Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Aldehyde doai
Reexamination Certificate
1999-03-09
2001-03-13
Dodson, Shelley A. (Department: 1617)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Aldehyde doai
C514S703000, C514S705000, C424S045000
Reexamination Certificate
active
06201026
ABSTRACT:
BACKGROUND OF THE INVENTION
Among the many types of organic compounds that have been used as insecticides, very little attention has been paid to aldehydes. The only aldehyde that has received thorough investigation is acetaldehyde (ethanal). Studies involving acetaldehyde gas are reported by Aharoni, Y., et al., in “Acetaldehyde—a Potential Fumigant for Control of the Green Peach Aphid on Harvested Head Lettuce,”
J. Econ. Entomol
. 72(4):493-5 (1979), by Aharoni, Y., et al., in “Thrips Mortality and Strawberry Quality after Vacuum Fumigation with Acetaldehyde or Ethyl Formate,”
J. Amer. Hort. Sci
. 105(6):926-929 (1980), and by Stewart, J. K., et al., in “Acetaldehyde Fumigation at Reduced Pressures to Control the Green Peach Aphid on Wrapped and Packed Head Lettuce,”
J. Econ. Entomol
. 73(1):148-152 (1980). Various exposure periods were used in these studies, with various reduced pressures in the latter two studies, and the results show activity but no clear trend in data nor statistical difference between treatments at different pressures. The use of acetaldehyde as a commercial fumigant was not pursued further.
Insecticidal studies with aldehydes of three or more carbon atoms are few and inconclusive. Ferguson, J., et al., “The Toxicity of Vapours to the Grain Weevil,”
Ann. Appl. Biol
., 35:532-550 (1948), tested 94 compounds differing widely in structure, four of which were aldehydes, in exposures of five hours at 25° C. and atmospheric pressure. A screening study by Hinman, F. G., “Screening tests of compounds as fumigants for eggs and larvae of the oriental fruit fly,”
J. Econ. Entomol
. 47(4):549-556 (1954) covered 189 compounds, one of which was propanal, which was not considered a promising candidate for further study. The same investigator participated in a second screening study, reported by Burditt, A. K., et al., “Screening of Fumigants for Toxicity to Eggs and Larvae of the Oriental Fruit Fly and Mediterranean Fruit Fly,”
J. Econ. Entomol
. 56(3):261-265 (1963), where acetaldehyde, butyraldehyde, and isobutyraldehyde were included among 108 compounds screened, without including propanal. Exposure times were two hours at 75° F. (approximately 25° C.) and atmospheric pressure.
No further studies were reported on the use of aldehydes as insecticides, apparently because the low-to-moderate toxicity that the aldehydes demonstrated in these studies rendered them too weak for commercial utility. Furthermore, none of these published studies involved tests performed in the presence of an agricultural crop.
Of further potential relevance to this invention is prior art on applying gaseous fumigants under partial vacuum. An early study was reported by Sasscer, E. R., et al., “A method for fumigating seeds,”
U.S.D.A. Bull. No
. 186: 1-6 (1915). The effect of vacuum can vary dramatically, however, with some compounds displaying increased potency under vacuum (Bhambhani, H. J., “Recent advances in vacuum fumigation,”
Wld. Rev. Pest Control
, 3:53-56 (1964), others decreased potency (Monro, H. A. U., et al., “The influence of vapor pressure of different fumigants on the mortality of two stored product insects in vacuum fumigation,”
J. Stored Prod. Res
. 1:207-222(1966), and still others no difference in potency (Aharoni, Y, et al., 1980, cited above). The advantage of vacuum fumigation as reported by the prior art is its effect in increasing penetration of a pesticide into a dense load (Monro, H. A. U., “Vacuum Fumigation” in
Manual of fumigation for insect control
, 2d edition, FAO, Rome, 1969; and Stewart, J. K., et al., cited above), such as densely packed dates (Brown, W. B. and Heuser, S. G., “Behaviour of fumigants during vacuum fumigation: I. Penetration of methyl bromide into boxes of dates,”
J. Sci. Food Agric
. 4:48-57 (1953)), rather than achieving an increase in potency of a pesticide in an otherwise empty container.
SUMMARY OF THE INVENTION
It has now been discovered that organic aldehydes having 3 or more carbon atoms when applied as gaseous fumigants under reduced pressure demonstrate a toxicity to insects that is substantially greater than the same compounds demonstrate at atmospheric pressure. In direct comparison with studies reported in the prior art, the inventors herein have found that lethal doses for the same level of toxicity were one-half to one-fifth when the aldehydes were applied under reduced pressure than when applied at atmospheric pressure.
These and other objects, features, and advantages of the invention will become more apparent from the description that follows.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
The aldehydes used in the practice of this invention are those having three or more carbon atoms, preferably from 3 to 12 carbon atoms, and include straight-chain, branched-chain, saturated, and unsaturated aldehydes, including both monounsaturated and polyunsaturated. More preferred are straight-chain and branched-chain saturated aldehydes having 3 to 10 carbon atoms, straight-chain and branched-chain monounsaturated aldehydes (i.e., those containing a single double bond) having 3 to 10 carbon atoms, and straight-chain and branched-chain diunsaturated aldehydes (i.e., those containing two double bonds) having 3 to 10 carbon atoms. Even more preferred are straight-chain and branched-chain saturated aldehydes having 3 to 7 carbon atoms, and straight-chain and branched-chain monounsaturated aldehydes having 3 to 7 carbon atoms. Specific examples of aldehydes whose use is within the scope of this invention are 1-propanal (1-propionaldehyde), 1-butanal (1-butyraldehyde), isobutanal (isobutyraldehyde), 1-pentanal, 1-hexanal, 1-heptanal, 1-octanal, 1-nonanal, 1-decanal, the 2-monounsaturated analogs of the above, the 2,4-diunsaturated analogs of those having 5 or more carbon atoms, and the 2-, 3- ,4-, 5-, or 6-substituted analogs (and analogs substituted at two or more of these locations) where the substituents are methyl, ethyl, propyl, isopropyl or combinations thereof. Particularly preferred aldehydes are 1-propanal, 1-butanal, 1-pentanal, isobutanal, 2-methylbutanal, 2-methylpentanal, 2-pentenal, 2-methyl-2-butenal, 2-methyl-2-pentenal, and 3-methyl-2-butenal. The aldehydes may be applied either individually or in combination.
In accordance with the invention, the aldehyde or aldehydes are applied to the pest-infested region or crop in vapor form in an atmosphere in which the total pressure surrounding the region or crop is less than 300 mmHg (absolute) (0.4 atmosphere), preferably from about 1 mmHg to about 100 mmHg, more preferably from about 5 mmHg to about 50 mmHg, and most preferably from about 10 mmHg to about 35 mmHg. These pressures are to be understood as the total pressure, which is not necessarily the partial pressure of the vaporized aldehyde, which may constitute either part or all of the total pressure. In most cases, the atmosphere will contain a mixture of the vaporized aldehyde and air or some other gas (such as CO
2
, for example) that is not harmful to the crop. The total pressure is distinct from the dosage of the aldehyde, which is addressed below.
The duration of exposure to the aldehyde in accordance with this invention will be that amount of time sufficient to achieve control of the insects, i.e., killing of the majority, preferably substantially all, and most preferably all, of the insect population. The exposure at these subatmospheric pressures may constitute the entire duration of the fumigation process or an initial portion of the fumigation process, followed by raising of the pressure to atmospheric pressure. In some cases pest mortality may be increased and damage to the crop decreased by allowing the treatment to continue at atmospheric pressure after prolonged exposure to low pressure. Accordingly, the low-pressure fumigation can be performed in an enclosed vessel under partial vacuum, followed by letting air (or an air/gas mixture such as 50% CO
2
) in to raise the total pressure to atmospheric. The period of low-pressure exposure may vary depending on the dosage, the type of in
Hammond David G.
Kubo Isao
Dodson Shelley A.
Pryor Alton
The Regents of the University of California
Townsend and Townsend / and Crew LLP
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