US3303601A

US3303601A - Destruction of nematodes

Info

Publication number: US3303601A
Application number: US489039A
Authority: US
Inventors: Whitney H Mears
Original assignee: Allied Chemical Corp
Current assignee: Allied Corp
Priority date: 1965-09-21
Filing date: 1965-09-21
Publication date: 1967-02-14
Anticipated expiration: 1984-02-14

Description

United States Patent 3,303,601 DESTRUCTION 0F NEMATODES Whitney H. Mears, Morris Plains, N.J., assignor to Allied Chemical Corporation, New York, N.Y., a corporation of New York No Drawing. Filed Sept. 21, 1965, Ser. No. 489,039 3 Claims. (Cl. 43132) This invention relates to the treatment of aqueous media containing nematodes and, more specifically, to the destruction of nematodes in said aqueous media.

Ultrasonic vibrations have been suggested for pest control in view of the fact that ultrasonics do not contaminate the medium in which they are used and do not require high, and, consequently, unsafe voltages for their operation. The use of ultrasonics has been limited, however, due to the lack of a specific effective mode of application and has not been used heretofore for the destruction of nematodes.

An object of this invention is to provide a method for the destruction of nematodes by ultrasonic vibration. A further object of this invention is to provide a method for the destruction of nematodes in an aqueous medium. Other objects and advantages will become apparent hereinafter.

In accordance with the invention, a method for the destruction of nematodes has been found which comprises applying modulated ultrasonic waves, at a frequency of about to about 100 kilocycles per second and at a power of about 50 to about 200 watts per gallon of aqueous medium, to such aqueous medium containing nematodes, for about 0.25 to about 10 minutes.

A more detailed description of the invention follows:

Water, or other aqueous media, containing the nematodes in any proportion can be run into a tank or pipe of known capacity. An ultrasonic generator is then attached to a transducer or a plurality of transducers which are inserted into the tank or pipe. The number of transducers can be determined by: (a) the capacity of the tank or section of the pipe, conveniently measured in gallons, to which the ultrasonic treatment is to be applied; (b) the power transmitted through the transducer; and (c) the rate of flow of the aqueous medium if such medium is not stationary. A transducer transmitting about 50 to about 200 watts per gallon of aqueous medium is effective providing the aqueous medium is in the transducer field for about 0.25 to about 10 minutes.

The number of watts per gallon of water transmitted by a transducer is determined as follows:

Energy appiled rated power output efficiency volume time tank volume Units can be watts, gallons, and minutes. Efficiencies of the generators are about 85%. It is assumed in this formula that energy is uniformly distributed over the tank volume. The energy applied must be taken as an estimate since sound can have maximum and minimum pressure regions depending on the wave lengths which can travel across the tank. FM modulation gives a wider band of frequencies than does AM modulation with consequent increased uniform distribution of power.

It is not understood why the foregoing combination of variables is effective. It can only be theorized that unmodulated waves give poor volume coverage; optimum carrier frequencies are dependent on the relationship of the corresponding wave lengths to the dimensions of the container; and the reflection of sound Waves complicates the intensity pattern.

It is advantageous to get an even distribution of the ultrasonic waves in the field which is bounded by the dimensions of the tank or by the pipe section, i.e., the full effect of the ultrasonic waves is preferably concentrated on the entire field as designated. The transducer can be conveniently placed in the corner of the three-dimensional area, which it is to service. This permits the power to be evenly distributed throughout the area. The transducer radiation patterns are not uniform but look like flashlight patterns with a wide angle of spread. Usually the waves radiate out into one half of a sphere and back-radiation is minimal. In the case of unidirectional transducers, the unit can be located in the lower corner of a rectangular tank and in the case of a transducer with a circular pattern, the transducer can be located in the center of a tank at a middle depth. The three-dimensional area is preferably as close to cubic or spherical in shape as practicable so that the distance from the transducer to the boundaries of the area are approximately equidistant. Where larger volumes are contemplated, each transducer can be placed in the center of the area, which the ultrasonic vibrations of the particular transducer are to influence. A matrix-like arrangement of transducers can be availed of in this event. Economy and simplicity suggest that a small tank which is constantly emptied and refilled or a narrow cross section of pipe give the most practicable application since a smaller number of transducers can service these areas and the capacity of the generator to power these transducers does not have to be so great. Where the aqueous medium is flowing through a pipe of narrow cross section, the transducers can be arranged along the path of the pipe so that the aqueous medium is continuously in the ultrasonic wave field for the required period of time.

It has been found that one transducer transmitting about 50 to about 200 watts per gallon of aqueous medium is satisfactory to accomplish the objective in a tank where the liquid medium is stationary although such tank can be emptied and refilled with different batches of water after the ultrasonic treatment is accomplished. Where the water is flowing through a pipe the number of transducers necessary is determined according to the power of the transducer, the area of the cross section of the pipe, and the rate of flow of the aqueous medium through the pipe, i.e., each gallon of aqueous medium must be in the ultrasonic field for about 0.25 to about 10 minutes.

The range of frequencies which can be used must be from about 10 to about 100 kilocycles per second. The preferred range is from about 20 to about kilocycles per second. The ultrasonic waves must be modulated, i.e., either amplitude modulated or frequency modu lated, with the latter modulation being preferred. The modulation is accomplished by the introduction of a wave whose frequency swings from about a carrier frequency of +50% down to about a carrier frequency of 50% at a swing rate of 10 to 10,000 cycles per second and is preferably 60 cycles per second. The preferred frequency modulation ranges from about 40+15 kilocycles per second to about 40-15 kilocycles per second and is preferably about 40: 15 kilocycles per second at 60 cycles second, As noted, the time required for exposure to the modulated ultrasonic field is from about 0.25 to about 10 minutes. The preferred time for exposure to the amplitude modulation modulated ultrasonic field is from about 0.50 to about 5 minutes. The preferred time for exposure to the frequency modulated ultrasonic field is from about 0.25 to about 2 minutes.

Example I Table I describes four units each of which includes an ultrasonic generator, a transducer, and a tank. The

3 ultrasonic generators used in this example were manufactured by the Narda Ultrasonic Corp. of Westbury, New York.

4 medium are generally opaque under low power magnification, being filled with food base. Treated nematode suspensoids were examined under a binocular micro- TABLE I Generator Characteristics Transducer Characteristics I Tank Unit Frequency, Modulation Watts Efficiency, Number of Watts (Gallon KC./Sec. Percent Transducers per Gal. Capacity) 1 20 AM 60 c.p.s 500 85 8 110 4 2 40 AM 60 c.p.s 500 85 8 110 4 8 90 wave AM 60 c.p.s 50 85 1 170 M 4 40:1;15 FM 60 c.p.s 300 85 8 60 4 Table II shows the destruction of nematodes by ultra- 15 scope to determine the percent kill by the ultrasonic sonic radiation using the uni-ts described in Table I.

TABLE II Unit Time Cycle Percent Kill 1. 1 min. 60 1 5 min 2. 1 min- 90 2 2 min 95 min. 100 15 sec. on; 10 sec. on; see. on 1 min 98 l min., 25 sec 99 2 min. (l'ocussed) 90 2 min. +1 min. (interrupted)- 98 5 min- 100 1 min 100 4. 1 min 100 4 30 sec 100 4 10 sec- 79 1 Not efiective. Norm:

Kc./sec.=kilocycles per second. AM=amplitude modulation. FM=trequency modulation. C.p.s.=cycles per second. Gal.=gallon.

Min.=minutes.

Sec.=seconds.

Focussed is defined as a narrow transducer beam angle of about degrees. The tank is therefore not covered by radiation but the radiation in some areas is more intense.

The tests shown in Table 11 above were accomplished with the use of a pure culture of the sour paste nematode, Panagrellus redivivus. This culture was grown on an oatmeal medium and the resultant nematodes were used as test organisms. The nematodes were separated from the oatmeal by washing and settling in a water column. After separation, the nematodes were diluted in distilled water to a concentration of approximately per ml. and were used in this solution in the tests set forth above in Table II. Nematodes grown on an oatmeal treatment. Dead nematodes were determined by observing their activity, i.e., these nematodes when alive generally oscillate at the rate of 120 times per minute; by their appearance, which is translucent with the body wall ruptured and the internal body contents removed; and by their failure to revive one hour subsequent to treatment.

I claim:

1. A method for the treatment of an aqueous medium containing nematodes comprising applying modulated ultrasonic waves, at a frequency of about 10 to about kilocycles per second and at a power of about 50 to about 200 watts per gallon of aqueous medium, to the aqueous medium containing nematodes for about 0.25 to about 10 minutes, whereby the nematodes are destroyed,

2. A method for the treatment of an aqueous medium containing nematodes as defined in claim 1 wherein the modulated ultrasonic waves are amplitude modulated.

3. Amethod for the treatment of an aqueous medium containing nematodes as defined in claim 1 wherein the modulated ultrasonic waves are frequency modulated.

References Cited by the Examiner UNITED STATES PATENTS 2,424,375 7/1947 Van Allen 116-437 2,448,372 8/ 1948 Horsley 99-217 X 2,585,103 2/1952 Fitzgerald 99217 X 2,715,384 8/1955 Meng 99217 X 2,922,999 1/1960 Carlin 340-384 FOREIGN PATENTS 474,187 10/ 1937 Great Britain.

SAMUEL KOREN, Primary Examiner.

F. MEDEERY, Examiner,

Claims

1. A METHOD FOR THE TREATMENT OF AN AQUEOUS MEDIUM CONTAINING NEMATODES COMPRISING APPLYING MODULATED ULTRASONIC WAVES, AT A FREQUENCY OF ABOUT 10 TO ABOUT 100 KILOCYCLES PER SECOND AND AT A POWER OF ABOUT 50 TO ABOUT 200 WATTS PER GALLON OF AQUEOUS MEDIUM, TO THE AQUEOUS MEDIUM CONTAINING NEMATODES FOR ABOUT 0.25 TO ABOUT 10 MINUTES, WHEREBY THE NEMATODES ARE DESTROYED.