield 50 WG28,38. In Africa, incorporating Actellic

300CS in nationwide malaria control programs led to significant reductions in malaria cases and _Anopheles_ spp. numbers46. SumiShield 50 WG has been recently evaluated in trials, showing

important reductions of _Anopheles_ spp. entomological indices47. Alternative formulations using clothianidin exist, however these also contain pyrethroids which are already highly resisted

by _Aedes_ mosquitoes (Fludora Fusion, Bayer, clothianidin + deltamethrin), but do still appear to be effective in areas where pyrethroid resistance is prevalent.Our study is the first field

trial of both insecticides against field (pyrethroid resistant) _Ae. aegypti_ and provides evidence of non-pyrethroid active ingredients with high potential for preventive control. While

Actellic 300CS had slightly higher efficacy and longer residual effect, the community had more negative reactions to it (due to smell and staining of walls) than SumiShield 50 WG. Our

findings point to an important factor in the development of new residual insecticide formulations for urban areas: the need for maximizing both entomological efficacy and community

acceptability of the insecticide and its application. The control and both insecticide treatment arms showed a decreased trend in _Ae. aegypti_ density during the month predicted as the peak

of ABV transmission. While our study team lacked entomological information to determine whether 2018 was a ‘typical’ year with regards to _Ae. aegypti_ numbers, we can attribute such

reduction in the control to factors other than our study intervention. The low number of cases reported in southern Merida (only 18 cases, Fig S2) was an indicator that 2018 was not a high

transmission year. Too much rain can impact negatively mosquito populations48. In 2018, Hurricane Michael formed in the Caribbean increasing the frequency and amount of rainfall in

September–October in the Yucatan peninsula. The increased rainfall from those storms may have impacted _Ae. aegypti_ numbers in the period of predicted peak dengue activity. Other factors,

such as increased household use of insecticides (which can have an effect on _Ae. aegypti_) after storms due to the invasion by salt marsh _Aedes taeniorhynchus_ mosquitoes, cannot be ruled

out. Despite these effects, all preventive TIRS treatments led to a significant reduction in _Ae. aegypti_ indices compared to the control arm. In our study, WHO cone bioassays showed poor

residual efficacy of SumiShield 50WG, yet entomological indicators showed significant reductions over a 5 month period. This mismatch may be explained by clothianidin’s unique mode of

action. A recent study conducted by our team using _Ae. aegypti_ from the trial site showed that cone bioassays provide poor results in surfaces treated with SumiShield 50 WG compared to the

insecticide's impact on free-flying mosquitoes (released in experimental houses). While delayed mortality in cones reached a maximum of 60% at 1 month post-spraying, delayed

mortalities higher than 80% were maintained up to 7 months when mosquitoes were exposed in experimental houses49. This difference may be the product of the insecticide mode of action.

Clothianidin targets the nicotinic acetylcholine receptor (nAChR) in the insect central nervous system50, leading to a delayed effect on the mortality of mosquitoes. As seen with other

insecticide, chlorfenapyr51, clothianidin increases its efficacy when mosquitoes are free-flying. A recent study, conducted in towns surrounding Merida, estimated a weekly cost of releasing

_Wolbachia_-carrying male _Ae. aegypti_ (with the _w_AlbB strain) for population suppression of US$403.8 (or US$8.1 per hectare, or US$0.4 per house)52. Excluding infrastructure costs

required to produce mosquitoes, _Wolbachia_-based population suppression would cost US$1.6 per house/month, or US$9.6/house to cover a 6-month transmission season. The same study estimated

that a single round of peridomestic ULV using Malathion would cost US$863.8 per 50-hectares52, or (assuming 20 houses per block) US$0.86 per house. To have meaningful entomological impact,

ULV has to be performed in multiple weekly cycles (a minimum of 4)53, which means costs per month of ULV would be around $3.44 per house, or $20.6 per house for the 6-month transmission

season. Therefore, the cost of preventive TIRS at the cost of insecticides for Mexico’s MOH (US$ 10.5) would make this intervention competitive to existing and novel approaches. As options

for residual insecticides in urban areas broaden, prices for MOHs in the Americas should lower, leading to lower TIRS intervention costs. Our estimate (using Global Fund costs of

insecticides36) of US$4.2 per house would make TIRS much more appealing option for MOHs. A Phase-III clinical trial ongoing in Merida, Mexico, is quantifying the epidemiological impact of

preventive TIRS on ABV illness and infection in a cohort of 4600 children25. Results from such study will provide an opportunity not only to quantify the efficacy of preventive control

interventions, but also an avenue to quantify the cost-effectiveness of this approach under different levels of insecticide coverage and entomological efficacy. The global context of ABV

transmission requires innovative approaches that are effective and scalable. Conducting preventive residual insecticide applications can maintain _Ae. aegypti_ densities at low levels

year-round with important implications for preventing dengue, chikungunya and Zika epidemics. DATA AVAILABILITY The datasets analyzed during the current study are available in the

MendeleyData repository, Mendeley Data, V1, https://doi.org/10.17632/d7ft5vdwhr.1. https://data.mendeley.com/datasets/d7ft5vdwhr. REFERENCES * Dzul-Manzanilla, F. _et al._ Identifying urban

hotspots of dengue, chikungunya, and Zika transmission in Mexico to support risk stratification efforts: A spatial analysis. _Lancet Planet Health_ 5, e277–e285.

https://doi.org/10.1016/S2542-5196(21)00030-9 (2021). Article  Google Scholar  * Ryan, S. J., Carlson, C. J., Mordecai, E. A. & Johnson, L. R. Global expansion and redistribution of

Aedes-borne virus transmission risk with climate change. _PLoS Negl. Trop. Dis._ 13, e0007213. https://doi.org/10.1371/journal.pntd.0007213 (2019). Article  Google Scholar  * Kolimenakis, A.

_et al._ The role of urbanisation in the spread of Aedes mosquitoes and the diseases they transmit—A systematic review. _PLoS Negl. Trop. Dis._ 15, e0009631.

https://doi.org/10.1371/journal.pntd.0009631 (2021). Article  Google Scholar  * Duong, V. _et al._ Asymptomatic humans transmit dengue virus to mosquitoes. _Proc. Natl. Acad. Sci. USA_ 112,

14688–14693. https://doi.org/10.1073/pnas.1508114112 (2015). Article  ADS  CAS  Google Scholar  * Ten Bosch, Q. A. _et al._ Contributions from the silent majority dominate dengue virus

transmission. _PLoS Pathog._ 14, e1006965. https://doi.org/10.1371/journal.ppat.1006965 (2018). Article  CAS  Google Scholar  * Stoddard, S. T. _et al._ House-to-house human movement drives

dengue virus transmission. _Proc. Natl. Acad. Sci. USA_ 110, 994–999. https://doi.org/10.1073/pnas.1213349110 (2013). Article  ADS  Google Scholar  * Bowman, L. R., Donegan, S. & McCall,

P. J. is dengue vector control deficient in effectiveness or evidence? Systematic review and meta-analysis. _PLoS Negl. Trop. Dis._ 10, e0004551.

https://doi.org/10.1371/journal.pntd.0004551 (2016). Article  CAS  Google Scholar  * Achee, N. L. _et al._ A critical assessment of vector control for dengue prevention. _PLoS Negl. Trop.

Dis._ 9, e0003655. https://doi.org/10.1371/journal.pntd.0003655 (2015). Article  CAS  Google Scholar  * World Health Organization. _Dengue Guidelines for Diagnosis, Treatment, Prevention and

Control _2nd ed. (2009). * Pan American Health Organization. _Handbook for Integrated Vector Management in the Americas_. (2019). * Roiz, D. _et al._ Integrated Aedes management for the

control of Aedes-borne diseases. _PLoS Negl. Trop. Dis._ 12, e0006845. https://doi.org/10.1371/journal.pntd.0006845 (2018). Article  Google Scholar  * Horstick, O., Runge-Ranzinger, S.,

Nathan, M. B. & Kroeger, A. Dengue vector-control services: How do they work? A systematic literature review and country case studies. _Trans. R. Soc. Trop. Med. Hyg._ 104, 379–386.

https://doi.org/10.1016/j.trstmh.2009.07.027 (2010). Article  Google Scholar  * Moyes, C. L. _et al._ Contemporary status of insecticide resistance in the major Aedes vectors of arboviruses

infecting humans. _PLoS Negl. Trop. Dis._ 11, e0005625. https://doi.org/10.1371/journal.pntd.0005625 (2017). Article  CAS  Google Scholar  * World Health Organization. _Global Vector Control

Response 2017–2030_ (WHO, 2017). Google Scholar  * Utarini, A. _et al._ Efficacy of wolbachia-infected mosquito deployments for the control of dengue. _N. Engl. J. Med._ 384, 2177–2186.

https://doi.org/10.1056/NEJMoa2030243 (2021). Article  Google Scholar  * Manrique-Saide, P. _et al._ Insecticide-treated house screening protects against Zika-infected _Aedes aegypti_ in

Merida, Mexico. _PLoS Negl. Trop. Dis._ 15, e0009005. https://doi.org/10.1371/journal.pntd.0009005 (2021). Article  CAS  Google Scholar  * Hladish, T. J. _et al._ Designing effective control

of dengue with combined interventions. _Proc. Natl. Acad. Sci. USA_ 117, 3319–3325. https://doi.org/10.1073/pnas.1903496117 (2020). Article  ADS  CAS  Google Scholar  * Cavany, S. M. _et

al._ Optimizing the deployment of ultra-low volume and indoor residual spraying for dengue outbreak response. _PLoS Comput. Biol._ 16, e1007743. https://doi.org/10.1371/journal.pcbi.1007743

(2020). Article  CAS  Google Scholar  * Soper, F. L. The 1964 status of _Aedes aegypti_ eradication and yellow fever in the Americas. _Am. J. Trop. Med. Hyg._ 14, 887–891 (1965). Article 

CAS  Google Scholar  * World Health Organization. _Pesticides and their Application for the Control of Vectors and Pests of Public Health Importance_. 6th edn,

(WHO/CDS/NTD/WHOPES/GCDPP/2006.1, 2006). * Giglioli, G. An investigation of the house-frequenting habits of mosquitoes of the British Guiana coastland in relation to the use of DDT. _Am. J.

Trop. Med. Hyg._ 28, 43–70 (1948). Article  CAS  Google Scholar  * Nathan, M. B. & Giglioli, M. E. Eradication of Aedes aegypti on Cayman Brac and Little Cayman, West Indies, with Abate

(Temephos) in 1970–1971. _Bull. Pan Am. Health Organ._ 16, 28–39 (1982). CAS  Google Scholar  * Dzul-Manzanilla, F. _et al._ Indoor resting behavior of _Aedes aegypti_ (Diptera: Culicidae)

in Acapulco, Mexico. _J. Med. Entomol._ 54, 501–504. https://doi.org/10.1093/jme/tjw203 (2017). Article  Google Scholar  * Pan American Health Organization. _Manual for Indoor Residual

Spraying in Urban Areas for Aedes aegypti Control_ (Pan American Health Organization, 2019). Google Scholar  * Manrique-Saide, P. _et al._ The TIRS trial: Protocol for a cluster randomized

controlled trial assessing the efficacy of preventive targeted indoor residual spraying to reduce Aedes-borne viral illnesses in Merida, Mexico. _Trials_ 21, 839.

https://doi.org/10.1186/s13063-020-04780-7 (2020). Article  Google Scholar  * Vazquez-Prokopec, G. M., Montgomery, B. L., Horne, P., Clennon, J. A. & Ritchie, S. A. Combining contact

tracing with targeted indoor residual spraying significantly reduces dengue transmission. _Sci. Adv._ 3, e1602024. https://doi.org/10.1126/sciadv.1602024 (2017). Article  ADS  Google Scholar

  * Vazquez-Prokopec, G. M. _et al._ Deltamethrin resistance in _Aedes aegypti_ results in treatment failure in Merida, Mexico. _PLoS Negl. Trop. Dis._ 11, e0005656.

https://doi.org/10.1371/journal.pntd.0005656 (2017). Article  CAS  Google Scholar  * Knapp, J., Macdonald, M., Malone, D., Hamon, N. & Richardson, J. H. Disruptive technology for vector

control: The Innovative Vector Control Consortium and the US Military join forces to explore transformative insecticide application technology for mosquito control programmes. _Malar. J._

14, 371. https://doi.org/10.1186/s12936-015-0907-9 (2015). Article  Google Scholar  * Hladish, T. J. _et al._ Forecasting the effectiveness of indoor residual spraying for reducing dengue

burden. _PLoS Negl. Trop. Dis._ 12, e0006570. https://doi.org/10.1371/journal.pntd.0006570 (2018). Article  Google Scholar  * Bisanzio, D. _et al._ Spatio-temporal coherence of dengue,

chikungunya and Zika outbreaks in Merida, Mexico. _PLoS Negl. Trop. Dis._ 12, e0006298. https://doi.org/10.1371/journal.pntd.0006298 (2018). Article  Google Scholar  * Agossa, F. R. _et al._

Efficacy of a novel mode of action of an indoor residual spraying product, SumiShield(R) 50WG against susceptible and resistant populations of _Anopheles gambiae_ (s.l.) in Benin, West

Africa. _Parasites Vectors_ 11, 293. https://doi.org/10.1186/s13071-018-2869-6 (2018). Article  CAS  Google Scholar  * Sherrard-Smith, E. _et al._ Systematic review of indoor residual spray

efficacy and effectiveness against _Plasmodium falciparum_ in Africa. _Nat. Commun._ 9, 4982. https://doi.org/10.1038/s41467-018-07357-w (2018). Article  ADS  CAS  Google Scholar  *

Correa-Morales, F. _et al._ Bioefficacy of two nonpyrethroid insecticides for targeted indoor residual spraying against pyrethroid-resistant _Aedes aegypti_. _J. Am. Mosq. Control Assoc._

35, 291–294. https://doi.org/10.2987/19-6866.1 (2019). Article  Google Scholar  * Vazquez-Prokopec, G. M., Galvin, W. A., Kelly, R. & Kitron, U. A new, cost-effective, battery-powered

aspirator for adult mosquito collections. _J. Med. Entomol._ 46, 1256–1259 (2009). Article  Google Scholar  * Manrique-Saide, P. _et al._ Multi-scale analysis of the associations among egg,

larval and pupal surveys and the presence and abundance of adult female _Aedes aegypti_ (_Stegomyia aegypti_) in the city of Merida, Mexico. _Med. Vet. Entomol._ 28, 264–272.

https://doi.org/10.1111/mve.12046 (2014). Article  CAS  Google Scholar  * The Global Fund. https://www.theglobalfund.org/media/9353/psm_irsreferenceprices_table_en.pdf). * Rozendaal, J.

_Vector Control: Methods for Use by Individuals and Communities_ (1997). * Kleinschmidt, I. _et al._ Combining indoor residual spraying and insecticide-treated net interventions. _Am. J.

Trop. Med. Hyg._ 81, 519–524 (2009). Article  Google Scholar  * Scott, T. W., Morrison, A. C. & Takken, W. _Aedes aegypti_ density and the risk of dengue-virus transmission. (2003). *

Esu, E., Lenhart, A., Smith, L. & Horstick, O. Effectiveness of peridomestic space spraying with insecticide on dengue transmission; systematic review. _Trop. Med. Int. Health_ 15,

619–631. https://doi.org/10.1111/j.1365-3156.2010.02489.x (2010). Article  Google Scholar  * Samuel, M. _et al._ Community effectiveness of indoor spraying as a dengue vector control method:

A systematic review. _PLoS Negl. Trop. Dis._ 11, e0005837. https://doi.org/10.1371/journal.pntd.0005837 (2017). Article  Google Scholar  * Reiner, R. C. Jr. _et al._ Estimating the impact

of city-wide _Aedes aegypti_ population control: An observational study in Iquitos, Peru. _PLoS Negl. Trop. Dis._ 13, e0007255. https://doi.org/10.1371/journal.pntd.0007255 (2019). Article 

Google Scholar  * Ritchie, S. A. _et al._ _Innovative Strategies for Vector Control_ Vol. 6, 59–89 (Wageningen Academic Publishers, 2021). Book  Google Scholar  * Morin, C. W., Sellers, S.

& Ebi, K. L. Seasonal variations in dengue virus transmission suitability in the Americas. _Environ. Res. Lett._ 17, 064042. https://doi.org/10.1088/1748-9326/ac7160 (2022). Article  ADS

  Google Scholar  * Pan American Health Organization. _Technical Document for the Implementation of Interventions Based on Generic Operational Scenarios for Aedes aegypti Control_ (PAHO,

2019). Google Scholar  * Keating, J. _et al._ Retrospective evaluation of the effectiveness of indoor residual spray with pirimiphos-methyl (Actellic) on malaria transmission in Zambia.

_Malar. J._ 20, 173. https://doi.org/10.1186/s12936-021-03710-5 (2021). Article  CAS  Google Scholar  * Kweka, E. _et al._ Novel indoor residual spray insecticide with extended mortality

effect: A case of sumishield 50WG against wild resistant populations of _Anopheles arabiensis_ in Northern Tanzania. _Glob. Health Sci. Pract._ 6, 758–765.

https://doi.org/10.9745/GHSP-D-18-00213 (2018). Article  Google Scholar  * Seidahmed, O. M. & Eltahir, E. A. A sequence of flushing and drying of breeding habitats of _Aedes aegypti_

(L.) prior to the low dengue season in Singapore. _PLoS Negl. Trop. Dis._ 10, e0004842. https://doi.org/10.1371/journal.pntd.0004842 (2016). Article  Google Scholar  * Che-Mendoza, A. _et

al._ Residual efficacy of the neonicotinoid insecticide clothianidin against pyrethroid-resistant _Aedes aegypti_. _Pest. Manag. Sci._ https://doi.org/10.1002/ps.7231 (2022). Article  Google

Scholar  * Tomizawa, M. & Casida, J. E. Neonicotinoid insecticide toxicology: Mechanisms of selective action. _Annu. Rev. Pharmacol. Toxicol._ 45, 247–268.

https://doi.org/10.1146/annurev.pharmtox.45.120403.095930 (2005). Article  CAS  Google Scholar  * Che-Mendoza, A. _et al._ Efficacy of targeted indoor residual spraying with the pyrrole

insecticide chlorfenapyr against pyrethroid-resistant _Aedes aegypti_. _PLoS Negl. Trop. Dis._ 15, e0009822. https://doi.org/10.1371/journal.pntd.0009822 (2021). Article  CAS  Google Scholar

  * Martin-Park, A. _et al._ Pilot trial using mass field-releases of sterile males produced with the incompatible and sterile insect techniques as part of integrated _Aedes aegypti_ control

in Mexico. _PLoS Negl. Trop. Dis._ 16, e0010324. https://doi.org/10.1371/journal.pntd.0010324 (2022). Article  Google Scholar  * World Health Organization. _Guidelines for Efficacy Testing

of Insecticides for Indoor and Outdoor Ground-Applied Space Spray Applications_ (2009). Download references FUNDING This project received support from Innovative Vector Control Consortium

(Award ID:48835), Emory Global Health Institute and Marcus Foundation (00052002), and partly by the National Institutes of Health, National Institute of Allergy and Infectious Disease

(U01AI148069; Vazquez-Prokopec, PI). The findings and conclusions in this paper are those of the authors and do not necessarily represent the official position of the funders. AUTHOR

INFORMATION AUTHORS AND AFFILIATIONS * Department of Environmental Sciences, Mathematics and Science Center, Emory University, 400 Dowman Drive Ste: E530, Atlanta, GA, 30322, USA Gonzalo M.

Vazquez-Prokopec & Oscar D. Kirstein * Unidad Colaborativa Para Bioensayos Entomologicos, Universidad Autonoma de Yucatan, Mérida, Mexico Azael Che-Mendoza, Wilberth Bibiano-Marin, 

Gabriela González-Olvera, Anuar Medina-Barreiro & Pablo Manrique-Saide * National Institute of Public Health, INSP, Cuernavaca, Mexico Hector Gomez-Dantes * Centro de Investigaciones

Regionales, Autonomous University of Yucatan, Mérida, Mexico Norma Pavia-Ruz Authors * Gonzalo M. Vazquez-Prokopec View author publications You can also search for this author inPubMed 

Google Scholar * Azael Che-Mendoza View author publications You can also search for this author inPubMed Google Scholar * Oscar D. Kirstein View author publications You can also search for

this author inPubMed Google Scholar * Wilberth Bibiano-Marin View author publications You can also search for this author inPubMed Google Scholar * Gabriela González-Olvera View author

publications You can also search for this author inPubMed Google Scholar * Anuar Medina-Barreiro View author publications You can also search for this author inPubMed Google Scholar * Hector

Gomez-Dantes View author publications You can also search for this author inPubMed Google Scholar * Norma Pavia-Ruz View author publications You can also search for this author inPubMed 

Google Scholar * Pablo Manrique-Saide View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS Conceptualization: G.V.P., P.M.S., H.G.D., N.P.R.

Access and verification of data: G.V.P., A.C.M., P.M.S. Formal analysis: G.V.P., A.C.M., G.G.O., O.D.K. Funding acquisition: G.V.P. Methodology: W.B.M., A.M.B., N.P.R., A.C.M., G.G.O.,

H.G.D. Writing—original draft: G.V.P., P.M.S., A.C.M. Writing—review and editing: all co-authors. CORRESPONDING AUTHOR Correspondence to Gonzalo M. Vazquez-Prokopec. ETHICS DECLARATIONS

COMPETING INTERESTS The authors declare no competing interests. ADDITIONAL INFORMATION PUBLISHER'S NOTE Springer Nature remains neutral with regard to jurisdictional claims in published

maps and institutional affiliations. SUPPLEMENTARY INFORMATION SUPPLEMENTARY INFORMATION. RIGHTS AND PERMISSIONS OPEN ACCESS This article is licensed under a Creative Commons Attribution

4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and

the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's

Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not

permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit

http://creativecommons.org/licenses/by/4.0/. Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Vazquez-Prokopec, G.M., Che-Mendoza, A., Kirstein, O.D. _et al._ Preventive

residual insecticide applications successfully controlled _Aedes aegypti_ in Yucatan, Mexico. _Sci Rep_ 12, 21998 (2022). https://doi.org/10.1038/s41598-022-26577-1 Download citation *

Received: 05 September 2022 * Accepted: 16 December 2022 * Published: 20 December 2022 * DOI: https://doi.org/10.1038/s41598-022-26577-1 SHARE THIS ARTICLE Anyone you share the following

link with will be able to read this content: Get shareable link Sorry, a shareable link is not currently available for this article. Copy to clipboard Provided by the Springer Nature

SharedIt content-sharing initiative