SYSTEM FOR SPRAYING A COMPOSITION OF LIVE BIOLOGICAL CONTROLS

Description

FIELD OF THE INVENTION

[0001] The invention relates to a system for the dispersal of live biological control agents, for example from the phytoseid family of the genus Phytoseiulus. STATE OF THE ART

[0002] During the dispersal of predatory mites of the genus Phytoseiulus, Traditionally, bottles containing an inert solid support, such as vermiculite, are used, in which the mites move. The mites naturally move towards the top of the packaging, resulting in a very uneven distribution of mites as they exit the bottles.

[0003] It is also known to deposit the support directly onto the plants targeted for biological control. However, the support can fall off the plants, resulting in the loss of predatory mites and thus a decrease in the effectiveness of this biological control method.

[0004] Therefore, there is a need for another method of dispersing live and mobile mites in an aqueous environment onto plants or growing media as part of a biocontrol strategy.

[0005] However, mites of the genus Phytoseiulus are known to be fragile, strictly aerial and unsuited to the aquatic environment, for example when they are at ground level, because they only frequent the aerial part of plants where their prey are found.

[0006] US document 5,735,459 A describes a support configured for suspending biological control agents, the support having adjustable adhesive properties so as to deposit and retain the biological control agents in a target area of ​​the treated plant. DISCLOSURE OF THE INVENTION

[0007] One aim of the invention is to provide a system for dispersing live biological control agents homogeneously in cultures.

[0008] This objective is achieved within the framework of the present invention through a system for dispersing live biological control agents, comprising: a reservoir of live biological control agents in liquid phase, a pressurized air source, a nozzle, the nozzle being connected to the reservoir of biological control agents by a biological control agent line, and to the pressurized air source by a pressurized air line, the nozzle comprising a spray mouth, the biological control agent conduit having a liquid phase outlet adapted to allow a liquid phase jet to exit the mouthpiece in a principal direction, and the pressurized air conduit having at least one air outlet, the mouthpiece comprising a wall, the liquid phase outlet being defined by an orifice on the wall of the mouthpiece, the air outlet(s) being arranged on the wall of the mouthpiece, the shape of the wall being configured to direct a principal air flow exiting the air outlet(s) convergently towards the liquid phase jet, the principal air flow preferentially having axial symmetry with respect to the principal direction.

[0009] The invention is advantageously complemented by the following features, taken individually or in any of their technically possible combinations: The nozzle comprises at least two air outlets arranged symmetrically with respect to the main direction, the shape of the wall being configured to direct a first airflow exiting one of the air outlets towards the liquid phase jet, and to direct a second airflow exiting the other air outlet towards the liquid phase jet, the first and second airflows being symmetrical with respect to the main direction. The system comprises a liquid-phase enzyme reservoir, the enzyme reservoir being fluidly connected to the biological control agent line, preferably by a mixer adapted for mixing live liquid-phase biological control agents and an enzyme solution. The system comprises means for pressurizing the biological control agent reservoir and / or the enzyme reservoir.adapted to induce flow from the biological control agent reservoir and / or from the enzyme reservoir to the liquid phase outlet, the orifice has a diameter greater than 1 mm, and preferably greater than 1.5 mm, the pressurization means are implemented by a pressurization line connecting the pressurized air line and the biological control agent reservoir, and / or connecting the pressurized air line and the enzyme reservoir, the biological control agent reservoir comprises an aqueous composition, and biological control agents are dispersed in the aqueous composition, the aqueous composition comprises a gel prepared from one or more thickeners and / or gelling agents and an aqueous solution, the live biological control agents being homogeneously dispersed in the gel,said thickeners and / or gelling agents being non-toxic to said biological control agents and said gel having a zero-velocity gradient dynamic viscosity between 1 and 30,000 mPa.s, the live biological control agents are motile, the live biological control agents are selected from the group consisting of mites and / or mite predatory insects, the live biological control agents are mites of the family Phytoseiulus, the live biological control agents are insects of the type, Chrysopral predators of insect pests, particularly aphids,

[0010] Another object of the invention is a method for dispersing live, preferably mobile, biological control agents, the method comprising a step of spraying an aqueous composition of live biological control agents by a system according to an embodiment of the invention, in which a main air flow is driven from the pressurized air source to the spray nozzle, a flow of an aqueous composition comprising the live biological control agents in liquid phase is driven to the orifice, an average velocity of the air flow in the air line being adapted to spray the aqueous composition by shearing the aqueous composition by the air flow.

[0011] Advantageously, the diameter of the orifice and the average velocity of the aqueous composition flow are adapted so that the liquid phase jet is not sprayed out of the orifice.

[0012] Advantageously, the aqueous composition comprising the biological control agents is sprayed only by the main air flow after exiting the orifice.

[0013] Advantageously, in a method according to an embodiment of the invention, the system includes means for pressurizing the biological control agent reservoir adapted to cause a flow from the biological control agent reservoir and / or from the enzyme reservoir to the liquid phase outlet, and the pressurization means are controlled so as to impose a pressure strictly less than 3 bar in the biological control agent reservoir, and preferably less than 0.5 bar. DESCRIPTION OF FIGURES

[0014] Other features, purposes and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which: [ Fig. 1 ] There figure 1 schematically illustrates a system for the dispersal of live biological control agents according to an embodiment of the invention. Fig. 2 ] There figure 2 illustrates the survival rate of live biological control agents after being dispersed by a system according to an embodiment of the invention and by other systems. Fig. 3 ] There figure 3 illustrates the survival rate of live biological control agents after being dispersed by a system according to four embodiments of the invention.

[0015] Across all figures, similar elements bear identical references. DEFINITION

[0016] In all the embodiments of the invention described, "bar" means a unit of pressure exactly equal to 100,000 pascals, the zero point of which corresponds to atmospheric pressure. The "bar" thus defined is also called a "gauge bar" (denoted barg), the definition of which is strictly identical. The term "bar" does not mean a unit of absolute pressure, denoted "para," the zero point of which represents absolute vacuum. DETAILED DESCRIPTION OF THE INVENTION Architecture générale du système

[0017] With reference to the figure 1A system 1 for dispersing live biological control agents includes a reservoir of live biological control agents 6 in liquid phase. The reservoir of biological control agents 6 may have a volume greater than two liters, preferably greater than five liters, and in particular greater than 10 liters. The reservoir of biological control agents 6 may preferably comprise an aqueous composition 18, the aqueous composition 18 comprising dispersed live biological control agents.

[0018] System 1 also includes a pressurized air source 3. The pressurized air source 3 can preferably be implemented by a ventilation turbine 5, which allows system 1 to be portable while allowing the pressurized air source 3 to produce air with a pressure greater than 1 bar, preferably greater than 2 bar.

[0019] System 1 includes a nozzle 2. The nozzle 2 is connected to the biological control agent reservoir 6 by a liquid-phase biological control agent line 8. The biological control agent line 8 is preferably a flexible tube. The biological control agent line 8 has a liquid-phase outlet 15.

[0020] The nozzle 2 is also connected to the pressurized air source 3 by a pressurized air line 4. The pressurized air line 4 is preferably a flexible tube. The pressurized air line 4 has an air outlet 16.

[0021] The nozzle 2 includes a spray outlet 13. The biological control agent line 8 has a liquid phase outlet 15 adapted to allow a liquid phase jet 12 to exit the outlet 13 in a main direction 20. A "liquid phase jet" is defined as a continuous flow of liquid phase surrounded by a gaseous phase, which is not atomized into droplets. Immediately after the liquid phase 15 exits the orifice 21, during system operation, the liquid phase jet 12 is not yet atomized. The pressurized air line 4 has at least one air outlet 16. The pressurized air source 3 can be configured so that the air, at the inlet 13, and preferably at the air outlet(s) 16, has a velocity between 5 m / s and 30 m / s, in particular between 10 m / s and 25 m / s. The inlet 13 includes a wall 19.The liquid phase outlet 15 is defined by an orifice 21 on the wall 19 of the mouth 13. The air outlet(s) 16 are also arranged on the wall 19 of the mouth 13. The shape of the wall 19 is configured to direct a main air flow 17 exiting from the air outlet(s) 16 convergently towards the liquid phase jet 12, the main air flow 17 preferentially having axial symmetry with respect to the main direction.

[0022] Thus, an aqueous composition containing live biological control agents can be predominantly, and preferably exclusively, sprayed by the airflow encountering the liquid phase jet containing the aqueous composition at the liquid phase outlet 15. Shear forces are applied at the interface of the aqueous composition. This shear forces the jet, and therefore the aqueous composition, into very small droplets. A sprayed jet 22 is thus produced at the nozzle outlet 2.

[0023] Since this shearing is achieved by air at the interface of the composition, the composition can be atomized, significantly increasing the survival rate of the live biological control agents in the aqueous composition. The inventors discovered that the passage of live biological control agents through a nozzle that causes atomization by mechanical stress of a solid portion is detrimental to their survival after dispersion, due to the risk of injury to the agents, particularly when the pressure applied to the aqueous composition exceeds 0.5 bar. Nozzle 2 according to one embodiment of the invention avoids this cause of mortality for the live biological control agents.

[0024] With reference to the figure 1The nozzle 2 comprises at least two air outlets 16 arranged symmetrically with respect to the main direction 20, the shape of the wall 19 being configured to direct a first airflow exiting from one of the air outlets 16 towards the liquid phase jet 12, and to direct a second airflow exiting from the other air outlet 16 towards the liquid phase jet 12, the first airflow and the second airflow, forming the main airflow 17, being symmetrical with respect to the main direction 20. Thus, it is possible to spray the liquid phase jet 12 comprising the aqueous composition predominantly by air / liquid contact, and preferably only by air / liquid contact, in a direction determined by the position in space of the nozzle 2.

[0025] Alternatively, the air outlet 16 can be defined by a ring completely surrounding the orifice 21. Alternatively, the wall can have four or more air outlets 16, for example eight air outlets 16, arranged symmetrically around the orifice 21.

[0026] Preferably, the shape of the wall can be configured so that the direction of the main airflow 17 forms an angle with the main direction 20 of between 30 and 60 degrees, and preferably between 40 and 50 degrees. Thus, the atomization of the aqueous composition can occur both by shearing the airflow upon contact with the aqueous composition flow and by the entry of the airflow into the aqueous composition flow, and by the convergence of the air jets towards the aqueous composition flow.

[0027] The diameter of orifice 21 is configured so that, for a predetermined flow rate of the aqueous composition, or for a predetermined average flow velocity of the aqueous composition 18 in the biological control agent conduit 8, the exit of the liquid phase jet, comprising the aqueous composition 18, from the nozzle 13 does not cause spraying of the aqueous composition. Thus, the live biological control agents can exit the nozzle 2 without experiencing mechanical stress strong enough to injure them as they pass through orifice 21. Indeed, spraying is physically driven by both a sufficiently small orifice diameter and a sufficiently high flow velocity.Thus, a person skilled in the art, for a predetermined flow velocity, will be able to adjust the orifice diameter in such a way—that is, sufficiently large—that the liquid phase jet is not predominantly atomized by orifice 21. Furthermore, the diameter of orifice 21 is chosen according to the size of the live biological control agents. Preferably, the diameter of orifice 21 is chosen to be more than twice, and in particular more than three times, the size of the live biological control agent. In this way, the live biological control agent undergoes limited shear, which increases the survival of the live biological control agents at the outlet of system 1 during their dispersion. For the preferred flow velocities of the embodiments of the invention, orifice 21 has a diameter greater than 1 mm, and preferably 1.5 mm.Thus, the aqueous composition is not predominantly sprayed by passing through the orifice 21, but mainly during shearing with the air flow 17. The biological control agent reservoir 6 can be pressurized, preferably by the pressurized air source 3 via a pressurization line 10, so as to cause a flow of aqueous composition 18 at the orifice 21 of between 2 mL / s and 4.5 mL / s. Composition d'agents de contrôle biologique

[0028] The sprayable aqueous composition comprises live biological control agents homogeneously dispersed in a gel prepared from one or more thickeners and / or gelling agents and an aqueous solution. The thickeners and / or gelling agents are non-toxic to said biological control agents, and said gel has a zero-velocity gradient dynamic viscosity between 1 and 30,000 mPa·s.

[0029] Preferably, said gel has a zero velocity gradient dynamic viscosity between 10 and 25,000 mPa.s, more preferably between 2 and 5,000 mPa.s, more preferably between 60 and 4,500 mPa.s, more preferably between 80 and 150 mPa.s.

[0030] Preferably, live biological control agents are selected from among mobile live biological control agents. By "mobile," we mean that the live biological control agent exists in a form that allows it, at the time of system use, to be mobile in space, and particularly within a culture. Indeed, inventors have discovered that mobile live biological control agents are particularly affected by shear spraying by a solid material. Thus, spraying driven primarily by shear between air and the aqueous composition allows for the spraying of mobile live biological control agents with a high survival rate.

[0031] Preferably, live biological control agents can be chosen from the group consisting of mites and / or insect predators of crop pests, preferably mites.

[0032] Preferably, live biological control agents are insects of the type Chrysopral Predators of crop pests, particularly aphids. Live biological control agents can be in the form of eggs.

[0033] According to one embodiment, said live biological control agents are mites of the family Phytoseiidae or predatory soil mites, preferably Hypoaspis miles; Macrocheles robustulus; Gaeolaelaps acule; fer.

[0034] Preferably, said biological control agents from the family Phytoseiidae are chosen from the group consisting of the genera Phytoseiulus, preferably Phytoseiulus persimilis, Phytoseiulus macropilis, Phytoseiulus longipes Or Phytoseiulus fragariae, and gender Amblyseius, preferably Amblyseius swirskii, Amblyseius californicus, Amblyseius cucumeris, Amblyseius andersoni And Amblyseius montdorensis.

[0035] According to one embodiment, said live biological control agents are dipteran insects, preferably of the family Cecidomyiidae or hymenoptera, preferably from the families of Brachonidae, Aphelinidae or Trichogrammatidae.

[0036] Preferably, said biological control agents of the family of Cecidomyiidae are chosen from the group made up of Feltiella mite And Aphidoletes aphidimyza.

[0037] Preferably, said biological control agents of the family of Brachonidae are chosen from the group made up of Aphidius colemani ; Aphidius ervi , Aphids of the matricaria.

[0038] Preferably, said biological control agents of the family of Aphelinidae are chosen from the group made up of Aphelinus abdominalis, Encarsia formosa; Eretmocerus eremicus; Eretmocerus world.

[0039] According to one embodiment, said live biological control agents are nematodes of the family Steinernematidae or from the family of Heterorhabditis or from the family of Rhabditidae.

[0040] Preferably, said biological control agents of the family of Steinernematidae are chosen from the group made up of Steinernema carpocapsae; Steinernema kraussei, Steinernema feltiae.

[0041] Preferably, said biological control agents of the family of Heterorhabditidaeare chosen from the group made up of Heterorhabditis bacteriophora.

[0042] Preferably, said biological control agents of the family of Rhabditidae are chosen from the group made up of Phasmarhabditis bacteriophora.

[0043] Preferably, said biological control agents are present in the aqueous composition in the form of larvae, nymphs, pupae and / or adults.

[0044] Preferably, said biological control agents are present in the composition in the form of any stage of development except eggs.

[0045] Preferably, system 1 allows at least 60%, preferably at least 70%, even more preferably at least 80%, particularly preferably at least 90% of the biological control agents of the phytoseiulus genus to remain alive for at least 2h, preferably 6h, even more preferably 12h.

[0046] Preferably, system 1 maintains at least 60%, preferably at least 70%, even more preferably at least 80%, particularly preferably at least 90% of the control lifetime of biological control agents of the phytoseiulus family for at least 2h, preferably 6h, even more preferably 12h.

[0047] There " longevity witness » is defined as a mortality rate of less than 20% at 5 days.

[0048] Preferably, system 1 maintains at least 60%, preferably at least 70%, even more preferably at least 80%, particularly preferably at least 90% of the control fecundity of biological control agents of the phytoseiulus family for at least 2h, preferably 6h, even more preferably 12h.

[0049] There " fertility indicatoris defined as a fecundity greater than or equal to 10 eggs / female / 5 days, particularly for biological control agents of the phytoseid family of the genus Phytoseiulus.

[0050] The composition allows, after its dispersion or spraying in drops, a gel release rate of biological control agents of the family of phytoseids of the genus Phytoseiulus greater than 60%, in particular greater than 80%. Thickeners / gelling agents

[0051] The appropriate thickeners / gelling agents and their concentration for preparing the sprayable aqueous composition are selected to satisfy the viscosity criterion described above, to allow homogeneous dispersion in the composition of the biological control agents, in particular of the phytoseid family of the genus Phytoseiulus, and to be non-toxic to the living biological control agents.

[0052] "Non-toxic"means less than 20% of biological control agents dead after 2 hours.

[0053] In addition, the appropriate thickeners / gelling agents for preparing the composition are selected to be non-toxic to the targeted crop plants, nor to the consumer of said plants or by-products of said plants.

[0054] Preferably, the appropriate thickeners / gelling agents for preparing the composition are food-grade thickeners / gelling agents.

[0055] Preferably, the appropriate thickeners / gelling agents for preparing the composition are chosen from the group consisting of: Polysaccharides and glycosides. Examples of this family include: alginate, modified corn starch, amylopectin, carrageenan, chitosan, dextrin, guar gum, xanthan gum, glycerol, and konjac gum. Polyacrylate salts. Examples of this family include: Carbomer 940 (polyacrylic acid) and Gel maker emu (sodium polyacrylate). Povidone derivatives. Examples of this family include: PVP (polyvinylpyrrolidone). Cellulose derivatives. Examples of this family include: carboxymethylcellulose and hydroxypropylcellulose. Metallic salts. Examples of this family include: calcium chloride, potassium chloride, and aluminum sulfate.

[0056] Preferably, said thickeners / gelling agents are used in the composition at a concentration between 0.5 and 200 g / L, preferably between 1 and 90 g / L, preferably again between 2 and 40 g / L.

[0057] Preferably, the appropriate thickeners / gelling agents for preparing the composition are chosen from the group consisting of polysaccharides and glycosides.

[0058] In a particularly preferred manner, said polysaccharides and glycosides are chosen from the group consisting of modified maize starch, carrageenans, xanthan gum and konjac gum.

[0059] Preferably, modified maize starch is used at a concentration between 30 and 90 g / L, preferably at 34 g / L.

[0060] Preferably, a modified maize starch gel is used with a zero velocity gradient dynamic viscosity between 60 and 25,100 mPa.s, preferably at 80 mPa.s.

[0061] Preferably, carrageenans are used at a concentration between 1 and 10 g / L, preferably at 3 g / L.

[0062] Preferably, a carrageenan gel is used with a zero velocity gradient dynamic viscosity between 1 and 4900 mPa.s, preferably at 2 mPa.s.

[0063] Preferably, xanthan gum is used at a concentration between 0.5 and 5 g / L, preferably at 2 g / L.

[0064] Preferably, a xanthan gum gel is used with a zero velocity gradient dynamic viscosity between 7 and 1680 mPa.s, preferably at 135 mPa.s.

[0065] Preferably, konjac gum is used at a concentration between 0.5 and 10 g / L, preferably at 4 g / L.

[0066] Preferably, a konjac gum gel is used with a zero velocity gradient dynamic viscosity between 1 and 450 mPa.s, preferably at 27 mPa.s. Enzymes

[0067] The aqueous composition may further comprise an enzyme capable of degrading the gel prepared from one or more thickeners and / or gelling agents and an aqueous solution at a concentration of the enzyme in the aqueous solution allowing total degradation of said gel in less than 10 minutes, preferably in less than 5 minutes, even more preferably in less than 2 minutes.

[0068] Adding the enzyme to the composition improves the gel release rate of live biological control agents, particularly those from the phytoseid family of the genus Phytoseiulus living after dispersion or spraying of the composition.

[0069] Preferably, the yield rate of a composition according to the invention with enzyme is greater than 80%.

[0070] Preferably, the enzyme is added last to the composition according to the invention, in particular after the gelling agent or thickener and after the live biological control agents.

[0071] Preferably, the enzyme is added to the aqueous composition less than 2 hours before dispersion / spraying, preferably just before dispersion / spraying.

[0072] System 1 preferably comprises a liquid-phase enzyme reservoir 7. The enzyme reservoir 7 is fluidically connected to the biological control agent line 8. Thus, during the dispersion of the live biological control agents, it is possible to add the enzyme immediately before spraying the aqueous composition, thereby avoiding degradation of the rheological properties of the aqueous solution prior to spraying. Preferably, the enzyme reservoir 7 is connected to the biological control agent line 8 by a fluid mixer adapted to mix live liquid biological control agents and an enzyme solution. The mixer can be selected from a water aspirator that allows the aspiration of one liquid through the passage of another, thereby mixing the two liquids, and a fluid junction system.Alternatively, the mixer can be arranged between the nozzle 2 and the fluidic connection linking the biological control agent line 8 and a line linking to the enzyme reservoir 7.

[0073] The enzyme is of course suitable for degrading said thickener / gelling agent of the composition.

[0074] The most favorable conditions are obtained when the enzyme rapidly degrades the gel, since the more rapidly the gel is degraded, the more rapidly the biological control agents are released.

[0075] A person skilled in the art will know how to choose the concentration of the enzyme based on its enzymatic activity, the optimal temperature, the concentrations of thickener and the desired hydrolysis time.

[0076] Preferably, the enzyme concentration is chosen to degrade 100% of the gel in less than 12 hours, preferably in less than 6 hours, even more preferably in less than 2 hours, particularly preferably in less than 1 minute.

[0077] For example, enzymes will be used: Hydrolyzing glycosidic bonds for the family of glycosides / polysaccharides.

[0078] In the case of alginate, alginate lyase degrades alginate by 6-elimination of glycosidic bonds.

[0079] In the case of modified corn starch, alpha-amylase hydrolyzes alpha (1,4) glycosidic bonds. For example, an alpha-amylase with an enzymatic activity of 800 FAU / g at 20°C is used, with 1 FAU hydrolyzing 17 mg of starch per minute. To degrade 100 mL of modified corn starch at 34 g / L in 1 minute, 200 FAU, or 0.25 g of alpha-amylase, is required. For degradation in two hours, 1.6 FAU, or 0.002 g of alpha-amylase, is required. Finally, for degradation in 12 hours, 0.27 FAU, or 0.3 mg of alpha-amylase, is required.

[0080] In the case of amylopectin, alpha-amylase hydrolyzes alpha (1,4) glycosidic bonds.

[0081] In the case of dextrins, the limited glycosylated dextrinase hydrolase hydrolyzes the alpha (1,6) glycosidic bonds.

[0082] In the case of carrageenans, k-carragenase hydrolyzes alpha (1,4) glycosidic bonds.

[0083] In the case of guar and xanthan gums, beta-mannanase randomly hydrolyzes (1,4)-β-D-mannosyl bonds. For xanthan gum, xanthan lyase hydrolyzes beta-D-mannosyl-beta-D-1,4-glucuronosyl bonds.

[0084] In the case of chitosan, chitosanase hydrolyzes the beta (1,4) glycosidic bonds between D-glucosamine residues.

[0085] In the case of konjac, endo-1,4 beta-mannanase hydrolyzes the beta (1,4) glycosidic bonds of glucomannan residues. For cellulose derivatives: Endocellulase: breaks down the crystalline structure of cellulose into polysaccharide chains. Exocellulase: cleaves 2-4 units at the ends of the polysaccharide chains. β-Glucosidase: hydrolyzes the polysaccharide chains into monosaccharides. Oxidative cellulase: depolymerizes cellulose. Cellulose phosphorylase: depolymerizes cellulose using phosphates. Fluid flows in system 1

[0086] System 1 may include means for pressurizing the biological control agent reservoir 6 and / or the enzyme reservoir 7. These pressurization means are adapted to drive flow from the biological control agent reservoir 6 and / or the enzyme reservoir 7 to the liquid phase outlet 15. This allows for the implementation of flows containing live biological control agents without risking a decrease in their survival rate. Indeed, some pumps can cause mechanical pressure injuries and impair the survival of live biological control agents.

[0087] Preferably, the pressurization means are implemented by a pressurization line 10 connecting the pressurized air line 4 and the biological control agent reservoir 6, and / or connecting the pressurized air line 4 and the enzyme reservoir 7. The pressurization line 10 can be sized so as to pressurize the biological control agent reservoir 6 and / or the enzyme reservoir 7 to a predetermined pressure, depending on the pressure of the air source 3. Thus, it is possible to simultaneously trigger the air flow 17, the aqueous composition flow and preferably an enzyme flow by controlling only the pressurized air source 3.

[0088] It is also possible to use peristaltic type pumps to move the solutions from the biological control agent reservoir 6 and / or from the enzyme reservoir 7 to the liquid phase outlet. The process of preparing the composition

[0089] The process for preparing the composition according to the invention comprises the following steps: Dissolution of the thickener(s) and / or gelling agent(s) in an aqueous base, preferably water, until a gel forms, followed by the addition of biological control agents, particularly from the phytoseid family of the genus Phytoseiulus, and their dispersion in a homogeneous manner in the gel, preferably by light stirring of the solution, possibly with the addition of an enzyme capable of degrading the gel at a concentration allowing total degradation of said gel in less than 12 hours, preferably in less than 2 hours.

[0090] This preparation process is preferably carried out between 18°C ​​and 25°C, particularly preferably at 20°C.

[0091] This preparation process is preferably carried out at a relative humidity above 30%, preferably 60%. The method of dispersing the aqueous composition

[0092] One aspect of the invention is a method for dispersing live biological control agents. The method comprises a step of spraying the aqueous composition of live biological control agents by a system according to an embodiment of the invention.

[0093] The method includes a step in which an air flow 17 is drawn from the pressurized air source 4 to the spray nozzle 13.

[0094] The method also includes a step in which a flow of an aqueous composition comprising the live biological control agents in liquid phase is drawn to the spray nozzle 13.

[0095] The method is implemented such that an average airflow velocity 17 in the air duct 4 is suitable for atomizing the aqueous composition by shearing it. Preferably, the ratio between the average airflow velocity in the air duct 4 and the average flow velocity of the aqueous composition is greater than a predetermined ratio, above which the aqueous composition can be atomized by shearing the airflow 17. Preferably, the average airflow velocity at the inlet 13, and preferably at the air outlet(s) 16, is between 5 m / s and 30 m / s, and in particular between 10 m / s and 25 m / s. Preferably, the average flow velocity of aqueous composition is between 1 m / s and 5 m / s, in particular between 1.5 m / s and 3 m / s.Thus, it is possible to atomize the aqueous composition without shearing it with a solid material, thereby reducing the mechanical stress exerted on the biological control agents at a constant flow rate of aqueous composition, and consequently increasing the survival rate of live biological control agents. Indeed, atomizing the aqueous composition with air increases the survival rate of live biological control agents.

[0096] Preferably, the aqueous composition is sprayed only by the main air flow 17 after exiting the orifice 21. Thus, the survival rate of live biological control agents can be increased compared to the survival rate of biological control agents sprayed at least partly by contact between the aqueous composition and the orifice.

[0097] Preferably, the pressurization means are controlled to maintain a pressure strictly below 3 bar and preferably strictly below 1 bar in the biological control agent tank 6, in particular below 0.5 bar, and preferably below 0.3 bar. Indeed, it has been observed that storing biological control agents at excessively high pressure, particularly above 3 bar, and especially above 0.5 bar, increases the mortality of the biological control agents. Examples

[0098] With reference to the figure 2The survival rate of live biological control agents was measured after spraying the aqueous composition for different systems. Measures (a), (b), (c), and (d) correspond to spraying the aqueous composition through nozzles that cause the composition to be sprayed by passing through a small orifice before exiting the system. Measure (e) corresponds to spraying the aqueous composition through a nozzle according to an embodiment of the invention. It is observed that the survival rate of live biological control agents is significantly higher during measure (e), i.e., using a system according to an embodiment of the invention. In particular, the survival rate of live biological control agents dispersed by a system 1 according to an embodiment of the invention is greater than 80%.

[0099] With reference to the figure 3, an experiment was carried out using two nozzles according to an embodiment of the invention.

[0100] Measurements (f) and (h) were obtained with a first nozzle having a spray orifice diameter of 1.8 mm and a diameter between 1 mm and 1.5 mm. This first nozzle has two air outlets located on either side of the orifice, each with a diameter of 7 mm. The air velocity at the outlet is approximately 20 m / s.

[0101] Measurements (g) and (i) were obtained with a second nozzle having a spray orifice larger than 1.5 mm, more precisely 2.2 mm. This second nozzle has two air outlets positioned on either side of the orifice, each with a diameter of 8 mm. The air velocity at the outlet is approximately 20 m / s.

[0102] Measures (f) and (g) were obtained using a composition of biological control agents placed in a gel comprising a modified maize starch thickener / gelling agent further comprising enzymes.

[0103] Measurements (h) and ig) were obtained using a composition of biological control agents placed in a gel comprising an enzyme-free Xanthan Gum thickener / gelling agent.

[0104] The results of the experiment illustrated in figure 3 They notably show that the survival rate of mites is higher when using enzyme-free xanthan gum rather than corn starch modified with enzymes.

[0105] For both types of gel, the nozzle with a larger diameter spray mouthpiece orifice allows for a higher survival rate.

Claims

1. A system (1) for dispersing living biological control agents, the system comprising: - a reservoir of living biological control agents (6) in liquid phase, - a source of air (3) under pressure, - a nozzle (2), the nozzle (2) being connected to the biological control agent reservoir (6) by a biological control agent line (8), and to the pressurized air source (3) by a pressurized air line (4), the nozzle (2) comprising a mouthpiece (13), the biological control agent line (8) having a liquid phase outlet (15) configured to allow a liquid phase jet (12) to exit the mouthpiece (13) in a main direction (20), and the pressurized air line (4) having at least one air outlet (16), characterized in that the mouthpiece comprises a wall (19), the liquid phase outlet (15) being defined by an orifice (21) on the wall (19) of the mouthpiece (13), the air outlet(s) (16) being arranged on the wall (19) of the mouthpiece (13), the shape of the wall (19) being configured to direct a main air flow (17) exiting from the air outlet(s) (16) convergently towards the liquid phase jet (12), the main air flow (17) preferably being axially symmetrical with respect to the main direction (20).

2. System (1) according to claim 1, wherein the nozzle comprises at least two air outlets (16) arranged symmetrically with respect to the main direction (20), the shape of the wall (19) being configured to direct a first air flow exiting from one of the air outlets (16) towards the liquid phase jet (12), and to direct a second air flow exiting from the other air outlet (16) towards the liquid phase jet (12), the first air flow and the second air flow being symmetrical with respect to the main direction (20).

3. System (1) according to one of the preceding claims, comprising an enzyme reservoir (7) in liquid phase, the enzyme reservoir (7) being fluidically connected to the biological control agent line (8), preferably via a mixer (9) configured to mix liquid-phase living biological control agents and an enzyme solution.

4. A system (1) according to any of the preceding claims, comprising means for pressurizing the biological control agent reservoir (6) and / or the enzyme reservoir (7), configured to cause a flow from the biological control agent reservoir (6) and / or from the enzyme reservoir (7) to the liquid phase outlet (15).

5. System (1) according to claim 4, wherein the pressurizing means are implemented by a pressurizing line (10) connecting the pressurized air line (4) and the biological control agent reservoir (6), and / or connecting the pressurized air line (4) and the enzyme reservoir (7).

6. System (1) according to one of the preceding claims, wherein the orifice (21) has a diameter greater than 1 mm, and preferably greater than 1.5 mm.

7. A system (1) according to any of the preceding claims, wherein the biological control agent reservoir (6) comprises an aqueous composition, and biological control agents dispersed in the aqueous composition.

8. A system (1) according to claim 7, wherein the aqueous composition comprises a gel prepared from one or more thickeners and / or gelling agents and an aqueous solution, the living biological control agents being homogeneously dispersed in the gel, said thickeners and / or gelling agents being non-toxic to said biological control agents and said gel exhibiting a zero-velocity gradient dynamic viscosity of between 1 and 30,000 mPa.s.

9. System (1) according to one of the preceding claims, in which the living biological control agents are mobile.

10. System (1) according to one of the preceding claims, wherein the living biological control agents are selected from the group consisting of mites and / or predatory insects.

11. System (1) according to the preceding claim, wherein the living biological control agents are mites of the phytoseiid family of the genus Phytoseiulus.

12. System according to claim 8, in which the living biological control agents are insects of the Chrysoperla type which predate insect pests.

13. A method of dispersing live biological control agents, comprising a step of spraying an aqueous composition of live biological control agents through a system (1) according to any one of claims 1 to 12, wherein a main air flow (17) is driven from the pressurized air line (4) under pressure to the mouthpiece (13), a flow of an aqueous composition comprising the living biological control agents in liquid phase is driven to the orifice (21), an average velocity of the main air flow (17) in the pressurized air line (4) being configured to spray the aqueous composition by shearing of the aqueous composition by the air flow.

14. A method of dispersing living biological control agents according to the preceding claim, wherein the aqueous composition comprising the biological control agents (18) is sprayed only by the main air flow after exiting from the orifice (21).

15. A method of dispersing live biological control agents according to claim 13 or 14, wherein the system (1) comprises biological control agent reservoir pressurizing means configured to cause a flow from the biological control agent reservoir (6) and / or from the enzyme reservoir (7) to the liquid phase outlet (15), wherein the pressurizing means is controlled so as to impose a pressure strictly below 3 bar in the biological control agent reservoir (6), and preferably below 0.5 bar.