Insect repellent fixture and method

A fixture (100) for gradually releasing a spatially effective semiochemical, for example a repellant. The fixture includes a slotted tube (140), that may be formed for example, from a porous material, a peripheral tube (102) having a plurality of apertures and disposed outward from the slotted tube, a base (110) that engages the slotted tube and the outer tube, a funnel member (160) that engages a top end of the slotted tube and the peripheral tube, and a cap (130). In an embodiment the base includes a lighting element (150).

BACKGROUND

Repellents provide excellent protection against vector-borne diseases, including malaria, dengue fever, Zika fever, and leishmaniasis. In addition to the well-known topical repellents (e.g., DEET), recent attention has been paid toward the discovery of active spatial repellents. A spatial repellent is a repellent that is effective at a distance from the point of application. The spatial repellent includes an inhibiting compound that, when dispensed into the atmosphere of a three dimensional environmental space, inhibits the ability of mosquitoes to locate and track a target, such as humans or livestock. Many natural essential oils can be effective as spatial repellent against mosquitoes, biting flies, and stinging insects. Without wishing to be bound by theory, it is believed that repellency is positively correlated to the overall release rate of the active spatial repellent compounds. One of the major challenges for insect repellent product development is to design a release device that could maximize the release rates of the active repellent compounds for optimal repellency.

Accordingly, there is a need for release devices that can increase release rates of active repellent compounds. The present disclosure seeks to fulfill these needs and provides related advantages.

SUMMARY

In one aspect, the present disclosure features a spatial repellent fixture including (i) a slotted tube that is configured to adsorb a liquid repellent such that volatiles of the adsorbed liquid repellent are gradually released, wherein the tube includes a plurality of elongate slots; (ii) a peripheral tube having a plurality of apertures therethrough, wherein the peripheral tube is disposed radially outwardly from the slotted tube; (iii) a base that engages a bottom end of the slotted tube and a bottom end of the peripheral tube; and (iv) a cap assembly that engages a top end of the slotted tube and a top end of the peripheral tube.

In another aspect, the present disclosure features a spatial repellent system including a fixture including (i) a slotted tube having a plurality of elongate slots; (ii) a peripheral tube having a plurality of apertures therethrough, wherein the peripheral tube is disposed radially outwardly from the slotted tube; (iii) a base that engages a bottom end of the slotted tube and a bottom end of the peripheral tube; and (iv) a cap assembly that engages a top end of the slotted tube and a top end of the peripheral tube; and a liquid repellent configured to be adsorbed onto the slotted tube such that volatiles of the adsorbed liquid repellent are gradually released from the slotted tube.

In some embodiments, the spatial repellent systems of the present disclosure repel stinging insects, biting insects, or both stinging and biting insects. For example, the spatial repellent system can repel mosquitoes, paper wasps, hornets, yellow jackets, cockroaches, ants, or any combination thereof. As another example, the spatial repellent system can repel mosquitoes, paper wasps, hornets, yellow jackets, or any combination thereof.

DETAILED DESCRIPTION

Disclosed herein are porous plastic-based repellent fixtures that release volatile spatial repellent formulations into the air at a steady and optimal rate to achieve a desired repellency effect. A repellent fixture100in accordance with the present disclosure is shown inFIG. 1. In this embodiment the fixture100comprises an outer tubular member forming a peripheral wall102. The peripheral wall102includes a plurality of large apertures104therethrough that allow and encourage air flow through the fixture100. In the current embodiment the large apertures104provide an aesthetically pleasing decorative appearance to the fixture100.

Refer now also toFIG. 2, which shows an exploded upper-front view of the fixture100and toFIG. 3, which shows an exploded lower-front view of the fixture100. The peripheral wall102includes an open lower end103, with an inner bead or flange103A and an open upper end105with an inwardly threaded portion105A. The lower end103of the peripheral wall102is closed by a base110. The base110has an upper cylindrical portion that includes an annular protrusion111sized to engage the flange103A of the peripheral wall102, and a flange portion112that supports the peripheral wall102. A lower wall portion113extends downwardly from the flange portion112. The upper face of the base110defines a center post114that is sized and configured to slidably receive and support an inner slotted tube140, as described in more detail below.

Optionally, the base110may further comprise a light assembly150. In the current embodiment the light assembly150includes a body portion151that includes a battery compartment152and cover158configured to receive one or more conventional batteries (not shown), and a decorative surrounding wall153. In the current embodiment the surrounding wall153is open upwardly, and is sized and configured to receive the lower wall portion113of the base110. A circuit board154is supported on the body portion151above the battery compartment152and includes a light element155, for example a light emitting diode. A switch156extends through an aperture157in the body portion151, and is operable to permit the user to activate the light element155. If the optional light assembly150is included, preferably the base110, or a selected portion of the base110, is formed from a transparent or translucent material.

The upper end105of the peripheral wall102is closed by a threaded cap130. The threaded cap130in this embodiment includes an upper dome portion131that preferably defines an aperture132to facilitate placement of the repellent fixture100, for example to allow the fixture100to be suspended from a branch, eave, or the like.

An outwardly-extending flange133is sized to abut the upper end105of the peripheral wall102. An annular wall portion134is sized to be threaded onto the upper end105of the peripheral wall102.

Refer now also toFIG. 4A, which shows a funnel member160in cross section, with the slotted tube140partially shown in phantom. The funnel member160has a lower portion that receives an upper end of the slotted tube140and an upper portion that is received into the threaded cap130. The funnel member160includes an outer wall portion161that is sized and configured to engage the annular wall portion134of the cap130(not shown inFIG. 4A), and an inner wall portion162having an angled segment that extends downward from the top end of the outer wall portion161and a second segment that engages the slotted tube140. A sloped upper wall163, preferably a generally conical wall, extends over the inner wall portion162. A plurality of narrow slots between the upper wall163and the cylindrical portion of the inner wall162define ports164in the top of the funnel member160, with sloping walls162and163on either side of the ports164. It will be appreciated that the sloping wall162will funnel liquid material poured onto the top of the funnel member160(for example, a liquid repellent), through the ports164and onto the slotted tube140. In this embodiment the deposited liquid material flows onto an inner surface of the slotted tube140, and as it travels down by gravity portions of the liquid will flow through the slots143onto an outer surface of the slotted tube140.

A second embodiment of a suitable funnel member160′ is shown inFIG. 4B. In this embodiment the funnel member160′ includes an annular portion161′ that is sized to be received into the threaded cap130(not shown) and a plurality of posts162′ that extend down and support a sloped surface163′, preferably a generally conical wall, that is located on top of the slotted tube140. The open areas between the posts162′ define ports164′. It will be appreciated that the sloped surface163′ will funnel liquid material poured onto the top of the funnel member160′ (for example a liquid repellent), through the ports164′ and onto the slotted tube140. In this embodiment the deposited liquid material flows onto an outer surface of the slotted tube140, and as it travels down by gravity portions of the liquid will flow further along the outer surface of the slotted tube140.

The inner slotted tube140in the present embodiment is a right circular tube, sized and configured to slidably engage the center post114in the base110and the cylindrical portion of the inner wall162or the outer wall161in the funnel member160. Therefore, the slotted tube140is positioned within the peripheral wall102by the base110and the funnel member160. In the present embodiment the slotted tube140is coaxially arranged with the peripheral wall102. However, it will be readily apparent to persons of skill in the art that the slotted tube140may be alternatively shaped. For example, the slotted tube may be a non-circular tube, with corresponding changes to the post114and the inner annular wall135. Similarly, the slotted tube140may be configured to be disposed off-center, or at an angle with the peripheral wall102. It is also contemplated that the diameter of the slotted tube140may vary along its length, for example tapering from the top to the bottom, having a maximum diameter near the center, or having multiple bulges along its length.

The slotted tube140in a current embodiment is formed as a porous tube, and may be formed, for example from a porous polypropylene or polyethylene. In a current embodiment the porous material has a pore size of between 10-150 microns, and a thickness between 1-10 mm. The slotted tube140in the current embodiment has a diameter or maximum transverse dimension between 10-300 mm, and a length between 50-400 mm. As discussed below, the porous plastic tube140is loaded with a liquid insect repellent that is configured to evaporate or volatilize over time. The volatilized repellent will escape gradually, forming a plume to provide an extended period of protection from the insect species targeted by the repellent. In one embodiment the slotted tube has a cross-section that is star-shaped cross-section to increase the surface area of the slotted tube, e.g., to achieve a desired volatilization rate for the liquid repellent, as well as to increase the repellent-storage capacity of the slotted tube140. Similarly, it is contemplated that the slotted tube140may be formed with inwardly-extending and/or outwardly-extending fins (not shown).

The slotted tube140includes a plurality of circumferential, generally horizontal slots143therethrough. In the present embodiment the slots143are arranged in eight overlapping columns along the length of the slotted tube140. The slots143aid in preventing or slowing the downward migration of liquid repellent adsorbed into the porous plastic tube140. Therefore, the upper portion of the slotted tube140is less prone to dry out before the lower portion of the slotted tube140. In the current embodiment the slots143are oriented horizontally, approximately perpendicular to the axis of the slotted tube140. In an embodiment the slots143are formed by a process that partially or fully seals the micro-pores in the tube in the edge of the slots143, to aid in preventing downward migration of the repellent.

Of course other shapes and arrangements of the slots are possible and contemplated by the present disclosure. For example, the slots may be formed with a concave upper edge, such that liquid repellent is less likely to flow around the slots. More or fewer columns of slots may be provided. For example, the slots may be arranged in two or more overlapping or staggered columns. In some embodiments, the slots140account for 5% or more (e.g., 10% or more, or 15% or more) and/or 20% or less (e.g., 15% or less, or 10% or less) of the total tube surface area. In the currently preferred embodiment the slots140account for 5% to 20% of the total tube surface area.

The slots143also provide for air flow through the slotted tube140. Therefore volatiles that are released from the inner surface of the tube140will more readily escape to contribute to the formation of the repellent plume. This arrangement will allow the density of volatiles to periodically increase inside the slotted tube140until a breeze urges more of the interior volatiles to escape, producing a desirable wafting effect of increasing plume density.

As noted above, the fixture may include a light assembly150that is configured to direct light through the base110and into the slotted tube140. The light assembly150may improve the aesthetics of the fixture100. In addition, the light element155may generate heat to encourage convective flow within the slotted tube140, to improve the release rate of the volatiles. It is contemplated that the light element155may be replaced by, or supplemented with, a low-power, low-volume fan (not shown) configured to direct air upwardly through the slotted tube.

In use, the slotted tube is loaded with a liquid repellent. The liquid repellent may be loaded onto or into the slotted tube140in a number of different ways. In one embodiment the slotted tube is immersed in a reservoir of liquid repellent for a period of time, optionally in a pressurized enclosure, such that the liquid repellent is urged into the porous plastic substrate. In other embodiments the liquid repellent is sprayed onto, painted onto, or flowed over the slotted tube140, such that it adheres to the surface. In yet another embodiment the slotted tube140is packaged in a leak-resistant packaging that also contains a quantity of liquid repellent, such that the liquid repellent is adsorbed into the substrate over a longer period of time.

In a current embodiment it is contemplated that the slotted tube140is periodically replenished with liquid repellent by removing the cap130and pouring a quantity of liquid repellent onto the funnel member160. The viscous liquid repellent will gradually flow by gravity through the inlets164and along the slotted tube140. The slots143in the slotted tube140will reduce the downward migration effect of the liquid repellent after loading by creating many partially separated disk regions along the length of the tube140. The slots143may also reduce the required repellent loading quantity, and increase the release/loading ratio (by an estimated 30-70%). The slots143will also increase the overall release rate by an estimated 20-50%, depending the number and area of the slots by improving the air-flow through the slotted tube140.

Although the fixture100is disclosed with regard to a spatial repellent functionality, it will be appreciated that it is sometimes desirable to attract insects into a particular area, for example honeybees or other pollinators. The fixture100described above is also effective to provide a spatial attractant, with the use of a suitable semiochemical formulation, as are known in the art.

The liquid repellent that is loaded into the slotted tube can include a combination of essential oils. In some embodiments, the liquid repellent includes (consists essentially of, or consists of) clove oil, lemongrass oil, peppermint oil, cinnamon oil, geranium oil, rosemary oil, and/or citronella oil. For example, a general liquid repellent can include, consists essentially of, or consists of clove oil, lemongrass oil, peppermint oil, and cinnamon oil. In some embodiments, a liquid repellent includes, consists essentially of, or consists of clove oil, lemongrass oil, peppermint oil, and cinnamon oil, and can be used to repel mosquitoes. In some embodiments, a liquid repellent includes, consists essentially of, or consists of clove oil, lemongrass oil, geranium oil, and rosemary oil, and can be used to repel paper wasps, hornets, yellowjackets, and other stinging or biting insects. In certain embodiments, a liquid repellent includes, consists essentially of, or consists of lemongrass oil, peppermint oil, geranium oil, rosemary oil, and citronella oil, and can be used to repel cockroaches or ants.

The liquid repellent can include, consists essentially of, or consists of the essential oils in any proportion. For example, a general liquid insect repellent can include, consists essentially of, or consists of clove oil, lemongrass oil, peppermint oil, and cinnamon oil in a weight ratio of 1:1:0.25:0.1, respectively. In some embodiments, the general insect liquid repellent includes, consists essentially of, or consists of from about 30% (e.g., from about 35%, or from about 40%) to about 50% (e.g., to about 45%, to about 40%, or to about 35%) (e.g., 42.5%) by weight clove oil; from about 30% (e.g., from about 35%, or from about 40%) to about 50% (e.g., to about 45%, to about 40%, or to about 35%) (e.g., 42.5%) by weight by weight lemongrass oil; from about 5% (e.g., from about 8%, from about 10%) to about 15% (e.g., to about 12%, or to about 11%) (e.g., 10.6%) by weight peppermint oil, and/or from about 1% (e.g., from about 3%, or from about 5%) to about 10% (e.g., to about 5%, or to about 3%) (e.g., 4.2%) by weight cinnamon oil, based on the total weight of the essential oil combination, and so long as the total % by weight of the essential oils adds to 100% by weight.

As another example, the clove oil, lemongrass oil, peppermint oil, and cinnamon oil in a liquid repellent that can be used to repel mosquitoes can be present in a ratio of1:1:1:0.1, respectively. In some embodiments, the liquid repellent includes, consists essentially of, or consists of from about 20% (e.g., from about 25%, from about 30%, or from about 35%) to about 40% (e.g., to about 35%, to about 30%, or to about 25%) (e.g., 32.3%) by weight clove oil; from about 20% (e.g., from about 25%, from about 30%, or from about 35%) to about 40% (e.g., to about 35%, to about 30%, or to about 25%) (e.g., 32.3%) by weight lemongrass oil, from about 20% (e.g., from about 25%, from about 30%, or from about 35%) to about 40% (e.g., to about 35%, to about 30%, or to about 25%) (e.g., 32.3%) by weight peppermint oil, and from 2% (e.g., from about 2.5%, from about 3%, or from about 3.5%) to 4% (e.g., to about 3.5%, to about 3%, or to about 2.5%) (e.g., 3%) by weight cinnamon oil, based on the total weight of the essential oil combination, and so long as the total % by weight of the essential oils adds to 100% by weight.

As yet another example, the clove oil, lemongrass oil, geranium oil, and rosemary oil in a wasp, hornet, yellowjacket wasp, and other biting insect liquid repellent can be present in a ratio of 199:199:1:1, respectively. In some embodiments, the liquid repellent includes, consists essentially of, or consists of from about 40% (e.g., from about 45%, from about 50%, or from about 55%) to about 60% (e.g., to about 55%, to about 50%, or to about 45%) (e.g., 49.75%) by weight clove oil; from about 40% (e.g., from about 45%, from about 50%, or from about 55%) to about 60% (e.g., to about 55%, to about 50%, or to about 45%) (e.g., 49.75%) by weight lemongrass oil, from about 0.1% (from about 0.2%, or from about 0.3%) to about 0.4% (e.g., to about 0.3%, or to about 0.2%) (e.g., 0.25%) by weight geranium oil, and from 0.1% (from about 0.2%, or from about 0.3%) to about 0.4% (e.g., to about 0.3%, or to about 0.2%) (e.g., 0.25%) by weight rosemary oil, based on the total weight of the essential oil combination, and so long as the total % by weight of the essential oils adds to 100% by weight.

As yet another example, the lemongrass oil, peppermint oil, geranium oil, rosemary oil, and citronella oil in a cockroach liquid repellent can be present in an amount of 5:3:1:0.5:0.5, respectively. In some embodiments, the liquid repellent includes, consists essentially of, or consists of from about 40% (e.g., from about 45%, from about 50%, or from about 55%) to about 60% (e.g., to about 55%, to about 50%, or to about 45%) (e.g., 50%) by weight lemongrass oil, from about 20% (e.g., from about 25%, from about 30%, or from about 35%) to about 40% (e.g., to about 35%, to about 30%, or to about 25%) (e.g., 30%) by weight peppermint oil, from about 5% (e.g., from about 7%, from about 10%, or from about 12%) to about 15% (e.g., to about 12%, to about 10%, or to about 7%) (e.g., 10%) by weight geranium oil, from about 1% (e.g., from about 3%, from about 5%, or from about 7%) to about 10% (e.g., to about 7%, to about 5%, or to about 3%) (e.g., 5%) by weight rosemary oil, and from about 1% (e.g., from about 3%, from about 5%, or from about 7%) to about 10% (e.g., to about 7%, to about 5%, or to about 3%) (e.g., 5% by weight) citronella oil, based on the total weight of the essential oil combination, and so long as the total % by weight of the essential oils adds to 100% by weight.

The combination of essential oils can be a neat liquid repellent composition, where the liquid repellent composition does not include carriers. In some embodiments, the combination of essential oils can include additional carriers, antioxidants, and/or preservatives.

Exemplary oils to use with liquid repellent include, but are not limited to, oils derived from plants such as vegetable oils and nut oils. These are widely available and cost effective. Formulations can include oils such as canola oil, cottonseed oil, palm oil, safflower oil, soybean oil, corn oil, olive oil, peanut oil, sunflower oil, sesame oil, nut oils, and coconut oils. Nut oils include, but are not limited to, almond oil, cashew oil, hazelnut oil, macadamia oil, mongongo nut oil, pecan oil, pine nut oil, pistachio oil, sacha inchi oil, and walnut oil. Melon and gourd seed oils are very common and inexpensive. The oils listed above include saturated, monounsaturated, and polyunsaturated fatty acids that are soluble in many compositions, especially the less polar or non-polar ones.

Exemplary antioxidants for use with the liquid repellent include, but are not limited to, tocopherols (e.g., α-tocopherol, γ-tocopherol, etc), ascorbic acid, as well as synthetic antioxidants such as propyl gallate, tertiary butylhydroquinone, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), phenolic alcohols, flavonoids, catechins, related molecules thereof, and anthocyanins and their glycosides. The antioxidants can be soluble in most of the compositions and can react efficiently with oxygen, and therefore offer a way to decrease oxidation, breakdown, and polymerization of the liquid repellent compositions. In some embodiments, the oxidant can also be a preservative.

While representative carriers, preservatives, and antioxidants have been listed above, it is to be appreciated that other carriers, preservatives, and antioxidants not specifically listed above can also be used.

In use, the repellent fixture can be placed in a location where biting and stinging insect repellence is desired. For example, in some embodiments, the repellent fixture is placed in an outdoor area to repel mosquitoes and other biting and stinging insects. The outdoor areas can include, for example, patio areas such as a table, an outdoor dining area, a deck; a picnic area; a camping ground, etc. In some embodiments, the repellent fixture can be hung or otherwise affixed from tree branches, garden posts, patio/deck umbrella posts, etc., to create a spatial repellent shield around the human activity.

The following examples are provided to illustrate, not limit, the invention.

Example 1 compares the repellent release rates of slotted plastic tubes versus solid plastic tubes. Example 2 compares the liquid repellent distribution in slotted plastic tubes versus solid plastic tubes. Example 3 compares light reflection and illumination using a light emitting diode (LED) in a slotted plastic tube and in a solid plastic tube.

EXAMPLES

Release Rate Comparison

This example has a slotted tube having 17% less surface area than an analogous solid tube having the same diameter and length. The slots can reduce the maximum repellent loading amounts and can increase the release/loading ratios.

Release Rates of Mosquito Repellent from Porous Plastic Tubes With/Without Slots

Release rate experiments for the repellent porous plastic tubes were conducted in a chemical ventilation hood in a laboratory at approximately 20° C. Each tube was placed onto the inside of a white cap with a diameter of 7 cm. These white caps were placed on a tray to elevate them slightly off the inside surface of the hood. Each tube was labeled on the tray for easy identification. The tubes were loaded on the balance with liquid mosquito repellent formulation from the top by a pipette to let it soak down the tube for uniform distribution. The weight of repellent was recorded. For Experiment 1, the release rates were started on Day 1. For Experiment 2, the release rates were also started on Day 1. For Experiment 3, the release rates were started on Day 7.

As shown in the Table 1, at similar or even lower repellent loading amounts, the repellent release rates from the tubes with only 6% open slot areas was 17-26%, 11-17%, and 6-13% higher than ones from the solid tubes, at 1sthour, 1stday and 2ndday, respectively. The repellent release rates from the porous plastic tubes with 17.4% open slot areas at 1sthour, 1stday and 2ndday were ˜50%, ˜34% and ˜19% higher than from the solid tubes, respectively, even at lower loading amounts.

The slots on the porous plastic tubes increase both the release overall rates and the release-loading ratios significantly, by creating more airflow through the tube body, and by having more uniform distribution of the repellent liquid on the slotted tube surface.

Liquid Repellent Distribution

Without wishing to be bound by theory, it is believed that the multiple staggered slots on the tubes not only reduce the overall loading areas and increase the airflow through the tubes, but also create multiple partially separated thin disks, which can reduce the running-down effect of the repellent liquid after application to the funnel member.

An experiment was conducted to study the running-down rate of a liquid repellent on slotted tubes versus solid tubes, after application to the tubes to a top funnel member connected to the tubes. The repellent liquid ran much faster on the solid tubes than on the slotted tubes. It took on average 45 minutes for the repellent liquid reach down to the bottom edge at all directions for the solid tubes, whereas 1-1.5 hours were needed for tubes with 45 slots. Twenty-four hours after loading a repellent liquid onto the slotted and solid tubes, the slotted tube showed a more uniform distribution of the repellent liquid over the length of the tube, when compared to the solid tube. Thus, with the staggered slots, the repellent liquid would not quickly run vertically to the bottom section by gravity but would go around the staggered slots slowly; thereby more uniformly distribute the liquid distribution on the tube surface than on the solid tube, resulting in more active-releasing surface areas.

LED Light Reflection and Illumination

An experiment was carried out to compare LED light illumination of a slotted tube vs. a solid tube. When an LED light is incorporated at the bottom of a slotted or solid tube, directing the light up through the tube, the slotted tube exhibited stronger and better light refection and illuminating effects than the solid tube.