Compositions and Methods for Attracting Mosquitoes and Repelling Sand Flies

Abstract

Compositions and methods for affecting dipteran hematophagous parasites. The compositions contain at least one dipteran semiochemical and at least one phagostimulant. The compositions may further include a pesticide. The semiochemical may be a floral attractant and the phagostimulants may be sugar-based. The compositions may be useful in attracting mosquitoes and/or repelling sand flies.

Claims

1. A composition for attracting mosquitos and repelling sand flies, the composition comprising at least one dipteran floral attractant semiochemical.

2. The composition of claim 1, further comprising a phagostimulant.

3. The composition of claim 1, further comprising a pesticide.

4. The composition of claim 1 comprising: TABLE-US-00005 linalool 5%-25% by weight; phenylacetaldehyde 5%-45% by weight; β-myrcene 0%-50% by weight; anethole 5%-45% by weight; anisic acid methyl ester 0%-25% by weight; phenethyl alcohol 1%-35% by weight; caryophyllene 2%-20% by weight; 4-methoxybenzyl alcohol 1%-25% by weight; methyl salicylate 0.1%-20% by weight; γ-terpinene 1%-45% by weight; α-terpinene 1%-45% by weight; limonene 5%-30% by weight; and BHT 1%-25% by weight.

5. The composition of claim 4 further comprising: TABLE-US-00006 eugenol or clove oil 0.001%-50% by weight; and guava oil or guava juice or guava extract 0.001%-50% by weight.

6. The composition of claim 1 comprising: TABLE-US-00007 linalool 5%-25% by weight; phenylacetaldehyde 5%-45% by weight; p-myrcene 0%-50% by weight; citronella oil 5%-45% by weight; eucalyptol 5%-25% by weight; geraniol 10%-20% by weight; camphene 5%-30% by weight; ocimene 1%-45% by weight; anethole 5%-45% by weight; ani sic acid methyl ester 0%-25% by weight; phenethyl alcohol 1%-35% by weight; caryophyllene 2%-20% by weight; 4-methoxybenzyl alcohol 1%-15% by weight; methyl salicylate 0.1%-20% by weight; γ-terpinene 1%-45% by weight; α-terpinene 1%-45% by weight; limonene 5%-30% by weight; BHT 1%-25% by weight; dipentene 1%-15% by weight; sugars 5%-60% by weight; thickeners 0.5%-5% by weight; preservatives 0%-2% by weight; antioxidants 0.1%-15% by weight; sunlight stabilizer 0.1%-10% by weight; wax 2%-40% by weight; emulsifier 0.5%-5% by weight; soybean oil 1%-40% by weight; and liquid carrier 1%-70% by weight.

7. The composition of claim 6 further comprising: TABLE-US-00008 eugenol or clove oil 0.001%-50% by weight; and guava oil or guava juice or guava extract 0.001%-50% by weight.

8. The composition of claim 1, wherein the semiochemical is contained within a substrate selected from the group consisting of a wax emulsion, microspheres, a latex solution, hot melt glue, a resin, and plastic flakes.

9. A composition for attracting, repelling, and/or disrupting the mating of dipteran hematophagous parasites comprising: at least one dipteran semiochemical; and at least one phagostimulant.

10. The composition of claim 9, wherein the semiochemical is a floral attractant.

11. The composition of claim 9, wherein the phagostimulant is sugar-based.

12. The composition of claim 9, wherein the semiochemical is a mosquito attractant.

13. The composition of claim 9, wherein the semiochemical is a sand fly repellant.

14. The composition of claim 9, wherein the semiochemical and phagostimulant are contained within a substrate selected from the group consisting of a wax emulsion, microspheres, a latex solution, hot melt glue, a resin, and plastic flakes.

15. The composition of claim 9 further comprising a pesticide.

16. A method of attracting mosquitoes and repelling sand flies comprising: administering a composition to a region known or suspected to contain dipteran hematophagous parasites, the composition comprising at least one dipteran floral attractant semiochemical that attracts mosquitoes and repels sand flies.

17. The method of claim 16, further comprising the step of monitoring the population of dipteran hematophagous parasites.

18. The method of claim 16, wherein the composition further comprises a pesticide.

19. The method of claim 16, wherein the composition does not negatively impact honey bee populations.

20. The method of claim 16, wherein the composition is administered in a form selected from the group consisting of a sprayable form, a monolithic lure, and a sticky trap adhesive.

Description

DETAILED DESCRIPTION

[0029] The detailed description set forth below is intended as a description of the presently preferred embodiment of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the functions and sequences of steps for constructing and operating the invention. It is to be understood, however, that the same or equivalent functions and sequences may be accomplished by different embodiments and that they are also intended to be encompassed within the scope of the invention.

[0030] The compositions described in the present disclosure, coined Vectrax, are long-term slow release formulations that protect all incorporated active ingredients (the potent attractants, phagostimulants and insecticides) from rain, decomposition and degradation. The dipteran pest control applications for which this formulation may be implemented are many and varied. By incorporating active ingredients (AIs) in such a controlled release matrix, the effectiveness and longevity of these AIs in the field can be significantly improved, to such an extent that a single application can provide weeks to months of protection against the target dipterans. As a result of this extended longevity and field hardiness, Vectrax can be deployed as a preventative measure, ahead of outbreaks of mosquitoes and other target biting dipterans. As a flowable, thick liquid formulation, this product is amenable to mechanical application through standard, readily available spray equipment, but it effectively anchors to the substrate to which it is applied, so that it doesn't dislodge during rain. Once the formulation has solidified, it protects the AIs continuously, so that it sustains consistent and effective AI release over an extended period of time, ensuring full strength attraction, phagostimulation and/or insecticidal effects, depending on the blend of components incorporated.

[0031] As floral- and sugar-based bait for mosquitoes, of both vector and nuisance species, so powerfully attractive to mosquitoes that it out-competes natural plant odors and attractants, Vectrax may be applied alone, to substantially improve monitoring efforts for vector mosquitoes of both established and emerging mosquito-borne pathogens in the U.S., by providing a lure that is as attractive or more so than current CO.sup.2-baited traps at only a very small fraction of the cost. For example, one trial showed that within a single hour, a single passive trap, baited with a small quantity of variant of the Vectrax lure, captured virtually every mosquito released in test rooms (featureless 5×4×3 m test rooms, temperature controlled at 27±3° C., humidity at 85±7%, lights off). An average of 98±1% (10 replicates) of 500 nulliparous Aedes aegypti females were captured within this interval. This result was achieved with the use of a very simple, inexpensive, passive glue trap design: a PVC tube (10.2 cm diameter, 30.5 cm tall) treated with a pressure sensitive glue to capture mosquitoes upon first contact of their tarsi, and thus preserve captured specimens for further identification and analysis. The enhanced monitoring capacity that could be achieved through the application of such a simple trap-lure system could help not only to improve strategic timing and location of mosquito control efforts (i.e., identification of key mosquito reproductive sites and targeting of high populations by insecticide sprays), but also to improve surveillance of mosquito-borne illnesses, both those already established in U.S. populations, such as WNV, and those threatening to invade from foreign regions, like the recent detections of Chikungunya and Dengue fever in the southern states.

[0032] Vectrax could also be blended with small quantities of insecticide to create an attract and kill (A&K) formulation that could be applied in strategic locations to draw mosquitoes away from potential hosts, both human and animal, and kill them before they have a chance to bite. Since Vectrax is designed to function primarily with insecticides that work by ingestion (requiring the target insects to actually consume the formulation in order to be effective), the formulation also contains extremely powerful sugar- and protein-based phagostimulants (feeding stimulants), which have been shown to induce target mosquitoes to feed continuously on Vectrax until fully engorged, even when the formulation contains lethal doses of insecticide. In large semi-field trials conducted in the large mesocosms at Ohio State University, a single 100 mL point source of Vectrax, impregnated with 2% permethrin (by weight of emulsion), applied to a single leaf within the mesocosm, successfully attracted and killed roughly half of the 500 virgin two-day-old female Anopheles gambiae mosquitoes released the first night after their release, despite the presence of many other plants known to be attractive to sugar-seeking mosquitoes. The remaining half of the released mosquitoes were killed during the second night, eliminating virtually every mosquito in the treated mesocosms within 48 hours. In contrast, more than 90% of the mosquitoes released in the control mesocosms remained alive at the end of the second day following their release.

[0033] In addition to this exceptional level of efficacy, careful design of the attractant and phagostimulant AIs, as well the various components of the controlled release emulsion, has resulted in a product that can be tank mixed with a broad range of registered pesticides, ensuring that Vectrax will be adoptable in virtually any location, regardless of what toxicants are most effective against a given species in a given environment or situation. This adaptability also presents a considerable advantage in terms of long-term applicability: because Vectrax can function effectively as an A&K system with so many different types of insecticides, it is nearly invulnerable to the development of resistance in the target insects. It is also a more sustainable method for the control of dipteran pests than traditional insecticide cover sprays. Vectrax is composed entirely of organic ingredients, for maximum safety to humans and the environment, even when toxicants are incorporated. By selecting only reduced-risk insecticides, those that work as stomach poisons rather than simply by contact, chances are lessened that non-target species will be harmed: only insects that are attracted to the Vectrax point source and actually feed upon the material will suffer negative effects. Of particular importance and value is Vectrax's lack of negative effects on honey bee (Apis mellifera) populations, especially given the severe and still largely unexplained decline in honey bee populations around the world. Vectrax is surprisingly repellent to honey bees and other Hymenoptera. Preliminary studies showed that honey bees completely avoided the floral attractant when it was placed in their foraging zones: during 5-minute observations of feeding stations containing 20% sugar solution, an average of 33±5.8 bee visitations was observed. There were no visitations to feeding stations containing the same 20% sugar solution spiked with 0.01% of our floral attractant. Finally, Vectrax will be designed to reduce the exposure of the pesticide in the environment by retaining, protecting and slowly releasing the AI from discreet Vectrax point sources (instead of the blanket cover sprays used for conventional insecticides). These point sources become beacons for the target species, and are easily avoidable by non-targets. Alternatively, larger quantities of Vectrax can be deposited in bait stations, which would be particularly useful in areas of high pest population density.

[0034] Vectrax can also be deployed as a vehicle for the controlled release of repellent plant volatiles, to manage sand fly populations. Although originally evaluated as a sand fly attractant, as it was for mosquitoes, ISCA Technology scientists discovered a number of volatile plant-derived compounds that have demonstrated an extremely high degree of repellency against both New and Old World sand flies, using only miniscule AI quantities, and in lab tests it has been observed to exert a “halo effect” of repellency not seen in topically applied products. In a series of dual-choice bioassays, in which two leishmaniasis vectors, Lutzomyia longipalpis and Phlebotomus dubosqui, were given a choice between a chamber treated with a variant of Vectrax and a control chamber, both species overwhelmingly chose the control (95% L. longipalpis; 100% P. dubosqui), demonstrating strong repellency. In comparison, the same experiment conducted with N, N-diethyl-meta-toluamide (DEET), considered the gold standard in insect repellents, demonstrated weaker repellency to P. dubosqui than Vectrax—only 79% flies selected the untreated over the treated chamber, despite a higher application rate (1,200 mg DEET vs. 1 mg Vectrax). This plant-based repellent formulation could reduce sand fly populations in a number of ways. Female sand flies repelled from host environments by Vectrax will be less likely to obtain a blood meal, reducing egg production, while lek formation by males, which typically occurs near hosts, will also be impeded by the presence of a repellent. Both of these interventions will lead to a decrease in reproductive success within the treated area, and over time, a reduction in sand fly population size. The volatile nature of this blend suggests that when incorporated into a controlled-release formulation, it will act over greater distances than current repellent formulations (e.g. DEET)—and is therefore capable of protecting an entire area from sand flies, rather than a single individual—and will remain active for longer periods.

[0035] Vectrax formulations belong to a “matrix-type” or “monolithic” category of controlled-release devices. These monolithic dispensers are defined as devices where the active ingredient (AI) is dispersed or dissolved in a polymer matrix. Release of the AI from a monolithic device occurs by diffusion and can be described macroscopically by Fick's Law, which states that the movement of a molecule by diffusion is directly proportional to the concentration of that molecule in a system. Microscopically, if one follows the movement of a molecule of an active agent through a matrix, this molecule begins its journey in one of two ways. If it is dispersed in the matrix, it begins its journey by dissociating from other molecules in its crystal cell and solubilizing into the polymer phase. If it is dissolved in the matrix, then this step is bypassed. The molecule then diffuses through amorphous regions in the matrix that comprise the free volume of the system. The molecule can move through the matrix in one of two ways. If it is very small compared to the size of the amorphous spaces in the matrix, then it will diffuse through the matrix by moving from one such space to another. If it is very large compared to the size of those spaces, then segments of the polymer comprising the matrix will have to be rearranged for diffusion of the active agent molecule to occur. Crystalline regions in the matrix are virtually impermeable to molecules of the active agent. Upon reaching the surface of the matrix, it will be released into the environment. A series of factors influence the rate of release of an active agent from a monolithic device and include properties of the matrix material as well as properties of the active agent. The temperature of the matrix influences release of the active agent; at higher temperatures the free volume is increased, and diffusion occurs faster. At lower temperatures, the free volume is decreased, and diffusion is slower. The thermal history of a polymer can also increase or decrease the free volume of the system and lead to changes in the diffusional rate of an active agent. The property of the AI having the greatest influence on its release rate is its molecular weight. Generally, larger molecules take more time to make their way through the free space of a matrix. The partition coefficient of the active agent between the matrix and the environment can also influence the release rate of that agent. If the agent readily partitions to the environment, then its rate of release will be diffusion-controlled and first order. If, however, partitioning of the active agent to the environment is relatively slow, then its partition coefficient will determine its release rate from the matrix, and the device will exhibit zero-order release kinetics. The partitioning of the AI to the environment is a function of its solubility in the matrix; compounds more soluble in the matrix partition to the environment more slowly. Vectrax emulsions in a field environment exhibit diffusion-controlled release. The surface area of the device also influences its release rate. Vectrax dispensers with larger surface areas release AIs at faster rates. The release rate of a Vectrax formulation containing a fixed amount of semiochemical can be modulated simply by changing a few parameters of the formulation, which include the type of components used (e.g., wax composition, emulsifiers), their proportion in the formulation (e.g., percentage of water, oil or wax), the stage in manufacturing when different components are added, rheology, and finally, the characteristics of the dispenser upon application in the field (e.g., applied as microdollops of 1-10 μg each or larger dollops of 1-5 g each).

[0036] Application methods for the invention:

[0037] Vectrax for mosquitoes.

[0038] Vectrax can be deployed to manage nuisance and vector mosquito populations in outdoor environments in three ways: 1) for monitoring purposes, when applied as a lure in virtually any form of trap; 2) in self-contained bait stations, either as an attractant alone, to draw the insects away from important or vulnerable areas, or in combination with an insecticide to attract and kill them, permanently removing them from the environment; and 3) as a sprayable A&K formulation that can be applied manually or through a wide variety of mechanized equipment, directly to foliage within the mosquitoes' habitat. Though this formulation highly flexible in terms of application rate and method, a guideline application procedure for each method described above is included below.

[0039] Monitoring. Vectrax (attractant only) may be applied as a lure either by itself, or as a complement to any other type of attractant, including CO.sub.2, in virtually any type of trap. To use the formulation in this way, a small quantity of Vectrax, shaken or stirred to ensure that all incorporated AIs are in suspension, is deposited onto a stable substrate, such as a cotton ball or a segment of cotton gauze, and then secured within the trap, typically through the application of some form of adhesive. The applied point source may range in size from a few μg to 10s of grams in size, depending on a) the concentration/dilution of the attractant, and b) how long the attractant is desired to maintain its activity in the field. Alternatively, a quantity of the Vectrax attractant could be blended directly into the adhesive itself, before being applied within the trap. Blending may be accomplished through a wide variety of manual or mechanized mixing equipment. Vectrax-baited traps may be deployed at single locations, in order to lure mosquitoes away from sensitive areas (i.e., rural residences, backyards, recreational activity sites) and remove them from the environment by trapping them, or as part of a mosquito management strategy, placed at whatever locations and whatever density is thought to be required to effectively suppress mosquito populations.

[0040] Vectrax Bait Stations. To apply Vectrax within bait stations, the formulation—again, previously shaken or stirred—is loaded into a reservoir that provides the target insects with easy access to the attractant material, similar to a hummingbird feeder. The attractant formulation may be applied by itself or blended with a small quantity of an appropriate insecticide (the insecticide cyazypyr has proven quite effective in laboratory and mesocosm trials). In order to maintain maximum A&K efficiency, the toxicant component should be blended into the Vectrax attractant formulation as close to the time of application as possible. The attractant or A&K formulation may be loaded into the bait station in amounts ranging from a few grams to several liters, depending on the desired field life. If desired, a sponge or other absorbent material may be applied with the formulation, to facilitate landing by the mosquitoes. As with Vectrax-baited traps, Vectrax bait stations may be deployed singly, as a means to divert or attract and kill mosquitoes in sensitive environments (i.e., rural residences, backyards, recreational activity sites), or as part of a mosquito management strategy, placed at whatever locations and whatever density is thought to be required.

[0041] Sprayable A&K As with a Vectrax A&K formulation deployed in bait stations, a formulation intended to be applied directly to foliage as a liquid material should be blended with its toxicant component immediately prior to its application. Once the formulation is thoroughly blended, it may be applied by hand, using simple tools such as knives, spatulas, brushes, or syringes; or mechanically, using anything from a backpack sprayer to a tractor or aerial spray equipment. The rate and quantity at which the formulation should be applied will depend on the needs of the specific pest management situation, such as the desired field longevity (larger point sources will maintain their activity for a longer period than smaller point sources) and the density of the pest population at the site, but for many studies examining Vectrax as an A&K product, an application rate of 1 liter per hectare has proven adequate. Vectrax for sand flies.

[0042] To apply Vectrax as a spatial and contact repellent for New or Old World sandflies, the formulation may be applied in an identical manner as for bait stations for mosquitoes or sprayable liquid formulation (see above) though in this case, these measures will serve the opposite purpose of repelling the target pest away from treated sites, rather than drawing the insects to them for removal or monitoring. Because of this dual activity, in areas treated with the Vectrax sand fly repellent where mosquitoes are also present, a small amount of insecticide active against biting Diptera can be blended with the formulation prior to application. Once the formulation has been properly blended, it may be applied near sensitive sites, such as the outdoor area surrounding a home, outdoor worksites known to be heavily infested with sand flies, or key sand fly reproductive sites. When deploying the repellent in a self-contained repellent station, the amount of formulation to be applied may range from a few grams to several liters, as with mosquito bait stations, depending on the desired field longevity. When applying as a spray over larger areas, application rates/quantities are similarly flexible, but an application rate of 1 kg per acre has proven effective in most previous tests.

[0043] Experimental Results containing insecticide:

[0044] Materials:

[0045] Two formulations 250 mls each were prepared: i) Control formulation containing blank vectrax, and ii) Treatment formulation containing vectrax+insecticide (permethrin). Cotton wool. Thatching materials (bamboo leaves). Plastic sheet.

[0046] Procedure:

[0047] One hour before the release of mosquitoes, i) a plastic sheet was laid on the roof of each respective control and treatment Hut, ii) Thatching materials were fixed on top of the plastic sheet for both huts in control and treatment spheres (the plastic sheet was to prevent contaminations of original thatching materials of the huts), and iii) Then cotton wool soaked in the blank vectrax for control sphere and vectrax+insecticide for the treatment sphere were placed on paper cups turned upside down to six stations of this kind in both spheres

[0048] Mosquitoes release:

[0049] At 10 AM on the day of release, 1 to 2 days old female An.gambiae ss were separated at equal numbers in the cages and starved until the time of release (1 to 2 days old because at that age sugar is the preferred meal). At eight hours of starvation, the mosquitoes were released in both spheres at an equal number. The release was made by placing the cage at one corner of the sphere and providing a small exit from the cage (approximately 15 cm). Then mosquitoes were left in hut for 24 hrs so that they could acclimatize with the Vectrax control or Treatment Vectrax. After 24 hrs, a human subject went in the respective nets in huts and counted the number of mosquitoes coming to bite. The recapturing went on for three days following the release. Scores were then recorded and totaled.

[0050] The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein, including the use of various semiochemicals and pesticides to achieve the same intended effect. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.