Abstract:
Predatory mites contained in an enclosed housing are provided with a continuous food source (i.e. spidermites) so that the healthy adult predatory mites migrate upwards to a collection container at the apex of the housing where a user harvests the predatory mites. The predatory mites are provided with spidermite-infested vegetation disposed in planar trays. The trays are chronologically arranged in a vertical stack within the housing so that as new trays loaded with spidermites are added to the top of the stack, old trays depleted of spidermites are removed from the bottom of the stack. The predatory mites intuitively display negative geotropism and positive phototropism so that the mites naturally move upwards and toward the light. Consequently the predatory mites migrate to the upper trays as new trays are added and eventually reach the collection container at the apex of the housing.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a system and method of continuously producing predatory mites. Specifically, the invention relates to a system and method of providing predatory mites a continuous supply of food so that successive generations of mites hatch, feed, and move into a collection container. 
     BACKGROUND OF THE INVENTION 
     Spidermites ( Tetranychus urticae ) are one of the most common insect pests. Spidermites are the direct cause of millions of dollars in damage per year to a wide variety of plant types. Spidermites generally attach themselves to the leaves of a plant and suck the moisture out of plant foliage. Spidermites will stunt or wilt new plant growth and, in severe infestations, may kill the host plant. Spidermites are particularly damaging to plants that are already subject to heat or drought-related stress. 
     Predatory mites feed on spidermite eggs and adult spidermites, and are one means of controlling spidermite populations. Predatory mites are particularly popular with organic growers seeking non-chemical biological pest control agents. The predatory mites are generally quicker and more agile (although not necessarily larger) than the spidermites that they prey on, and they can seek out prey in areas that may be missed or are inaccessible to perfunctory chemical sprays. Additionally, unlike chemical sprays, spidermites cannot develop a tolerance or immunity to predatory mites. Predatory mites may also be used against several species of thrips. 
     Predatory mites are a particularly successful pest control agent in greenhouses because of the high degree of control that the grower has over the greenhouse environment. The most prolific and effective types of predatory mites function best in a specific temperature and humidity envelope. However, several predatory mite species are successfully used to suppress spidermites in non-greenhouse environments on crops such as apples, citrus, and avocados as well as strawberries and raspberries. 
     In the preferred embodiment, the current invention is directed to producing the predatory mite  Phytoseiulus persimili . However, the invention may also be used to produce a variety of other mites and insects. For the purposes of this patent specification, the term “predatory mites” will be used to generally refer to any mite species that feeds on other arthropods. 
     Predatory mites are currently produced and marketed by several commercial organizations. An index of beneficial insect producers (including predatory mite producers) is available from www.bugladyconsulting.com/Suppliers%21of %21beneficial%21insects.htm. 
     Most predatory mite production is currently done in greenhouses in an essentially uncontrolled manner. Predatory mites are simply deposited on vegetation that is infested with spidermites and left for a pre-determined amount of time. Workers then harvest the predatory mites remaining in the vegetation. Strict protocols (and generally separate greenhouses) are required to keep the predatory mites separate from the spidermites until a specifically prescribed stage in the production process. The prior art process is not continuous and one cycle requires about six weeks from start to harvest. 
     While the prior art method is simple, it is also relatively labor-intensive and inefficient, and it results in inconsistent harvests. Further, there is always a significant time gap between the start of the predatory mite production process and the window in which the mites can be harvested. 
     The need exist for a systematic means of continuously feeding and harvesting predatory mites so that good quality predatory mites are produced. The current invention provides an enclosed, modular, and systematic means of continuously producing healthy predatory mites. Once the system is up and running, maintaining the system requires minimal operator skill and knowledge and enables the operator to produce predatory mites for an essentially indefinite period of time. In laboratory tests, the process of the current invention has been shown to increase predatory mite production by 21-300% relative to prior art processes involving similar time periods and similar resources. 
     SUMMARY OF THE INVENTION 
     The disclosure is directed to a system for producing arthropods (predatory mites). The system includes an enclosed housing (a “cage”) with an upper portion and a lower portion. A plurality of predatory mites and a food source (spidermites) are introduced into the lower portion of the cage. A collection container is attached to the upper portion of the cage. In operation, the predatory mites consume the spidermites and the offspring of the predatory mites migrate upward into the collection container for harvest. 
     The invention is also directed to a method of producing predatory mites. An operator provides an enclosed cage with an upper portion and a lower portion. A collection container is positioned adjacent the upper portion. A plurality of predatory mites and spidermites are introduced into the lower portion. An operator then periodically harvests the offspring of the predatory mites from the collection container adjacent to the upper portion of the cage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the cage. 
         FIG. 2  is a perspective view of an empty tray. 
         FIG. 3  is a perspective view of the cage at the beginning of the predatory mite production process as the first tray of infested vegetation is added to the cage. The sides of the cage are shown as transparent so that the tray stack within the cage is visible. 
         FIG. 4  is a perspective view of the tray transfer assembly in the raised position (pins extended). 
         FIG. 5  is a perspective view of the mite collection apparatus. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The present invention comprises a system and method for continuously producing predatory mites. As generally shown in  FIG. 1 , the system comprises a translucent enclosed housing C with an upper portion  20  and a lower portion  40 . The lower portion  40  includes an upper access means  21 , a lower access means  41  and a tray transfer assembly  50 . A collection apparatus  110  is connected to the upper portion  20  of the housing C. 
     In the preferred embodiment, the enclosed housing comprises a “cage” C, and the upper and lower access means comprise upper  21  and lower  41  “windows”. The cage C holds multiple stackable trays  22  of the type best shown in  FIG. 2 . As shown in  FIG. 3 , at the beginning of the predatory mite production process, vegetation infested with spidermites is deposited on the first tray  22  and placed in the cage C through the upper window  21 .  FIG. 3  shows the sides of the cage C as transparent so that the tray stack within the cage C is visible. Predatory mites are deposited on the vegetation  24  so that the predatory mites eventually consume the spidermites that infest the vegetation  24 . As the process progresses, new trays  22  loaded with infested vegetation  24  are added to the upper window  21 , and old trays  22  depleted of spidermites with dead vegetation are removed through the lower window  41 . The tray transfer mechanism  50  (best shown in  FIG. 4 ) is used to lower the stack of trays  22  each time a new tray  22  is added to the top of the stack through the upper window  21 . As the trays  22  in the upper portion of the cage C become saturated with predatory mites, the predatory mites naturally migrate further upward into the collection apparatus  110 . The preferred embodiment of the collection apparatus is shown in detail in  FIG. 5 . 
     The current invention takes advantage of the predatory mites&#39; natural instincts to move up (negative geotropism) and towards a light (positive phototropism). This instinct ensures that as new predatory mites hatch and mature, the healthy predatory mites move upwardly into the new incoming trays, and then further upwardly to the collection apparatus  110  where they are harvested. Living organisms (including insects and mites) that naturally move or grow upwardly (most likely using gravity as an orienting stimulus) display negative geotropism. Similarly, organisms (including insects and mites) that naturally move or grow in the direction of light display positive phototropism. Although the preferred embodiment is directed specifically to predatory mites, other arthropods (including insects) that display negative geotropism and/or positive phototropism should be considered within the scope of the disclosure. 
     The invention is discussed in greater detail infra. 
     As generally shown in  FIG. 1  and briefly discussed supra, the system of the current invention has a generally modular design so that the predatory mite breeding and feeding processes occur within the cage C. In the preferred embodiment, the cage C is translucent and generally semi-transparent so that at least some light penetrates the walls of the cage C. In alternative embodiments, the cage C may be completely transparent, or the lower portion  40  may be opaque and the upper portion  20  may be more translucent so that the predatory mites are drawn toward the upper portion  20  of the cage C. In the preferred embodiment, at least the collection container  114  (see  FIG. 5 ) is generally transparent. 
     A drape such as a plastic tarp or a shower curtain may be disposed around the cage to aid in the control of the relative humidity within the cage. The predatory mites of the preferred embodiment ( Phytoseiulus persimili ) reproduce and function most effectively when the relative humidity is approximately 70% and the temperature is between 59° F. and 86° F. 
     At the initiation of the predatory mite production process, vegetation  24  is collected on a series of trays  22 . As best shown in  FIG. 2 , in the preferred embodiment, each tray  22  is comprised of a rectangular frame  26  with a polypropylene net  28  extending over the interior of the frame  26 . A leg  30  projects upwardly from each corner of the tray  22  so that the trays  22  can be easily stacked. 
     In the preferred embodiment, vegetation  24  is collected on the trays  22  through a specific growing process. A plant container (not shown) is planted with vegetation  24  and a tray  22  is placed immediately above the plant container. The vegetation  24  grows upwardly through the frame net  28  and then spreads outward as the leaves further develop and grow. When the vegetation  24  is fully grown and the tray  22  is ready to be used, the vegetation  24  is infested with spidermites and clipped off at ground level by an electric hedge trimmer (or the like) so that the vegetation  24  above the net  28  is supported by the tray  22  (See  FIG. 3 ). 
     In the preferred embodiment, the vegetation  24  is comprised of multiple bean plants. In alternative embodiments, the vegetation  24  may be of any variety known in the art so long as the vegetation  24  is able to support the growth of the spidermites. Similarly, the vegetation  24  may be grown, gathered, and deposited on the trays in any manner known in the art. 
     As shown in  FIG. 3 , once the vegetation  24  has been gathered and infested with spidermites, a first tray  22  loaded with infested vegetation  24  is inserted in the upper window  21  of the cage C. In  FIG. 3 , the sides of the cage C are shown as transparent so that the tray  22  stack is partially visible. Approximately 2 to 3 days after the first tray  22  is placed in the cage C, a new tray  22  with infested vegetation  24  is added to the upper window  21  and a tray  22  is removed from the lower window  41 . This tray  22  addition/removal cycle is repeated in another 2 to 3 days and may continue indefinitely thereafter. Predatory mites that are ready for harvest generally begin to appear in the collection apparatus  110  about 3 days after the initiation of the process. 
     In the preferred embodiment, there are four trays in the cage C during the predatory mite production process. Although the first few trays  22  removed from the lower window  41  will be completely empty, beginning with the fourth tray  22 , the removed trays will be filled with dead vegetation  24  and will be generally depleted of spidermites. Essentially, it takes three tray addition/removal cycles for an exemplary tray  22  to move from the top position in the tray stack to the bottom position in the tray stack. During the fourth tray  22  addition/removal cycle, the exemplary tray  22  is removed from the cage C. 
     As best shown in  FIG. 1 , in the preferred embodiment, the upper  21  and lower  41  windows are essentially identical in design. The upper and lower windows  21 ,  41  are generally comprised of hinged rectangular panels  32 ,  42 . The windows  21 ,  41  must be of sufficient size to easily accommodate a user maneuvering successive trays  22  into and out of the windows  21 ,  41 . 
     In alternative embodiments, the windows  21 ,  41  and trays  22  may be of any shape or design known in the art consistent with their associated function. Although the windows  21 ,  41  are shown as having a rectangular shape, they may have other shapes, as required, to enable an operator to maneuver trays  22  into and out of the cage C. The number of trays  22  in the cage C during the production process may be more or less than the four trays  22  of the preferred embodiment. Further, the time intervals associated with the tray  22  addition/removal cycle may vary depending upon multiple factors associated with the process. Additionally, more than one tray  22  may be added or removed in a given cycle. 
     In additional alternative embodiments, the entire upper and/or lower and/or front and/or back and/or side portions of the cage C may be hinged or removable so that a user can directly add or remove trays  22  in the cage C without the need for windows  21 ,  41  or the tray transfer assembly  50 . The trays  22  may also be positioned in a rack within the cage C so that the trays  22  are not stackable and the rack directly supports the weight of the trays  22 . 
     With regard to the tray transfer assembly  50 , there are multiple means known in the art for manipulating the tray stack described herein. The trays  22  may be lowered or otherwise shifted with a hand cranked mechanism (as described in the preferred embodiment) or through a powered means such as an electrical, hydraulic, or pneumatic motor (or the like). The movement of the trays  22  may be automated based on a timer or based on operator-supplied programmable instructions, or any other means known in the art. 
     The tray transfer assembly  50  of the preferred embodiment is generally shown in  FIG. 4 . The tray transfer assembly  50  comprises a support pin control apparatus  52 , and a tray lowering mechanism  70  disposed on each side of the cage C. Specifically, a first support pin control apparatus  52  and a first tray lowering mechanism  70  are disposed on one side of the cage C, and a second support pin control apparatus and a second tray lowering mechanism are disposed on a second (opposite) side of the cage C. Essentially, the support pin control apparatus  52  and tray lowering mechanism  70  on the first side of the cage C is a mirror image of the support pin control apparatus and tray lowering mechanism on the second side of the cage C (with the exception of hand crank  72 ). As shown in  FIG. 1 , a common shaft  74  extends across the front of the cage C and connects the tray lowering mechanisms  70  on each side of the cage C. For the sake of simplicity, only one support pin control apparatus  52  and one tray lowering mechanism  70  will be described and shown in detail (see  FIG. 4 ), however it should be understood that the components described are duplicated on both sides of the cage C. 
     With regard to the support pin control apparatus  52 , as shown in  FIG. 4 , the support pin control apparatus  52  is comprised of a support frame  54  extending outwardly away from the cage C. Elongated support pins  56 ,  58  extend through the support frame  54  and into the cage C. The support pins  56 ,  58  also extend through a retraction bar  62  positioned between the support frame  54  and the cage C. Compression springs  64  are disposed around the support pins  56 ,  58  between the retraction bar  62  and the support frame  54  so that the compression springs  64  urge the retraction bar  62  towards the cage C and away from the support frame  54 . An “L” shaped locking bracket  66  is also attached to the retraction bar  62 . 
       FIG. 4  shows the retraction bar  62  in the released position so that the support pins  56 ,  58  are extended into the cage C.  FIG. 4  shows the cage C as empty, however during the normal production process, the bottom tray  22  is supported by the support pins  56 ,  58  and swing pins  96 ,  98  shown in  FIG. 4 . 
     With regard to the tray lowering mechanism  70 , as shown in  FIG. 5 , the tray lowering mechanism  70  is comprised of an upper pulley  76  in communication with first  78  and second  80  lower pulley assemblies. A fan belt-type elastomeric band  82  connects the upper pulley  76  with first lower pulley assembly  78 , and a similar second band  84  connects the first lower pulley assembly  78  with the second lower pulley assembly  80 . 
     As discussed supra, a common shaft  74  (see  FIG. 1 ) extends across the front of the cage C and connects the upper pulleys  76  on each side of the cage C. In the preferred embodiment, a hand crank  72  is disposed on the upper pulley  76  on one side of the cage C. Turning the hand crank  72  causes the upper pulleys  76  and lower pulley assemblies  78 ,  80  on each side of the cage C to rotate simultaneously. 
     As best shown in  FIG. 4 , the lower pulley assemblies  78 ,  80  further comprise shafts  86 ,  88  that extends through structural bracing and into the cage C. The shafts  86 ,  88  are connected to generally “L” shaped swing arms. Only the horizontally extending end portions  96 ,  98  of the swing arms are visible in  FIG. 4 . As also shown in  FIG. 4 , a vertically extending trip bar  100  is disposed on the shaft  88  along with the first lower pulley assembly  78  so that rotating the hand crank  72  also rotates the trip bar  100 . 
     In operation, the tray lowering mechanism  70  (in coordination with the pin control apparatus  52 ) lowers the bottom tray  22  so that the tray  22  is accessible through the lower window  41 . As best shown in  FIG. 5 , in normal production mode, the support pins  56  and  58  extend into the cage C and the swing arms are in the raised position so that both the support pins  56 ,  58  and the swing pins  96 ,  98  (associated with the swing arms) support the bottom tray  22 . After a new tray  22  is added to the upper window  21 , a tray  22  must be removed from the lower window  41 . To remove a tray from the lower window  41 , the bottom tray must be lowered and the pins  56 ,  58 ,  96 ,  98  supporting the bottom tray  22  must be transitioned to support the next lowest tray  22  thereby freeing the bottom tray  22  for removal. 
     To accomplish the transition, a user first retracts the pins  56 ,  58  from the interior of the cage C by pulling the retraction bar  62  away from the cage C. The locking bracket  66  is then connected to the support frame  54  so that the retraction bar  62  is retained in a distal position relative to the cage C. After the support pins  56 ,  58  are retracted, only the swing pins  96 ,  98  remain to support the bottom tray  22  in the stack. 
     To move the bottom tray  22  downwardly, a user turns the hand crank  72  so that the swing arms and associated swing pins  96 ,  98  start to move downwardly. Simultaneously the trip bar  100  rotates in the direction of the arrow  99 . As the hand crank  72  is rotated, the trip bar  100  contacts the locking bracket  66  on the retraction bar  62  and thereby causes the locking bracket  66  to detach from the support frame  54 . As the locking bracket  66  detaches, the compression springs  64  propel the retraction bar  62  and associated support pins  56 ,  58  inward toward the cage C so that the support pins  56 ,  58  catch and support the next tray  22  above the bottom tray  22 . Since the tray  22  stack now rests on the next tray above the bottom tray, the support pins  56 ,  58  effectively support the tray stack. A user can then freely slide the bottom tray  22  out of the cage C without affecting the other trays  22  in the stack. Once the lowest tray  22  has been removed, the user simply rotates the hand crank  72  until the swing pins  96 ,  98  are once again in position under the (new) bottom tray  22 . 
     As described supra, at periodic intervals during the process predatory mites are collected in the collection apparatus  110  connected to the upper portion  20  of the cage C. In the preferred embodiment, predatory mites are harvested 2-3 days after initiation of the process and every 2-3 days thereafter. As shown in  FIG. 5 , the collection apparatus  110  comprises a funnel component  112  positioned adjacent to the upper portion  20  of the cage C, and a collection container  114  connected to the funnel component  112 . In the preferred embodiments, the collection container  114  is generally transparent and screws onto the funnel component  112 . An operator can simply observe the collection container  114  to detect the presence and concentration of predatory mites in the container  114 . 
     In alternative embodiments, the harvest frequency may be varied based on the volume of the food source supplied and the population density of the predatory mites within the cage C. The exact structure of the collection apparatus  110  may also be varied so that the funnel component  112  is elongated, truncated, or segmented. The size and shape of the collection container  114  may also be varied. In further alternative embodiments, a light source may be positioned in or adjacent to the components of the collection apparatus  110  to provide added stimulus to draw the predatory mites to the collection apparatus  110 . 
     For the foregoing reasons, it is clear that the invention provides an innovative system and method for continuously producing predatory mites. The invention may be modified in multiple ways and applied in various technological applications. The current invention may be modified and customized as required by a specific operation or application, and the individual components may be modified and defined, as required, to achieve the desired result. Although the materials of construction are not described, they may include a variety of compositions consistent with the function of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.