Abstract:
The present invention provides a method and apparatus for generating the mosquito bait as well as simulating the human body&#39;s surface temperature and emanated odor. A well-controlled heating assembly can be used to generate a suitable thermal gradient for incubating both microorganisms and evaporating the bait. A bait-releasing unit is used to enhance the release of the mosquito bait. The bait comprises at least the bacterial decomposition and the yeast fermentation solution. The bait is not poisonous to human beings and produces mosquito attractants from natural products of fermentation or decomposition. The apparatus according to this invention comprises at least an upper compartment for trapping mosquitoes and a bottom compartment including the bait and the heating assembly. This invention can also combine with electrocution grids or insecticide webs to destroy attracted mosquitoes.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application is a continuation-in-part of prior application Ser. No. 09/749,353, filed Dec. 27, 2000. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of Invention  
           [0003]    The present invention relates to means for insect control. More particularly, the present invention relates to a microbe-mediated method of attracting mosquitoes for control purposes or for destroying mosquitoes.  
           [0004]    2. Description of Related Art  
           [0005]    Insect control has been in great demand throughout human history. It is necessary to control harmful insects like mosquitoes, to prevent the spread of disease, such as malaria and yellow fever. Public health authorities everywhere have expended intense effort on eliminating mosquito-related disease; however, this effort has not been wholly successful, largely because of the difficulty of eliminating mosquitoes. In addition to eliminating mosquito-related disease, another reason for eliminating mosquitoes is abatement of the nuisance caused by mosquito bites. Therefore, there has been a perennial call for means of effective mosquito control, including means to attract, capture, or destroy active mosquitoes.  
           [0006]    Female mosquitoes seek a human host from which they obtain a blood meal for egg development. Mosquitoes locate hosts through a combination of chemicals characteristic of the hosts. It is believed that the volatiles emanating from the human host are responsible for the attractant. These volatiles contain 300-400 compounds and originate from either the secretions of skin glands, or the decomposition of the skin microflora, or both. The mosquitoes use their olfactory structures to detect the attractant from as far away as 90 meters.  
           [0007]    Current methods of control only attack the mosquito population as a whole by chemical means or seek to remove their breeding sites. These methods are cumbersome, labor-intensive and often disruptive, in that they may introduce dangerous amounts of toxic chemicals into the environment. Some other attempts have been made to construct mosquito traps. For trapping mosquitoes, light, warmth, carbon dioxide, octenol, water vapor and lactic acid have all been used as attractants.  
         SUMMARY OF THE INVENTION  
         [0008]    The invention provides a method for controlling mosquitoes by attracting mosquitoes using bacterial decomposition and yeast fermentation products as the attractants for blood-feeding female mosquitoes and for non-host seeking mosquitoes respectively. This invention has combined heat and simulating attractants to achieve a highly efficient attraction. Furthermore, this invention is coupled with an attractant releasing mechanism, which enhances the release of the mosquito baits into the environment. The invention also comprises methods for trapping mosquitoes for control purposes or for destroying mosquitoes after attracting them.  
           [0009]    Another objective of the present invention is to provide a method and apparatus for generating the mosquito bait, as well as simulating the human body&#39;s surface temperature and emanated odor. A well-controlled heating assembly can be used to generate a suitable thermal gradient for incubating both microorganisms and evaporating the bait. The release of the bait can be further enhanced by a bait-releasing unit. The bait comprises at least the bacterial decomposition and the yeast fermentation solution. The bait is not poisonous to human beings and produces mosquito attractants from natural products of fermentation or decomposition. This invention can also combine with electrocution grids or insecticide webs to destroy gathered mosquitoes.  
           [0010]    As embodied and broadly described herein, the present invention provides a portable mosquito controlling system for trapping mosquitoes, for use indoors or outdoors, the system comprising an upper compartment including a plurality of channels for admitting and trapping mosquitoes; a bottom compartment; and a thumbscrew container for connecting the upper compartment and the bottom compartment. The thumbscrew container includes at least an upper thumbscrew, a bottom thumbscrew and a grid between the upper thumbscrew and the bottom thumbscrew. The mosquito controlling system further comprises a first fixture for holding a first bottle containing at least a yeast fermentation, a second fixture for holding a second bottle containing at least a microbe culture and controllable heating means for generating heat for the microbe culture and the yeast fermentation.  
           [0011]    As embodied and broadly described herein, the present invention further includes a bait-releasing unit for boosting the release of the bait into the environment. The bait-releasing unit mainly utilizes spraying mechanisms for spreading the bait as finely droplets (i.e. mist) into the environment. Therefore, the diffuse rate and evaporation rate of the bait in a certain space is increased, thus enhancing efficiency of the mosquito bait and increasing the effective distance for attracting mosquitoes.  
           [0012]    The bait-releasing unit comprises at least a spray nozzle and a pump. The spray nozzle includes an inner tube and an outer tube. The outer tube, acting like a siphon, can suck up (siphon) the liquid outside the spray nozzle to a top of the spray nozzle. Air or gas is pumped into the outer tube by the pump and then is ejected out in high speed from a top hole of the inner tube, so that the liquid bait can be sprayed out as fine droplet (i.e. mist), thus boosting diffusion and evaporation of the bait.  
           [0013]    It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings,  
         [0015]    [0015]FIG. 1 is a display view of an apparatus according to one preferred embodiment of the present invention;  
         [0016]    [0016]FIG. 2A is a perspective view of an apparatus according to one preferred embodiment of the present invention; and  
         [0017]    [0017]FIG. 2B is a partially exploded perspective view of the apparatus shown in FIG. 2A.  
         [0018]    [0018]FIG. 3 is a display view of a bait-releasing unit in the apparatus according to another preferred embodiment of the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    Some Coryneform bacteria, existing in human sweat, are known to produce methanethiols that emanate as both cheese and foot odor. The microbes may be responsible for producing human odors from human perspiration. Evidence for direct microbial involvement in producing the volatile attractants in human hosts has been demonstrated by showing that incubation of sweat enhances its attraction. Therefore, it is very useful to identify these microbes and use these microbes for simulating human odors, as a means for attracting the haematophagous mosquitoes.  
         [0020]    Nectar is the only food source of male mosquitoes, while the females of many species take a sugar meal before engaging in blood feeding. For the host-seeking flight, sugar is presumably the energy source and the initial differences in energy reserves affect the response to host volatiles. Additionally, that CO2 shows non-species limited attraction of mosquitoes has been reported in a dose-dependent response. In this invention, the mosquito attractants include at least a human odor simulator simulating human host volatiles, a sugar source and a CO2 supply source. The human odor simulator is provided by specific bacteria decomposition, while a steady increased CO2 concentration and a flavored sugar meal is provided by yeast fermentation using fruit juice as the culture medium.  
         [0021]    Experimental data:  
         [0022]    Some experiments were applied to mosquitoes, described as following:  
         [0023]    Mosquitoes The  Aedes aegypti  were maintained and assayed at 23-25° C., 60-80% relative humidity, and 12 hrs light/12 hrs dark. Adults were kept in 30 cm3 gauze-covered cages and fed with a 10% (v/v) sugar solution. In the bioassay 30 of the 4-8 day-old females that had not received a blood meal were released into a dual-port olfactometer. The olfactometer consisted of a flight chamber (1.6 m×0.6 m×0.6 m) in which mosquitoes were released. Air pumped from the room source was filtered by charcoal, passed through two bottles of distilled water, and one of the two ports (5 cm diameter, 30 cm apart), and then released into the flight chamber. The odor source was placed in the port, where the temperature was kept at 30° C. by a water circulation system, while the room temperature was maintained at 23-25° C. The observation time of the bioassay was 15 minutes after releasing mosquitoes. All parts of the olfactometer were cleaned with 75% alcohol and blow with strong fans for 20 minutes between test series. In addition, to counteract the effect of any biased directional response of unknown origin, the positions of the treatment and control were alternated between ports after each test.  
         [0024]    Bacteria Strains of two Coryneform bacteria,  Brevibacterium epidermidis  (BE) and  B. linens  (BL), purchased from Deutsche Sammlung von Mikrooranismen and Zellkulturen GmbH, Braunschweig, Germany and Food Industry Research &amp; Development Institute, Hsinchu, Taiwan, ROC, respectively, were used for bioassay. The bacteria were grown in three different mediums: TSB, MB and NB. The ingredients of the three mediums are listed as following: TSB (15 grams of tryptone+5 grams of soytone+5 grams of NaCl/liter, pH 7.3), MB (50 grams of milk powder+2.5 grams of peptone/liter, pH 7.2), and NB (5 grams of peptone+1.5 grams of beef extract+1.5 grams of yeast extract+5 grams of NaCl/liter, pH 7.4) at 30° C., 200 rpm for two days.  
         [0025]    In order to screen the different combinations of bacteria and medium for the highest efficiency of mosquito attraction, 4 ml of the 2-day-old bacterial cultures from different combinations were tested in the olfactometer.  
         [0026]    As shown in Table 1, most Corynebacterial strains grown in any of these three mediums can attract mosquitoes, except for strain BE9585 that did not show attraction. Among them, strain BE9586 is the only one to show attraction with all three growing mediums, of which that cultured with the NB medium had the highest attraction percentage. In general, the attraction efficiency was not higher than 30% in the absence of the heating device.  
                                     TABLE 1                           Bacterial cultures attracting adult female mosquitoes                Strains   TSB   MB   NB                       BE20660   + a     −   −           BE9585   −   −   −           BE9586   +   +   +++           BE20659   NA b     +   NA           BL20158   −   ++   NA           BL20425   −   +   NA           BL20426   +   +   +                                              
 
         [0027]    In order to further identify the attraction of strain BE9586 grown in the NB medium, the supernatant obtained from centrifugation of the bacterial culture was assayed in the olfactometer. Referring to Table 2, up to 86.7% of adult female mosquitoes were attracted toward the supernatant of the bacterial culture. This percentage of attraction was approximately 20% higher than NB medium alone and higher than blank solution without the odor source. It suggests that volatiles emanating from decomposition of the bacterial culture can exclusively attract adult female mosquitoes. In this assay, the heating itself showed 61.7% attraction, higher than previous non-heated odor sources. In addition, the heating device may also function for better evaporation of the bacterial decomposition.  
                             TABLE 2                           Percentage of mosquitoes attracted toward the supernatant of the       bacterial culture, conducted in the olfactometer.            Supernatant a     Nutrient Broth b     Blank c                 86.7 ± 4.2 d     67.5 ± 4.2   61.7 ± 11.8                                                  
 
         [0028]    [0028]FIG. 1 is a display view of an apparatus according to one preferred embodiment of the present invention. Referring to FIG. 1, the apparatus  100  is divided into an upper compartment  102  and a bottom compartment  104 , connected by a thumbscrew container  106 . A shield  108  is connected to the top of the upper chamber  102  with a supporting means, such as a supporting stock with extension walls for leading mosquitoes into passing channels. The shield  108  is separated from the upper compartment  102  by a distance of about 1-2 cm. Under the shield  108 , the top of the upper compartment includes a plurality of passing channels  110  that open inward to the internal space of the upper chamber  102 . The passing channels  110  have openings large enough for mosquitoes to pass through, while the channels  110  open inward to prevent the escape of incoming mosquitoes. After the upper compartment  102  is fit into the thumbscrew container  106 , a first bottle  120  is placed inside the upper compartment  102  and on a grid  112  of the thumbscrew container  106 . The first bottle  120  comprises at least odor simulators and a steady source for supplying CO2, as well as a sugar source. Preferably, the human odor simulators and the steady source for CO2 can be provided by the yeast fermentation with a medium. The medium may contain juice, further serving as a sugar source.  
         [0029]    Referring to FIG. 1, the bottom compartment  104  includes an adjustable heating assembly  114 , comprising at least a time-control means and a temperature-control means. The time-control means can set up an application time based on the user&#39;s schedule. The temperature-control means can generate heat to a specific (set-up) temperature and maintain the temperature, and comprises, for example, at least a metallic heater  116  that is controlled by a logic circuit. The adjustable heating assembly  114  can be controlled by the user&#39;s set-up to generate a regulated thermal gradient for bacteria incubation and evaporation of the bacterial decomposition components. A second bottle  122  is placed inside the bottom compartment  104  and on the bottom of the bottom compartment  104 . The second bottle  122  comprises host odor simulators, for example, bacterial decomposition. After incubating specific microorganisms (bacteria) with cultivating mediums, bacteria can generate metabolic products or decompose the cultivating medium so as to produce bacterial decomposition, Preferably, Corynebacterial strains and cultivating conditions used in previous experiments are used. For example, strain BE9586 grown in the NB medium [5 grams of peptone+1.5 grams of beef extract+1.5 grams of yeast extract+5 grams of NaCl/liter, pH 7.4] is used to provide bacterial decomposition. The heater  116  is provided inside the bottom compartment  104  and above the second bottle  122  for heating up the chamber of the bottom compartment  104 , thus providing heat for microbe incubation in the second bottle  122 . A conversion funnel  118  is used to gather the heat, provided by the heater  116 , in the chamber of the bottom compartment  104  and transfer heat to the chamber of the upper compartment  102 , thus providing heat for incubating the yeast fermentation. As a result, two different thermal zones are generated in two compartments. Preferably, the thermal zones of the upper and bottom compartments should maintain at about 30° C. and 37° C. respectively. These maintained thermal zones of the two compartments provide heat for microbe incubation of both microorganisms and for helping emanation of the attractants produced in the bacteria culture. Furthermore, the maintained thermal zone can simulate human body temperature and act as an attractant for attracting mosquitoes.  
         [0030]    Experiments performed by the inventors for the effect of heat combined with odor simulators on the mosquito species  Aedes aegypti  showed that bacterial decomposition along with heat evaporation could attract 60% of the mosquitoes, more than the 44% of mosquitoes attracted by yeast fermentation in a 60 minutes observation. Moreover, the synergistic effect could be observed in the combination of bacterial decomposition, yeast fermentation and heat evaporation, as 85% of mosquitoes were trapped after a 12-hours incubation within the olfactometer. Using bacterial decomposition as the mosquito bait attracts more mosquitoes in a certain period when compared with other baits, probably due to the dominant influence of odors in host-seeking behavior of mosquitoes.  
         [0031]    [0031]FIG. 2A is a perspective view of an apparatus according to one preferred embodiment of the present invention, while FIG. 2B is a partially exploded perspective view of the apparatus shown in FIG. 2A.  
         [0032]    Referring to FIG. 2A, an apparatus  200  is shown with an upper compartment  202  and a bottom compartment  204 , connected by a thumbscrew container  206 .  
         [0033]    Referring now to FIG. 2B, the apparatus  200  is shown in a partially exploded perspective view to further describe assembly details of the apparatus. A first bottle  220  is mounted on the center of a grid fixture  224 . The thumbscrew container  206  has an upper thumbscrew  226  and a bottom thumbscrew  228  in order to fit the upper compartment  202  and the bottom compartment  204  respectively, as well as a grid  212  between the upper thumbscrew  226  and the bottom thumbscrew  228 . A first O-ring  230  and a second O-ring  232  are used to seal up the upper compartment  202  and the bottom compartment with the thumbscrew container respectively. The grid fixture  224  is placed on the grid  212 , so that the first bottle  220  is located inside the upper compartment  202  after the upper compartment  202  fits with the thumbscrew container  206 . A collecting web  234  can be further included between the grid fixture  224  and the grid  212  for collecting dead mosquitoes. The collecting web  234  may also include a sticky material to trap mosquitoes or insecticides for killing mosquitoes. Furthermore, electric grids can also be included into the upper compartment  202  for killing mosquitoes.  
         [0034]    Referring to FIG. 2B, the bottom compartment includes a bottle fixture  236  with a removable undercarriage  238 , and a second bottle  222  is locked within the bottle fixture  236 . The removable undercarriage  238  can be dismantled from the bottle fixture  236 , so that the second bottle  222  can be refilled or cleaned. A heater  216  and a conversion funnel  218  are located above the bottle fixture  236 . The conversion funnel  218  has a narrower opening facing the center of the grid  212  and a wider opening facing the chamber of the bottom compartment  204 , so that heat gathered from the chamber can be transferred through the grid  212  to the upper compartment  202 .  
         [0035]    Bait-releasing Unit  
         [0036]    In another preferred embodiment of the present invention, the previously cited apparatus further comprises a bait-releasing means for enhancing the release and evaporation of the mosquito bait. The bait-releasing means, for example, utilizes spraying mechanisms for spreading the bait as finely droplets (e.g. with a diameter of about 5-50 microns) into the environment. Therefore, the diffuse rate and evaporation rate of the bait in a certain space is increased, thus enhancing efficiency of the mosquito bait and increasing the effective distance for attracting mosquitoes.  
         [0037]    A bait-releasing unit is taken as an example for the bait-releasing means of the present invention. FIG. 3 is a display view of a bait-releasing unit in the apparatus according to another preferred embodiment of the present invention. In FIG. 3, the bait-releasing (bait-spraying) unit  300  is disposed inside the aforementioned apparatus (shown as  303  in FIG. 3), either inside the upper compartment, inside the bottom compartment, inside the second bottle or between the upper and the bottom compartment. Moreover, the bait-releasing unit  300  can be coupled with the electric grids.  
         [0038]    The bait-releasing unit  300  comprises at least a spray nozzle  302 , made of stainless steel, and a small air pump  304 . The air pump  304  can be replaced by an air cartridge or by other mechanisms with similar functions. The spray nozzle  302  comprises an outer tube  306  and an inner tube  308  that is telescoped into the outer tube  306 .  
         [0039]    The air pump  304  pressurizes air through a tubing  309  into the inner tube  308  of the spray nozzle  302 . Because the outer tube  306  is immersed in the mosquito bait (in a liquid form) and a crevice  310  is in the bottom of the outer tube  306 , the liquid mosquito bait can be siphoned up to a cap  312  of the spray nozzle  302 . The air pressurized into the inner tube  308  then ejects at a high speed through a small hole  314 , thus spraying out the mosquito bait in a form of very fine droplets (shown as arrow in FIG. 3). The droplets have an average diameter of about 5-50, microns, for example. Therefore, the bait is turned to a mist that is volatile and easily diffusive.  
         [0040]    Because the apparatus  303  has an outer shell that can prevent large droplets of the bait from spreading out, only fine droplets of the bait are released into the environment. Therefore, each droplet can quickly and easily evaporate, thus enhancing efficiency of the mosquito bait and increasing the effective distance for attracting mosquitoes.  
         [0041]    Accordingly, the bait-releasing unit sprays out the mosquito bait in a form of fine droplets, so that the diffuse rate and evaporation rate of the bait in a certain space are increased, thus increasing the effective distance for attracting mosquitoes and boosting efficiency of the mosquito bait to a maximum.  
         [0042]    For testing the effect of the bait-releasing unit combined with mosquito attractants, experiments are carried out within a room dimensioned 3.5*3.5*3 meters on the mosquito species  Aedes aegypti.  The results showed that the mosquito capture rate is increased from 30% (without the bait-releasing unit) to 90% (with the bait-releasing unit).  
         [0043]    Therefore, the bait-releasing unit disclosed in the present invention indeed boosts diffusion of the mosquito bait and improves attraction toward mosquitoes, thereby increasing the capture rate of the mosquitoes.  
         [0044]    Furthermore, instead of the spraying mechanism of the aforementioned bait-releasing means, a foam blowing mechanism can also be used to help spreading out the mosquito bait. Through chemical reactions between specific foaming agents with solutions, gases, for example, carbon dioxide, can be produced to blow the mosquito bait into the surrounding environment. Therefore, it boosts the release of the bait and reinforces the attraction toward mosquitoes. One of the advantages of this foam blowing mechanism is no electrical power is required, thus suitable for outdoor usage in combination with pesticide or sticky materials.  
         [0045]    It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.