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Title:
PERSISTENT ATTRACTANTS FOR THE MEDITERRANEAN FRUIT FLY, THE METHOD OF PREPARATION AND METHOD OF USE
Document Type and Number:
WIPO Patent Application WO/1989/010055
Kind Code:
A1
Abstract:
Novel attractants for the Mediterranean Fruit Fly, "Medfly", are disclosed. The attractants comprise isomeric blends of esters of iodo-trans-2-methylcyclohexanecarboxylic acid. In use, the attractants are competitive in attraction with the "standard" Medfly attractant, Trimedlure, "TML", but are much more persistent than TML.

Inventors:
Mcgovern, Terrence P.
Cunningham, Roy T.
Application Number:
PCT/US1989/001501
Publication Date:
November 02, 1989
Filing Date:
April 14, 1989
Export Citation:
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Assignee:
THE UNITED STATES OF AMERICA, as represented by, THE SECRETARY, U
DEPARTMENT OF COMMERCE.
International Classes:
A01N37/08; C07C61/15; (IPC1-7): A01N25/00
Foreign References:
US4764366A1988-08-16
US4152422A1979-05-01
US3016329A1962-01-09
Other References:
AGRICULTURAL AND FOOD CHEMISTRY, Vol. 6, No. 8, August 1958, GERTLER et al., "Esters of 6-Methyl-3-Cyclohexene-1-carboxylic Acid as Attractants for the Mediterranean Fruit Fly", pages 592-594.
AGRICULTURAL AND FOOD CHEMISTRY, Vol. 9, No. 5, Sept/Oct. 1961, BEROZA et al., "New Attractants for the Mediterranean Fruit Fly", pages 361-365.
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Claims:
What Is Claimed Is:
1. An attractant useful to attract the Mediterranean Fruit Fly "Medfly," for prolonged periods of time wherein said attractant comprises a blend of compounds having the formulae wherein isomers A, and A consists of from 0% to 50% of the blend and isomers B1 and B2 consists of from 50% to 100% of the blend; wherein CH3 and COOR are in the trans configuration; and wherein R is an aliphatic radical having from 15 carbon atoms, said R in each of formulae A. , A2 , B, and B2 being identical.
2. The attractant of claim 1 wherein R is a radical selected from the group consisting • of methyl, ethyl, propyl, 1methylethyl, lmethyl2,2,2trifluoroethyl and 2,2,2trifluoroethyl.
3. The attractant of claim 1 wherein said attractant further comprises a Medfly control agent. 14 1 4. The attractant of claim 1 wherein the Medfly 2 " control agent is an insecticide. 3 5. A method of attracting the Mediterranean Fruit .
4. Fly, "Medfly," for prolonged periods of time comprising.
5. subjecting the Medfly for an extended period of time to an.
6. attractant which comprises a blend of compounds having the.
7. formulae.
8. wherein isomers A, and A2 consists of from 0% to 50% of the 9 blend and isomers B1 and B2 consists of from about 50% to.
9. 00% of the blend; wherein CH3 and COOR are in the trans 11 configuration; wherein R is an aliphatic radical having 12 from 15 carbon atoms, said R in each of formulae ,, A2, 13 B, and B2 being identical; and wherein the attractant is £4_ present in an amount sufficient to attract the Medfly. I5f 6. The method of claim 5 wherein R is a radical 16 selected from the group consisting of methyl, ethyl, 17 propyl, 1methylethyl, lmethyl2,2,2trifluoroethyl and 18 2,2,2tri luorethyl.
10. 7 The method of claim 5 wherein the composition further comprises a Medfly control agent.
11. 8 The method of claim 5 wherein the Medfly control agent is an insecticide.
12. 9 An attractant useful to attract the Mediterranean Fruit Fly "Medfly," for prolonged periods of time, wherein the attractant comprises a compound having the formula CH3 ,0 COOR wherein CH3 and COOR are in the trarisconfiguration and the iodo atom is equatorial and axial; and wherein R is an aliphatic radical having from 15 carbons atoms.
13. 10 The attractant of claim 9 wherein R is a radical selected from the group consisting of methyl, ethyl, propyl, 1methylethyl, lmethyl2,2,2trifluoroethyl and 2,2,2trifluoroethyl.
14. The attractant of claim 9 wherein said attractant further comprises a Medfly control agent.
15. The attractant of claim 9 wherein the Medfly trol agent is an insecticide.
Description:
- I - PERSISTENT ATTRACTANTS FOR THE MEDITERRANEAN FRUIT FLY, THE METHOD OF PREPARATION AND METHOD OF USE

Background of the Invention

Field of the Invention This invention relates to novel attractants for the Mediterranean Fruit Fly, Ceratitis capitata Wiedmann, hereinafter referred to as the "Medfly." More particularly, the present invention relates to novel isomeric blends of aliphatic esters of iodo-trans-2- methylcyclohexanecarboxylic acid, the method of their preparation and the method of use thereof to attract the Medfly for prolonged periods of time.

Description of the Prior Act Attacking over 250 varieties of fruits, nuts and vegetables, the Medfly is one of our most serious crop pests. Found predominately in Hawaii, Central America, and subtropical regions of the world, the Medfly has periodically invaded the mainland of the United states causing major economic losses. Consequently, there exists a great need for effective programs to control this pest. Several attractants for the Medfly are known. Siglure (1-methylpropyl trans-6-methyl-3-cyclohexenecarboxylate) was the first synthetic lure found to have significant attraction to the Medfly. Medlure (1-methylpropyl 4(and 5) -chloro-trans-2-methylcyclohexanβcarboxylate) ,

II hereinafter referred to as "TML," were later reported to be

2 " greatly superior as Medfly attractants.

3 Currently, TML is the "standard" attractant most

4 widely used in traps for survey and detection of the

5 Medfly. TML evaporates rapidly during hot weather thereby

6 necessitating frequent and costly rebaiting of the traps.

7 Further, the short residual life of TML (as well as Medlure

8 and Siglure) mitigates against the development of an 9, economical male-annihilation formulation of attractantplus

1335 insecticide. TML also forms crystals during cold-weather

11" storage so that the amount of the attractant is reduced in

12 the supernatant. Because these crystals do not readily

13 redissolve, special storage problems can occur in large

14 volume programs. -

15 Summary of the Invention

16 An object of this invention is to provide novel

17 attractants which are highly attractive to the Medfly for

18 prolonged periods of time.

19 Another object of this invention is to provide

20 persistent Medfly attractants which are comparable in

21 attraction with TML but do not possess the deficiencies 22?—associated with TML.

23 We have accomplished the aforementioned objects by

24 providing certain isomeric blends of lower alkyl esters of

25 4(and 5)-iodo-trans-2-methylcyclohexanecarboxylic acid

26 which when applied in an amount sufficient to attract the

27 Medfly are highly effective for prolonged periods of time.

28 In addition to being much more persistent than TML, the

29 esters of the invention are not prone to crystallization as

30 is TML, and may be more facilely and economically produced

31 than TML.

Detailed Description of the Invention In general, esters useful in the present invention are represented by the general formulae

II wherein -CH 3 and -COOR are in the trans-confiαuration and I is in both the equatorial and axial conformation; and wherein R is an aliphatic radical having from 1-5 carbon atoms and is selected from the group consisting of lower alkyls and fluoro-substituted lower alkyls, said R in each of formulae I and II being identical. For purposes of the invention, the term "4 and 5" is used herein to designate a mixture of the 4- and 5-iodo isomers wherein the iodo atoms of the invention esters are in both an equatorial and axial conformation, thus providing a blend of four stereoisomers for each ester. The four stereoisomers are herein designated A.,, A~, B, and B 2 as follows:

1 Examples of esters useful in the present invention are

2' methyl 4(and 5)-iodo-trans-2-methylcyclohexanecarboxylate;

3 ethyl (and 5)-iodo-trans-2-methylcyclohexanecarboxylate;

4 propyl 4(and 5)-iodo-trjιns.-2-methylcyclohexanecarboxylate;

5 1-methylpropyl 4 (and 5)-iodo-trans-2 -

6 ethylcyclohexanecarboxylate; 2,2,2-trifluoroethyl 4(and

7 5)-iodo-trans-2-methylcyclohexanecarboxylate; 1-methyl-

8 2 ,2 ,2-trifluoroethyl 4 (and 5) -iodo-trans-2- mVi methylcyclohexanecarboxylate; 2,2,3,3,3-pentafluoro-1- 0 s m e ~ fcfe y l p r o p y l 4 ( a n d 5 ) - i o d o - t r a n s - 2 - 1 methylcyclohexanecarboxylate; and 2,2,3,3,4,4,4- 2 heptafluoro-1-methylbutyl 4(and 5)-iodo-trans-2- 3 methylcyclohexanecarboxylate. 4 Esters useful in the present invention may be prepared 5 as follows: The corresponding trans-6-methyl-3- 6 cyclohexenecarboxylic acid (as prepared by a Diels-Alder 7 reaction) is heated in a pressure vessel for 3 to 6 hours 8 at elevated temperatures with aqueous hydriodic acid in the 9 presence of an organic solvent, such as dioxane. The 0 resultant iodo-trans-2-methylcyclohexanecarboxylic acid is - a mixture of the 4- and 5-iodo iso ers and is converted to 2 the corresponding acid halide by reacting with a suitable Φ Iralσqenatinq agent, such as thionyl chloride, phosphorus 4 trichloride or phosphorus tribromide under mild conditions, 5 preferably at room temperature. The acid halide is then 6 reacted with the appropriate alcohol in a suitable solvent 7 such as benzene or anhydrous ethyl ether in the presence of 8 a hydrochloric acid scavenger, such as pyridine, to yield 9 the ester. 0 Isolation of the ester is accomplished by sequentially 1 washing the crude reaction mixture with dilute acid, dilute 2 base and saturated salt solutions. The crude product is 3 thereafter dried over a suitable drying agent, filtered and 4 the solvent removed. Final purification is accomplished by

fractional distillation under high vacuum. Individual stereoisomers of the esters can be separated by high- performance liquid chromotography. The stereoisomeric content of the esters can be easily varied by changing the reaction temperature during preparation of the ester. For example, invention esters synthesized by the addition of hydrogen iodide to the Diels-Alder acid adduct at moderately elevated temperatures, i.e., from about 65°C to 80°C, consist of a isomeric blend which has isomers A. and A 2 as its major components, with isomers B, and B- comprising about 10% to 20% of the blend. Esters synthesized by the addition of hydrogen iodide to the Diels-Alder acid adduct at about 95°C to 130°C consist of an isomeric blend which consists of greater than 50% of isomers B, and B 2 . Consequently, the higher the temperature the greater the B.,/B 2 isomeric content in the resulting ester. Of the four stereoisomers, the most attractive iso er is isomer B., having an equatorial iodo atom attached at the 5 carbon atom. For commercial practicalness, it is preferred to use a blend of isomers consisting predominately of isomers B 1 and B 2 . Preferably, the blend comprises an isomeric content of from about 50% to 100% of isomers B 1 and B 2 with isomers A, and A 2 comprising from about 0% to 50% of the blend. The esters may be used as is or they may be dissolved in volatile inert solvents such as liquid hydrocarbons, emulsified in water, or admixed with any other solid or inert liquid carrier. When used in actual practice in the field, the compounds may be impregnated on a solid carrier such as paper, cloth, sawdust, wood chips, or other absorbent material. The attractants may also be dispersed into the atmosphere by spraying or by dipping wicks into containers holding the ester composition. Further, the

attractants may be used in bait traps usually provided with ' means to prevent the exit of insects so that the size and location of infestations may be ascertained. For optimum results, the esters of the invention should be used in a substantially pure form, that is, the esters must be free of undesirable contaminants that tend to mask or otherwise inhibit their effectiveness as an attractant. It is within the compass of the invention to 5 usesthe., esters either individually or in combination. The G invention esters may also be used with - other Medfly ' attractants or control agents, such as insecticides, chemosterilants or the like. When used, however, these agents should be used in an amount which, as readily determined by one skilled in the arts, will not interfere with the effectiveness of the invention esters. Although the preparative procedures described above are the preferred synthesis for the compounds of the invention, it is within the scope of this invention to prepare- the esters using any suitable hydriodic acid addition, and esterification procedures. The invention is further demonstrated by the following examples which are intended only to further illustrate the invention- and not to limit the scope of the invention as defined by the claims.

Example 1 The preparation of a blend of ethyl 4(and 5)-iodo- trans-2-methylcyclohexanecarboxylate comprising more than 50% of isomers B, and B 2 using the Diels-Alder acid adduct intermediate is hereinafter illustrated. 21 g of trans-6-methyl-3-cyclohexenecarboxylie acid (0.15 mole) were added to a pressure bottle along with 60 ml CE 57% hydriodic acid and 30 ml of p-dioxane. The pressure bottle was equipped with a magnetic stirrer,

securely capped, and placed in an oil bath held at 115 to 125°C. The reaction mixture was stirred vigorously while being held in the bath for 3 hours. After cooling, the reaction mixture was poured into water and the organic layer was taken up in ether. The ether layer was washed 2 times with water, then the organic acid was extracted from the crude reaction mixture with 10% aqueous sodium hydroxide. The alkaline portion was strongly acidified. The released organic acid was taken up in ether and was washed 3 times with water, then with dilute sodium bisulfite solution, again with water, dried over anhydrous magnesium sulfate and filtered. After removal of the solvent the crude iodo acid (ca 36 g) was used directly in the acid chloride synthesis. 26.8 g of the iodo acid (0.1 mole) was dissolved in 25 ml of benzene and 9 ml of thionyl chloride (0.125 mole) was added dropwise at room temperature. The reaction mixture was stirred overnight and the excess thionyl chloride and benzene were removed under vacuum with slight warming (40°C) . The crude acid chloride was added dropwise to an excess of ethanol (12 ml) and 8 ml of pyridine in anhydrous ether. After standing overnight, the reaction mixture was extracted sequentially with water, dilute aqueous hydrochloric acid and sodium hydroxide and .finally with saturated salt solution. After drying over anhydrous magnesium sulfate, the crude product was isolated and purified by fractional distillation under high vacuum, b.p. 81°C/ 0.15mm Hg, n 25 & 1.5130, recovered yield 15.0 g, approximately 67% of which consisted of isomers B, and B 2 and 33% of isomers A. and A- (from gc peak height measurement) . If the product darkens excessively after distillation, the excessive color can be removed by washing the product with dilute sodium bisulfite solution.

1 Example 2

2 ' An isomeric blend of propyl 4(and 5)-iodo-trans-2-

3 methylcyclohexanecarboxylate was synthesized in a 0.02 mole

4 reaction in accordance with the procedure described in

5 Example 1, and purified by distillation under high vacuum,

6 b.p. 85°C 0.15 mm, n 25 D 1.5065, recovered yield 2.67 g (about

7 67% isomers B. and B 2 and about 33% isomers A. and A 2 from

8 gc peak height measurement) .

99 ' Example 3

10 To determine the effectiveness of the blends of the

11 invention a field test was conducted in a macada ia nut 12. orchard at Keaau, Hawaii, in October 1987.

13 Medfly captures using isomeric blends of methyl,

14 propyl, l-methy1 thyl, l-methyl-2 / 2,2-trifluoroethyl and

15 2 , 2 , 2-trifluoroethyl 4 (and 5)-iodo-trans-2-

16 methylcyclohexanecarboxylate were compared with those

17 captures obtained by using TML. The ester blends used were

18 (1) blends which consisted of about 100% B., and B 2 isomers;

19 and/or (2) normal blends, that is, blends comprising 20 ^ isomers 1f and A 2 , B 1 and B 2 wherein isomers A 1 and A 2 21 comprise more than 50% of the blend.

2_V - Treatments were applied to cotton wicks (9.5 mm diam.

23 x 12.7 mm length; Johnson and Johnson No. 2) in standard

24= Jackson sticky traps. Each attractant was applied in a

25 " 0.025 ml dosage undiluted to a wick. Six replicates were

26 used. The TML wick was allowed to age along with the other

27 attractants. Sterile laboratory-reared medflies were

28 released throughout the test plot in a uniform manner at 0,

29 1, 2, 3, 4, 8, 10 and 13 days posttreatment. Fresh sticky

30 inserts were placed in the traps prior to each release and

31 remained in the trap throughout the test interval.

32 The TML used in the tests was obtained commercially

33 from UOP in East Rutherford, N.J.

Data was analyzed by analysis of variance, and means ' were separated by Duncan's multiple range test at the P = 0.05 level (Duncan 1951). The results are recorded in Table I. Table I clearly shows the high attraction and superior persistence of ester blends comprising only isomers B t and B 2 over the normal blends. All of the B t B 2 blends were significantly more attractive than their corresponding normal blends. In no case throughout the test did the catch of the normal mixture equal the catch obtained with the corresponding B^ blend. Of the ester blends tested, the B t B 2 isomeric blend of the ethyl ester was the most attractive. Although not as initially attractive as the ethyl ester blend, the B^ isomeric blends of the propyl and the 1-methylethyl esters showed significant persistence over TML. After 2 days TML began to fail while the propyl and 1-methylethyl esters were effective up to 13 and 8 days, respectively. Further, the propyl and 1-methylethyl blends outlasted the ethyl ester up to 5 and 2 days, respectively.

Example 4 The relative attractiveness of the four stereoisomers o f ethy l 4 ( and 5 ) - i o d o - t ra n s - 2 - methylcyclohexanecarboxylate, and mixtures thereof, were determined in a field test conducted in a macadamia nut orchard at Keaau, Hawaii, in February 1988. Medfly captures obtained with fresh and aged TML was compared to captures obtained using the ethyl ester having the following isomeric content: (1) high A 1 and A 2 , that is, more than 50% of isomers A, and A-; (2) isomer A 2 ; (3) isomers B 1 and B 2 ; (4) isomer B 1 and (5) isomer B 2 with ca. 2.5% of isomer B 1 .

The bioassay was the same as described in Example 4 ' except that a freshly baited TML wick was added to the test prior to each fly release and medflies were released at 0, 1, 3, 4, 8, 9, 10, 11 and 14 days postreatment. Data were analyzed in accordance with Example 4. The results are reported in Table II. Table II shows that of the four stereoisomers of the ethyl ester, the most attractive isomer was the B. isomer. - Traps with the B, isomer had higher mean catches than those 3 σf fresh TML in the first 6 test periods and in 7 of the 9 test periods overall, Medfly captures with blends comprising the B, isomer were significantly as attractive as fresh TML up to 10 days. All isomeric mixtures of the ethyl ester tested were more persistent than aged TML which began to fail between days 1 and 3. It is understood that modifications and variations may be made to the foregoing disclosure without departing from the spirit and scope of the invention.

TABIE I

Attraction of the Mediterranean Fruit Fly to Esters of 4(and 5)-Iodo-trans-2-methvlcyclohexane-l-ca_±)θxylic Acid When Compared With Trimedlurβ (TML), October, 1987, Keaau, Hawaii

leaner Weight π^n catς-h/t ra after IrrUcatøa foyg of ex o^-ire in th<? f jeiςfo s/

Ester blend 8 /

TML-aged 162a 176a 122bc 14f Of 0θ Od OC

Methyl Normal 5f 5a 6f 9f 7ef Oe Od Oe Bl B- 3Ida 38d 45de 49de 48d 0a Od Oc

Ethyl B A 157a 216a 190ab 200a 229a 93b Od Oc

Propyl Normal 33da 62θd 56de 97bσ 91od 52c 23b • 6b B lB - 69bc 143ab 122bc 147ab 165ab 146a 65a 49a

1-Methylethyl Normal 12ef 36d 49de 58odβ 90cd 19d 7c Oc B A 47od 84c 94cd 93bσ 125bc 34cd 8c Oc l-Methyl-2,2,2- trifluoroethyl Normal 16ef 39d 33θ 29ef 14e Oe Od Oc B A 49od 102bc 52de 64od 65d Oe Od Oc

2,2,2-Tri .fluoroethyl Normal 107b 197a 207a 167a 144bc Oe Od Oc

^Normal blend is composed of 4 isomers, A- A 2 , B 1# and B2 wherein iscmars K and A 2 are more than 50% of the blend

^6 replicates; 0.025 ml dosage

^Catches followed by the same letter within a column are not significantly different (£ > 0.05; Duncan's [1951] multiple range test).

TABLE: II

Attraction Of The Medi£err-tf!paη Fruit FJy φ V$ryij>g Isomeric Blends Of Ethyl 4 (and 5) -iodo-trans-2-tnethyl- cyclohexanecarboxyiata And To Its ' Individual ϊsq e s A 2 , B χ , AND B2 When Oαipared With φjrijnedlurθ (TML) .

Isomer Weighted mean cqtch/trao after Indicated dava in the fleld^

Con e ^/ 0 1 3 4 8 9 10 11 14

.ML-(fresh) 152a 44ab 63a 92a 136a 130ab 125a 52b 119a

IML-(aged) 78bα 19b 10b Oc Oc Od Oe 0d 0c

High ^--^ 19da 2c 5b 23b 15b 15c 12d 2od 3b

Λ 2 4e Oc Oc Oc Oc Od Oe Od 0c

High B 1 B 2 ≤/ 113ab 4 ab 50a 109a 96a 91b 41bc 7c 0c

B A 135ab 60a 65a 123a 126a 109ab 28cd 6c Oc

B l 172a 63a 73a 121a 139a 144a 103a 85a 116a ^ •*0od 3c βb 22b 15b 12c le Od Oc

^ e 4 isomers that cαtifose the tran_) blend are designated At, A 2 . Bt and B 2'

^catc es followed by the same letter within a column are not significantly different (£ > 0.05; Duncan's [1951] multiple range test); 0.02 ml dosage; 6 replicates.

^Hi A A 2 consists of isomers A 1# A 2 , B j and B wherein isomers A j and A 2 are more than 50% of the blend. High Bι/B 2 consists of isomers A^ A 2 , B j _ and B 2 wherein isomers B^ and B are more the 501 of the lend.

^/contained ca. 2.5% isomer Bl.