Bait stations for biting flies in blood-seeking mode and methods therein

Abstract

The present invention discloses devices for a durable insect bait station for biting flies in blood-seeking mode and methods therein. The devices include: an elastomeric membrane for providing access to the bait station, the elastomeric membrane adapted to be permeable to volatile components, and the elastomeric membrane configured to allow easy insect-probe penetration for biting flies in blood-seeking mode; a bait core for providing bait to the bait station, the bait core including: at least one blood-feeding stimulant (BFS) for inducing feeding of the biting flies on the bait core; and at least one insect toxin; wherein the bait core is configured to be substantially in direct contact with the elastomeric membrane; and a support element for attaching the elastomeric membrane and the bait core to a fixed structure. Alternatively, the BFS for inducing the feeding is operative at an ambient temperature below an average mammal temperature.

Claims

1. A device for a durable insect bait station for biting flies in blood-seeking mode, the device comprising: (a) a protective membrane for providing access to the bait station, said protective membrane adapted to be permeable to volatile components, and said protective membrane configured to allow easy insect-probe penetration for biting flies in blood-seeking mode; (b) a bait core for providing bait to the bait station, said bait core including: (i) at least one blood-feeding stimulant (BFS) for inducing feeding of said biting flies on said bait core, wherein said at least one BFS is at least one component selected from the group consisting of: adenosine triphosphate (ATP) and adenosine diphosphate (ADP), and wherein said at least one BFS for inducing said feeding is operative at an ambient temperature below 37? C.; and (ii) at least one insect toxin; wherein said bait core is configured to be substantially in direct contact with said protective membrane; and (c) a support element for attaching said protective membrane and said bait core to a fixed structure; wherein the device, including said protective membrane, said bait core, said at least one BFS, said at least one insect toxin, and said support element, is devoid of any external heating element.

2. The device of claim 1, wherein said protective membrane: (i) has a thickness of less than 100 microns and a hardness of less than 60 Shore A; (ii) is configured to be resistant to degradation caused by ultraviolet (UV) exposure; and/or (iii) is composed of at least one polymeric material.

3. The device of claim 1, wherein said bait core is free of any whole blood-source agent.

4. The device of claim 1, wherein said bait core is free of any sugar-source agent.

5. The device of claim 1, wherein said bait core is adapted to elicit an extended contact time of said biting flies with said protective membrane and/or said bait core.

6. The device of claim 5, wherein said extended contact time is greater than double the contact time of said biting flies in the absence of said bait core.

7. The device of claim 1, wherein said at least one BFS for inducing said feeding is operative on at least one biting-fly type selected from the group consisting of: mosquitoes of the genera Aedes, Culex, and Anopheles; sand flies; and biting midges.

8. The device of claim 1, wherein said at least one insect toxin includes an oral, gut insect toxin.

9. The device of claim 1, wherein said bait core is free of any contact insect toxin.

10. The device of claim 1, wherein said at least one insect toxin is selected from the group consisting of: dinotefuran, a chemical toxin, a biological toxin, a bacterial agent, a fungal agent, and an entomopathogenic agent.

11. The device of claim 1, wherein said at least one oral insect gut toxin includes at least one carrier agent selected from the group consisting of: sodium chloride (NaCl), sodium bicarbonate (NaHCO.sub.3), a water-retaining agent, and a gel.

12. The device of claim 1, wherein said fixed structure is a netting component configured to act as a barrier to prevent said biting flies from penetrating said netting.

13. The device of claim 12, wherein said netting component includes at least one component selected from the group consisting of: a bed net, an aperture-screen housing, a screen component, and a mesh component.

14. The device of claim 1, wherein said support element includes at least one component selected from the group consisting of: an adhesive material, a fibrous material, a strap, a hook, a connector, a magnet, and a mounting hole.

15. The device of claim 1, said bait core further including: (iii) at least one blood-feeding lure (BFL).

16. The device of claim 15, wherein said at least one BFL includes at least one component selected from the group consisting of: carbon dioxide, lactic acid, octenol, acetone, ammonia, butanone, fatty acids, hexanoic acid, indole, 6-methyl-5-hepten-2-one, and a phenolic component of urine.

17. The device of claim 15, wherein said at least one BFL is operative to create a BFL-rich gaseous environment in the vicinity of said bait core.

18. The device of claim 17, wherein said BFL-rich gaseous environment is present in the vicinity of said fixed structure.

19. The device of claim 1, the device further comprising: (d) an optical target for said biting flies.

20. The device of claim 19, wherein said optical target has a dark external appearance relative to said fixed structure.

21. A method for providing a durable insect bait station for biting flies in blood-seeking mode, the method comprising the steps of: (a) providing a protective membrane for access to the bait station, wherein said protective membrane is adapted to be permeable to volatile components, and wherein said protective membrane is configured to allow easy insect-probe penetration for biting flies in blood-seeking mode; (b) formulating a bait core for providing bait to the bait station, wherein said bait core includes: (i) at least one blood-feeding stimulant (BFS) for inducing feeding of said biting flies on said bait core, wherein said at least one BFS is at least one component selected from the group consisting of: adenosine triphosphate (ATP) and adenosine diphosphate (ADP); and (ii) at least one insect toxin; wherein said bait core is configured to be substantially in direct contact with said protective membrane; (c) providing a support element for attaching said protective membrane and said bait core to a fixed structure; and (d) inducing said feeding while maintaining said at least one BFS at an ambient temperature below 37? C. during operation.

22. A method for providing a durable insect bait station for biting flies in blood-seeking mode, the method comprising the step of: (a) applying a protective membrane to be substantially in direct contact with a bait core, wherein said protective membrane adapted to be permeable to volatile components, and wherein said protective membrane configured to allow easy insect-probe penetration for biting flies in blood-seeking mode, and wherein said bait core includes: (i) at least one blood-feeding stimulant (BFS) for inducing feeding of said biting flies on said bait core, wherein said at least one BES is at least one component selected from the group consisting of: adenosine triphosphate (ATP) and adenosine diphosphate (ADP); (ii) at least one insect toxin; and (iii) a support element for attaching said protective membrane and said bait core to a fixed structure; and (b) inducing said feeding while maintaining said at least one BFS at an ambient temperature below 37? C. during operation.

23. The method of claim 21, wherein the durable insect bait station, including said protective membrane, said bait core, said at least one BFS, said at least one insect toxin, and said support element, is devoid of any external heating element.

24. The method of claim 22, wherein the durable insect bait station, including said protective membrane, said bait core, said at least one BFS, said at least one insect toxin, and said support element, is devoid of any external heating element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is herein described, by way of example only, with reference to the accompanying drawing, wherein:

(2) FIG. 1 is a simplified, cross-sectional schematic diagram of a durable insect bait station having a protective membrane and a bait core, according to embodiments of the present invention.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

(3) The present invention relates to devices for bait stations for biting flies in blood-seeking mode and methods therein. The principles and operation for providing such devices and methods, according to the present invention, may be better understood with reference to the accompanying description and the drawing. Exemplary embodiments of the present invention are detailed below in the following experimental studies and results.

(4) Referring now to the drawing, FIG. 1 is a simplified, cross-sectional schematic diagram of a durable insect bait station having a protective membrane and a bait core, according to embodiments of the present invention. The durable insect bait station is shown having a durable, outer, protective membrane 2 that encapsulates a bait core 4.

EXPERIMENTAL STUDIES

(5) Preliminary Cage Experiments:

(6) Rectangular cages (1?1?1 m) made from metal frames covered with gauze, with two sleeved openings, were used to perform preliminary experiments. A simple flat substrate served as the support for the bait station (15?15 cm) having a 3:1 ratio mixture of ATP to ADP, respectively, at a concentration of 1 mM (W/V, weight to volume concentration), as a blood-feeding stimulant (BFS) for the biting flies was found to exhibit the best engorgement response comparable to whole human blood.

(7) A concentration of 0.1% W/V of dinotefuran as a gut toxin was included in the bait-core formulation with the BFS. Finally, sodium chloride (NaCl) and sodium bicarbonate (NaHCO.sub.3) at effective concentrations totaling 0.8%-1% W/V of the solutes were also included in the final formulation with a water-retaining gel. The final bait-core formulation was then covered by a directly-contacting, black, pierceable membrane.

(8) It is noted that a range of about 0.25 mM to about 1.5 mM of both ATP and ADP at ratios ranging between about 3:1 to about 1:1, with final formulation concentrations of phosphorylated adenosines between about 0.5 mM to about 3 mM can be used. In addition, NaCl (for controlling pH) and sodium bicarbonate at effective concentrations totaling about 0.8% to about 1% of the solutes in the final formulation in order to have a bioavailable concentration in the gel that is isotonic.

(9) Furthermore, effective concentrations of toxins vary with the toxin employed. As examples, for dinotefuran, a concentration of about 0.03% to about 0.25% can be used. For linseed oil a concentration of about 0.05% to about 0.3% can be used. For sodium dodecyl sulfate, a concentration of about 0.05% to about 0.25% can be used. Similarly, a suitably-identified concentration of boric acid or spinosad can be employed. Moreover, suitable contact toxins, without an exhibited toxin resistance (discussed below), can be used as well.

(10) In the preliminary cage experiments, the bait stations with gut toxin killed 85.3% of the exposed female Aedes, Anopheles, and Culex trial-specimens overnight while in the cages (with more or less equal effectiveness for 10 repetitions, N: 1,000). Similar bait stations without the gut toxin resulted in only 7.1% lethality of the exposed female Aedes, Anopheles, and Culex trial-specimens being killed (with more or less equal response for 10 repetitions, N: 1,000).

(11) Patch Experiments:

(12) The simple bait station configuration described above in the preliminary cage experiments served as the basis for all the following experiments. The substrate, BFS/toxin bait, and membrane combination is referred to hereinafter as the basic patch.

(13) A series of patch experiments were conducted using basic patches having various membrane colors as the only difference between trials. The patches were tested in the rectangular cages described above. The patch colors tested black, red, blue, yellow, and white. Patches with darkly-colored membranes (i.e., black, red, and blue) attracted and killed significantly more biting flies than lightly-colored patches (i.e., yellow and white).

(14) A series of patch experiments were conducted using black-membrane, basic patches of various sizes as the only difference between trials. Larger patches attracted and killed significantly more biting flies than smaller patches. The biting flies were indifferent to patch shape.

(15) Release-Chamber Control Experiments:

(16) All the following experiments were conducted in experimental chambers (4?7?3 m) used as release chambers in the insectary of the laboratories of Westham Ltd. in Israel. The environmental conditions were: a temperature of 27? C., a relative humidity of 80%, and a photoperiod of 16:8 hours (light:dark).

(17) Within the release chambers, human volunteers remained inside a bed net overnight (18:00 to 6:00) outside the direct reach of the released insects, such volunteers served as the attracting hosts for the insects. Bed nets used for the experiments were impregnated with pyrethroids (purchased locally in Mali). Bed nets fulfill two purposes. On one hand, bed nets physically separate biting flies from a person inside the net (i.e., provide personal protection). On the other, if impregnated with a contact toxin, bed nets kill biting flies while attempting to find the blood host (i.e., provide general protection). The second aspect of the bed nets is important for public-health reasons in order to reduce the overall population of blood-questing mosquitoes and other biting flies, which carry diseases.

(18) The released Culex pipiens trial-specimens used were resistant to pyrethroids in order to demonstrate a well-known fact regarding toxin resistance in biting flies. The trial-specimens were provided with ad libitum access to water and a 10% sucrose solution prior to the experiments, but without access to a blood meal (i.e., 24-hr. blood starvation period). All flies were discarded after being used in a single experiment (i.e., no repeated use of experimental flies).

(19) To retrieve the deceased biting flies for counting after the experiments were conducted, the floor of the room was covered prior to the release of the biting flies with white cotton sheets. The morning following the experiments, the biting flies were collected at 11:00 to 12:00, and the remaining live biting flies were knocked down later inside the same rooms with ethyl acetate, and retrieved for counting from 13:00 to 15:00.

(20) Toxin-Resistance Control-Study Results:

(21) A control patch was used having the same characteristics as the basic patch described above in the preliminary cage experiments, except for the absence of a BFS. Using the release chambers and fly trial-specimens described above, an average daily survival rate of 78.5% of released female Culex pipiens trial-specimens was found for 5 overnight trials (N: 1,000). The high survival rate indicates that the resistance of the Culex against a contact pesticide on the bed net negates public-health effects of the bed nets.

(22) Toxin-Resistance BFS-Study Results:

(23) To overcome the negating effect of toxin resistance, a BFS-infused patch incorporated into a bait station was configured to be mounted on any type of netting component (e.g., a bed net, a window screen, an aperture-screen housing, a screen component, and a mesh component), on the opposite side in which human or animal (e.g., cattle) blood hosts are located, serve as a lure for attracting biting flies in blood-seeking mode. The bait station (either flat or three-dimensional) contained a BFS and a gut toxin within a carrier agent (e.g., a liquid gel or solid material) that can be penetrated by the proboscis of the biting flies covered with a directly-contacting, pierceable membrane.

(24) The importance of using a gut toxin is emphasized to underscore the fact that such toxins provides a different mode of action than a contact toxin, which the biting flies can develop, or have already developed, a resistance to the effects of such contact toxinsrendering such toxin agents ineffective.

(25) In the second toxin-resistance study, the same type of experiments as in the toxin-resistance control study was conducted, releasing same type and number of mosquitoes. However, a BFS-infused patch, having the same characteristics as the basic patch described above in the preliminary cage experiments, was used outside the bed net. In the toxin-resistance BFS study, an average daily survival rate of 38.6% of released female Culex pipiens trial-specimens was found for 5 overnight trials (N: 1,000)a significantly-reduced survival rate in comparison to the toxin-resistance control study.

(26) It is clear from the above that the effect of toxin resistance in biting flies is significant. The same general phenomenon applies to other pyrethrum-resistant blood-feeders as well. In the remaining experiments described below, the biting-fly trial-specimens used had no toxin resistance.

(27) BFS Experiments:

(28) The feeding of various biting flies (MosquitoesAedes albopictus, Culex pipiens, and Anopheles sergentii; sand fliesPhlebotomus papatasi; and biting midgesCulicoides sp.) a BFS-infused patch versus a control patch was studied in which the release chambers were maintained at ambient room temperature conditions (25? C.). The BFS experiments were conducted using non-resistant biting flies and with non-impregnated bed nets.

(29) Preparation of the biting-fly trial-specimens and their blood-meal starvation regimen was performed in an identical manner to the procedures described above. The BFS formulation and concentration used in the BFS-infused patch was identical to the procedure in the preliminary cage experiments described above. The control patch only differed from the BFS-infused patch in that the control patch lacked any BFS (i.e., no BFS present).

(30) The BFS-infused and control patches were placed on the exterior surface of the bed net. Both patches were externally affixed to the bed net for each trial, providing the biting flies with equal opportunity to access either bait station. The bait cores (i.e., the BFS, toxin, and carrier agent) in the patches were stained with different food dye colors in order to verify whether the biting flies fed on the patches. The gut area of the biting flies could be readily observed externally to exhibit the color of the dye for a given patch, if the bait core material was ingested by the biting flies.

(31) Experiments were conducted overnight with 10 releases of 200 female biting flies per trial (N: 2,000). Female biting flies were released inside the experimental huts with a sleeping human host under a bed net. Biting flies could not reach the sleeping subjects in order to obtain a blood meal due to the protection provided by the bed net.

(32) BFS Experiment Results:

(33) Results obtained from patch-feeding trials involving Anopheles sergentii with and without a BFS are presented in Table 1.

(34) TABLE-US-00001 TABLE 1 Results obtained from patch-feeding trials involving Anopheles sergentii with a BFS (BFS-infused patch) and without a BFS (control patch). Release trial 1 2 3 4 5 6 7 8 9 10 Total Release 200 200 200 200 200 200 200 200 200 200 2,000 amount Patch feeding 29 37 45 26 15 43 25 73 62 43 398 (w/BFS) Patch feeding 3 2 12 4 7 9 10 19 27 11 104 (w/o BFS)

(35) Feeding rates for Anopheles on the BFS-infused patches were approximately 3.8 times greater in total than on the control patches without a BFS. The average contact times with the BFS-infused patches for Anopheles were approximately 3.5 times greater than the average contact times for the control patches, as measured by video-monitoring assessment.

(36) Results obtained from patch-feeding trials involving Culex pipiens with and without a BFS are presented in Table 2.

(37) TABLE-US-00002 TABLE 2 Results obtained from patch-feeding trials involving Culex pipiens with a BFS (BFS-infused patch) and without a BFS (control patch). Release trial 1 2 3 4 5 6 7 8 9 10 Total Release 200 200 200 200 200 200 200 200 200 200 2,000 amount Patch feeding 15 81 65 72 49 41 66 38 75 40 542 (w/BFS) Patch feeding 6 4 9 2 5 0 17 5 6 3 57 (w/o BFS)

(38) Feeding rates for Culex on the BFS-infused patches were approximately 9.5 times greater in total than on the control patches without a BFS. The average contact times with the BFS-infused patches for Culex were approximately 5.5 times greater than the average contact times for the control patches, as measured by video-monitoring assessment.

(39) Results obtained from patch-feeding trials involving sand flies (Phlebotomus papatasi) with and without a BFS are presented in Table 3.

(40) TABLE-US-00003 TABLE 3 Results obtained from patch-feeding trials involving sand flies with a BFS (BFS- infused patch) and without a BFS (control patch). Release trial 1 2 3 4 5 6 7 8 9 10 Total Release 200 200 200 200 200 200 200 200 200 200 2,000 amount Patch feeding 31 22 51 19 40 15 9 64 36 57 344 (w/BFS) Patch feeding 5 1 5 2 5 3 4 10 11 6 52 (w/o BFS)

(41) Feeding rates for sand flies on the BFS-infused patches were approximately 6.6 times greater in total than on the control patches without a BFS. The average contact times with the BFS-infused patches for sand flies were approximately 4.4 times greater than the average contact times for the control patches, as measured by video-monitoring assessment.

(42) Results obtained from patch-feeding trials involving Aedes albopictus with and without a BFS are presented in Table 4.

(43) TABLE-US-00004 TABLE 4 Results obtained from patch-feeding trials involving Aedes albopictus with a BFS (BFS-infused patch) and without a BFS (control patch). Release trial 1 2 3 4 5 6 7 8 9 10 Total Release 200 200 200 200 200 200 200 200 200 200 2,000 amount Patch feeding 18 10 9 15 7 23 20 8 15 6 131 (w/BFS) Patch feeding 2 1 0 2 1 5 3 5 4 1 24 (w/o BFS)

(44) Feeding rates for Aedes on the BFS-infused patches were approximately 5.5 times greater in total than on the control patches without a BFS. The average contact times with the BFS-infused patches for Aedes were approximately 4.2 times greater than the average contact times for the control patches, as measured by video-monitoring assessment.

(45) Results obtained from patch-feeding trials involving biting midges (Culicoides sp.) with and without a BFS are presented in Table 5.

(46) TABLE-US-00005 TABLE 5 Results obtained from patch-feeding trials involving biting midges (Culicoides sp.) with a BFS (BFS-infused patch) and without a BFS (control patch). Release trial 1 2 3 4 5 6 7 8 9 10 Total Release 200 200 200 200 200 200 200 200 200 200 2,000 amount Patch feeding 17 5 4 6 10 11 10 24 8 15 110 (w/BFS) Patch feeding 3 0 1 0 2 2 0 0 1 0 24 (w/o BFS)

(47) Feeding rates for biting midges on the BFS-infused patches were approximately 4.6 times greater in total than on the control patches without a BFS. The average contact times with the BFS-infused patches for biting midges were approximately 3.9 times greater than the average contact times for the control patches, as measured by video-monitoring assessment.

(48) Surprisingly, in all the above BFS experiments, the biting flies were induced to feed from the bait stations in the presence of the BFS without the need to have the temperature of the bait core be at the temperature of an average mammal in order to simulate a real host.

(49) BFL Experiments:

(50) The addition of a Blood-Feeding Lure (BFL) to attract or lure blood-feeding flies to the bait station when such flies are in blood-seeking mode was also investigated. It was observed in general that BFLs only achieve their full potential as chemical attractants when employed in combination with CO.sub.2, which can be provided by human subjects, animal subjects, or other CO.sub.2 other sources.

(51) Lactic acid, for example, is significantly more effective in stimulating host-seeking biting flies when CO.sub.2 is also present for Aedes aegypti. Because CO.sub.2 induces and maintains flight, biting flies may be reluctant to terminate flight and land under such conditions, particularly in the absence of other odors.

(52) The luring effect is further enhanced by the addition of a dark external appearance to the patch used (relative to the surrounding structure). In the studies conducted, a black patch was compared to a white patch as the optical target, with a white bed net serving as the surrounding structure.

(53) A systematic functional analysis for biting flies across the conventional odorant receptor repertoire indicates that each odorant receptor manifests a distinct odor-response profile and tuning breadth. The large diversity of tuning responses ranges from odorant receptors that are responsive to a single or small number of odorants (specialists) to more broadly-tuned receptors (generalists).

(54) The additive effects of the various BFLs and optical targets can be understood as being part of a cascade response behavior to guide the blood-foraging of the biting flies toward the bait station. Input from a single specific odor (i.e., an odor specialist), such as CO.sub.2, is adequate to induce a response behavior for biting-fly orientation. In this context, the CO.sub.2 receptor can be considered a labeled line. The input from several such odor specialists (e.g., receptors for lactic acid, CO.sub.2, and temperature, and possibly, receptors for as-yet-unidentified host odors) is necessary to evoke the complete response behavior leading the biting fly to the location and identification of an intact host. Such insights need to be carefully considered when using a bait station as a simulated host for biting flies in blood-seeking mode.

(55) Patch Placement Experiments:

(56) A pair of thermoreceptor units at the tip of the antennae of various biting flies (e.g., the sensilla coeloconica on Aedes aegypti) exhibit a strong temperature sensitivity. Such pairs typically have one receptor that is warm-sensitive, responding with a phasic-tonic increase in spike frequency to sudden increases in temperature. The second thermoreceptor is typically cold-sensitive, responding with a phasic-tonic increase in spike activity to sudden decreases in temperature.

(57) In a series of experiments, the optimum location on a bed net to mount a patch was investigated. Maximum phasic sensitivity is observed in response to temperature changes of ?0.2? C., but the thermoreceptors can respond to changes as low as 0.05? C.

(58) Warm, moist convection currents emanating from a host are important host-seeking cues to biting flies in blood-seeking mode. Such convection currents have been shown to have local thermal differentials of as much as 0.05? C. exist at distances greater than two meters away from a host (a 2- to 3-kg rabbit was used in the studies). Such temperature changes are well within the range of detection of the thermoreceptors of the biting flies.

(59) The mosquitoes in the studies were found to preferably feed predominantly on patches that were affixed to the upper part of the bed nets as opposed to the lower part (i.e., patches mounted 1.5 m above the ground had greater activity than 0.5 m above the ground). Sand flies were found to prefer to feed on low-mounted patches.

(60) Two-Chamber Experiments:

(61) In a series of experiments, survival rates of biting flies in a two-chamber arrangement was investigated. The two chambers were separated by a screened window. In one chamber, a human subject was located, protected by the window screen. While in the second chamber, biting flies were questing for blood meals. A BFS-infused patch was mounted on the window screen in the second chamber in the experimental trials, while a control patch was mounted on the window screen in the second chamber in control trials. Mortality of the biting flies exposed to the BFS-infused patches was significantly higher (4.5 to 12.8 times greater) than biting flies exposed to the control patches without BFS infusion.

(62) Durable Bait Stations

(63) Durable insect bait stations can be constructed from a substrate material that is used to support the bait core and a protective, semi-permeable, pierceable film, which encloses bait core. Suitable substrate materials and protective films assist in preventing erosion, sagging, and cold flow of the bait core as well as lowering surface tack.

(64) Substrate materials can be mechanically-roughened materials (e.g., reinforced cardboard and plastic) as well as materials constructed to have high surface area (e.g., woven functional fabrics and meshes, open-pore foams, fibrous mats, corrugated materials, and honeycomb fabricated materials).

(65) Furthermore, natural substrates can be found in the environments of the area in which one wants to utilize the attractants. For example, green vegetation and similar foliage that are non-flowering, or are utilized when they are not in their flowering phase (in order not to attract bees), are excellent substrates. Typically, such natural substrates have roughened or textured surfaces that are ideal for supporting such bait cores. In addition, such natural substrates eliminate any concern of generating any environmental waste by-product in the environment.

(66) Protective films can be suitable polymeric materials (e.g., thermoplastics, thermosetting polymers, carbon black-filled butyl rubber, acrylic polymer, plasticized PVC, polyurethanes, neoprene, natural rubber, and butadiene rubber). Such materials may contain elastomers (e.g., polydimethyl siloxanes (PDMS), silicone rubbers, silicone elastomers, silicone gels, ethylene-vinyl acetate, ethylene-acrylic ester copolymers and terpolymers, ethylene-propylene rubber, plastomers such as ethylene-hexene and ethylene-octene copolymers, thermoplastic vulcanized rubber (TPV); hydrogenated block styrene-ethylene butylenes (SEBS); and block styrene isoprene (SIBS).

(67) Such materials may further contain plasticizers (e.g., aliphatic polyesters) and light stabilizers (e.g., UV stabilizers), as well as other additives such as carbon black, pigments and dyes, fillers, and bactericides, fungicides, and other microbial-activity suppressants. Such protective films assist in physically supporting the bait core in order to prevent sagging and cold flow, while allowing for effusion of volatile components of the bait core.

(68) While the present invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications, and other applications of the present invention may be made.

LITERATURE

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