Abstract:
The system produces beneficial parasites by depositing parasite-infected cadavers adjacent to a filtering device inside an enclosed package. The parasites are then allowed to migrate from the infected cadavers, through the filtering device, and into a parasite-sustaining medium. After the migration is complete, the spent cadavers and the filtering device are removed and the package is closed. In the preferred embodiment, beneficial nematodes migrate through a screen matrix into polyacrylamide gel to create a package of beneficial nematodes.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a system and method for producing beneficial parasites. Specifically, the invention relates to a system and method for producing beneficial nematodes. 
     BACKGROUND OF THE INVENTION 
     For multiple reasons, farmers are seeking biologically-based pest control alternatives to commercial synthetic chemical pesticides. One “biocontrol” strategy is to increase the presence of the insects&#39; natural enemies. These natural enemies may include beneficial entomopathogenic nematodes such as  Steinernema  spp or  Heterorhabditis  spp. These beneficial nematodes are parasites that prey on a variety of damaging insects but pose no danger to plants or humans. 
     Commercial production of beneficial nematodes can be in vitro (e.g., in fermentation tanks), or in vivo using susceptible insect hosts. Although both production systems have advantages, in vivo systems generally result in the production of better quality and more virulent nematodes. Further, more nematode species can be produced in vivo, and in vivo production methods do not require the use of expensive and complex equipment. 
     The current process for in vivo production and packaging of nematodes is based on the “White trap” method in which nematodes are collected in a solution, the solution is strained, and then the nematodes are concentrated and deposited into a package for shipment. While this method is generally effective, it is also relatively labor intensive, and manipulation of the nematodes causes damage and stress to the nematodes and generally results in a less-than-optimal nematode product. 
     The need exists for a nematode production system and process that requires minimal labor and produces superior quality nematodes. The process and system of the current invention is simple and efficient and produces virulent nematodes that have not been stressed or damaged. 
     SUMMARY OF THE INVENTION 
     The current invention is directed to a parasite production system comprising, at least one nematode-infected cadaver, a filtering device, and a parasite-sustaining medium. The system is structured so that as a parasite emerges from the infected cadaver, the parasite migrates through the filtering device and into the parasite-sustaining medium. 
     The current invention is also directed to a method of producing a package of parasites. A filtering device is provided inside an open package and parasite-infected cadavers are placed adjacent to a first side of the filtering device, and parasite-sustaining medium is placed adjacent to a second side of the filtering device. Parasites are allowed to migrate from the cadavers, through the filtering device, and into the parasite-sustaining medium. The cadavers and the filtering device are then removed and the package is closed to produce the package of parasites. 
     In the preferred embodiment, the system and process of the current invention are used to produce a package of beneficial nematodes. In accordance with the current invention, beneficial nematodes (within a sealable ventilated plastic bag) migrate from infected mealworm cadavers through a screen matrix, and into polyacrylamide gel. The cadavers and the screen are removed from the bag and then the bag is sealed to create a package of beneficial nematodes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional schematic of the current invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     As generally shown in  FIG. 1 , the present invention comprises a system  10  for producing beneficial parasites. The system  10  comprises an outer packaging  12  which encloses the system&#39;s other components. The system  10  further comprises a plurality of host cadavers  14  that have been infected by beneficial parasites. Although multiple host cadavers  14  are disclosed in  FIG. 1 , for the sake of simplicity, only one reference number is shown. 
     The host cadavers  14  are positioned on a restrictive filtering device  16  over a parasite-sustaining medium  20 . As the parasites begin to emerge from the cadavers  14 , the parasites migrate from the cadavers  14 , through the filtering device  16 , and into the medium  20 , which sustains the parasites. A breathable patch  22  may be placed on the packaging  12  either before, during, or after the parasites emerge to ensure adequate ventilation. If the patch  22  is left in place after the parasites emerge, it should be constructed (or placed) to prevent the inadvertent escape of any of the parasites. Once essentially all of the parasites have emerged from the host cadavers  14 , the filtering device  16  and the cadavers  14  are (generally) removed from the packaging  12  and the packaging  12  is closed and prepared for shipping. 
     In the preferred embodiment, the cadavers  14  comprise mealworm larvae ( Tenebrio molitor ) and the parasites are nematodes (typically  Steinernema  spp or  Heterorhabditis  spp). The packaging  12  is designed so that approximately one hundred host cadavers  14  are enclosed in each package  12 . In the preferred embodiment, five million nematodes are produced in each package. In alternative embodiments, other types of cadavers may be used to produce different types of nematodes or beneficial parasites. The packaging  12  may also be larger or smaller than the preferred embodiment to accommodate various production requirements. In the preferred embodiment, the package  12  comprises a sealable plastic bag, however other constructions should be considered within the scope of the invention. 
     The nematodes typically begin to emerge approximately ten days after the cadavers  14  are infected. The filtering device  16  comprises a polyester screen with a mesh size of approximately 1×2 mm so that the nematodes emerge from the mealworm cadavers  14  and migrate through the screen  16  and into the parasite sustaining medium  20 . As shown in  FIG. 1 , the screen  16  may include a small vertical lip to ensure that the cadavers remain within the circumference of the screen  16 . 
     A breathable patch  22  is added to the plastic bag packaging  12  to ensure that the packaging is properly ventilated. In the preferred embodiment, the patch is comprised of TYVEK material (manufactured by the DuPont™ corporation), although other breathable materials should be considered within the scope of the invention. In alternative embodiments, an air tube (such as a filtered or unfiltered straw-type tube) may be used. 
     The parasite-sustaining medium  20  of the preferred embodiment comprises a long term sustaining medium. For the purposes of this invention, a long term parasite sustaining medium comprises a medium that enables a parasite to live for at least two weeks. The packaged nematodes are generally stored under refrigerated conditions at 4 to 13° C. 
     In the preferred embodiment, the parasite sustaining medium  20  comprises polyacrylamide gel. A typical package of comprises about 1 gram of polyacrylamide gel with 75 ml of water added for saturation. The unique properties of polyacrylamide crystals allow more oxygen to remain in solution thereby significantly enhancing the amount of time that the nematodes can remain viable. In the polyacrylamide gel  20 , the produced nematodes can remain viable for more than six months. 
     During the nematode production process, the infected cadavers  14  exude substances that fall into polyacrylamide gel  20  and these exudates remain in the gel  20  after the screen  16  and the cadavers  14  are removed. The inventors have found that these exudates further enhance the virulence and viability of the produced nematodes. However, if the entire cadavers  14  are allowed to remain in the gel, the decomposing cadavers promote the growth of bacteria that may be harmful to the nematodes. 
     Once the packaged nematodes reach a target site, application of the polyacrylamide gel  20  to target plants prolongs a humid micro-climate that further sustains the nematodes and may also have other advantages. However, once the packaged nematodes reach the target site they can also be removed from the package (and the polyacrylamide gel) and distributed by any means known in the art. 
     For the foregoing reasons, it is clear that the invention provides an innovative system and method for producing beneficial nematodes. The invention may be modified in multiple ways and applied in various technological applications. For example, the current invention may be used to produce other organisms wherein the emergence of the organism from a host cadaver is a part of the organism&#39;s reproduction process. 
     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 generally 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.