Field trial finds promising evidence on Spinosad: a bio-larvicide for mosquito control in urban settings in Bengaluru, India

Abstract

Background

Mosquitoes are primary vectors for various diseases, with urban areas particularly vulnerable due to dense populations and favourable breeding conditions. In India, mosquito-borne diseases such as malaria, dengue, and lymphatic filariasis remain pressing public health concerns. This study assessed the effectiveness and longevity of Spinosad, a naturally derived bio-larvicide, as an eco-friendly alternative to conventional insecticides.

Methods

A large-scale field study, following WHO protocols, tested three Spinosad formulations – DT (7.48%), EC (20.6%), and G30 (2.5%) against Aedes aegypti and Anopheles stephensi. EC (2.5%) and G30 were also tested against Culex quinquefasciatus across seasons. Reapplication was performed when immature-mosquito densities in treated sites matched those in controls.

Results

All formulations documented rapid and significant immature-mosquito densities reduction. Efficacy duration varied by formulation, species, and habitat: reapplication for Aedes, was required on day 28(EC), day 35(G30) and day 56(DT) (P = 0.104); for Anopheles, on day 52.5 (53)(EC), day 49(G30) & day 70(DT) (P = 0.736); for Culex, on day 35(EC, G30) in drains and day 49(G30) or day 63(EC) in cement tanks (p = 0.896).

Conclusion

The study underscores Spinosad’s strong larvicidal effect at low dosages, significantly outperforming conventional larvicides. In the context of rising insecticide resistance and recurring disease outbreaks, Spinosad is an effective, and sustainable tool for mosquito larval control.

Background

Sustainable development goal (SDG) 3.3 lists the priority for communicable diseases where malaria and other neglected tropical diseases are highlighted as important vector-borne diseases aimed for elimination in 30 countries by 2030 [1]. Vector-borne diseases (VBDs) in general pose a significant threat to global public health, affecting more than 80% of the world's population [2]. Mosquitoes, in particular, transmit a range of potentially fatal diseases, such as malaria, dengue, chikungunya, Zika, lymphatic filariasis and Japanese encephalitis (JE). As per NCVBDC (National Centre for Vector Borne Disease Control), 209,000 cases were reported for malaria, 186,000 for dengue, 619,000 for lymphoedema, 17, 821 confirmed cases for Chikungunya across India during 2024 [3]. World Health Organization (WHO) estimated 68,000 JE cases every year from Asian countries. In India, JE is endemic in 355 districts across 24 states/UTs of India, with Assam alone contributing 30–50 percent of total cases in recent years [4]. During the 2024 Zika outbreaks, a total of 13 cases were reported, 3 from Karnataka and 10 from Maharashtra [5]. Environmental factors, unplanned urbanization, climate change, insecticide resistance contributed to the spread of these mosquito borne diseases [6, 7].

Mosquitoes of the genera Anopheles, Aedes and Culex (Diptera: Culicidae) transmit the major vector borne diseases [8]. Aedes aegypti and Aedes albopictus are responsible for transmission of arboviral diseases, such as dengue, chikungunya and Zika, while Anopheles species transmit malaria, and Culex species are responsible for lymphatic filariasis and JE. Anopheles spp. are known to typically breed in clean water sources like cement tanks, river bed pools, overhead tanks, containers [9]. Similarly, Aedes spp. breeds in clean, stagnant waters found in overhead tanks, underground water storage tanks, potable water, small water receptacles including leaf axils [10]. Culex species prefer polluted water habitats like sinkholes, sewer ditches, cesspits, cesspools and drains etc. and occasionally paddy fields [11]. The diverse breeding habitats of these vectors makes curtailing disease transmission a challenge. Therefore, effective vector control strategies need to take cognizance of the ecology and vector’s behaviour to combat these diseases [12].

Vector control strategies can be targeted at either the larval stage or at the adult stage. Larval control with larvicide is crucial in reducing the mosquito density by decimating them before they reach the epidemiologically important adult stage. Larval control could be employed outdoors, as well as both in domestic and peri-domestic habitats. In contrast, the major adult management methods such as LLINs and IRS are prescribed for indoors only. With adult mosquitoes developing multi-insecticide resistance, larval control serves as a valuable additional intervention, particularly effective where the larval habitats are limited, permanent and accessible for larvicide applications.

The World Malaria Day 2025 theme calls for re-energizing the efforts at all levels for malaria control [13]. The present research work is one such attempt, evaluating the effectiveness of Spinosad, in controlling mosquito populations in an urban metropolitan city, Bengaluru, India. Spinosad is a tetracyclic macrolide compound which occurs naturally and belongs to the class Spinosyns of insecticides with novel mode of action and acts as a nicotinic acetylcholine receptor (nAChR) allosteric modulator (IRAC-MoA, 2024). It is a mixture of two naturally occurring metabolites (Spinosyn A and D) produced by a soil actinomycete, Saccharopolyspora spinosa [14–16] which activates the acetylcholine nervous system through nicotinic receptors [17] that leads to exhaustion and death of the insect [18, 19] and is in use as an agricultural pesticide since 1990[16, 20]. Spinosad formulations have also been proven as effective larvicides against a variety of mosquito species [21] and has been found to be effective against multiple-insecticide resistant larvae [22, 23]. The long-lasting larvicidal activity, combined with its effective bio-degradability, makes it an effective alternative to chemical insecticides and for resistance management [24]. Subsequently, studies have been done with Spinosad formulations tested against various larval species in laboratory and field [22, 25–27]. (Indian Council of medical Research) ICMR-VCRC (Vector Control Research Centre), Puducherry carried out one such study which focused on the laboratory (Phase I) and small-scale field trial (Phase II) to evaluate the bio-efficacy of the Spinosad formulations against vector mosquitoes [28, 29] and the suggested dosages were tested in the current large scale studies. This paper discusses the findings from a large scale (Phase III) study which evaluates the efficacy of three formulations developed by Clarke Environmental Technologies (I) Ltd, Mumbai, India, against immature stages of mosquito species of different genera in urban settings of Bengaluru city. The study covered all the seasons to observe, fluctuations if any, during the treatment in different seasons. Moreover, it also assessed the formulation’s effectiveness in reducing larval densities across diverse urban breeding habitats and varied environmental conditions.

Methods

Study site

Bengaluru is located in the Southeast of the South Indian state of Karnataka, at an average elevation of + 900 m (+ 2,953 ft) MSL. It is located at 12.97°N and 77.56°E and covers an area of 741 km2. The cooler month is December with an average temperature of 26.6 °C (79.9°F) and the warmer month is April with an average temperature of 35 °C (95°F). Bengaluru receives rainfall from both the North East and the South West monsoons with the wet months being August, September and October receiving long period average (LPA) of 140, 230 and 170 mm rainfall, respectively [30]. Widespread construction activities throughout the city have resulted in the creation of man-made mosquito breeding habitats. Yelahanka (North zone of Bengaluru) and Ramamurthy Nagar (East zone of Bengaluru) were selected as study sites based on the abundance of the targeted mosquito larvae breeding habitats i.e. Ae. aegypti, An. stephensi and Cx. quinquefasciatus.

Study duration

The field trials were conducted during the rainy season (July 2021 to October 2021), winter season (September 2021 to January 2022) and summer season (March/April 2022 to June/July 2022) to cover the three meteorological seasons.

Formulations

Three formulations of Spinosad (Natular) which are 20.6% Emulsifiable Concentrate (EC), 2.5% Granular (G30) and 7.48% Dispersible Tablet (DT) were used in the current study [31, 32].

Habitat selection

Baseline larval surveys were conducted during the months of March and April, 2021 to select the potential breeding habitats for Ae. aegypti, An. stephensi and Cx. quinquefasciatus (Table 1). Larval samples were collected as per the WHO protocol using a larval dipper (500 mL capacity) from different habitats [33]. The immature (larvae and pupae) were brought to the laboratory and reared for adult emergence. The emerged adults were identified using standard morphological identification keys [34–36]. Each of the breeding habitats (cement tank, plastic containers etc.) were considered as a replicate. Habitats such as drains were divided into sectors of 10 m length and each 10 m length was considered as a replicate for treatment and control. It was ensured that the control habitats were at least 3 km away from the larvicide treated habitats. In the selected habitats, larval and pupal densities were recorded for three consecutive times and suitable breeding habitats with consistent larval density were selected for the evaluation as per WHO standard guidelines for the large-scale field testing of bio-larvicides [31–33]. Mosquito breeding habitats were designated for the treatment with the three formulations and controls. For treatment with each formulation, an adequate number (at least 25 habitats) of habitats were selected in each season. The study localities are shown in the map (Fig. 1).

Table 1.

Habitat details for all seasons with type of water containers

Mosquito species	Formulation	Container type	No. of Containers
Ae. aegypti	DT	Plastic drums,	25
	G30	Cement tanks	25
	EC		25
An. stephensi	DT	Plastic drums,	25
	G30	Cement tanks	25
	EC		25
Cx. quinquefasciatus	G30	Cement tanks	15
	EC	Cement tanks	10
Cx. quinquefasciatus	G30	Drains	25
	EC

Fig. 1.

Locations indicating the study sites where the habitats were selected in Bengaluru, Karnataka, India. [Image resource from Google Earth Pro (version 7.3)]

Treatment

The larval habitats (cement tanks and street drains having clear water and polluted water) in each of the study sites were treated with formulations at the optimum field application dosages determined in the small scale (Phase II) field trial [28, 29]. The EC formulation was applied @ 0.274 mg (a.i)/L for Ae. aegypti breeding habitats and @ 0.073 mg (a.i)/L for An. stephensi breeding habitats. The granular formulation was applied @ 0.06 mg (a.i)/L for Ae. aegypti breeding habitats and @ 0.074 mg (a.i)/L for An. stephensi breeding habitats. The DT formulation was applied at ½ tablet/100L or one tablet/200 L against Ae. aegypti and An. stephensi breeding. G30 granular formulation with 2.5% was applied at 150 mg (a.i)/m2 against Cx. quinquefasciatus. The 20.6% EC formulation was applied at 25 mg (a.i)/m2 dose using a hand-held compression sprayer (2-L capacity) with a jet nozzle (Foggers India Pvt. Ltd.) for small habitats and 10 L compression sprayer for larger street drains. DT formulation was dropped in the larval habitats onto the surface of the water. However, DT formulation was not evaluated against Cx. quinquefasciatus; Only GR and EC formulations were evaluated against this mosquito species (Table 1).

Community acceptance

The perception survey was conducted for post-application periods of the larvicides. A pre-tested, close-ended questionnaire was utilized to gather insights relating to aspects like; individual’s reactions to treated habitats (allergies, smell), perception of reduction in mosquitoes, willingness to allow further application of the Natular formulations in future, etc. Respondents were residents or individuals residing near the treated habitats of the three formulations, oral informed consent was taken while collecting data for community acceptance.

Statistical analysis

The mean number of pupae and larvae collected per dip from each type of habitat was calculated for each day of sampling for each treatment as well as for control. The first (L1) and second (L2) instar larvae were grouped as early instar and the third (L3) and fourth (L4) instars were grouped as late instars. The data was collected for early and late instars, and results were analysed combining the stages. The percentage reduction of early and late instar larval and pupal densities on different days of post-treatment was estimated using Mulla’s formula [33]. The efficacy criterion of 80% reduction in (L3 & L4) larvae/pupae counts standard benchmark for larvicide efficacy as per WHOPES (WHO Pesticide Evaluation Scheme) guidelines were used to determine the efficacy of the treatments as per the WHO larvicide guidelines [31, 32]. Pre- and post-density measures of immature forms of different mosquito species across different formulations in the intervention and control groups were analysed through Wilcoxon Signed Ranks Test. Kruskal Wallis test H(P = 0.104) with (confidence level of 95%) was performed to compare the days required for immature density reduction and reapplication day between the treatments using SPSS version 29.0.

Results

The habitats were observed from the day of intervention till day 70 (10 weeks). Efficacy in terms of earliest reduction in larval density was observed over the WHOle 70 days. Wilcoxon Signed Ranks Test was performed to compare pre- and post-density measures of immature forms of different mosquito species across different formulations (DT, G30, EC) between groups (intervention and control) on day one of post intervention. For Ae. aegypti significant reductions were observed in post-density compared to pre-density for all formulations (DT: p = 0.008, G30: p = 0.008, EC: p = 0.005) among the intervention group while in control group only EC showed a significant difference (p = 0.028) (can be due to environmental variation/natural variability). Significant reductions for all formulations (DT: p = 0.008, G30: p = 0.008, EC: p = 0.012) were observed in An. stephensi and also (G30: p < 0.001, EC: p = 0.002) in Culex. While for EC in Cx. quinquefasciatus control was p = 0.023 (can be due to environmental variation/natural variability) (Table 2).

Table 2.

Immature form densities (pre and post intervention) in intervention and control groups for effectiveness of three formulations against different mosquito species

Mosquito	Formulation	Pre-density in intervention group median (IQR)	Post-density in intervention group on day 1 median (IQR)	P value*	Pre-density control group median (IQR)	Post-density control group on day 1 median (IQR)	P value*
Ae. aegypti	DT	2.61 (1.25–2.79)	0 (0–0.06)	0.008	2.59 (2.05–3.22)	3.1 (2.33–4.16)	0.086
	G30	2.14 (1.10–3.55)	0 (0–0.50)	0.008	2.29 (1.15–2.92)	3.66 (1.96–5.11)	0.109
	EC	2.65 (0.79–4.32)	0 (0–0.07)	0.005	2.11 (1.32–3.44)	3.49 (1.97–5.48)	0.028
An. stephensi	DT	1.26 (1.03–2.74)	0 (0–0.01)	0.008	0.93 (0.49–1.48)	1.02 (0.85–1.45)	0.097
	G30	1.02 (0.55–1.70)	0 (0–0.06)	0.008	0.93 (0.49–0.1.51)	1.02 (0.83–1.49)	0.109
	EC	1.53 (0.96–3.29)	0 (0–0.10)	0.012	1.05 (0.44–1.54)	1.01 (0.68–1.41)	0.575
Cx. quinquefasciatus	G30	3.43 (2.75–10.80)	0 (0–0.72)	< 0.001	6.01 (2.34–11.35)	6.82 (2.17–11.42)	0.1
	EC	6.59 (2.99–14.17)	0 (0–1.39)	0.002	8.79 (4.57–12.70)	6.46 (3.35–12.04)	0.023

^*Wilcoxon Signed Ranks Test

It was observed (Table 3) that, irrespective of the larval stage and the seasons for different species of mosquitoes and all three formulations, the earliest reduction of larval density was observed on day 1 for all mosquito species except Cx. quinquefasciatus in drains. The minimum and maximum period recorded for reduction was 1 day and 5.5 days, respectively. The (Kruskal Wallis test H) applied for different formulations for a given mosquito species was not statistically significant.

Table 3.

Earliest reduction day observed for different mosquitoes and formulations

Mosquito species	Earliest reduction day median (Q1-Q3), [Minimum and maximum] days [NA*:-Surveys were not carried out]			Kruskal Wallis test H (P value)
	DT	EC	G30
Ae. aegypti	1 (1,1) [1]	1 (1,1) [1]	1 (1,1) [1]	4.52 (0.104)
An. stephensi	1 (1,1) [1]	1 (1,1) [1]	1 (1,1) [1]	0.613 (0.736)
Cx. quinquefasciatus (cement tanks)	NA	1 (1,1) [1]	1 (1,1) [1]	0.019 (0.896)
Cx. quinquefasciatus (drains)	NA	1 (1,5.50) [1]	1 (1,1) [1]	1.336 (0.248)

For a given mosquito species, the formulations were protective for at least 4 weeks (28 days) with a median of 28 days (14,59.5) for EC formulation for Ae. aegypti, a median of 35 days for G30 and 56 days for DT. These differences when compared among different formulations were not statistically significant, however, in field conditions, DT formulation was effective for 56 days. This could be considered effective enough for a significant period of protection against immature forms of Ae. aegypti and An. stephensi. The details for other mosquito species are given in Table 4.

Table 4.

Earliest reapplication required for different formulations with respect to different mosquito species

Mosquito species	Earliest reapplication day median (Q1-Q3), [Minimum and maximum] days			Kruskal Wallis test H (P value)
	[NA*:-Surveys were not carried out]
	DT	EC	G30
Ae. aegypti	56 (42,70) [35,70]	28 (14,59.5) [14,70]	35 (21,70) [14,70]	4.52 (0.104)
An. stephensi	70 (17.50,70) [7,70]	52.50 (8.75,68.25) [7,70]	49 (21,70) [7,70]	0.613 (0.736)
Cx. quinquefasciatus (cement tanks)	NA	63 (28) [28,70]	49 (26.25,70) [21,70]	0.019 (0.896)
Cx. quinquefasciatus (drains)	NA	35 (17.50,35) [3, 35]	35 (24.50,38.50) [14,70]	1.336 (0.248)

In addition to measuring the initial reduction in larval density, the study also recorded the duration of sustained larval suppression following, i.e., the duration of continual reduction in immature density reduction of less than 80–100%, until re-application was initiated on those days when immature density reduction was less than 80%. Table 3 depicts the earliest re-application days of the median and interquartile range of days, along with minimum and maximum days observed for each of these habitats, irrespective of the density of the immature form and seasons. The minimum and maximum earliest application days per season are mentioned in Table 5.

Table 5.

Earliest reapplication required for different mosquitoes and formulations season wise

Mosquito species	Formulations	Earliest reapplication day median (Q1-Q3), [Minimum and maximum] days [NA*: Surveys were not carried out]
		Monsoon	Summer	Winter
Ae. aegypti	DT	(35,70)	(49,56)	(70,70)
	EC	(14,70)	(21,28)	(35,70)
	G30	(70,70)	(21,70)	(14,35)
An. stephensi	DT	(70,70)	(7,28)	(56,70)
	EC	(70,70)	(7,14)	(42,63)
	G30	(70,70)	(7,49)	(35,70)
Cx. quinquefasciatus (cement tanks)	EC	NA*	(28,70)	(70,70)
	G30	(70,70)	(21,28)	NA*
Cx. quinquefasciatus (drains)	EC	(35,35)	(3,28)	(35,35)
	G30	(35,42)	(14,70)	(35,35)

Micro and macro climate variables

Each habitat selected was monitored for pH and temperature during the scheduled visits. An average of 25 habitats were analysed for each formulation. The minimum and maximum pH and temperature has been tabulated in Table 6. It is to be noted that no major variation was observed among the habitats for any of the mosquito species for the three formulations. Temperature, rainfall and rainy days in a month during study period is plotted (Fig. 2) as obtained from India Meteorological Department (IMD).

Table 6.

Microclimate variables (pH and Temperature) of the habitats

Mosquito species	Formulation	pH (Min–Max)	Temperature (Min–Max)
Ae. aegypti	DT	7.1–7.4	24.85–25.54
	G30	7.0–7.11	24.24–25.01
	EC	7.0–7.1	24.79–27.13
An. stephensi	DT	7.0–7.3	24.82–27.08
	G30	7.0–7.2	24.81–27.90
	EC	7.0–7.1	24.38–25.08
Cx. quinquefasciatus (cement tanks)	G30	7.6–8.5	24.78–24.88
	EC	8.0–8.0	24.75–24.75
Cx. quinquefasciatus (drains)	G30	7.6–9.1	24.75–24.90
	EC	9.0–9.1	24.75–25.81

Fig. 2.

Temperature, rainfall and rainy days in a month during study period (June 2021 to August 2022) in study area, Bengaluru, Karnataka, India [India Meteorological Department] (IMD) official report for the study time period)

Community perception

In addition to assessing the efficacy of the said Natular formulations, the study also examined community perspective on their use as it plays a vital role in the successful implementation of any vector control program. The study employed a structured questionnaire to gather insights from residents in areas treated with the three Natular formulations: EC (6 respondents), G30 (10 respondents), and DT (14 respondents). It is to be noted that areas treated with EC were plant nurseries with numerous habitats per respondent, while areas treated with G30 and DT had fewer habitats (1–3 habitats) per respondent. The study in its investigation of potential side effects associated with the use of water treated with the various Natular formulations found that none of the respondents reported any skin reactions or irritations, implying minimal risk, when used as directed. However, one respondent from each of the treatment groups reported slight odour in the treated water and could be a potential barrier to community acceptance when implemented on a larger scale. However, none of the respondents reported a change in taste, indicating that the formulations didn't considerably affect water palatability.

NTO (non-targeted organism)

No adverse effect of Natular formulations was observed on NTOs (cohabiting target mosquito species) in both clean and polluted water habitats, at the dosages applied for controlling mosquito larvae.

Discussion

The present study conducted in the urban city of Bengaluru, India showed crucial evidence of reduction in the immature stages of the mosquito vector following the application of the three formulations of Spinosad larvicide. The persistence of larvicidal efficacy varied across mosquito species and breeding habitats, influenced by factors such as formulation type, water quality, and organic matter content, similarly reported in some other studies [23, 31]. This United States Environmental Protection and WHO-recommended larvicide, which lies in the vector-control-products/prequalified-product-list [32] showed its effectiveness and persistence capabilities even in the city of Bengaluru which faces a dynamic change in environmental conditions throughout the year. The study conducted over the year tested various aspects of Spinosad larvicide through different seasons.

Efficacy of each formulation was assessed based on their ability to reduce immature densities. As observed in Table 3, efficacy of Spinosad reported from day one, though it is not statistically significant for different formulations for given mosquitoes, it is observed the efficacy is retained for 4–7 weeks (Table 4). A similar study done on Suspension Concentrate (SC) formulation of Spinosad at 1 or 5 ppm (mg a.i./litre) reported 6–8 weeks of immature reduction in Ae. aegypti, Ae. albopictus, Cx. quinquefasciatus and Cx. coronator during dry and rainy seasons [37]. From public health point of view, 4–7 weeks efficacy is good enough to employ as effective larvicide for field conditions. Since it requires limited reapplication, it reduces the manpower compared to routine frequent vector control methods. This study highlights the variability in the efficacy of different formulations across diverse habitats, emphasizing the need for a tailored approach to vector control that considers both the target species and the characteristics of the breeding environment. For example, for habitats of plastic drums and cement tanks containing Aedes spp., application of DT formulation once, shall provide sustained larval reduction for 56 days. Hence application of this formulation once in 8 weeks (56 days) can be considered as feasible on an operational scale. A Spinosad study done in Western Kenya also reported that application of two long-lasting formulations significantly reduced the numbers of indoor resting Anopheles mosquitoes compared to the untreated control [26]. In some studies, Spinosad formulations were reported to be more effective against Cx. quinquefasciatus [38]. Studies indicated that with application dose @1 or 5 ppm SC treated water containers effectively prevented the development of Aedes spp, while with G30 treated habitats maintained reduced immature density (100%) for a longer period compared to EC. It was also observed that G30 maintained a 100% reduction in immature density for 2 to 4 weeks post- treatment [39].

To complement the entomological evaluations, a community perception survey was conducted as it is a crucial aspect of any vector control program. The survey brought to the fore an overall positive perception towards the three Natular formulations exhibiting high acceptance rates (by all respondents for EC and G30 arms and all but one respondent—for DT arm). When combined with minimal reports of side effects, it could be put forth that integrating these formulations into mosquito control programs could be a feasible intervention measure.

Conclusion

The present study demonstrates that all three tested formulations of Spinosad reduced immature larval densities within one day of application. While the duration of efficacy varied by mosquito species, habitat type and formulation types, significant reductions were consistently observed across all formulations in the intervention group from day one. The absence of such trends in the control group strengthens the attribution of efficacy to the intervention, in spite of natural or environmental fluctuations. In terms of residual effect, the DT formulation exhibited the longest duration of efficacy up to 56 days in Aedes habitats and 70 days in Anopheles habitats. For Culex mosquitoes, reapplication was required after 63 days (EC formulation) in cement tanks and 35 days (EC and G30) formulations when applied in drains. These differences underscore the influence of habitat characteristics and formulation type on larvicidal performance. Selecting the appropriate Spinosad formulation based on ecological and species-specific factors ensures optimal mosquito control with minimal application frequency. Moreover, the community acceptance towards the use of Spinosad further enhances its feasibility in vector control intervention, reinforcing its operational feasibility. In the era of insecticide resistance, Spinosad serves as a valuable complement in integrated vector management. Its efficacy aligns seamlessly with the targets of Sustainable Development Goal (SDG 3.3). Spinosad stands out as a potent, community-friendly, and a forward-looking solution in the global vector control programs.

Limitations

The impact of unpredictable weather patterns, during the course of the study. Data collected from Metrological Department of India, Bengaluru region (IMD) during the course of the study showed that a number of the selected study sites were impacted by the monsoon drift turbulence, which would have caused rain to wash out the drains at certain times and periodic water scarcity at other time-points. This could have resulted in abnormalities in the water retention measure and could have resulted in minor variations at certain habitats. Additionally, regular exposure to sunlight in several habitats may have reduced the efficacy of Spinosad due to photo-degradation.

Abbreviations

ICMR

Indian Council of medical Research

EC

Emulsifiable concentrate

LF

Lymphatic filariasis

JE

Japanese encephalitis

nAChR

Nicotinic acetylcholine receptor

VCRC

Vector control research Centre

MSL

Moisture sensitivity level

LPA

Long period average (LPA)

G30

Granular

LPA

Long period average

WHO

World Health Organization

AI

Active Ingredient

WHOPES

WHO pesticide evaluation scheme

pH

Potential of hydrogen

IQR

Interquartile range

SC

Suspension concentrate

ppm

Parts-per million

DT

Dispersible tablets

MDI

Metrological department of India

NTO

Non-targeted organism

SC

Suspension concentrate

Author contributions

SU and RK were responsible for conceptualizing and initiating the study, as well as selecting the study sites. VHC, SU, SBM, SNN, and AE carried out and oversaw the implementation of the trial methodology. GS recorded observations and curating the data. VHC conducted the formal data analysis. RS prepared the original manuscript draft. VHC, RS, SU, RK, SBM, SNN, and AE contributed to reviewing and editing the manuscript. All authors have read and approved the final version for publication.

Funding

The study was funded by Clark Environmental Technologies (I) Ltd. Mumbai, India. The funders had no role in study design, data collection, analysis, or manuscript preparation also the written approval is taken for data publication.

Data availability

The data presented in this study are available from the corresponding author upon request.

Declarations

Ethics approval and consent to participate

No human participants were directly involved in the study, and no biological samples were collected. However, oral informed consent was obtained from community members for their participation in the community acceptance survey, which was conducted prior to the commencement of the study. The study protocol was reviewed by the Institutional Ethics Committee (IEC) and was granted a waiver by the ICMR-National Institute of Malaria Research, New Delhi. The research involved the use of three formulations of Natular larvicide, which were applied exclusively in non-potable water habitats. Given the nature of the intervention in selected water habitats, an IEC waiver was considered appropriate.

Competing interests

The authors declare no competing interests.