Liquid-core capsules for pest control

Abstract

Liquid-core capsules (10) for pest control are provided, wherein the liquid-core capsules (10) have an aqueous core (11) and a diffusion-inhibiting, functional outer shell (13). The core (11) contains at least one pest control agent. The outer shell (13) contains at least one attractant for the pests.

Claims

1. Liquid-core capsules having a mean diameter in a range between 1 and 10 mm for control of plant pests having piercing-sucking mouthparts, wherein each liquid-core capsule of the liquid-core capsules has an aqueous core and a diffusion-inhibiting, functional outer shell, wherein the core comprises at least one pest control agent and wherein the outer shell comprises at least one attractant for the pests and wherein the aqueous core comprises at least one phagostimulant.

2. The liquid-core capsules according to claim 1, wherein the outer shell comprises a base substance and an oil, wherein the base substance comprises fats and/or waxes and wherein the oil comprises a vegetable oil.

3. The liquid-core capsules according to claim 1, wherein the base substance is paraffin or soft paraffin.

4. The liquid-core capsules according to claim 2, wherein a portion of the oil in the outer shell is in a range of between 1% and 25% w/w.

5. The liquid-core capsules according to claim 2, wherein the outer shell has an outer region that is free of attractant.

6. The liquid-core capsules according to claim 1, wherein the at least one phagostimulant comprises at least one carbohydrate, at least one amino acid, at least one fat, a nutritional composition, or mixtures thereof.

7. The liquid-core capsules according to claim 1, wherein the aqueous core is enclosed by a hydrogel shell.

8. The liquid-core capsules according to claim 7, wherein the hydrogel shell is formed from a biopolymer composition comprising alginate, pectin or a mixture thereof.

9. The liquid-core capsules according to claim 8, wherein the biopolymer composition furthermore comprises additives comprising shellac, waxes or a mixture thereof.

10. The liquid-core capsules according to claim 1, wherein the at least one attractant is a volatile attractant, wherein the at least one attractant is selected from the group consisting of (Z)-3-hexenyl-acetate, (Z)-3-hexen-1-ol, (E)-β-carophyllene, 1-hexanol, nonanal, hexyl butyrate, (E)-2-hexenyl butyrate and mixtures thereof.

11. The liquid-core capsules according to claim 1, wherein the plant pests are at least one of true bugs, lice, thrips, and cicadas.

12. A method for manufacturing the liquid-core capsules according to claim 1, comprising the following method steps: providing a mixture for an aqueous core of the liquid-core capsule, wherein the mixture comprises a pest control agent and at least one phagostimulant, providing at least one mixture for a diffusion-inhibiting, functional outer shell of the liquid-core capsule, wherein the at least one mixture comprises an attractant for the pests, and manufacturing the liquid-core capsules using the mixture for the aqueous core and the at least one mixture for the functional outer shell.

13. The method according to claim 12, further comprising providing a hydrocolloid solution, manufacturing primary capsules, each primary capsule of the primary capsules having a hydrogel shell and an aqueous core, using the mixture for the aqueous core and the hydrocolloid solution, and spray coating the primary capsules with the at least one mixture for the functional outer shell in a fluidized bed thereby manufacturing the liquid-core capsules.

14. A method for controlling plant pests having piercing-sucking mouthparts, comprising applying a preparation to crops, wherein the preparation comprises the liquid-core capsules according to claim 1.

15. The method according to claim 14, wherein the plant pests are at least one of true bugs, lice, thrips, and cicadas.

Description

(1) Additional features and advantages of the invention result from the description of exemplary embodiments in the following in conjunction with the drawings. The individual features may be realized alone or in combination with one another.

(2) In the drawings it is shown:

(3) FIGS. 1 and 2 schematic depictions of the structure of liquid-core capsules according to the invention, with and without hydrogel shell;

(4) FIGS. 3 to 5 release of active substances ((Z)-3-hexen-1-ol in FIG. 3, hexyl butyrate in FIG. 4, (E)-β-caryophyllene in FIG. 5) in a model system having different oil contents in the layer containing the active substance;

(5) FIG. 6 temporal course of the active substance release in different types of liquid-core capsules;

(6) FIG. 7 olfactometer results with different active substances (attractants) in terms of their ability to attract true bugs (0.01 μg/μL); and,

(7) FIGS. 8 and 9 effect of different active substances on true bugs using electrophysiological examinations (0.1 μg active substance in FIG. 8, 10 μg active substance in FIG. 9).

DESCRIPTION OF EXEMPLARY EMBODIMENTS

(8) The liquid-core capsule 10 depicted in FIG. 1 is formed by a core 11 that comprises a liquid phase. The aqueous core 11 contains the pest control agent or, possibly, a plurality of pest control agents, and preferably a phagostimulant, in particular a food composition for the pests to be controlled. This core 11 is enclosed by a hydrogel shell 12. The hydrogel shell 12 is preferably formed by biopolymers, in particular alginate and/or pectin, that due to cross-linking form a shell around the aqueous core 11. The aqueous core 11, together with the hydrogel shell 12, form the so-called primary capsule. This primary capsule is enclosed by a functional outer shell 13. The outer shell 13 contains the attractant or attractants and possibly one or a plurality of piercing stimulants for the pests. The outer shell 13 is embodied such that it may be pierced by the mouthparts of the pests to be controlled, in particular by biting-sucking and/or piercing-sucking mouthparts. Due to the attractant or attractants integrated in the outer shell 13, the pests are attracted and prompted to pierce the outer shell 13 with their mouthparts and to ingest at least some of the aqueous content of the core 11. This causes injury to, immobilization of, and/or death of the pests, depending on the action of the pest control agent contained in the core 11.

(9) For manufacture of the liquid-core capsules 10 according to the invention, first a primary capsule is manufactured in which the aqueous core 11 is enclosed by a hydrogel shell 12. Then the wet primary capsules are coated in a fluidized bed in order to form the dry, functional outer shell 13.

(10) Due to the addition of additives for the hydrogel shell 12, water diffusion through the shell of the primary capsule is reduced. This may significantly reduce the adhesion forces between the primary capsules so that they may be moved (fluidized) separated from one another in an air flow for spray coating and the water content in the core mixture essentially remains just as high. This is very advantageous for spray coating in a fluidized bed.

(11) The hydrocolloid solution for the hydrogel shell 12 is manufactured based on sodium alginate, for instance. For this, for instance approximately 0.5 to 2% alginate (w/v) may be dissolved in distilled water by stirring for a prolonged period. Shellac may be used as an additive, wherein for example a 25% aqueous shellac solution is added to the alginate solution (e.g. 20 parts shellac solution+80 parts alginate solution).

(12) Preliminary experiments have demonstrated that the losses in mass from the core may be effectively reduced by adding additives to the hydrogel shell. The following table summarizes the absolute losses in mass for alginate model cylinders (d=13 mm, h=13 mm) after 240 minutes, with the addition of various additives in their most suitable concentrations and the relative losses in mass compared to the losses in mass of the standard specimen without the additives (MCC—microcrystalline cellulose, EC—ethyl cellulose).

(13) TABLE-US-00001 Specimen loss in mass after Loss in mass Loss in mass 240 min [%] [%] compared to Added after 240 min after 240 min Standard loss in concentration without additive with additive mass Additive [%] (“Standard”) (“Specimen”) [%] Shellac 15.0 6.59 5.46 −17.12 Chitosan 0.75 5.22 4.52 −13.45 Stearic acid 0.90 7.43 6.92 −6.87 Bee's wax 0.90 5.22 4.72 −9.51 MCC 0.30 6.56 6.03 −8.15 EC 0.75 5.83 5.34 −8.34

(14) This demonstrates that the loss in mass may be reduced by approximately 17%, for instance by the addition of shellac.

(15) The possibly provided hydrogel shell preferably forms approximately 10 to 15% of the diameter of the primary capsule, so that sufficient space is provided for the liquid phase of the core. In one exemplary mean total diameter of the liquid-core capsules of about 4 mm, the thickness of the hydrogel shell may than be, for example, approximately 250 μm. This provides sufficient strength for the primary capsules, which withstand the forces of the spray coating in the fluidized bed. Selecting suitable hydrogels and adapting the substance concentrations and the process parameters attains a water diffusion rate that is as low as possible in the primary capsules so that optimum coating may take place in the fluidized bed. The reduction in water diffusion by the hydrogel shell is attained in particular using the added additives.

(16) The primary capsules may be manufactured by means of a special nozzle that is used for adding the mixture for the aqueous core to the hydrocolloid solution by droplet. Adding the mixture for the core by droplet to the hydrocolloid solution is accomplished while stirring. The temperature, pressure, mixing ratios, pH, stirring speed, viscosity, pump power, and process times may be adjusted and optimized depending on the materials used. Bivalent ions, such a for instance calcium lactate or calcium chloride, may be added in advance to the mixture for the core. Alternatively, magnesium chloride may be used, for example. The primary capsules embodied during this process contain an aqueous core and an enclosing hydrogel shell made of cross-linked biopolymer (alginate). During manufacture, the alginate shell deposits to a certain extent on the droplets of the mixture for the core. After one or a plurality of rinse steps, the primary capsules are dried off and spray-coated in a fluidized bed coater for manufacturing the functional outer shell in the fluidized bed. The attractant or attractants is/are integrated into the outer shell while this is done. The strength of the outer shell should therefore be created such that it may be pierced, for instance, by true bugs. On the other hand, the outer shell is stable enough that it can withstand the mechanical stresses during output of the liquid-core capsules according to the invention and moreover protects the contents of the liquid-core capsules from harmful environmental aspects, e.g. drying out and UV radiation. The liquid-core capsules according to the invention may thus develop their effect over an extended period of time in that the attractants are output into the environment over an extended period of time and thus attract the pests. The pest control agent in the interior of the liquid-core capsules is also protected and stable over an extended period of time and its effect may thus develop.

(17) FIG. 2 also illustrates a liquid core capsule 20 according the invention having a liquid core 21 and a diffusion-inhibiting functional outer shell 23. In this embodiment, no hydrogel shell is provided, since the manufacturing process for this liquid core capsule does not use the intermediate step of stabilizing the liquid core in the form of a primary capsule. For example, the so-called Inducap®-CORE technology may be used in principle for such a manufacturing method, in which method the liquid starting mixtures for the core and the functional outer shell are portioned into individual liquid volumes via a concentric two-material nozzle by means of hydraulic pulses and are added to a consolidation area so that a liquid droplet of the core liquid is enclosed by the consolidated shell liquid. A temperature chamber, the temperature of which is less than the melting point of the material of the outer shell is suitable for the consolidation area, for example.

(18) The functional outer shell 13, 23 of the liquid-core capsules is essentially dry and diffusion-inhibiting so that the liquid-core capsules 10, 20 according to the invention are pourable, in principle, and thus is simple to manage during use. The outer shell 13, 23 ensures protection against evaporation so that the liquid-core capsules 10, 20 may be applied to crops and their effect may develop there for a prolonged period of time.

(19) The liquid-core capsules according to the invention may be used in combination with various pest control agents, in particular with biological and natural pest control agents that protect against plant-damaging true bugs. By selecting appropriate pest control agents and selecting suitable attractants, the liquid-core capsules according to the invention may be adapted to the specific type of pest to be controlled, wherein the manufacturing method for the liquid-core capsules is usefully adapted to the specific substances.

(20) The pest control agent should kill off the pest as rapidly as possible, or at least weaken it such that no more damage is caused by the pest. Of the group of biological active substances, especially Bt isolates and active substances of the neem tree are suitable for controlling true bugs. Both substances have a broad spectrum of action, demonstrate rapid effect, and are also permitted for organic farming. In a suitable pest control agent for a pest to be controlled, following direct ingestion of the active substance by the pest, the damage rate to the pest (mortality and/or cessation of food ingestion) should preferably reach greater than 70%, wherein the effect should begin after a few hours. Neem tree active substances, especially, in combination with the liquid-core capsules have proven particularly effective in controlling the true bugs.

(21) The decision rate of the pests in an olfactometer trial may be used for evaluating the attractiveness of the attractants used according to the invention compared to a plant (host plant for the pests). The decision rate should preferably be clearly greater than 50% for the attractant used. For identifying suitable attractants in adaptation to a pest to be controlled, in a first step natural odors may be concentrated, for example by extraction with a suitable solvent. The active components of the concentrated odors may then be identified more precisely and their effect may be increased, for instance, as concentrated synthetic substances. Different sources of odor may be investigated for identifying suitable attractants. For instance, complete plants, plant parts, extracts, saps, or solutions may be used and investigated in olfactometer tests so that effective substances may be identified. The effective substances may furthermore be analyzed by gas chromatograph and further investigated. The attractants identified may preferably be integrated into the outer shell, in concentrated and essentially pure form, with or without additives, to further increase the luring effect of the liquid-core capsules.

(22) The attractants are identified and obtained by steps, for instance: Selection of suitable attractant sources, for example, known host plants for the pests or preferably fruits; Obtaining plant odors (odor mixtures) by producing extracts; Checking suitability in olfactometer tests; Electroantennography (see below) in combination with separation by gas chromatography for identifying the active components in the odor mixtures; Manufacture of a mixture of a synthetic or partly synthetic attractant based on the active substance(s) determined.

(23) Suitable for attractants are in particular non-polar volatile substances that are mixed with waxes and/or fats and may be applied in a common layer as a functional outer layer of the liquid-core capsules. If polar substances are used as attractants, they are preferably applied in the form of an extra layer so that there is no increase in the evaporation of water from the aqueous core.

(24) Green leaf volatiles (GLV) and/or volatile organic compounds (VOC) are especially suitable for attractants. As a rule GLV may be derived from the C6 body (Z)-3-hexenal. VOC are in particular lipophilic substances that can be categorized into the following classes: terpenoids, derivatives of fatty acid metabolism, phenylpropane (incl. benzene derivatives), compounds containing nitrogen, and compounds containing sulfur. It is particularly preferred that (Z)-3-hexenyl acetate and/or (Z)-3-hexen-1-ol and/or (E)-β-caryophyllene and/or 1-hexanol and/or nonanal and/or hexyl butyrate and/or (E)-2-hexenyl butyrate and/or mixtures thereof are used as attractants. Homogenized (puréed) potato plants may also be used as attractants, for instance. A mixture of caryophyllene, (Z)-3-hexen-1-ol and hexyl butyrate is particularly preferred. The particularly advantageous effect of these substances in terms of attracting true bugs was demonstrated by the inventors.

(25) The composition of the liquid-core capsules according to the invention is preferably adjusted such that attractant is released over a period of 14 days or more, wherein the liquid-core capsules have a greater attracting action on the pests than the plants that are to be protected.

(26) The strength of the outer shell is preferably adjusted such that it is soft enough that the pests can pierce it. At the same time, the strength of the outer shell is adjusted such that it demonstrates adequate stability for machine application. The strength of the outer shell may be modified, for instance, by the use of waxes having different melting points or by the use of different long-chain fatty acids. Brittle or hard outer shells may be softened, for instance by adding in glycerin. The composition of the functional outer shell is usefully further adjusted such that there is adequate permeability for the attractant or attractants.

(27) The following description of exemplary embodiments illustrates particularly preferred options for manufacturing the liquid-core capsules.

(28) A. Method for Manufacturing Liquid-Core Capsules

(29) Two methods that essentially differ from one another in the type of nozzle used and the associated technical functionalities (regulation, yield, process safety) were used for manufacturing the inventive liquid core capsules. A differentiation should be made between manufacturing liquid-core capsules with a hydrogel shell and manufacturing liquid-core capsules without a hydrogel shell. The hydrogel shell is a kind of auxiliary structure that stabilizes the liquid capsule core during the manufacturing process and forms the primary capsule. Its function develops as soon as the outer shell is applied in a second method step. The primary capsule occurs as an intermediate product and may be manufactured by means of special single-material or two-material nozzles (coextrusion nozzles). Liquid-core capsules without a hydrogel shell are manufactured using special two-material nozzles. Shape, stabilization, and coating are combined in one process during the manufacture of liquid-core capsules having no hydrogel shell. As a result, the core is enclosed directly by the outer shell.

(30) A.1 Liquid-Core Capsules Having a Hydrogel Shell

(31) 6% (w/w) calcium lactate, relative to the water content of the nutrient solution, is added to a conventional nutrient mixture for insects. A suitable nutrient mixture comprises, for instance: 68% dist. water, 5% dry yeast, 6% yeast extract, 10% powdered egg yolks, 5% sugar, 5% honey, and 1% casein, with a total water content of 73%.

(32) Then the plant protection agent NeemAzal®-T/S is added to the mixture at a ratio of approximately 1:200. These compounds form the core solution of the liquid-core capsules to be manufactured.

(33) A 0.1% sodium alginate solution is prepared as a cross-linkable hydrocolloid solution. An additive is also added to the hydrocolloid solution in order to improve, in the manner desired, the shell properties of the primary capsule to be produced. A 20% aqueous shellac solution that is mixed with the hydrocolloid solution at a ratio of 1:6 is used as an additive in one batch. In another batch, 0.9% (w/w) bee's wax is used in the hydrocolloid solution. For the mixture with the bee's wax, it is useful to produce a hot melt of approximately 80° C. and to disperse it in the hydrocolloid solution at about 20,000 to 25,000 rpm for at least 3 minutes. In another batch, 0.3% MCC is dispersed in the sodium alginate solution.

(34) A.1.1 Manufacturing the Primary Capsules by Means of Droplet Formation

(35) The core solution is added to the hydrocolloid solution by droplet by means of a nozzle while stirring. The primary capsule form, and after a few minutes are separated by screening from the hydrocolloid solution and rinsed with water. The nozzle comprises a channel from which the core solution exits by droplet. The channel is concentrically surrounded by a second channel through which air flows. The size of the droplets may be regulated, and the break-away from the outlet opening may be significantly accelerated, using the air quantity set (separating air). The central channel has an inner diameter between 0.5 to 1.5 mm, the surrounding channel has a diameter between 1.5 and 3 mm. This basic structure is relatively simple technically and may be reproduced as desired, for the most part, in order to increase production performance. Thus, e.g., 128 dual channels may be combined in one nozzle head. The core solution is delivered from a supply container using a pump or pressure build-up. The supply quantity is preferably between 0.5 to 2 g per minute and nozzle channel.

(36) Alternatively, the primary capsules may also be manufactured by means of a two-material nozzle in which two streams of liquid may be conveyed at the same time (coextrusion). It is also possible to manufacture relatively small (0.5 to 1 mm) and especially uniform primary capsules with coextrusion nozzles. Compared to single-material nozzle, these nozzles have reduced output, require greater technical regulation, and are not as easy to combine to create larger units. In addition to the single-material nozzle described in the foregoing, the coextrusion nozzle has another channel. The nutrient solution is conveyed in the inner channel, the hydrocolloid solution in the surrounding channel. At the outlet opening, a covering made of the hydrocolloid solution deposits around the spherical core droplet and the cross-linking reaction (formation of the hydrogel shell) begins immediately, from inside to outside. As already described in the foregoing for the single-material nozzle, the break-away from the outlet opening may be accelerated by an additional separation air channel. Two-material nozzles that do not convey material continuously, but instead convey the core solution through the exiting hydrocolloid solution by means of a pulse, may also be used. The droplet formation and ejection may occur as with the technology of an ink-jet printer. The result is the same in each case: upon passing through a second liquid, the core liquid droplets are enclosed by this second liquid. Finally, the primary capsules already forming in free-fall are added by droplet to a bath of cross-linking solution, which contains, for example 1% calcium chloride or 6% calcium lactate, in order to completely form and stabilize the hydrogel shell. The primary capsules are then separated from the cross-linking solution (e.g. separation by screening method) and rinsed with water.

(37) A.1.2 Manufacture of the Functional Outer Shell

(38) The coating mixture for the outer shell essentially comprises three components: a wax-like base substance, for example soft paraffin, rapeseed oil as a piercing stimulant and as a regulator for release of the active substance, and an attractant. The attractant used comprises a composition of the most widely used components of green leaf volatiles (GLV) and volatile organic compounds (VOC) from plants. A suitable mixture of the attractant may include, for example, hexenol, (Z)-3-hexenyl acetate, (Z)-3-hexenal, (E,E)-α-farnesene, β-bourbonen isomer (+), (Z)-3-(Z)-3-hexenylbutanoat, β-caryophyllene isomer (−), and/or (E)-4,8-dimethyl-1,3,7-nonatriene. Pure forms of these substances may be obtained from chemical companies (e.g. SigmaAldrich Co. LLC) and may be mixed precisely as needed. Moreover, odor mixtures obtained from leaves (e.g., cucumber, alfalfa, horse chestnuts, tobacco) by means of special extraction methods (e.g. headspace sampling or solid phase microextraction (SPME)) may be used. One particularly preferred attractant mixture is manufactured from (Z)-3-hexene-1-ol, hexyl butyrate and (E)-b-caryophyllene in a 1:1:1 ratio. The base substance (approximately 90%), the piercing stimulant (approximately 9.8%) and the attractant (approximately 0.2%) are mixed. First a preliminary mixture of attractant and piercing stimulant is manufactured, and this mixture is then stirred into the base substance melt. The temperature of the melt is at least 10 to 30° C. above the melting point of the base substance. A dispersion device (approximately 20,000 rpm) is used to obtain a very uniform and fine distribution of the preliminary mixture.

(39) Following manufacture of the primary capsules and preparation of the coating mixture, the outer shell is applied to the primary capsules using a spray coating system (coating process). Approximately 300 to 400 g of primary capsules created by droplets may be coated in a production container that holds about 1 Liter. The production quantity may be increased significantly depending on the production system. The required fluidization of the primary capsules is attained at a process air quantity between 50 and 70 m.sup.3/h. Immediately following fluidization, the coating mixture, in the form of a melt, is sprayed into the production container. The required functionalities may be attained with the following parameters: temperature of the melt 30 to 50° C. above the melting point of the base substance, spray rate between 4 and 7 g/min. The coating process is terminated when approximately 15% to 35% (relative to the capsule weight), especially 15% to 30%, and preferably 20% to 30%, of the coating mixture has been applied to the primary capsules. With this method of manufacture, the desired properties for the liquid-core capsules may be precisely and reproducibly adjusted, especially with respect to the layer thickness of the outer shell and the sharpness of the boundary surface formation.

(40) Due to the lower viscosity of the piercing stimulant (rapeseed oil) and the attractant mixed therein compared to the base substance, these substances slowly leak from the base substance of the outer shell so that they can exert their long-range effect on the pests. The speed of this release process increases with the temperature. Preliminary tests have indicated that, for example, approximately 15% of the rapeseed oil has left a wax block weighing 100 g and originally containing 10% rapeseed oil within 10 days at 25° C. This effect leads to continuous release of piercing stimulant and attractant and provides the required action at a distance and long-term effect of the liquid-core capsules.

(41) A.2 Liquid-Core Capsules without Hydrogel Shell

(42) Coextrusion nozzles (two-material nozzles) that have an inner channel for the core solution and a concentric, surrounding channel for a melt of the coating mixture are used for the manufacture of liquid-core capsules without a hydrogel shell. When the core liquid droplet passes through, it is enclosed by the coating mixture. The temperature of the core liquid is approximately 10° C. below the melting point of the coating mixture, so that the melt hardens very rapidly from inside to outside and stabilizes the droplets. The capsules are added by droplet to a cooled water bath (approximately 10 to 20° C.) while stirring in order to finish the hardening.

(43) B. Controlling the European Tarnished Plant Bug Lygus Rugulipennis

(44) The bug Lygus rugulipennis is very common throughout Europe and attacks about 400 types of host plants from more than 50 families of plants. Economic damages are suffered, e.g. for strawberries, cucumbers, potatoes, cabbage, alfalfa, carrots, tobacco, and various ornamental plants like, for instance, chrysanthemums and fuchsia (HOLOPAINEN, J. K. & VARIS, A.-L. 1991: Host Plants of the European tarnished plant bug Lygus rugulipennis. J. Appl. Ent. 111 (1991). 484-498; DRAGLAND, S. 1991: Lygus rugulipennis, a harmful insect to many cultivated plants—II. Damage in cabbage fields and control measures. Håret entege. II. Skadar i kålfelt. 67-76; BECH, R. 1967: Zur Bedeutung der Lygus-Arten als Pflanzenschädlinge. Biol. Zentrbl. Heft 2. 205-232).

(45) Experiments were conducted with Lygus rugulipennis and the liquid-core capsules according to the invention, wherein an aqueous nutrient solution having 0.5% NeemAzal® T/S (biological active substance: azadirachtin 0.1%) was present in the core of the capsules. Another experiment was conducted with the chemical active substance acetamiprid (0.01%). When they had contact with the liquid-core capsules, the true bugs used their proboscis to pierce the outer shells of the liquid-core capsules and ingest at least some of the core solution. This was evidenced, inter alia, in petri dishes (d=35 mm), to each of which one fully developed bug (imago) or an older nymph (L4/L5) was added, together with the liquid core capsules, and the behavior of the true bugs was observed for a period of 5 min. The animals were subjected to a 6-hour hunger phase prior to the beginning of the experiment. All of the animals whose proboscis had contact with the outer shell of the liquid-core capsules according to the invention also pierced said outer shell and ingested the core liquid. The lengthy dwell time of the proboscis in the capsule permits this conclusion. With the imago insects, this was an average of 160 seconds, 150 seconds with the nymphs. With the imago insects, this was preceded by a mean testing period (feeling the capsule with the proboscis) of about 30 seconds. With the nymphs, on the other hand, the proboscis was used for piercing almost immediately after initial contact. 28% of all of the animals observed did not test the capsules during the observation period, but rather experienced lengthy resting phases or simply passed over the capsule.

(46) The true bugs ceased their activity nearly entirely about 1 day after ingesting the core liquid with the active substance azadirachtin and died after 5 days, on average. The chemical active substance acetamiprid took effect a few seconds after being ingested. The animals were observed quivering violently, death occurred a few minutes later.

(47) C. Applying the Liquid-Core Capsules to Crops

(48) Using olfactometer selection experiments it was determined that a suitable mean capsule interval in the cultivated area to be treated is approximately 5 cm, so that approximately 400 capsules/m.sup.2 was calculated for application to the crops. Given a mean capsule weight of 15.1 mg, the required quantity is approximately 61 kg/ha. The option of applying the liquid-core capsules according to the invention over a large surface area was tested by means of a pneumatic seeding machine, type PS 250 from APV-Technische Produkte GmbH. With this machine it was possible to distribute the required 61 kg uniformly on 1 ha in approximately 30 min, at a mean travel velocity of 3 km/h and a spread of 7 m. The amount thrown off per unit of time is regulated using the seed shaft speed. In the aforesaid example, the set value required was 75%. A comparison of mechanically unstressed liquid-core capsules according to the invention to stressed liquid-core capsules that were ejected through the seeding machine yielded a damage rate of less than 2%. Loss of mass due to evaporation was used as a measure for damage. The outer shell thus had adequate strength to withstand application by machine.

(49) In addition to uniform distribution, the capsules may also be applied pointwise to the crops to be protected. Small carrier cards made of stiff cardboard (approx. 30×80 mm in size) to which the liquid-core capsules are adhered are suitable for this. The cards are preferably equipped with a suitable hook to permit simple and rapid attachment to each plant. This application format is suitable especially for protected crops, e.g. crops in a greenhouse or polytunnel. The crop areas therein are frequently not accessible for large machines and individual plants are not distributed uniformly, but rather are disposed on special tables, so that surface application is difficult.

(50) D. Model System for Release of Attractants as a Function of the Composition of the Outer Shell

(51) Odor Mixture (Active Substances) 3 components in a 1:1:1 ratio Green leaf volatiles and sexual pheromone Volatility among the individual components varies

(52) Variants

(53) Model system for shell mixture in petri dishes, layer thickness approximately 0.5 mm Shell mixture 1 composition: 1.2 g paraffin, 10% vegetable oil, 30 μg odor mixture Shell mixture 2 composition: 1.2 g paraffin, 1% vegetable oil, 30 μg odor mixture Shell mixture 3 composition: 1.2 g paraffin, 10% vegetable oil, 3 mg odor mixture Shell mixture 4 composition 4: 1.2 g paraffin, 1% vegetable oil, 3 mg odor mixture

(54) Implementation

(55) For manufacturing the model system, a paraffin melt was prepared at 80° C. 1% or 10% vegetable oil was stirred into the melt. Then the three odors (mixtures) were added in two different quantities (30 μg and 3 mg per 1.2 g mixture) by means of microliter injection. The mixture was poured into petri dishes at a layer thickness of approximately 0.5 to 1 mm.

(56) Directly following manufacture of the specimens, the odor was collected by means of special apparatus (headspace sampling). The collection filter was removed after an appropriate period of time and frozen until analysis. The odors underwent chemical analysis by means of gas chromatography with mass spectrometry coupling=GC-MS.

(57) Results

(58) In the model system it was demonstrated that the odors are given off relatively constantly (linearly) over a time period of 72 h. The experiment was terminated after 72 h. Only a fraction of the odor contained in the model system was given off during this period. If it is assumed that the linear release will remain somewhat constant, it would be approx. 100 days before all of the odor would be used up.

(59) FIGS. 3, 4 and 5 graphically illustrate the quantity of odor released over the course of time (up to 72 h) for each odor individually. A nearly linear release per hour is evident. The total quantity in ng/h of the odor mixture (all three components) is e.g. 1% oil and 3 mg total quantity of odor mixture at (250+325+80=655) 655 ng/h. I.e., at a constant release, the capsules would release odor for up to 190 days (3000 μg/0.655 μg=191 days).

(60) Furthermore, it may be seen that compared to batches with 1% oil, in batches with 10% oil a smaller odor release was evident nearly continuously. This indicates that the oil quantity influences the release of the odor. Increasing the oil content leads to reduced release. This effect was evident in the concentrations of the two odors. As a result, therefore, the attractant release may be reduced or delayed by increasing the oil portion.

(61) E. Comparison of Active Substance Release in Liquid-Core Capsules in Two Manufacturing Variants

(62) Liquid-Core Capsules

(63) Manufacturing variant, type 1: first spray phase (inner wall region) 10% paraffin (relative to capsule weight), second spray phase (outer wall region) 10% shell mixture 4 (see Section D) Manufacturing variant type 2: first spray phase (inner wall region) 15% shell mixture 4, second spray phase (outer wall region) 15% paraffin

(64) The liquid-core capsules were manufactured as described in Section A. The experiment was conducted in principle as in the model system described in Section D in terms of odor collection and analysis using gas chromatography with mass spectrometry coupling. The following table and FIG. 6 summarize the results of the experiment.

(65) TABLE-US-00002 Total quantity of odor per unit of time 1 week 1 week Type 1 Type 2 (Z)-3-hexen-1-ol 15.2 235.1 Hexyl butyrate 58.8 592.0 (E)-b-caryophyllene 205.2 781.0 Total quantity of odor/μg 279.2 1608.2 (Z)-3-hexen-1-ol 0.5 7.8 Hexyl butyrate 2.0 19.7 (E)-b-caryophyllene 6.8 26.0 Odor collected/% 9.3 53.6

(66) Elevated release was observed for the liquid-core capsules of manufacturing variant Type 1. Nearly all of the odors had escaped after only 1 week, since the at this point in time the capsules hardly gave off any more odor. On the other hand, it was only possible to collect 9.3% of the added odors. The difference may be explained as loss during the manufacturing process that is unavoidable due to the high volatility of the attractants.

(67) A reduced release was attained with the liquid-core capsules from the manufacturing variant Type 2. After a release that was initially somewhat higher in the first hour, the rate remained quite constant over the measured period of 1 week. The absolute odor release was approx. 50%. Significant quantities of odor were still given off after 1 week. Thus the odor supply at this point in time had still not been exhausted and it was possible to avoid a very high loss of odor during manufacture. FIG. 6 illustrates the temporal course of the release of the active substance in both types of capsules, each separately for the individual odors. The figure illustrates each quantity released per hour, these being calculated from the quantities collected at collection times 1 h, 3 h, 24 h, and 168 h. Given the trend of the release curve in FIG. 6, there is a release period of at least 2 weeks with this variant.

(68) It is clear from comparing the two manufacturing variants that in principle this period of time could be extended significantly, e.g. by applying 20% pure paraffin as a final layer and 10% shell mixture, or even using a layer of 25% paraffin on the outside and 5% on the inside.

(69) The results demonstrate that the escape of the odor may be delayed or accelerated, depending on the capsule manufacturing variant. Type 1, in which the odor mixture is sprayed on as the last layer, exhibits increased release of the odor. In contrast, for Type 2 the odor mixture is then enclosed by a layer of pure paraffin. In addition, the layer thicknesses are increased from 10% by weight application to 15% by weight application. Process management thus has a direct effect on capsule structure and the release of the odor.

SUMMARY

(70) It may be seen that the time span for the odor release and the released odor concentration/per unit of time may be modified very easily. This may be done using different combinations of odor concentration, vegetable oil, and paraffin. Adapting the method when spraying on the shell mixture can also attain targeted modification of odor release. Thus there are very good options for adapting the system to different requirements for pest control (type of pest, type of plant, cultivation system). The odor concentrations required for attracting the pests may be adjusted and released over an extended period of time, wherein a reaction time period of about 1 week is generally considered acceptable for plant protection measures.

(71) F. Olfactometer Experiments for Investigating the Attractant Effect on True Bugs

(72) Comparative behavior studies were conducted on the bug species Lygus rugulipennis in the olfactometer for identifying suitable attractants (odors). The attracting action of a total of 28 different concentrations of substances and substance mixtures was determined in about 380 individual tests. A result was considered purely coincidental if 50% of the animals decided in favor of an odor and 50% decided against. The odor is considered attractive if more than about 65% of the animals move towards it. Because of the nature of the experiment, a decision rate of nearly 100% is not to be expected, because elements of other behavior patterns in which odors do not play any role (e.g. escape, stress) are also always a factor. The certainty of the evaluation increases with the number of tests and is accepted after about 10 repetitions. FIG. 7 presents a selection of the results, wherein an attractant concentration of 0.01 μg/μL was used for the tests from which these results derive.

(73) Hexane, the solvent used, has no effect on the directional decision. A precisely coincidental distribution of 50% of the controls also demonstrated that there was no preference for one side or the other in the olfactometer.

(74) Some of the pure attractants demonstrated very strong attracting action. For instance, 80% of the true bugs ran in the direction of the attractant when offered (Z)-3-hexen-1-ol or (E)-β-caryophyllene. The sexual attractant hexyl butyrate, which is described as attractive in the literature, was not preferred in olfactometer experiments. Attraction was also attained with a three-component mixture. In addition, it was found that the concentrations of the individual attractants influenced the outcome. For example, it was found that an increase in the concentration can change the attracting action. Thus, e.g. the effect of (Z)-3-hexen-1-ol and β-caryophyllene is reduced in increased concentrations, while that of nonanal increases, wherein nonanal at a concentration of 0.01 μg/μL had an attracting action of about 45%, and at a concentration of 1 μg/μL had an attracting action of about 60%.

(75) The attractant concentrations that may be released with the liquid-core capsules according to the invention are in the range of perception for true bugs, as the olfactometer tests conducted confirm. Consequently, the true bugs register the odor mixture used at least in the investigated concentration range from 10 ng to 10 μg. A very good attracting action was found at a concentration of 100 ng. This required release range may be attained with nothing further with the functional outer shell of the liquid-core capsules according to the invention.

(76) G Electrophysiological Examinations of True Bugs

(77) Electroantennography is a method for measuring the olfactory reactions of an insect by recording electrical signals on the antennae, wherein slow changes in receptor potential that are preferably recorded in the extracellular space within the insect antenna are analyzed. Complex odor mixtures may be investigated using this method. For instance, the use of electroantennography for identifying attractants for wasps is known from DE 11 2010 005 095 T5.

(78) FIGS. 8 and 9 summarize the results of electrophysiological examinations of true bugs. Green leaf volatiles (Z)-3-hexenyl acetate, (Z)-3-hexen-1-ol, 1-hexenal, the terpenoids (E)-β-caryophyllene, methyl salicylate, ocimene, phenylacetaldehyde, nonanal, alpha-pinene, and geraniol were tested as plant odors, hexyl butyrate and (E)-2-hexenyl butyrate were tested as pheromones of insects, and a synthetic active substance mixture made of (Z)-3-hexen-1-ol, (E)-β-caryophyllene, and hexyl butyrate were tested. FIG. 8 provides the responses in female (a) and male (b) true bugs at an active substance concentration of 0.1 μg/μL. FIG. 9 provides the responses in female (a) and male (b) true bugs at an active substance concentration of 10 μg/μL.

(79) The results show that the true bugs have chemoreceptors on their antennae and they are quite able to register the group of pheromones and GLVs with these chemoreceptors. Of the group of eating-induced plant odors, only nonanal and phenylacetaldehyde were registered in the higher concentration, wherein nonanal was essentially registered by the females. The strength of the antenna stimulation in the odor mixture also demonstrated in principle a possible increase in the attracting action when active substances are combined.