A CASE REPORT ON PRODUCT ROTATION TO MANAGE SEVERE LYSINIBACILLUS SPHAERICUS RESISTANCE IN CULEX PIPIENS FROM SALT LAKE CITY, UTAH.

The Salt Lake City Mosquito Abatement District (SLCMAD) detected a 20,000-fold resistance to Lysinibacillus sphaericus (Lsph) in Culex pipiens occurring in catch basins of Salt Lake City during 2016. In response, SLCMAD suspended use of Lsph and rotated use of spinosyn and s-methoprene products for the next three years. At the end of the third year, Lsph was evaluated again and efficacy similar to susceptible colony strains. During the second year of Lsph use, technicians observed lack of control of larvae at some urban sites. Bioassays performed during 2021 showed recurrence of some resistance to Lsph to varying degrees across SLCMAD urban areas. The rapidity with which resistant phenotypes reemerged clarifies that SLCMAD cannot in the near future rely on repeated use of Lsph, even after suspending use for three years and using within-season product rotations. Prior reports in other research groups have found long-term selection to Lsph, as is the case at SLCMAD, to not regress in spite of halting use of the products. However, our findings offer some optimism that regression may be relatively quick. More operational review is needed, and future work should characterize resistance alleles in field populations. Collectively, there is a lack of concrete data supporting the prevailing assumptions from adjacent industries that were adopted into mosquito abatement. We provide this short note as additional guidance for mosquito and vector control districts weighing options to remediate Lsph resistance.

Short report: unmanned aerial vehicle for wide area larvicide spraying (WALS) using Vectobac® WG at Kota Kinabalu, Sabah.

INTRODUCTION: Given the stagnating progress in the fight against dengue in Kota Kinabalu, there is an urgent need to use other strategies to complement the existing vector control, focusing on larviciding. Unmanned aerial vehicle (UAV) technology has been used in vector control programs in many countries. The aim of this study was to determine the feasibility of using UAVs for larviciding to control Aedes mosquitoes in urban areas. METHODOLOGY: The Hexarotor Agro Drone (Polardrone Sdn Bhd, Malaysia) was used to carry out larviciding using Vectobac® manufactured by Valent BioSciences LLC, Libertyville, USA. The drone flew at a height of 10 feet and at a speed of 5 m/s. A total of 32 items with 10 larvae in each item were placed to test the effectiveness of larviciding using UAV. RESULTS: Out of 32 items used, 4 containers had a 100% larva mortality (13.3% mortality). The drone was not able to reach the designated spraying route that had been pre-programmed. This was due to interference with the electromagnetic waves emitted from the home satellite dishes, that were in front of the houses along the route. CONCLUSIONS: This trial showed that UAVs will be more suitable for use in larviciding in an open area without electromagnetic disturbances from electric house poles and satellite TV dishes that are commonly present in urban areas.

Biocontrol effects of chemical molecules derived from Beauveria bassiana against larvae of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae).

In this study, we conducted tests on the isolation, identification, characterization, and extraction of chemical molecules from Beauveria bassiana against Tuta absoluta larvae. The enzyme responses of T. absoluta to the crude extract were examined 24 h after treatment, and the number of dead larvae was calculated 24 and 48 h after treatment. Molecular docking studies were conducted to assess the interaction of important molecules with the acetylcholinesterase enzyme. The larvicidal activity of crude chemicals from fungi was high 24 h after treatment, with LC50 and LC90 values of 25.937 and 33.559 µg/mL, respectively. For a period of 48 h, the LC50 and LC90 values were 52.254 and 60.450 µg/mL, respectively. The levels of acetylcholinesterase, α-carboxylesterase, and ß-carboxylesterase enzymes were lower in the treatment group after 24 h compared to the control group. The GC-MS test revealed that the crude extract consisted mainly of 9,10-octadecadienoic acid, which was the primary compound. Docking results indicated that 9,10-octadecadienoic acid showed a strong interaction with acetylcholinesterase (AChE). Our findings suggest that the chemical molecule 9,10-octadecadienoic acid derived from the entomopathogenic fungus B. bassiana is more toxic to T. absoluta larvae. We plan to conduct studies to test its effectiveness in semi-field conditions and to evaluate its stability in field conditions. We believe that this 9,10-octadecadienoic acid molecule could be used to control T. absoluta larvae in the near future without causing environmental pollution.

Sustainable use of plastic-derived nanocarbons as a promising larvicidal and growth inhibitor agent towards control of mosquitoes.

Nanoscale carbon was obtained from six widely used plastics (PET, HDPE, PVC, LDPE, PP and PP) via thermal degradation (600 °C) under inert atmosphere. The thermally degraded products were processed through bath sonication followed by lyophilisation and the same was characterized through proximate analysis, UV-Vis spectroscopy, Scanning electron micrograph (SEM) with energy dispersive X-ray (EDX) analysis, Transmission electron micrograph (TEM), Dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). A series of aqueous solution of nanoscale carbon (5-30 mg/L) were prepared and same were used as both mosquito growth inhibitor and larvicidal agent against 3rd and 4th instar larvae of Culex pipiens. The significant percent mortality results were recorded for LDPE (p < 0.007) with average particle size of 3.01 nm and 62.95 W% of carbon and PS (p < 0.002) with average particle size of 12.80 nm and 58.73 W% of carbon against 3rd instar larvae, respectively. Similarly, for 4th instar larvae, both significant pupicidal and adulticidal activity were also recorded for PET (F = 24.0, p < 0.0001 and F = 5.73, p < 0.006), and HDPE (F = 26.0, p < 0.0001) and F = 5.30, p < 0.008). However, significant pupicidal activity were observed for PVC (F = 6.90, p < 0.003), and PS (F = 21.30, p < 0.0001). Histological, bio-chemical and microscopic studies were revealed that nanoscale carbon causes mild to severe damage of external and internal cellular integrity of larvae. However, nanoscale carbon does not exhibit any chromosomal abnormality and anatomical irregularities in Allium cepa and Cicer arietinum, respectively. Similarly, non-significant results with respect to blood cell deformation were also recorded from blood smear of Poecilia reticulata. Therefore, it can be concluded that plastic origin nanoscale carbon could be a viable sustainable nano-weapon towards control of insects.

Widespread Resistance to Temephos in Aedes aegypti (Diptera: Culicidae) from Mexico.

Organic synthetic insecticides continue to be part of the arsenal for combating vector-borne diseases in Mexico. Larvicides are a fundamental part of the process in programs for mosquito control, temephos being one of the most widely used in Mexico. In the present study, we analyzed the frequency of temephos resistance in twenty-three Aedes aegypti populations using the discriminating concentration (DC) of 0.012 mg/L. We also tested 5× DC (0.6 mg/L) and 10× DC (0.12 mg/L) of temephos. The resistance distribution to temephos was interpolated to unsampled sites using the inverse distance weighting (IDW) method. The populations of Ae. aegypti showed a high frequency of resistance (1× DC) with mortality rates below 93% in 22 of the 23 populations analyzed. Moderate resistance intensity (5× DC) was found in 78% of the populations, and high intensity (10× DC) in 30%. Predicted mortality was below 60% in the populations of the Pacific Coast, along the Gulf of Mexico, and in the state of Coahuila in Northeastern Mexico in relation to 1× DC; the Pacific Coast and Northeast patterns hold for 5× and 10× DC. The results suggest the need for rotation of the larvicide to effectively control the larval populations of the vector in the country.

Chitinase from Streptomyces mutabilis as an Effective Eco-friendly Biocontrol Agent.

Blood sucking parasites not only cause economic loss but also transmit numerous diseases. Dermanyssus gallinae, an obligatory blood feeding ectoparasite causes huge production loss to the poultry industry. Mosquitoes act as vector for transmitting several viral and parasitic diseases in humans. Acaricide resistance limits the control of these parasites. The present study was aimed to control the parasites using chitinase that have selective degradation of chitin, an important component in exoskeleton development. Chitinase was induced in Streptomyces mutabilis IMA8 with chitin extracted from Charybdis smithii. The enzyme showed more than 50% activity at 30-50 °C and the optimum activity at 45 °C. The enzyme activity of chitinase was highest at pH 7.0. The kinetic parameters Km and Vmax values of chitinase were determined by non-linear regression using Michaelis-Menten equation and its derivative Hanes-Wolf plot. The larvicidal effect of different concentrations of chitinase was evaluated against all instar larvae (I-IV) and pupae of An. stephensi and Ae. aegypti after 24 h of exposure. The percentage of mortality was directly proportional to the chitinase concentration. Bioassay for miticidal activity showed that chitinase had excellent miticidal activity (LC50 = 24.2 ppm) against D. gallinae. The present study suggested the usage of Streptomyces mutabilis for preparation of chitinase in mosquito and mite control.

Larvicidal activity of the photosensitive insecticides, methylene blue and rose bengal, in Aedes aegypti and Anopheles gambiae mosquitoes.

BACKGROUND: Insecticides are critical for controlling mosquito populations and mitigating the spread of vector-borne disease, but their overuse has selected for resistant populations. A promising alternative to classical chemical insecticides is photosensitive molecules - here called photosensitive insecticides or PSIs - that when ingested and activated by light, generate broadly toxic reactive oxygen species. This mechanism of indiscriminate oxidative damage decreases the likelihood that target site modification-based resistance evolves. Here, we tested whether the PSIs, methylene blue (MB) and rose bengal (RB), are viable insecticides across the mosquito lineage. RESULTS: MB and RB are phototoxic to both Aedes aegypti and Anopheles gambiae at micromolar concentrations, with greatest toxicity when larvae are incubated in the dark with the PSIs for 2 h prior to photoactivation. MB is ten times more toxic than RB, and microscopy-based imaging suggests that this is because ingested MB escapes the larval gut and disperses throughout the hemocoel whereas RB remains confined to the gut. Adding food to the PSI-containing water has a bidirectional, concentration-dependent effect on PSI toxicity; toxicity increases at high concentrations but decreases at low concentrations. Finally, adding sand to the water increases the phototoxicity of RB to Ae. aegypti. CONCLUSION: MB and RB are larvicidal via a light activated mechanism, and therefore, should be further investigated as an option for mosquito control. © 2023 Society of Chemical Industry.

Neochloris aquatica induces larval mortality, molting defects, and unstable flightless adults in the Asian tiger mosquito.

The Asian tiger mosquito, Aedes albopictus, is a highly invasive and aggressive species capable of transmitting a large number of etiological agents of medical and veterinary importance, posing a high risk for the transmission of emerging viruses between animals and humans. In this work, we evaluated the mosquitocidal activity of Neochloris aquatica against A. albopictus throughout its development and analyzed whether this effect was potentiated when the microalga was cultivated under stress conditions due to nutrient deprivation. Our results suggest that N. aquatica produces metabolites that have negative effects on these insects, including larval mortality, interruption of pupal development, and incomplete emergence of adults when fed on microalgae in the larval stages. When microalgae were cultured under stress conditions, an increase in molting defects was recorded, and the number of healthy adults emerged drastically decreased. Histological studies revealed severe signs of total disintegration of different tissues and organs in the thorax and abdomen regions. The muscles and fat bodies in the midgut and foregut were severely distorted. In particular, larval intestinal tissue damage included vacuolization of the cytoplasm, destruction of brush border microvilli, and dilation of the intercellular space, which are distinctive morphological characteristics of apoptotic cells. Evidence suggests that N. aquatica produces metabolites with mosquitocidal effects that affect development and, therefore, the ability to vector etiological agents of medical and veterinary importance.

Laboratory Evaluation of Efficacy of the Larvicide Spinosad Against AnophelesStephensi in Jigjiga, Ethiopia.

We report the efficacy of a commercial formulation of the insecticide spinosad against larvae of Anopheles stephensi populations found in the city of Jigjiga, Somali Region, eastern Ethiopia. Batches of 25 larvae (late III to early IV instars) collected from large water storage reservoirs associated with construction sites (the primary An. stephensi larval site in the dry season) were tested under laboratory conditions against each insecticide at a dose recommended by the manufacturer (Natular® G30, 0.02 g/5 liter), following World Health Organization guidelines. Mortality at 24-48 h postexposure was 100%. Results show that spinosad is effective against An. stephensi larvae and suggest that it may be a useful tool as part of larval source management plans aimed at controlling this invasive malaria vector in Ethiopia.

Response to An Outbreak of Locally Transmitted Dengue in Key Largo, FL, by The Florida Keys Mosquito Control District.

Dengue virus (DENV) is an ever-increasing threat to the residents of South Florida. Seventy-two cases of locally acquired dengue were contracted by residents and visitors of Key Largo, FL, in 2020. The primary vector, Aedes aegypti, has been a large focus of the Florida Keys Mosquito Control District's (FKMCD) control measures for over a decade. This paper recounts the 2020 outbreak of DENV in Key Largo, FL, and the FKMCD's Ae. aegypti operational response. The overall House Index (13.43%) during the outbreak was considered high (>5%) risk for local transmission. Larval habitat characterized from property inspections was similar to previous larval (τ = 0.78, P < 0.005) and pupal (τ = 0.745, P < 0.005) habitat studies. Adult surveillance of the active dengue transmission area provided 3 positive pools out of 1,518 mosquitoes tested resulting in a minimum infection rate of 1.976. Increased personnel response with long-term larvicide formulations and increased aerial, truck, and handheld ultra-low-volume adulticide control measures quickly reduced the Ae. aegypti surveillance numbers below the action threshold. No active cases of dengue have been reported since October 2020.

Demonstration of RNAi Yeast Insecticide Activity in Semi-Field Larvicide and Attractive Targeted Sugar Bait Trials Conducted on Aedes and Culex Mosquitoes.

Eco-friendly new mosquito control innovations are critical for the ongoing success of global mosquito control programs. In this study, Sh.463_56.10R, a robust RNA interference (RNAi) yeast insecticide strain that is suitable for scaled fermentation, was evaluated under semi-field conditions. Inactivated and dried Sh.463_56.10R yeast induced significant mortality of field strain Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus larvae in semi-field larvicide trials conducted outdoors in St. Augustine, Trinidad, where 100% of the larvae were dead within 24 h. The yeast was also stably suspended in commercial bait and deployed as an active ingredient in miniature attractive targeted sugar bait (ATSB) station sachets. The yeast ATSB induced high levels of Aedes and Culex mosquito morbidity in semi-field trials conducted in Trinidad, West Indies, as well as in Bangkok, Thailand, in which the consumption of the yeast resulted in adult female mosquito death within 48 h, faster than what was observed in laboratory trials. These findings support the pursuit of large-scale field trials to further evaluate the Sh.463_56.10R insecticide, a member of a promising new class of species-specific RNAi insecticides that could help combat insecticide resistance and support effective mosquito control programs worldwide.

Mosquito larvae exposed to a sublethal dose of photosensitive insecticides have altered juvenile development but unaffected adult life history traits.

BACKGROUND: Larvicides are critical for the control of mosquito-borne diseases. However, even sublethal exposure to a larvicide can alter development and life history traits, which can then affect population density and disease transmission dynamics. Photosensitive insecticides (PSIs) are a promising class of larvicide that are toxic when ingested and activated by light. We investigated whether the time of day when exposure occurs, or the process of pupation, affects larval susceptibility to PSI phototoxicity in the mosquito Anopheles gambiae, and whether sublethal exposure to PSIs alters life history traits. METHODS: Larvae were treated with lethal concentrations of the PSIs methylene blue (MB) and rose bengal (RB), and larval survival was measured at various times of day. Additionally, larvae were exposed to two concentrations of each PSI that resulted in low and medium mortality, and the life history traits of the surviving larvae were measured. RESULTS: Pupation, which predominantly occurs in the evening, protected larvae from PSI toxicity, but the toxicity of PSIs against larvae that had yet to pupate was unaffected by time of day. Larval exposure to a sublethal concentration of MB, but not RB, shortened the time to pupation. However, larval exposure to a sublethal concentration of RB, but not MB, increased pupal mortality. Neither PSI had a meaningful effect on the time to eclosion, adult longevity, or adult melanization potential. CONCLUSIONS: PSIs are lethal larvicides. Sublethal PSI exposure alters mosquito development, but does not affect adult life history traits.

Nanoliposomal Trachyspermum ammi (L) sprague essential oil for effective control of malaria mosquito larvae, Anopheles stephensi Liston.

Controlling mosquito vectors at immature stages using larvicides is a practical strategy to stave off mosquito-borne diseases such as malaria. Developing nanoliposomes bearing essential oil is a promising approach to improving the efficacy and stability of EOs-derived larvicides. The main aim of this investigation was to assess the efficacy of nanoliposome containing Trachyspermum ammi L. EO (TAEO-NL) as a new potential formulation to control Anopheles stephensi Liston (Diptera, Culicidae) mosquito larvae. The chemical constituents of T. ammi L. essential oil (TAEO) were first investigated using gas chromatography-mass spectrometry (GC-MS) analysis; its dominant component (48.22%) was thymol. TAEO-NL with a particle size of 54.6 ± 5 nm and zeta potential of -18 ± 0.5 mV were then prepared using the ethanol injection method. Besides, the successful loading of TAEO was confirmed using Attenuated Total Reflection-Fourier Transform Infra-Red (ATR-FTIR) spectroscopy analysis. A significant difference (P < 0.05) was observed in the efficacy of TAEO-NL and TAEO with lethal concentration 50% (LC50) values of 14.09 and 59.47 µg/mL against An. stephensi larvae. However, free nanoliposomes show negligible larvicidal effects (<5%). This nano-formulation could thus be suggested as a green product against insects to impede transmission of deadly infectious diseases with possible field applicability scope.

Outlook on RNAi-Based Strategies for Controlling Culicoides Biting Midges.

Culicoides are small biting midges with the capacity to transmit important livestock pathogens around much of the world, and their impacts on animal welfare are likely to expand. Hemorrhagic diseases resulting from Culicoides-vectored viruses, for example, can lead to millions of dollars in economic damages for producers. Chemical insecticides can reduce Culicoides abundance but may not suppress population numbers enough to prevent pathogen transmission. These insecticides can also cause negative effects on non-target organisms and ecosystems. RNA interference (RNAi) is a cellular regulatory mechanism that degrades mRNA and suppresses gene expression. Studies have examined the utility of this mechanism for insect pest control, and with it, have described the hurdles towards producing, optimizing, and applying these RNAi-based products. These methods hold promise for being highly specific and environmentally benign when compared to chemical insecticides and are more transient than engineering transgenic insects. Given the lack of available control options for Culicoides, RNAi-based products could be an option to treat large areas with minimal environmental impact. In this study, we describe the state of current Culicoides control methods, successes and hurdles towards using RNAi for pest control, and the necessary research required to bring an RNAi-based control method to fruition for Culicoides midges.

Susceptibility status of Aedes aegypti (Diptera: Culicidae) against insecticides of public health use in Delhi and NCR region, India.

BACKGROUND & OBJECTIVES: Aedes (Stegomyia) aegypti is a primary vector responsible for the transmission of various arboviral diseases in India. Without an effective drug or vaccine against these diseases, chemical insecticide-based vector control supplemented with source reduction remains the best option for their effective management. The development of insecticide resistance due to the continuous use of insecticides might affect the control operations. METHODS: Adults and larvae of Aedes aegypti were collected from different localities in Delhi. Larvae were exposed to discriminating (0.02mg/l) and application (1mg/l) doses of temephos. WHO tube assay was conducted for F1 adults using impregnated insecticide papers of dichlorodiphenyltrichloroethane (DDT), malathion, deltamethrin, permethrin, cyfluthrin, and lambda-cyhalothrin. RESULTS: Larvae of Ae. aegypti were found resistant (76.0%) to the discriminating dose of temephos, whereas suscep-tible (100.0%) to the application dose of the temephos. Adult Aedes (Fl) mosquitoes were resistant to DDT (23.7%), malathion (90.5%), deltamethrin (76.0%), permethrin (96.2 %) cyfluthrin (85.5%), and lambda-cyhalothrin (94.0%). INTERPRETATION & CONCLUSION: Indoor residual spray is not used in Delhi for vector control. Resistance in Aedes might be due to pesticide usage for agricultural activities in peripheral regions of Delhi. There is a need to investigate more on the insecticide resistance mechanisms for indirect resistance development. Understanding the insecticide susceptibility status of urban vectors is critical for planning effective control strategies.

Octadecadienoate derivatives from Michelia champaca seed extract as potential larvicide and pupicide against Dengue vector Aedes albopictus.

The present study was designed aiming at finding novel botanicals for controlling the vector population. Objective was to evaluate the larvicidal and pupicidal efficacies of crude and solvent extracts of Michelia champaca seed against the notorious dengue vector Aedes albopictus. 0.5% concentration of the crude extractive and 40 ppm concentration of ethyl acetate extractive were enough to execute 100% of larval mortality of all the instars after 72 h of exposure and the LC50 and LC90values (95% confidence level) of ethyl acetate extractive were 0.9880 ppm and 36.0491 ppm. In case of pupicidal bioassay, 100% mortality was observed at 200 ppm of ethyl acetate extract. Through TLC techniques, the bioactive compounds were isolated, which caused remarkable larval toxicity at 15 ppm concentration. Three-way factorial ANOVA analysis showed different concentrations, time intervals, and instars revealed a significant difference in larval death. FT-IR analysis revealed the presence several important functional groups. Presence of methyl 5,12-octadecadienoate and ethyl 9cis,11trans-octadecadienoate were ascertained by GC-MS analysis. The said bioactive compounds showed very low toxicity in non-target organisms such as damselfly (Ischnura sp.) and water bug (Diplonychus sp.) Thus, proclaiming the potentialities of Michelia champaca seed extracts as larvicidal and pupicidal agents against Ae. albopictus.

Cellulose microcrystalline: A promising ecofriendly approach to control Culex quinquefasciatus larvae.

The growing use of synthetic chemical compounds/substances in vector control of mosquitoes, associated with their adverse effects on the environment and non-target organisms, has demanded the development of eco-friendly alternatives. In this context, this study aimed to evaluate the larvicidal action of different cellulose microcrystalline (CMs) concentrations and investigate their toxicity mechanisms in Culex quinquefasciatus fourth instar larvae as a model species. Probit analysis revealed that the median lethal concentrations (LC50) for 24 h and 36 h exposure were 100 and 58.29 mg/L, respectively. We also showed that such concentrations induced a redox imbalance in the larvae, marked by an increase in the production of reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS), as well as a reduction in the activity of superoxide dismutase (SOD) and catalase (CAT). Furthermore, different alterations in the external morphology of the larvae were associated with the ingestion of CMs. On the other hand, exposure of adult zebrafish (Danio rerio) to LC5024h and LC5036h for seven days did not induce any behavioral changes or alterations mutagenic, genotoxic, biochemical, or in the production of cytokines IFN-γ and IL-10. Thus, taken together, our study demonstrates for the first time that the use of CMs can constitute a promising strategy in the control of C. quinquefasciatus larvae, combining insecticidal efficiency with an "eco-friendly" approach in the fight against an important mosquito vector of several human diseases.

Nanoemulsions and Solid Microparticles Containing Pentyl Cinnamate to Control Aedes aegypti.

The Aedes aegypti mosquito is a vector of severe diseases with high morbidity and mortality rates. The most commonly used industrial larvicides have considerable toxicity for non-target organisms. This study aimed to develop and evaluate liquid and solid carrier systems to use pentyl cinnamate (PC), derived from natural sources, to control Ae. aegypti larvae. The liquid systems consisting of nanoemulsions with different lecithins systems were obtained and evaluated for stability over 30 days. Microparticles (MPs) were obtained by the spray drying of the nanoemulsions using maltodextrin as an adjuvant. Thermal, NMR and FTIR analysis indicated the presence of PC in microparticles. Indeed, the best nanoemulsion system was also the most stable and generated the highest MP yield. The PC larvicidal activity was increased in the PC nanoemulsion system. Therefore, it was possible to develop, characterize and obtain PC carrier systems active against Ae. aegypti larvae.

Larvicidal constituents from Poncirus trifoliata root extracts.

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

Spent Coffee Grounds and Novaluron Are Toxic to Aedes aegypti (Diptera: Culicidae) Larvae.

Aedes aegypti (Diptera: Culicidae) is a vector for mosquito-borne diseases worldwide. Insecticide resistance is a major concern in controlling this mosquito. We investigated the chemical compounds in wet and dry spent coffee grounds (wSCGs and dSCGs) and evaluated the efficacy of dSCGs, wSCGs, and novaluron on the mortality and adult emergence inhibition of Ae. aegypti. We found higher concentrations of chemical compounds in wSCGs than in dSCGs. The wSCGs and dSCGs both contained total phenolic compounds, total flavonoid compounds, caffeic acid, coumaric acid, protocatechuic acid, and vanillic acid. Complete mortality was observed after 48 h of exposure to 50 g/L wSCGs, while similar mortality was found after 120 h of exposure to 10 µg/L of novaluron. The sublethal dose was a concentration of wSCGs (5 g/L) and novaluron (0.01, 0.1, and 1 µg/L) combined that resulted in a larval mortality lower than twenty percent (at 72 h) to determine their synergistic effects. The death rate of larvae exposed in sublethal combination of wSCGs and novaluron was significantly higher than that of its stand-alone. The findings indicate that the combination of wSCGs and novaluron at sublethal concentrations had synergistic effects on the mortality of Ae. aegypti larvae and could be applied as an alternative control measure.