Method for preparing an optimum density termite bait composition

Abstract

A composition in compacted form for use for termite monitoring and control comprises a cellulose material which may be purified cellulose or micro-crystalline cellulose as a base bait, the composition being compacted to an optimum density of not less than approximately 1.033 g/cc. Also disclosed is a method for monitoring and controlling termite infestations which comprises the steps of a) preparing such a composition; b) placing the composition in a bait station; c) monitoring the station at periodic time intervals for termites; and d) upon observing termite infestation in the bait station, replacing the above composition with a bait composition containing a termite killing agent.

Claims

1. A composition in extruded form for use for termite monitoring and control, said composition comprising a cellulose material as a base bait and an active ingredient for at least one of killing and controlling termites, said composition being compacted to a density of not less than 1.033 g/cc.

2. The composition as set forth in claim 1, wherein said active ingredient for at least one of killing and controlling termites is selected from the group consisting of chitin synthesis inhibitors, juvenile hormone mimics, stomach toxicants, contact insecticides, and mixtures thereof.

3. The composition as set forth in claim 1, wherein said active ingredient for at least one of killing and controlling termites comprises at least one chitin synthesis inhibitor.

4. The composition as set forth in claim 1, wherein said active ingredient for at least one of killing and controlling termites is present in a concentration from 0.01% to 10% by weight.

5. The composition as set forth in claim 1, wherein said composition is compacted to a density of not less than 1.196 g/cc.

6. The composition as set forth in claim 1, wherein said cellulose material is purified cellulose.

Description

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) In accordance with the present invention, it has now been found that by compacting a composition comprising purified cellulose or microcrystalline cellulose as a base bait to an optimum density of not less than approximately 1.033 g/cc, maximum loading of termite bait stations may be achieved resulting in an extension of the time period needed for monitoring and refilling the bait stations. Through the practice of the present invention, improvements in current termite bait application practices are realized by first processing the termite base bait composition into custom physical forms, such as tablet forms, with optimum densities of not less than 1.033 g/cc which permits bait compositions shape and form versatility and substantially greater loading of monitoring and control bait into current commercially available termite bait stations than current commercial baits. As can be seen from the tableting studies presented hereinafter, the optimum compaction/density parameters for the compositions of the invention include a density of approximately 1.196 g/cc, an area compaction pressure of 688.71 kg/cm.sup.2, a compaction pressure of 10,000 lbs. and a compaction ratio of 3.32.

(2) In carrying out the practice of the invention, a composition in compacted form is prepared, the composition comprising a cellulose material which may be purified cellulose or microcrystalline cellulose. The cellulose material may be a microcrystalline cellulose in powdered form sold under the trade designation Lattice NT-020 Microcrystalline cellulose having an average particle size of 20 micrometers (FMC Corporation) or noncrystallized cellulose sold under the trade designation Solka Floc (International Fiber Corp.) having an average particle size in the range of 20 to 100 micrometers. Other brands of purified cellulose or microcrystalline cellulose may also be employed in the practice of the invention. The cellulose composition is compacted into tablets, briquets, pellets, spikes, granules or extruded forms which may be made by tablet presses, roller compaction or other means known to those skilled in the art.

(3) A product such as TC-223 Termite Bait Powder (0.25% dimilin (diflubenzuron) and the balance being Lattice NT-020 or Solka Floc cellulose) is generally well suited to termite ingestion and provides maximum termite contact due to its fine particle size. However, the one disadvantage it has is low bulk density which limits the amount that can be loaded into a bait station tube to a maximum of 27 grams with conventional packaging equipment. Termite feed rates studies in a laboratory termite colony indicate that the ingestion of 9 grams per week of the TC-223 formulation base is a reasonable estimate. While in real world situations this rate will vary dramatically due to influences such as termite species, termite population size, alternate food sources, weather conditions etc., the rate of 9 grams per week is used for illustration purposes. At this rate, a conventional bait station tube filled with 27 grams of TC-223 Termite Bait Powder would be emptied in three weeks, substantially less than the standard one month time used for monitoring the bait and replacing the empty bait tube. In accordance with the present invention, the monitoring interval of, for example, 10 weeks may be extended to 11 weeks by utilizing a compacting pressure of 10,000 lbs., to 12 weeks by utilizing a pressure of 15,000 lbs. and to 13 weeks by utilizing a pressure of 20,000 lbs.

(4) If the cellulose material employed is in powder form rather than granule form, it must be deaerated either prior to compacting or during compacting to prevent capping which is a condition where a lamination of the tablet occurs when pressure is suddenly released after the compaction process. Powder contains a large amount of air which is compressed rather than vented during compaction. When the pressure is released, the air returns to its original volume causing cracks or laminations in the tablets.

(5) In addition to the cellulose material, the composition of the invention for use for termite monitoring and control may also contain additional termite attractants and/or pheromones. Any termite attractants known to those skilled in the art may be used such as paper and other forms of cellulose.

(6) Once the monitoring of the bait station confirms the presence of termites, the composition in the bait station is then filled with a bait composition containing a termite killing or controlling agent or termiticide. Any known termite killing or controlling agent or termiticide can be used in the practice of the invention. These include chitin synthesis inhibitors such as hexaflumuron, flufenoxuron, lufenurin and diflubenzuron (dimilin), juvenile hormone mimics such as methoprene and pyriproxyfen, stomach toxicants such as sulfuramide, abamectin, cryolite, boric acid and alkali and alkaline earth salts of boric acid, and contact insecticides such as thiamethoxam, imidicloprid and fipronil, or mixtures or combinations of these agents. The termite killing or controlling agent may be present in the bait composition in various concentrations such as 0.01 to 10% by weight.

(7) The following examples illustrate the practice of the invention

Example 1

(8) A Carver Model 3889 15 Ton Press equipped with the standard 1.125 inch inside diameter test mold kit was utilized to test various compaction characteristics and formulation parameters. The Carver Press employed was not equipped with heated platens on the jaws.

(9) The standard mold produces a tablet which fits nicely into a standard bait tube (1 inside diameter). The tube will hold 5 or more tablets depending upon the tablet height. Tablet height is a function of formulation weight, physical form (powder or fine granule) and compaction pressure. The formulation weight was kept constant at 15 grams per compaction test during the evaluation. Both TC-223 powder and fine granulation were evaluated through several compaction pressures. De-aeration of the powder was accomplished by filling the mold with 10 grams of powder, placing the upper punch into the mold and lightly pressing the powder by hand to force out the air. The remaining 5 grams then fit into the mold. Tablet diameter and height were measured and volumes and densities calculated.

(10) Compaction pressures of 3300, 7500, 10000, 15000 and 20000 lbs. were tested on powder and fine granulation formulations of TC-223. Both formulations were taken from pilot tests using a 10 cu. ft. Marion Mixer.

(11) The results are summarized in the following table:

(12) TABLE-US-00001 Tube Tab- Loading leting Tab- Multi Tablet Dia- Tablet Mold Tablet Com- Pressure leting Tabs Weight meter Area Height Volume Volume Density paction in Pressure Calc. Material (gm) (cm) (cm.sup.2) (cm) (cc) (cc) (g/cc) Ratio Pounds Kg/cm.sup.2 (gms) Comments Tablet From 15 2.9 6.6 2.6 41.59 17.16 0.874 2.42 3300 227.21 80.19 Too soft Fine Granule NT-200 Low Loading Tablet From 15 2.9 6.6 2.2 41.59 14.52 1.033 2.86 7500 516.53 94.77 Fair hardness Fine Granule NT-200 Fair Density Tablet From 15 2.9 6.6 1.9 41.59 12.54 1.196 3.32 10000 688.71 109.77 Hard, Fine Granule NT-200 Good loading Tablet From 15 2.9 6.6 1.75 41.59 11.55 1.299 3.60 15000 1033.06 119.18 Very Hard, Fine Granule NT-200 Excell. Loading Tablet From 15 2.9 6.6 1.65 41.59 10.89 1.377 3.82 20000 1377.41 126.36 Very Hard, Fine Granule NT-200 Max. Loading Tablet From 15 2.9 6.6 1.9 41.59 12.54 1.196 3.32 15000 1033.06 109.74 Hard, Deaerated Powder Good Loading Tablet From 15 2.9 6.6 1.7 41.59 11.22 1.337 3.71 20000 1377.41 122.65 Hard, Deaerated Powder Excel. Loading Tablet From 15 2.9 6.6 2.1 41.59 13.86 1.082 3.00 10000 688.71 99.29 Fair hardness Deaerated Powder Fair Density Tablet From 15 2.9 6.6 2.3 41.59 15.18 0.988 2.74 7500 516.53 90.65 Fair hardness Deaerated Powder Marginal Loading Tablet From 15 2.9 6.6 2.7 41.59 17.82 0.842 2.33 3300 227.27 77.22 Too soft, Deaerated Powder Low Loading Bayer Tube Calculated 2.9 13.9 91.77 Tablet Volume Bayer Tube Calculated 110.8 0.361 40.00 Fine Granule Vol. Fill

(13) From the table, it can be seen that optimum compacting characteristics were associated with the fine granulation formulation and that 7500 lb. compaction pressure on the granule formulation appears to be the lower limit for obtaining an acceptable density tablet. Using the assumed 9 grams per week termite ingestion number, enough bait could be added to last approximately 10 weeks. The desired monitoring time is at least 12 weeks (3 months). Increasing the compaction pressure to 10,000 lbs. using the fine granule formulation tableted well and gave a much denser tablet with an approximate calculated monitoring time of the desired 12 weeks. Compaction pressures of 15,000 lbs. and 20,000 lbs. using the fine granule formulation, again both tableted well and extended the monitoring time to 13 weeks and 14 weeks respectively.

(14) Based upon the results set forth in the above table, the optimum compaction/density parameters appear to be 10,000 lbs. compaction pressure, a density of 1.196 gm/cc, a compaction ratio of 3.32 and an area compaction pressure of 688.71 kg/cm.sup.2.

Example 2

(15) The following bait composition was prepared for tableting:

(16) TABLE-US-00002 Dimilin 5.56 grams Solka Floc granules 94.44 grams

(17) 40 gram slug tablets were made using the Carver Press with 2.25 diameter die at 20,000 lbs. tableting pressure. The slugs were then ground in a hand grist mill to granules. The granules were shifted to 12/20 and 20/45 mesh sizes. Overs were hand ground through a 12 mesh screen with a pestle. The 20/45 mesh granules were than tableted into 5 gram 1.25 diameter tablets using the Carver Press at 10,000 tableting pressure.

(18) In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

(19) As various changes could be made in the above methods and compositions without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.