Mosquitoes transmit a diverse range of pathogens6–10, and thus, an improved understanding of mosquito physiology and the development of novel control strategies are critically important. AL has afforded us new insights into mosquito larval respiration. The application of AL resulted in the expulsion of gas bubbles that originated from within the tracheal system. When the impinging acoustic frequency is equal to the resonant frequency of the gas within the tracheal system, that gas maximally absorbs acoustic energy and begins to pulsate in synchrony with the impinging frequency. As energy continues to be applied, the amplitude of the pulsation increases to the point of rupturing the DTTs. By adjusting the amplitude and pulse length of our acoustic signal, we observed the earliest manifestations resulting from AL, the severing of the DTTs, with minimal collateral tissue trauma.
This novel technique allowed us to reveal several new aspects of the larval tracheal system. Our study has five major outcomes. First, we improved our understanding of the mosquito tracheal system, including the possible isolation of the tracheal system from the atmosphere. Second, we presented a potential mechanism for the maintenance of pressure during impingement, which damages the DTTs (as opposed to gas venting through the siphon). Third, we provided new insights into the morphology of the siphon (the identification of the TO). Fourth, we confirmed that the damage-inducing mechanism of action of AL is the acoustic resonance of the gas within the tracheal system. Finally, we observed that the siphon does not play an obligate role in respiration for the following reasons: The TO appears to isolate and maintain the tracheal system at an elevated pressure thus making it at best an inefficient port for the two-way exchange of metabolic gasses. Larvae with completely blocked spiracles or severed DTTs continued to live for long periods of time. After acoustic exposure we did not observe any hemolymph (liquid, solids or gasses) pass by the TO as would have been expected if the siphon was open to the atmosphere.
Margaret L. Keister reported “… a survey of the literature (see Wigglesworth,’31) shows that there are numerous gaps and contradictions in our knowledge of insect tracheal systems”11. Our anatomical findings complement a recent revival of interest in mosquito respiratory physiology. However, some conflicts still exist12–16. Accordingly, it is important to define some terms used herein. The “FC” is identified by Keilin, Tate and Vincent as the terminal chamber between the spiracles and DTT17. An appreciation of the physiology of the DTTs is important in analyzing gas volumes. Regarding “active DTTs”, during the development of a given instar between molts, the DTTs are comprised of a chitinous partially gas-filled trunk; the active DTTs are enclosed in the large and fluid-filled living-tissue trunks of the future-instar DTTs (Supplemental 1a). However, the composition of this fluid is unknown18,19 and needs further investigation. The active DTTs are withdrawn during molting. While resting on the water surface with the five PLs extended, it appeared that mosquito larvae were in an ideal position to freely exchange metabolic gases, intake oxygen and expel carbon dioxide. Our results indicated that there was not an obligate need for this, and beyond the incidental cuticular exchange of gas with the atmosphere in the atrium, the direct exchange of tracheal gases with the atmosphere (breathing) is unlikely.
By comparing various anatomical and physical characteristics before and after acoustic exposure we identified the tracheal system to be at an elevated pressure. Mosquito larvae are nearly neutrally buoyant20. They are composed of solids, liquids and gasses. In order to maintain their buoyant condition, the volume proportions of the gas filled tracheal system to body volume must fall within a precise range. As reported by Ha, this percentage for Anopheles sinensis larvae was.34%16. The results of our observations and calculations using 37 A. aegypti samples was.33%. This is expected as most of the body is liquid therefore only a small percentage of body volume could be gas. We calculated that the mean post acoustic exposure proportion of gas bubbles to body volume is 2.02%.
This represents and expansion of 5.9 times meaning the initial pressure in the tracheal system was high. The mean direct expansion of the gas bubble was 5.0 times that of as original tracheal size. The function of pressurization in the DTT is unknown, and its potential relationship with tracheal filling or emergence should be further studied. A pressurized tracheal system makes the inhalation of oxygen difficult if not impossible. The TO is quite strong because it involves acoustically induced pressure oscillations that exceed the ability of the DTTs to contain them. The dimensions of the TO between surface-resting or submerged larvae do not change, suggesting that the restriction prohibits the exhaust of carbon dioxide.
Mosquitoes transmit a diverse range of pathogens6–10, and thus, an improved understanding of mosquito physiology and the development of novel control strategies are critically important. AL has afforded us new insights into mosquito larval respiration. The application of AL resulted in the expulsion of gas bubbles that originated from within the tracheal system. When the impinging acoustic frequency is equal to the resonant frequency of the gas within the tracheal system, that gas maximally absorbs acoustic energy and begins to pulsate in synchrony with the impinging frequency. As energy continues to be applied, the amplitude of the pulsation increases to the point of rupturing the DTTs. By adjusting the amplitude and pulse length of our acoustic signal, we observed the earliest manifestations resulting from AL, the severing of the DTTs, with minimal collateral tissue trauma. This Figure 4. Tracheal gases blocked from passing through the Tracheal Occlusion (TO). Note the gas (yellow arrow) internal to the DTTs is differentiated from liquid by higher transparency and refraction of light showing spectrum colors. This indicates the TO restricts the movement of gas between the tracheal system and external environment. The PLs are in a partial open condition. Ae. aegypti perispircular lobes (PL), Felt Chamber (FC).
Figure 5. Survival of Ae. aegypti larvae (plotted using Kaplan Meier survival curve) (n = 23) with ruptured DTTs after exposure to sublethal acoustic energy. Some mosquitoes died within 24 hours of acoustic exposure, others survived for an extended period, with visible damage to their DTTs. Note, four treated mosquitoes pupated; these mosquitoes were removed from further observation and are shown on the graph as pupation events. novel technique allowed us to reveal several new aspects of the larval tracheal system. Our study has five major outcomes. First, we improved our understanding of the mosquito tracheal system, including the possible isolation of the tracheal system from the atmosphere. Second, we presented a potential mechanism for the maintenance of pressure during impingement, which damages the DTTs (as opposed to gas venting through the siphon). Third, we provided new insights into the morphology of the siphon (the identification of the TO). Fourth, we confirmed that the damage-inducing mechanism of action of AL is the acoustic resonance of the gas within the tracheal system. Finally, we observed that the siphon does not play an obligate role in respiration for the following reasons:
The TO appears to isolate and maintain the tracheal system at an elevated pressure thus making it at best an inefficient port for the two-way exchange of metabolic gasses. Larvae with completely blocked spiracles or severed DTTs continued to live for long periods of time. After acoustic exposure we did not observe any hemolymph (liquid, solids or gasses) pass by the TO as would have been expected if the siphon was open to the atmosphere.
Margaret L. Keister reported “… a survey of the literature (see Wigglesworth,’31) shows that there are numerous gaps and contradictions in our knowledge of insect tracheal systems”11. Our anatomical findings complement a recent revival of interest in mosquito respiratory physiology. However, some conflicts still exist 12–16.
Accordingly, it is important to define some terms used herein. The “FC” is identified by Keilin, Tate and Vincent as the terminal chamber between the spiracles and DTT17. An appreciation of the physiology of the DTTs is important in analyzing gas volumes. Regarding “active DTTs”, during the development of a given instar between molts, the DTTs are comprised of a chitinous partially gas-filled trunk; the active DTTs are enclosed in the large and fluid-filled living-tissue trunks of the future-instar DTTs (Supplemental 1a). However, the composition of this fluid is unknown18,19 and needs further investigation. The active DTTs are withdrawn during molting. While resting on the water surface with the five PLs extended, it appeared that mosquito larvae were in an ideal position to freely exchange metabolic gases, intake oxygen and expel carbon dioxide. Our results indicated that there was not an obligate need for this, and beyond the incidental cuticular exchange of gas with the atmosphere in the atrium, the direct exchange of tracheal gases with the atmosphere (breathing) is unlikely.
By comparing various anatomical and physical characteristics before and after acoustic exposure we identified the tracheal system to be at an elevated pressure. Mosquito larvae are nearly neutrally buoyant20. They are composed of solids, liquids and gasses. In order to maintain their buoyant condition, the volume proportions of the gas filled tracheal system to body volume must fall within a precise range. As reported by Ha, this percentage for Anopheles sinensis larvae was.34%16. The results of our observations and calculations using 37 A. aegypti samples was.33%. This is expected as most of the body is liquid therefore only a small percentage of body volume could be gas. We calculated that the mean post acoustic exposure proportion of gas bubbles to body volume is 2.02%.
This represents and expansion of 5.9 times meaning the initial pressure in the tracheal system was high. The mean direct expansion of the gas bubble was 5.0 times that of as original tracheal size. The function of pressurization in the DTT is unknown, and its potential relationship with tracheal filling or emergence should be further studied.
A pressurized tracheal system makes the inhalation of oxygen difficult if not impossible. The TO is quite strong because it involves acoustically induced pressure oscillations that exceed the ability of the DTTs to contain them. The dimensions of the TO between surface-resting or submerged larvae do not change, suggesting that the restriction prohibits the exhaust of carbon dioxide. Dissection to sever the siphon anterior to the FCs also rendered AL ineffective, indicating that the TO is a necessary structure for the success of AL.
The condition of total dependence on cuticular (and/or gill- or filament-supported) respiration in immature aquatic insects is common and present in many close relatives of mosquitoes. Culicinae are joined by seven other families in the infraorder Culicomorpha whose immatures all respire in total submergence 21. The consideration that the siphon plays only a vestigial role in respiration is not without precedent. Corethra (also called midge and of the family Chaoboridae) were classified as mosquitoes until the early 1960s22; today, they are considered taxonomically separate but are thought to share a common ancestor 21. Corethra and mosquito larvae share common physiological traits, and many species look very much alike, including the presence of an apparent larval siphon 21–26. Krogh found that larvae of the genus Corethra appeared to respire through only the skin and concluded that this organism fills its air sacks with gas from a non-atmospheric source (i.e., tissues)27. He also noted that the DTTs did not contain air and that the connected bladders appeared to have no respiratory function.
Mochlonyx spp. (also in Chaoboridae) possess a siphon (Supplemental 3) but do not come to the surface to breathe 25,26,28,29; hence, the siphon is clearly not used for the exchange of atmospheric gases in this species. As noted by Förster and Woods, and Keister and Buck, filling of the tracheal system with gasses from an endogenous source has been observed in a variety of organisms 11,18,19.
It has been previously reported that mosquito larvae can survive for long periods of time without access to the atmosphere, indicating that aquatic respiration is possible30–36. For example, Macfie (1917) demonstrated that submerged larvae (isolated from surface air) of certain mosquito species can live for 20 days if the aquatic medium is adequately aerated. Mosquito larvae are found in aquatic environments with variable levels of dissolved oxygen32,37–40 and can survive in water with low levels of dissolved oxygen concentrations (e.g., 0.04 to 1.63 mg/L). However, we propose that previous reports on mosquito survivability in low dissolved oxygen concentrations failed to consider that the dissolved oxygen content at the surface of water is higher from that further down in the water column. Vacha and others noted that the concentration of dissolved oxygen at the air-water interface was enhanced41,42.
Mosquito larvae in a surface-resting posture position their body, especially their ventral fan, in the stratum with the highest oxygen concentration while simultaneously conserving energy. This may be an important behavior in sourcing metabolic oxygen. Therefore, future investigations should focus on the role of the ventral fan in mosquito larval respiration. Our observations may question the commonly accepted mode of action (suffocation) of petroleum surfactants. According to the literature, the most rapid mode of action may be neurological disruption, not suffocation30. Suffocation normally takes a long time, which may be related to reduced surface oxygen concentrations or the direct impairment of cutaneous gas exchange43–49.
Our results show that the tracheal system is isolated and maintained at an elevated pressure, thus making the free exchange of metabolic gases with the environment unlikely. We report a previously undescribed TO that appeared to isolate the tracheal system and enabled acoustic energy to intensify and rupture the DTT. Our findings are not without precedence; as with other family members in the infraorder Culicomorpha, it is common for immatures to totally source metabolic oxygen from and expel waste gases directly into the water. These findings appear to contradict the fundamental understanding of culicine larval respiration. Additional tests and research evaluating gas movements through the environment as well as within the animals needs to be done. With the new physical and physiological information from this study, possibly novel methods to control this deadly insect will be developed. For more details, visit :: https://www.nature.com/articles/s41598-020-59321-8.epdf?author_access_token=roSPkaGfNB2hNzo7c0wja9RgN0jAjWel9jnR3ZoTv0Oc7kL_Bsy4JhlLcTFSFjEI-_Y1rsA1_Dwl4n9QKpc6ND3WdlBOer7Oh_MofP-ZI4lTSkTRO4X17JyHdtuuhr1fTz60lyj_px0cRL8baw3J4g%3D%3D Visit to New Mountain Innovations here:: https://www.newmountain.com/ to know more about the eco-friendly mosquito control products and Sirenix Mosquito Control Trap online. Like Us in Facebook::https://www.facebook.com/New-Mountain-Innovations-143350012763074 The New Mountain Innovation Inc, Address:: 59772 Paradise Place, Marathon, FL 33050
There are many technologies are available to control the Mosquitoes into the household and commercial places, however the LARVASONIC Technology comes with advance technologies and this full line of Larvasonicproduct covers your urban larvicide requirements. With Acoustic Larvicides instantaneous results and single visit concept you can economically conduct surveillance and control simultaneously. Larvasonic systems are flexible and portable for efficiently treating urban habitats including: ditches, ponds, drums, above and below ground cisterns, culverts, wastewater treatment plants, abandoned swimming pools, idle fountains and the like.
GRAND PRAIRIE – The City of Grand Prairie’s Environmental Services Department can now “fight the bite” a little more easily. In July 2013, the city purchased a revolutionary tool, the Larvasonic Field Arm Acoustic Larvicide, or simply the Larvasonic, that allows for the immediate destruction of mosquito larvae. Grand Prairie is the first city in the metroplex to invest in the $6,900 device.
The Larvasonic, the result of a Intel International Science Fair project, is a device that emits sound waves into pools of stagnant water. The sound waves resonate at the frequency of mosquito larvae internal air volume, causing the larvae to burst. As a result, larvae and pupae are either killed or left to morph into flightless – and therefore harmless – mosquitoes.
The city has traditionally treated mosquito breeding grounds with larvicide, but this method is not always 100 percent effective. Larvicides often take two to three days to dissolve and activate in water. As a result, some larvae may hatch before the larvicide begins to take effect. In an attempt to remedy this, the city now complements its use of larvicide with the Larvasonic. After larvicide is applied to stagnant pools and drainage ditches, the Larvasonic is now used to immediately kill any larvae that are on the verge of hatching. By doing this, the city is able to stop more mosquitoes from hatching and taking flight. Further, because the Larvasonic is an alternative to chemical and biological treatments and does not appear to have any unintended consequences, it is an effective solution to the city’s mosquito problem.
The City of Grand Prairie is using maps and aerial photos supplied by its Geographic Information Systems Division to find vacant and unkempt swimming pools and backed-up drainage ditches in which mosquitoes are likely breeding. They then travel to the site, apply a larvicide and send sound waves into the pool with the Larvasonic.
For more information about the Larvasonic, call 972-237-8550. Go to www.gptx.org/FightTheBite to report a stagnant pool or drainage ditch.
The gas volume expelled from the previous test appeared relatively large compared to the volumes of the DTTs, indicating the possibility that the tracheal system was maintained at a higher pressure than the abdomen. Measurements and analysis of physical features and visible gas volumes before and after acoustic treatments of Ae aegypti larvae were conducted (Fig. 2a,b). Exposures and measurements were conducted on thirty-seven (n = 37) specimens see Supplemental Data Files. The percentage of Ae aegypti gas filled tracheal system to body volume (Fig. 2c) had a mean of 0.33%. The percentage volume of Ae aegypti released gas bubbles to body volume (Fig. 2d) had a mean of 2.02%. The gas expansion over Ae aegypti gas filled tracheal system (Fig. 2e) revealed a mean expansion of 4.97 times.
Analysis of pressure in the tracheal system of Ae. aegypti mosquito larvae. (a) Pre-exposed measurements of the larvae body and active DTT (millimeter dimensions in red) diameter and lengths. (b) Post-exposure measurements (millimeter lengths in red) of the length and diameter of the active DTT and the diameters of the expanded gas bubbles. (c) Volume proportions of gas filled tracheal system to body volume. (d) Volume proportion of released gas bubbles to body volume. (e) Gas expansion over gas filled tracheal system. n = 37.
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Acoustic larviciding (AL) occurs by exposing mosquito larvae to acoustic energy that ruptures their dorsal tracheal trunks (DTTs) by the expulsion of gas bubbles into the body. In studying this technique, we serendipitously identified undescribed anatomical and physiological respiratory features. The classical theory of respiration is that the siphon and DTTs play obligate roles in respiration. Our results contradict the accepted theory that culicine larvae respire via atmospheric gas exchange. We identified an undescribed tracheal occlusion (TO) at the posterior extremities the DTTs. The TOs appear necessary for the acoustic rupture of DTTs; this constriction prevents the escape of energized gas from the siphon and allows the tracheal system to be pressurized. With a pressurized isolated tracheal system, metabolic gas exchange directly with the atmosphere is unlikely and could mostly occur through the chitin and setae. Future studies are needed to explore respiration and elucidate the mechanisms of oxygen absorption and carbon dioxide elimination.
Introduction:
Of all the disease-transmitting insects, mosquitoes are the greatest threat, as they transmit pathogens that cause diseases. In 2015, mosquitoes were responsible for 438,000 malaria-related deaths1. An outbreak of West Nile virus, in Queens, New York, in 1999 prompted the development of a new larvicide technique, acoustic larviciding (AL), in addition to traditional chemical larvicides2. While the exact mechanism of action of AL in mosquito larvae is unknown, tissue damage appears to be caused by vibrations that occur when the frequency of acoustic energy is matched to the resonant frequency3 of materials (i.e., water, air, tissue) inside the mosquito larvae, resulting in the vibration of these materials (similar to the shattering of crystal goblets by an opera singer). Exposing mosquito larvae to acoustic energy within a certain frequency band results in the rupture of the walls of the dorsal tracheal trunks (DTTs), causing the expulsion of gas into the body cavity, resulting in mortality, arrested larval development, or flightless adult mosquitoes. The DTTs are two significant tubes running the length of the abdomen acting as a central convergence of the tracheal system. AL, as a physical intervention, is effective against all larval stages with minimal lethality to off-target aquatic organisms4,5. It has been shown that treated larvae show pronounced damage to the DTTs4 suggesting that gas contained within these structures or the tracheal system is resonated by the acoustic vibration. However, the exact mechanism by which this phenomenon occurs is not clear within the framework of our current understanding of mosquito tracheal physiology.
In this study we attempted to elucidate the mechanism of action of AL using a precision research-grade, underwater acoustic transmitter. This device transmits controlled sonic energy to acoustically disrupt (i.e., rupture) the DTTs. This precise application of sound causes only the release of gas from the within the tracheal system into the body cavity while minimizing trauma to surrounding tissue. There is not enough power for this energized gas to rupture the exoskeleton and therefore remains trapped within the body cavity and can be readily measured for analysis. This technique allowed us to sever the tracheal trunks from the inside providing a novel perspective for evaluation.
This new approach revealed unexpected results shedding new light on the respiratory system. Observations from this technique impact the classical theory of mosquito larval respiration. This better understanding may potentially improve future efforts in controlling mosquito populations and the associated diseases they transmit.
Results
Source of released gas into the abdomen
We found that AL treatment causes instantaneous and irreversible trauma to mosquito larvae. Before and after acoustic exposure of Aedes aegyptiand Culex pipiens larvae depicting the impact on internal structures such as the active and future instar DTTs are shown in Fig. 1. Unexposed specimens’ (Fig. 1a) DTTs are intact with the active DTTs internal to the liquid filled future instar DTTs. Observations of acoustically treated larvae (Fig. 1b,c) revealed trauma to the DTTs with outward flares of the active DTTs. The future instar DTTs sustained damage and gas bubbles were observed within the abdomen. We observed this breach to be typically located at the interface of the abdominal segment (the same point where the DTTs separates into segments during molting).
SIRENIXmosquito control system represents over 15 years of researching mosquito larvae physiology and behavior to give you a maintenance free and environmentally friendly method to control mosquitoes. We have joined the revolutionary Larvasonic technology with multiple natural attractants to lure pregnant (gravid) female mosquitoes ready to lay her eggs. Once the eggs are deposited in our system the unique Larvasonicacoustic energy kills the offspring, ending the lifecycle and reducing adult mosquito populations. This high quality Sirenix Mosquito Controlcomes with many advance features that effectively control the mosquito and save from mosquito disease.
Gravid female mosquitoes are naturally searching for the ideal place to lay her eggs. Her primary attractant is water, she can both see and smell the water in the SIRENIX. Many like a shady area such as typically found in abandoned tires, the SIRENIX geometry gives shade spot at all times of daylight. Certain colors and patterns also are attractive, black and white striped design attracts daylight fliers and our BLUE/UV led cycling light attracts by both the wavelength and the illusion of motion.
Once the eggs hatch into larvae they become susceptible to acoustic energy that is emitted into the water by the transducer. This acoustic energy vibrates the gas within the larvae causing it to rupture internal organs and instantly kills larvae. Combined natural attractants with pesticide free acousticlarvicide gives you a truly set-and-forget, effective and environmentally safe method of mosquito control.
The growing demand for green energy becomes more important for the global environment, and everyone is thinking about this green and environment friendly products for all type of business and services. Finding the high quality and eco friendly mosquito control products with new range of technology is growing everywhere. Thus, at New Mountain Innovations, we have developed technology that applies sound waves to water to economically reduce Mosquito populations at the breeding site.
From climate change to good and quality sustainable life, having eco friendly mosquito control products will assist the world to grow with green environment and also help our next generation to live with quality life. There are many eco friendly mosquito control products, and it comes with various features and types. Here at New Mountain Innovations, we develop advance range of mosquito control products with sound technologies and help to get rids from mosquito in your household and commercial places.
The New Mountain weather station instrument is the only all-in-one weather sensor that calculates apparent wind speed and direction, barometric pressure, air temperature, relative humidity, dew point and wind chill temperature. With the optional internal compass and Global Positioning System, true wind speed and direction can also be calculated. The UV stabilized, compact housing is fully waterproof and resistant to chemicals.
The NM 150 Weather Station Instrument comes with our exclusive Weatherview32 Software. Data can be viewed in both digital and analog format and can be saved for a set period of time. Data can be accessed from other computers as well as uploaded to host sites such as weatherunderground.com Standard NMEA sentences and an RS485 interface allows for the flexibility of designing your own software program to fit your specific application. Our comprehensive technical manual makes the job easy!
The New Mountain NM150 weather station Instrument utilizes a standard 1-14” UNS thread connection to accommodate standard mounting hardware. The waterproof base connector assures trouble-free installation and servicing, while a quick disconnect feature allows for easy removal. Standard cable lengths of 25 m connects to our serial interface. An optional USB converter is available.
Explore this high quality Total Ultrasonic Weather Station that comes with many advance features from the New Mountain Innovations, Inc (NMI). At NMI, we brings you a wide range of mosquito control products where mosquitos larvae are killed with acoustic energy.
The SD Mini is small for deployment into storm drains, small ponds, pools, ditches, water drums and the like. The SD Mini omnidirectional transducer can easily slip through standard two inch inch grate or other small openings. With 12 feet of cable and and additional mounting rod, the transducer can be custom mounted to fit any needs. The transducer distributes acoustic energy uniformly in the horizontal plane and has a 60 degree volume of vertical coverage. All mosquito larvae within this torrid are killed instantly.
newmountain 