LIQUID-CORE CAPSULES FOR PEST CONTROL

Abstract

Liquid core capsules are provided for pest control, wherein the liquid-core capsules have a liquid core comprising entomopathogenic nematodes and a surrounding hydrogel shell. The liquid core comprising the nematodes is formed on the basis of an emulsion comprising at least an oil and an aqueous liquid.

Claims

1. Liquid-core capsules for pest control, wherein the liquid-core capsules have a liquid core comprising entomopathogenic nematodes and a surrounding hydrogel shell, wherein the liquid core is formed on the basis of an emulsion comprising at least an oil and an aqueous liquid.

2. The liquid-core capsules according to claim 1, wherein the at least one oil is a vegetable oil, preferably sunflower seed oil and/or rapeseed oil and/or olive oil.

3. The liquid-core capsules according to claim 1, wherein the proportion of oil in the emulsion is at least 10% and at most 70% (w/w).

4. The liquid-core capsules according to claim 1, wherein the surrounding hydrogel shell is an alginate shell, in particular a calcium alginate shell.

5. The liquid core capsules according to claim 1, wherein the hydrogel shell comprises at least one additive, in particular a cellulose-based compound, preferably methyl cellulose, and/or at least one thickener, preferably xanthan and/or locust bean gum.

6. The liquid-core capsules according to claim 1, wherein the liquid-core capsules comprise an average of 1,000 to 15,000 nematodes per liquid-core capsule, preferably 1,500 to 7,500 nematodes per liquid-core capsule, particularly preferably 1,500 to 2,000 nematodes per liquid-core capsule.

7. The liquid core capsules according to claim 1, wherein the liquid-core capsules have an average diameter of between 1 to 30 mm, preferably between 3 to 10 mm, particularly preferably 3 to 6 mm.

8. The liquid-core capsules according to claim 1, wherein the liquid-core capsules have an average weight per liquid-core capsule of between 10 to 100 mg, preferably between 40 to 80 mg, particularly preferably 40 to 60 mg.

9. The liquid-core capsules according to claim 1, wherein the liquid-core capsules further comprise at least one attractant for the pests to be controlled, preferably at least one essential oil.

10. The liquid-core capsules according to claim 1, wherein the nematodes are representatives of the species Steinernema carpocapsae and/or Steinernema feltiae and/or Steinernema kraussei and/or Heterorhabditis bacteriophora and/or Heterorhabditis downesi and/or Phasmarhabditis hermaphrodita.

11. A plant substrate, wherein the liquid-core capsules according to claim 1 have been added thereto.

12. A method for the production of the liquid-core capsules according to claim 1, wherein the emulsion comprising the nematodes is dropped into a hydrocolloid solution in the presence of divalent ions.

13. The method according to claim 12, wherein the emulsion is stabilized at least for the period of the dropping-in process by the use of emulsifiers.

14. A method for controlling pests, wherein the liquid-core capsules according to claim 1 are applied to a plant stock.

15. The method according to claim 14, wherein the liquid-core capsules are used in a dosage of between 1 to 1,000 liquid-core capsules, preferably between 10 to 500 liquid-core capsules, per m.sup.2 of substrate area.

Description

[0045] Further features and advantages of the invention result from the following description of embodiments in connection with the drawings. The individual features here can each be implemented individually or in combination with one another.

[0046] In the drawings it is shown:

[0047] FIG. 1 Diagram of the weight loss of the liquid-core capsules (emulsion capsules) according to the invention in comparison with liquid-core capsules containing an aqueous core (water capsules) at 22° C. and 40% relative humidity;

[0048] FIG. 2 Diagram of the weight loss of the liquid-core capsules (emulsion capsules) according to the invention in comparison with liquid-core capsules containing an aqueous core (water capsules) at 25° C. and 70% relative humidity;

[0049] FIG. 3 Diagram of the weight loss of the liquid-core capsules (emulsion capsules) according to the invention in comparison with liquid-core capsules containing an aqueous core (water capsules) at 4° C. and 40% relative humidity;

[0050] FIG. 4 Vitality profile of the nematodes encapsulated according to the invention after application in a plant substrate;

[0051] FIG. 5 Comparison of the vitality of the nematodes in liquid-core capsules according to the invention (emulsion capsules) and in liquid-core capsules containing an aqueous core (water capsules) over time at 100% relative humidity;

[0052] FIG. 6 Effect of the nematodes (Steinernema carpocapsae) encapsulated according to the invention on mealworms as a reference organism in comparison with a watering application of the nematodes; and

[0053] FIG. 7 Effect of the nematodes (Steinernema feltiae) encapsulated according to the invention on mealworms as a reference organism in comparison with a watering application of the nematodes.

EXAMPLARY EMBODIMENTS

EXAMPLE 1

Production of the Liquid-Core Capsules

[0054] A preferred production process for the liquid-core capsules according to the invention is described in the following example. A Rotarus® multi-channel peristaltic pump having eight hoses (Hirschmann, Germany), two magnetic stirrers, stands, a dispersing device (ULTRA-TURRAX®, IKA-Werke GmbH & Co. KG, Germany), a mechanical stirrer, beakers and a sieve are provided for dripping and rinsing the capsules. Alternatively, drop formation by means of nozzles is also suitable for the production of the liquid-core capsules, in particular for the production of the liquid-core capsules on a larger scale.

[0055] In a preferred embodiment, 250 g of sunflower seed oil and 500 g of water are weighed out for the production of about 1 kg of liquid-core capsules and an emulsion is produced by means of ULTRA-TURRAX®. An emulsifier (1.2% by weight E405) is added to stabilize the emulsion. Furthermore, 3% by weight of calcium chloride is also added. A commercially available nematode product containing 50 million animals is suspended in 20 ml of water in a separate beaker. The nematode supply vessel is rinsed with 10 ml of water and both suspensions are combined. The 30 ml of the liquid having the nematodes are added to the emulsion and gently stirred in until a homogeneous mixture is formed. The vessel containing the resulting liquid for the core is attached to a stand, the eight hoses of the multi-channel pump being immersed in the liquid in this vessel.

[0056] The water used to produce the liquid for the core can be enriched with oxygen. This can have a further beneficial effect on the vitality of the nematodes. The water enriched with oxygen can be produced to make the emulsion and/or the suspension of the nematodes.

[0057] 1% by weight of sodium alginate (E401) is dissolved in water to prepare the hydrocolloid solution for the shell. Additives or stabilizers are optionally added, for example, methyl cellulose. The liquid for the core (emulsion containing nematodes) is pumped by means of the peristaltic pump for the dropping process. The outlet openings or their diameter can be adjusted depending on the desired droplet size, wherein different hose variants and/or additional elements such as pipette tips can be used. The height of the hoses above the provided solution can be varied depending on the drop weight in order to obtain round capsules that are as homogeneous as possible. The drop weight can be between 10 and 90 mg, for example. The diameter of the capsules can vary from a few millimeters to a few centimeters. The capsule shell forms immediately when the liquid for the core is dropped into the provided hydrocolloid solution. The calcium in the core liquid reacts immediately with the alginate in the provided solution. This forms the shell and the shape of the drop is directly stabilized. The thickness of the shell can be adjusted depending on the ratio of calcium to alginate, optionally plus additives. The dwell time of the capsules in the provided solution after being dropped in can also be used to influence the shell thickness. The reaction ends when all free calcium ions are consumed, or the reaction is terminated by sieving the capsules and then rinsing them with water. The capsule shell can then optionally be further solidified. For solidification, the capsules can be placed in a CaCl.sub.2 bath, for example, so that the hydrogel shell is saturated with calcium ions and thereby hardened. The liquid-core capsules are then ready for use or can be stored. The liquid-core capsules are expediently portioned, packaged and labeled for transport.

[0058] The liquid-core capsules produced in this way were examined with regard to water loss or drying out in comparison with liquid-core capsules containing an aqueous core. The aqueous core here means that apart from the nematodes, only water is contained in the core. The water loss was determined from the measured weight loss of the capsules. For these experiments, the capsules were placed in petri dishes and exposed to the respective conditions with regard to temperature and humidity. FIG. 1 shows the water loss of the liquid-core capsules at 22° C. and 40% relative humidity, FIG. 2 shows the water loss of the liquid-core capsules at 25° C. and 70% relative humidity and FIG. 3 shows the water loss of the liquid-core capsules at 4° C. and 40% relative humidity. In each case, the course of the water loss is shown for the liquid-core capsules (emulsion capsule) according to the invention and liquid-core capsules containing water in the core (water capsule). In all the conditions tested, it can be clearly seen that the drying out of the liquid-core capsules according to the invention is less than that of the liquid-core capsules containing water in the core. For example, for the water capsules at 22° C. and 40% humidity (FIG. 1), a weight loss of 80% is already achieved after 4 h. With the emulsion capsules, a weight loss of just under 80% can only be observed after 24 h. The weight loss is due to the evaporation of water from the shell and core. With the water capsules, a water or weight loss of almost 100% can be observed after 24 h. So by this point, the water capsules have, in a sense, dried up and shrunk greatly to a raisin-like shape. Even after 48 h, the emulsion capsules only show a weight loss of just under 80% and are round to oval in shape. This means that there is still a liquid portion in the emulsion capsules at this point in time, which is largely formed by the oil portion of the emulsion. The decisive factor here is that the vitality of the nematodes is still present at this point in time, as observed microscopically. The vitality of the nematodes can be traced back to the water that is still present, since said nematodes must be surrounded by at least a thin film in order to survive. However, the nematodes in the dried-out water capsules were no longer vital at this point in time. A very similar course was observed under the conditions of 25° C. and 70% humidity (FIG. 2), wherein the maximum evaporation was somewhat lower in both the water capsules and the emulsion capsules. At 4° C. (FIG. 3), the overall evaporation was significantly delayed for both capsule types.

[0059] When evaluating these test results, it should be noted that the experimental arrangement does not reflect the conditions for using the liquid-core capsules in a plant stock. In a plant stock, a certain degree of moistening of the liquid-core capsules is or should generally be ensured, so that complete evaporation of the aqueous portion should not occur. As the inventors were able to show in application experiments in plant cultures, the emulsion capsules show their effect over several weeks, in which nematodes leave continuously. Nevertheless, even under dry conditions, there would be a clear advantage of the emulsion capsules over water capsules, since the nematodes are still surrounded by a film of water by means of the water-in-oil emulsion and retain a certain level of vitality when the capsules are maximally dehydrated.

EXAMPLE 2

Examination of the Course of Vitality of the Nematodes Encapsulated According to the Invention After Application in a Plant Substrate

[0060] Emulsion capsules were produced with Steinernema carpocapsae according to Example 1 and mixed with a commercially available plant substrate (Floradur® B Seed, Floragard Vertriebs-GmbH, Germany). After this application, the plant substrate was kept permanently moist at 25° C. and the vitality of the nematodes was observed for 35 days. For each time point examined, 4 Petri dishes, to which 3 capsules had been added in each case, were set up with substrate. The evaluation was carried out microscopically by examining the substrate, wherein the ratio of the vital nematodes to the recognizable nematodes was determined overall. The measuring points in FIG. 4 represent mean values of the 4 shells considered in each case. The line represents a regression line. On average, the investigation shows a certain decrease in the vitality of the nematodes over a period of 35 days, the vitality dropping from around 85% at the beginning to around 60% after 35 days. Nevertheless, even after 35 days, a significant proportion of vital nematodes are still present in the emulsion capsules.

EXAMPLE 3

Comparative Examination of the Vitality of the Nematodes in Liquid-Core Capsules (Emulsion Capsules) According to the Invention and in Liquid-Core Capsules Containing an Aqueous Core (Water Capsules) Over Time at 100% Relative Humidity

[0061] Nematodes (Steinernema carpocapsae) (emulsion capsules) encapsulated according to the invention according to Example 1 and capsules having an exclusively aqueous core (water capsules) produced in a comparable manner were observed in Petri dishes (d=90 mm) at 25° C. and about 100% relative humidity over a period of 22 days. The proportion of vital nematodes compared to the total proportion of nematodes was determined microscopically after 7 days, 14 days and 22 days. The results are shown in FIG. 5. Under the conditions set here (100% relative humidity), the capsules do not dry out significantly. Nevertheless, a clear difference in the vitality of the nematodes can be determined after just 7 days. While a vitality of about 90% can be observed in the emulsion capsules, only 70% of the nematodes are vital in the water capsules. After 14 days, the vitality of the nematodes in the water capsules has dropped to 0%. The vitality of the nematodes in the emulsion capsules is still 80% at this point in time, but then drops to 10% by day 22. These results show that the oil content itself in the liquid-core capsules according to the invention exerts a positive effect on the vitality of the nematodes, regardless of its positive influence on drying out.

EXAMPLE 4

Examination of the Effect of the Nematodes Encapsulated According to the Invention (Steinernema carpocapsae, Steinernema feltiae, Heterorhabditis bacteriophora) on Mealworms as a Reference Organism in Comparison with a Watering Application of the Nematodes

[0062] An experiment was carried out to investigate the effect of the nematodes encapsulated according to the invention (Steinernema carpocapsae) in comparison with a watering application of the nematodes. The effect on mealworms was examined for this purpose. Mealworms (larvae of the flour beetle Tenebrio molitor) are an established reference organism for analyzing the effects of entomopathogenic nematodes (EPN). For the experimental arrangement, 1 l of plant substrate (Floradur® B Seed, Floragard Vertriebs-GmbH, Germany) was loosely poured into rectangular trays 170×130×120 mm (L×W×H). 55,000 EPN in liquid were poured onto the substrate for the liquid application (positive control). The liquid used for this test was the emulsion which represented the core solution in the production of the liquid-core capsules according to the invention. As the negative control the substrate was not treated further. For the application of the nematodes encapsulated according to the invention, an average of 12 capsules having a total of 55,000 EPN, which had been produced according to Example 1, were mixed into the substrate. 40 mealworms were then placed on the substrate. Because the non-encapsulated core solution, so to speak, was used for the suspension of the nematodes in the positive control, the approach using the watering application and the approach using the nematode capsules according to the invention differs solely in the capsule form of the nematode preparation. The experimental arrangement was observed over a period of 6 weeks, all mealworms being removed weekly and replaced with new mealworms (40 mealworms per batch). The nematodes were applied only once at point in time zero.

[0063] FIG. 6 shows the experimental results, wherein the individual measurement points represent the average mortality of the mealworms in percent (degree of effectiveness). The lines represent polynomial regressions. The sample size for the negative control was n=53, for the positive control n=33 and for the approach using the nematodes encapsulated according to the invention n=39. This means that a total of 53 experimental batches were evaluated for the negative control, a total of 33 experimental batches were evaluated for the positive control and a total of 39 experimental batches were evaluated for the approach using the nematodes encapsulated according to the invention. In weeks 1 and 2 (W 1 and W 2), after the application of the EPN, there was still no difference between the watering application (positive control) and the application of the liquid-core capsules according to the invention. In week 3 (W 3), however, only 60% mortality of the mealworms can be observed in the watering application, whereas the mortality of the mealworms in the liquid-core capsules according to the invention is still in the range of 90%. In the following weeks, the effect of the nematodes from the watering application on the mealworms decreases significantly and by week 6 (W 6), it falls to only 10%, which corresponds to the negative control without any application of nematodes. The effect of the liquid-core capsules according to the invention at time W 6, on the other hand, is still present with a mortality of about 55%. Overall, therefore, the application of the EPN in the form of the liquid-core capsules according to the invention is clearly superior to a watering application.

[0064] Emulsion capsules having Steinernema feltiae and Heterorhabditis bacteriophora were produced in a corresponding manner according to Example 1 and the effect of the emulsion capsules on the mortality of mealworms as a reference organism was examined according to the experimental approach described above.

[0065] FIG. 7 shows the experimental results with Steinernema feltiae, the individual measurement points representing the mean mortality of the mealworms in percent (degree of efficiency). Liquid-core capsules having Steinernema feltiae were examined in comparison to an untreated variant (negative control) and a variant applied as a watering formulation (positive control). Test conditions: 40 mealworms, 1 liter substrate, 200 cm.sup.2 area, 2 liter vessel, 25° C. A summary of 47 test series in three repetitions is shown. The filled circles represent the mean mortality after application of 20 capsules with a total of approximately 31,000 EPN. The filled rectangles represent the mean mortality after application of approximately 31,000 EPN in liquid (watering formulation). The filled triangles represent the mean mortality without application of EPN. The lines show the polynomial regressions of the respective measurement points.

[0066] It was also shown here (comparable to FIG. 6) that the application of the EPN in the form of the liquid-core capsules according to the invention is clearly superior to a watering application.

[0067] Liquid-core capsules according to the invention were also produced according to Example 1 using Heterorhabditis bacteriophora and examined with regard to their effect on mealworms (data not shown). In the first experiments, the effect of the liquid-core capsules was at least comparable to the watering application of the nematodes, so that the results show that Heterorhabditis bacteriophora can also be applied effectively in the form of the liquid-core capsules according to the invention and the special advantages of the liquid-core capsules according to the invention can thus be used, for example, with regard to shelf life and with regard to the special advantages during application in comparison with the conventional watering application.

EXAMPLE 5

Application of Liquid-Core Capsules in Plant Culture

[0068] For the following application examples, capsules are provided with an average nematode density of around 2,400 animals (Steinernema carpocapsae or Steinernema feltiae) per liquid-core capsule. This corresponds to around 16.5 million EPN/kg capsules.

[0069] For the first application, plant pots measuring 12×12×12 cm (for example, Göttinger square container) are filled with plant substrate (for example, “Floradur® B Seed” from Floragard) to a height of about 8 cm. The seedlings (for example, young cucumber plants) are placed therein or, alternatively, seeds of plants to be cultivated (for example, parsley) are spread on. Three liquid-core capsules are spread onto the substrate surface and the pots are then covered with a further substrate layer of about 2 cm. In principle, all conceivable methods, with which the liquid-core capsules can be worked into the substrate manually or mechanically in a comparable manner, can be used. In commercial plant production, the liquid-core capsules are particularly preferably incorporated into the substrate by machine. For example, the capsules can be injected into the substrate using fertilizer lances. This method is preferably suitable for application in individual vessels. The capsules can be spread onto the substrate and then covered with a further layer of substrate by means of so-called potting machines or sowing devices.

[0070] After application, the substrate is watered with sufficient water so that it is evenly moistened. Further plant cultivation takes place in the usual way, according to the required plant-specific conditions. In particular, prolonged dry phases in the substrate should be avoided over the entire cultivation period.

[0071] For a cultivation period of more than 4 weeks and a persistent pest infestation, follow-up treatment is preferably carried out at four-week intervals. About three capsules are spread on a plant pot and gently worked into the substrate with a small rod or a spoon, for example, so that the capsules are covered by about 1 to 2 cm of substrate. Alternatively, a planting stick can press a hole in the substrate, for example. The liquid-core capsules are then inserted and the holes closed again with some substrate.

[0072] The liquid-core capsules can also be used in the same way with all known organic or artificial plant substrates, substitutes (for example, expanded clay, vermiculite, perlite, rock wool, foam materials) or any customary mixtures of different substrates and substitutes.

EXAMPLE 6

Application of the Liquid-Core Capsules in Foam Elements for Plant Culture

[0073] For these application examples, capsules with an average nematode density (Steinernema carpocapsae or Steinernema feltiae) of approximately 2,400 animals per liquid-core capsule are provided. This corresponds to around 16.5 million EPN/kg capsules.

[0074] When cultivating plants (for example, orchids) in cylindrical foam elements (for example, diameter 7 cm), the foam elements are cut vertically up to about the central axis. A shoot section is inserted into the resulting notch together with 1 to 2 capsules. The foam element is then slightly compressed and placed in a suitable vessel (for example, round pots, diameter 6 cm), which prevents it from expanding again and thus provides the shoot with sufficient support.

[0075] After application, the foam element is watered with sufficient water so that it is evenly moistened. Further plant cultivation takes place in the usual way, according to the required plant-specific conditions. In particular, prolonged dry phases in the substrate should be avoided over the entire cultivation period.

[0076] For a cultivation period of more than 4 weeks and a persistent pest infestation, follow-up treatment is preferably carried out at four-week intervals. To do this, the foam elements are removed from the planter, two liquid-core capsules are inserted into the notch, slightly pressed together and placed back into the planter.

EXAMPLE 7

Application of the Liquid-Core Capsules in the Production of Substrate for Plant Culture

[0077] For this application example, capsules with an average nematode density (Steinernema carpocapsae or Steinernema feltiae) of approximately 7,200 animals per liquid-core capsule are provided. This corresponds to around 50 million EPN/kg capsules.

[0078] During the production of substrate (for example, “Floradur® Pot Cyclamen/Poinsettia” from Floragard), in which the different components are mixed (white peat, black peat, water, carbonated lime, fertilizer, wetting agent), approximately 100 g capsules per m.sup.3 of substrate are introduced into the mixing process. The final mixture is preferably delivered from the substrate manufacturer to the user within a week. Users are, for example, companies that produce ornamental plants. The type of delivery takes place in the conventional manner as bagged goods or as loose goods. The user processes the substrate in the usual way, preferably within 2 weeks, for example, for repotting cyclamen, potted roses, poinsettias or hydrangeas in plant pots 12×12×12 cm. After processing, there is an average of 7,200 EPN in a pot, partly present in the capsule and partly already distributed in the substrate.

EXAMPLE 8

Application of the Liquid-Core Capsules to Control Snails

[0079] Capsules containing nematodes of the species Phasmarhabditis hermaphrodita with a density of preferably about 1,000 animals per liquid-core capsule are provided. This corresponds to around 7 million EPN/kg capsules. The amount is sufficient to treat about 100 m.sup.2 of cultivated area.

[0080] Ideally, the application should take place at a time when snails are more common, for example, in warm, humid weather and little sunlight. For application, the liquid-core capsules are spread on the soil of the culture area to be treated. This can be done by hand in the simplest case and for small areas. Suitable technical means, for example, commercially available fertilizer or seed spreaders, can be used for larger areas. The liquid-core capsules are preferably applied where increased snail movements are to be expected, thus, for example, around the crops (for example, lettuce), between the rows of plants, on the edges of the crop area and on the edges of neighboring areas that are attractive for snails, into which the snails often retreat during the day and when it is dry. The culture area is kept moist after application.

[0081] For a cultivation period of more than 3 weeks and a persistent snail infestation, follow-up treatment is preferably carried out at three-week intervals. The follow-up treatment is carried out in the same way as previously described.

EXAMPLE 9

Use of Steinernema feltiae in the Form of Liquid-Core Capsules for Controlling the Larvae of Fungus Gnats in the Home and Garden or in Commercial Horticulture

[0082] Liquid core capsules containing the nematodes Steinernema feltiae were produced in principle according to Example 1, the material composition of the liquid-core capsules shown in the table below having been set:

TABLE-US-00002 Weight percentage of total Designation E number mass [%] Desalinated tap water — 72.8 Sunflower oil — 22.1 Nematodes (product — 3.7 nemaplus ®, e-nema GmbH, Germany) Calcium chloride E509 <1 Propylene glycol alginate E405 <1 (dissolved) Sodium alginate (natural E401 <1 substance)

[0083] Packaging units containing 50 million nematodes were provided for use in commercial horticulture, for example. Each packaging unit comprised about 32,000 individual capsules with a total weight (wet weight) of about 1.6 kg, said weight having been subject to certain fluctuations due to different amounts of water adhesion. The capsule size had an average diameter of 4-5 mm and the pouring properties of the capsules showed good flowability.

[0084] The primary packaging was in foil bags or vessels made of plastic which were provided with small holes on one side for oxygen supply to the nematodes. The filling level of the liquid-core capsules was between 5 and 10 cm.

[0085] Dark and cool storage (4-10° C.) was suitable as storage conditions. The shelf life was at least 2 months. During storage, regular mixing of the capsules, for example, by turning the vessels or bags several times, is recommended in order to optimize the oxygen supply to the nematodes. It was recommended not to cover the perforated areas of the packaging for longer periods and to let the water that emerged from the packaging drain off.

[0086] The capsules were introduced in the plant substrate or in the seed hole when the seeds were sown or seedlings were planted. With substrate mixtures, about 50 million nematodes were used for 2.5 m.sup.3 of substrate and were evenly distributed in the substrate. Alternatively, capsules were placed directly in the plant pot, for example, in the seed hole, wherein an average of 6-7 capsules, that is, around 10,000 nematodes per pot, were used per plant pot with a maximum filling volume of 1 l. Alternatively, the capsules were applied to the plant substrate and covered with at least 2 cm of substrate. The plant substrate was kept culture-moist during use.

[0087] These amounts were used for a light initial infestation or preventative treatment.

[0088] After introducing the capsules in the plant substrate, the shell of the capsules became permeable after about 1 week and the nematodes gradually migrated. Over a period of several weeks, more and more new nematodes got into the substrate and were able to effectively control fungus gnats the first time they appeared. In comparison to the application of nematodes by watering application, the treatment with the capsules had an almost doubled duration of action and could therefore also have a preventive effect against the larvae of the fungus gnat. The duration of action was about 6 weeks, the highest effectiveness observed between the 2nd and 4th week after application.