WO1992009199A1

WO1992009199A1 - Method of attracting male hessian flies

Info

Publication number: WO1992009199A1
Application number: PCT/US1991/008716
Authority: WO
Inventors: Stephen P. Foster; Marion O. Harris; Jocelyn G. Millar
Original assignee: Kansas State University Research Foundation
Priority date: 1990-11-23
Filing date: 1991-11-21
Publication date: 1992-06-11
Also published as: AU9125391A

Abstract

Male Hessian flies (Mayetiola destructor) are attracted and trapped by use of a fly trap charged with an effective amount of the sexual pheromone (2S)-(E)-10-tridecen-2-yl acetate, or a racemic mixture containing the same, and males and females are disrupted from finding mates at higher dosages. The pheromone is advantageously used at a level of up to about 500 νg in the fly trap method, more preferably at a level of from about 10-100 νg. The charged fly trap may be placed in proximity to a wheat field for monitoring and control of the Hessian fly. Mating between male and female Hessian flies is disrupted by release of amounts of (2S)-(E)-10-tridecen-2-yl acetate (or a racemic mixture containing the same) from a number of points throughout a region populated by Hessian flies at a rate of between 1 and 1000 mg/hectare/hour.

Description

METHOD OF ATTRACTING MALE HESSIAN FLIES

Background of the Invention 1. Field of the Invention

The present invention is broadly concerned with a method of controlling Hessian flies, which are known to be one of the most destructive pests of wheat. More particularly, it is concerned with a method of attracting and trapping male Hessian flies wherein (2S)-(E)-10- tridecen-2-yl acetate (or a racemic mixture containing the same) is used in an effective fly-attracting amount for attracting male Hessian flies to a fly trap. 2. Description of the Prior Art Wheat is the most widely cultivated plant in the world. It is grown in large acreage in every inhabited continent, and provides more than 20% of food calories consumed throughout the world. The Hessian fly, Mayetiola destructor (Say) , is one of the most destructive pests of wheat. It is found in most major wheat-growing areas of the world. Hessian flies have been shown to use a sex pheromone in their sexual communication. This pheromone is released by the female, from somewhere on her ovipositor, and elicits upwind flight by the male. Outbreaks of the Hessian fly are notoriously irregular and can be highly destructive (crop losses of over $100 million have been reported in the U.S.A. in a single year) . Because of this and because this pest is particularly difficult to monitor, it has been suggested that the sex pheromone could find great utility in moni¬ toring and control programs for this pest (MacKay and Hatchett, Ann. Entomol. Soc. Am.72:616-620 (1984)). No sex pheromones of species in the family Cecido yiidae have yet been identified, and hence no method of control based upon sexual attraction has been developed. Summary of the Invention

The present invention overcomes the problems described above, and provides an effective method for the monitoring and control of Hessian flies. In particular, the invention involves a method of attracting and trapping male Hessian flies which comprises exposing the flies to an insect trap charged with a fly-attracting effective amount of (2S)-(E)-10-tridecen-2-yl acetate, and also to a method of exposing male and female Hessian flies to effective amounts of (2S)-(E)-10 tridecen-2-yl acetate which comprises releasing the compound throughout a region populated by these flies; such release method disrupts the mating between male and female flies. This compound has been shown to be the principal female-produced sex phero- mone of the Hessian fly. In both uses, a racemic mixture containing (2S)-(E)-10-tridecen-2-yl acetate may also be used.

In preferred trap forms, the (2S)-(E)-10-tride- cen-2-yl acetate is used at a level of up to about 500 micrograms in a trap, and more preferably at a level of about 10 to 100 micrograms. Any conventional insect trap may be used, but preferably the (2S)-(E)-10-tridecen-2-yl acetate is placed on a rubber septum within such a trap. To be most effective, the traps should be placed in proximity to a wheat field.

In preferred mating disruption methods, the

(2S)-(E)-10-tridecen-2-yl acetate is released at a rate of up to 1000 mg/hectare/hour, and preferably at a level of about 1 to 500 mg/hectare/hour. To be most effective, the pheromone should be released from a number of point sources located throughout a region populated by Hessian flies. Brief Description of the Drawing

Figure 1 is a process flow diagram setting forth synthesis schemes for the synthetic production of the pheromone used in the present invention, as well as related insect species, such synthesis schemes being fully described in Example 1. -

Description of the Preferred Embodiment

In the development of the present invention, the crude sex pheromone of the Hessian fly was obtained by dissecting the terminal segments of the ovipositor of calling female Hessian flies, and extracting these seg¬ ments in pentane.

The extract of the female sex pheromone glands was hydrolysed, and reacted with (2S)-acetoxy-propionyl chloride in 10% pyridine/diethyl ether for approximately 24 hours at ambient temperature (Slessor, et al., J. Chem. Ecol. ljL:1659-1667 (1985)). The retention time (and mass spectrum) of the product from this reaction was compared with the retention times (and mass spectra) of the acetoxy lactate products obtained from the reactions of synthetic (2S)- and (2R)-(E)-10-tridecen-2-ol with (2S)-acetoxy- propionyl chloride. This demonstrated that the naturally occurring pheromone consisted entirely of the (S)-enantio- mer (detection limit <2% of (R)-enantiomer) .

The following example describes the laboratory synthesis of the Hessian fly pheromone, as well as the related structural isomer thereof and the racemic mix¬ tures. Such synthetic compounds were then used in bio- assays described below.

EXAMPLE 1 A synthetic route was required that would give access to all possible stereoisomers of the basic struc¬ ture of the Hessian fly pheromone, as neither the chiral- ity nor the double bond geometry had been ascertained in the insect-produced compound. The synthesis shown in Scheme 1 had the required flexibility. The synthesis was carried through with racemic material initially, and the double bond geometry of the natural pheromone was deter- mined by comparison of the retention times of the synthe¬ tic Z and E isomers with that of the insect-produced material. The synthesis was then repeated with a chiral synthon, S-(-)-propylene oxide, to produce the enantiomers of the pheromone. Thus, the lithium salt of 1-octyne 1 was reacted with racemic propylene oxide 2. in THF-HMPA, to give alkynol 3_¹. The triple bond was then isomerized to the terminal position using the modified acetylene zipper reaction², yielding alkynol 4.¹. The lithium salt of 4_. was alkylated with ethyl bromide in THF-HMPA, completing the carbon skeleton. Reduction of the product 5_. with sodium in liquid ammonia³, or P2-nickel and hydrogen⁴, gave 10E- and 10Z-tridecen-2-ols 6. and 8. respectively. Acetylation of the alcohols with acetyl chloride and triethylamine gave the racemic forms of the two possible pheromone structures 2 and 9.. The isomers were readily distinguish¬ able by capillary gas chromatography (DB-5 column) . The retention time of the natural pheromone exactly matched that of the 10E isomer 1_, confirming the double bond geometry as E.

With geometry of the alkene settled, the enanti¬ omers of 2 were prepared by the same route, substituting S-(-)-propylene oxide [S-(-)-2] for racemic 2. in the first step. Ring opening of the epoxide was accomplished with little or no loss of chirality⁵, yielding 2S-3_. with an enantiomeric excess (e.e) of >98% (vide infra) . 2S-3. was then carried through the same synthetic steps as racemic 3., with similar yields, and minimal loss of chirality, yielding 2S-(E)-10-tridecen-2-yl acetate, 2S-2- 2R-7 was synthesized via the intermediate alcohol, 2R-6., which in turn was prepared by inversion of the chiral center in alcohol 2S-6. by Kruizinga's method^6,7, Scheme 2. Thus, 2S-6_ was converted to mesylate 2S-10 by the usual conditions (MesCl/triethylamine in methylene chloride)⁷, followed by stereoselective nucleophilic displacement of the mesylate with cesium propionate in DMF. Base hydrolysis of the propionate 2R-11 gave alcohol 2R-J5 (e.e. >96%) , which was acetylated as before, giving 2R-2_/ with minimal loss of chirality.

Enantiomeric excesses of alcohols 3_-j> were determined by derivatization with 2S-2-acetoxy-propionyl chloride⁸. The resulting diastereomeric esters were readily resolved to baseline by capillary GC (DB-5 col- umn) .

EXPERIMENTAL Proton NMR spectra (CDC1₃) were recorded on a GE- 300 NMR spectrometer, at 300 MHz. IR spectra were record- ed as films of neat compounds on NaCl plates, with a Perkin-Elmer 137 spectrometer. Mass spectra (electron impact, 70 eV) were recorded with a Hewlett-Packard 5970 mass selective detector, interfaced to a H-P 5890 capil¬ lary GC. An HP-1 capillary GC column (12.5 m x .2 mm ID, 0.33 micron film; Hewlett-Packard) was used for all GC-MS work. Routine GC runs were carried out with an H-P 5890 GC with FID detection, fitted with a DB-5 column (20 m x .32 mm ID, 0.25 micron film; J&W Scientific) in split mode, using He carrier gas. GC signals were integrated with an H-P 3396A integrator. Optical rotations were measured with a Perkin-Elmer Model 241 polarimeter, using a 1 decimeter cell with a volume of approx. 1 ml.

Unless otherwise stated, reaction mixtures were extracted 3 times with the stated solvent, and the com- bined extracts were washed with brine, dried over anhyd. Na-,S0₄, and concentrated on a rotary evaporator under water aspirator vacuum. Flash chromatography was carried out with 230-400 mesh silica gel (Aldrich Chemical Co.).

Enantiomeric excesses of alcohols 3.-6_. were determined by derivatization of the alcohols with 2S-2- acetoxy-propionyl chloride. Thus, two equivalents of the acid chloride were added to dilute solutions (0.1 M) of the alcohols (1 equivalent) in a mixture of ether and triethylamine (approx. 5 equivalents) at room temperature. The mixtures were mixed thoroughly, and allowed to stand overnight. The mixtures were then extracted thoroughly with excess saturated aqueous NaHC0₃, the organic portions were dried over anhyd. Na₂S0₄, and the resulting solutions of diastereomeric esters were analyzed by capillary GC on a DB-5 column (20m x .32 mm ID, 0.25 micron film).

Enantiomeric excesses were determined by comparison of the integrated peak areas of the diastereomers. In all cases, baseline separation of the two diastereomers was achieved.

4-Undecyn-2-ol 3_.n-BuLi (60 ml of a 2.5 M solution in hexanes, 150 mmol) was added dropwise to a cooled (<-10°C) solution of 1-octyne 1_. (16.5 g, 150 mmol) in THF (250 ml) . The mixture was stirred for 30 min, then cooled to -20°C. HMPA (50 ml) was added, followed by dropwise addition of racemic propylene oxide 2. (10.15 g, 175 mmol) . The solution was warmed to 20°C overnight, then poured into water and extracted with hexane, and worked up as described above. The crude product was distilled under vacuum, yielding alcohol 2 (24.18 g, 96%) , bp 68-70°C (0.2 mm Hg) . Lit bp, 65-72°C (0.2 mm Hg)¹. NMR δ: 3.90 (m, IH; H-2) , 2.37 (ddt, IH, J=16.4, 4.9, 2.4 Hz; H-3), 2.27 (ddt, IH, J=16.4, 6.8, 2.3 Hz; H-3) , 2.15 (tt, 2H, J=6.9, 2.4 Hz; H-6) , 1.98 (d, IH, J=4.7, Hz; -OH), 1.55-1.44 (m, 2H; H-7) , 1.43-1.25 (m, 6H; H-8,9,10), 1.23 (d, 3H, J=6.2 Hz; H-l) , 0.89 (t, 3H, J=6.8 Hz; H-ll) . IRλ max cm^"'1: 3350 (s, broad), 2960 (s) , 2860 ( ) , 1465 (m) , 1375 (w) , 1075 (m) , 945 (m) . The NMR and IR spectral data were a good match with literature data⁹. MS m/z (Rel. abundance): 124 (2, M^÷-CH_jCOH) , 109 (3), 96 (15), 95 (23), 82 (17), 81 (21), 68 (31), 67 (39), 54 (100), 45 (68). The reaction was repeated, substituting S-(-)- propylene oxide (Fluka Chemical Corp., Ronkonka, NY) for racemic propylene oxide, yielding 2S-4-undecyn-2-ol (2S-3.) in 68% isolated yield, [α]²⁸ _D=+20.4±0.3° (c 1.22, CHC1₃) , and an enantiomeric excess (e.e.) of >98.3%, as determined by capillary GC (190°C, isothermal) of the diastereomeric ester formed by derivatization of 2S-3 with 2S-2-acetoxy- propionyl chloride. Spectra and chromatographic retention times of 2S-3 matched those of racemic 3.. l-Undecyn-10-ol 4. Lithium wire (5.21 g, 750 mmol) was dissolved in approx. 250 ml of 1,3-diaminopro- pane. The resulting blue solution was heated at 65°C until the blue colour was discharged (approx 2 hr) . The resulting white slurry was cooled to 20°C, and potassium t-butoxide (66 g, 590 mmol) was added in one portion. The orange slurry was stirred 30 min, followed by dropwise addition of racemic alcohol 3. (21.0 g, 125 mmol). The mixture was stirred 45 min (reaction complete by GC) , poured onto 1 kg of ice, and extracted with hexane. The hexane extracts were backwashed with 1 M HCl, then worked up as usual. The crude product was distilled under vacuum, giving alcohol 4. (19.63 g, 93%), bp 65-70°C (0.18 mm Hg) . NMR δ : 3.79 (m, IH; H-10) , 2.17 (td, 2H, J=7.0, 2.7 Hz; H-3) , 1.93 (t, IH, J=2.7 Hz; H-l) , 1.50 (m, 2H; H- 9), 1.45-1.22 (m, 11H; H-4 to H-8, -OH), 1.19 (t, 3H, J=7.8 Hz; H-ll) . IRλ max cm^*1: 3350 (s, broad), 3300 (m) , 2940 (s) , 2860 (s) , 2135 (w) , 1470 (m) , 1375 (w) , 1135 (m) , 1105 (m) , 1065 (m) . MS m/z (rel. abundance): 135 (1, M^÷-CH_j-HpO) , 125 (1), 107 (4), 95 (8), 93 (12), 81 (23), 79 (18), 67 (36), 55 (34), 45 (100), 41 (55). The reaction was repeated on smaller scale with 3.07 g of 2S-3 (18.3 mmol), yielding 2S-4 in 78% yield, [α]³⁰ _D=+7.2±0.3° (c 0.54, CHC1₃) , with e.e. >=98.3% by capillary GC (190°C isothermal) of the diastereomeric derivatives formed as for 3. above. Spectra and chromato¬ graphic retention times of 2S-4 matched those of racemic .

10-Tridecyn-2-ol 5_. n-BuLi (9 ml of a 2.5 M solution in hexanes, 22.5 mmol) was added to a cooled (<0°C) of alkynol 4. (1.68 g, 10 mmol) in 25 ml of THF. The resulting slurry was cooled to -40°C, HMPA (5 ml) was added, followed by dropwise addition of ethyl bromide (1.42 g, 15 mmol) in THF (5 ml). The mixture was warmed to 20°C overnight, poured into water and extracted 3 times with hexane. After workup as usual, the residue was purified by flash chromatography (15% EtOAc in hexane) , giving alkynol 5 (1.73 g, 88%). NMR δ : 3.79 ( , IH; H-2) , 2.14 (m, 4H; H-9, 12), 1.55-1.23 ( , 13H; H-3 to H-8, - OH), 1.19 (d, 3H, J=6.2 Hz; H-l) , 1.12 (t, 3H, J=7.4 Hz; H-13). IRλ max cm^"1: 3400 (s, broad), 2950 (s) , 2865 (s) , 1465 (m) , 1375 (m) , 1330 (m) , 1135 (m) , 1065 (m) . MS m/z (rel. abundance) : 163 (1, ϊ_pO-CH_j) , 149 (5) , 135 (5) , 121 (10), 107 (22), 93 (37), 82 (31), 81 (41), 79 (49), 67 (100), 55 (56), 45 (99), 41 (98). 2S-5 was prepared in identical fashion in 91% yield, [α]³¹ _D=-r-5.7+0.2° (c 0.76, CHC1₃) , with an e.e. of _>98.1% as determined by capillary GC (210°C isothermal) of the diastereomeric derivatives, formed as for 3_. above. Spectra and chromatographic retention times of 2S-5 matched those of racemic 5..

(Z)-10-tridecen-2-yl acetate 9.. Nickel acetate tetrahydrate (63 mg, 0.25 mmol) was dissolved in 10 ml of

95% EtOH. Under a strong flush of argon, 250 ul of a 1 M solution of NaBH₄ in EtOH was added in one portion. The flask was flushed with H₂ and ethylene diamine (33 ul, 0.5 mmol) was added, followed by alkynol 5. (0.5 g, 2.55 mmol) . The mixture was stirred under a slight positive pressure of H₂ until the reduction was complete (approx 2 hours) . The mixture was then filtered with suction through a plug of activated charcoal, rinsing the charcoal well with ethanol. The filtrate- was concentrated, taken up in hexane, washed with 1 M HCl, and worked up as usual. The crude product 8. (0.37 g, 74%) was 98% pure by capillary GC, and so was used without further purification. Alcohol _ was taken up in ether (25 ml) , cooled in an ice bath, and triethylamine (1 ml) and acetyl chloride (0.29 ml, 4 mmol) were added sequentially. The mixture was warmed to room temperature overnight, poured into hexane, washed with 1M HCl, and worked up as usual. The crude product was purified by flash chromatography on 10% AgN0₃ on silica gel, eluted with 5% ether in hexane. The purified acetate was Kugelrohr distilled (oven temp 110°C, 0.2 mm Hg) , yielding 0.27 g (44% from 5) of acetate , >99.5% chemically pure by capillary GC. NMR δ : 5.33 (m, 2H; H-10,11) 4.88 (m, IH; H-2) , 2.02 (s, 3H; acetate CH₃) , 2.02 (m, 4H; H-9, 12), 1.6-1.4 (m, 2H; H-3), 1.4-1.25 (m, 10H; H-4 to H-8) , 1.20 (d, 3H, J=6.3 Hz; H-l) , 0.96 (t, 3H, J=7.5 Hz; H-13) . IRλ max cm^"1: 2950 (s) , 2865 (s) , 1750 (s) , 1465 (m) , 1370 (m) , 1250 (s, broad), 1070 (m, broad) . MS m/z (rel. abundance) : 225 (trace, M^-IS) , 180 (3, M÷-CH_jCOOH) , 138 (5), 124 (5), 110 (8), 96 (17), 82 (41), 68 (47), 55 (36), 43 (100), 41 (56).

(E)-10-tridecen-2-yl acetate 2«Sodium pellets (0.52 g, 23 mmol) were dissolved in 40 ml of a 1:1 solu- tion of THF:liquid NH₃. Alcohol 5. (0.41 g, 21 mmol) was added, and the mixture was stirred under reflux for 5.5 hr. The reaction was quenched by addition of solid NH₄C1 (5 g) and the NH₃ was allowed to evaporate overnight. The residue was taken up in water and extracted with hexane, followed by the usual workup, giving crude alcohol _5 (0.41 g) . The alcohol was acetylated and purified as described for 8. above, giving acetate 2 (0.39 g, 78% from j5) . NMR δ : 5.40 (m, 2H; H-10,11), 4.88 (m, IH; H-2) , 2.02 (s, 3H; acetate CH₃) , 1.97 (m, 4H; H-9,12), 1.6-1.4 (m, 2H; H-3) , 1.4-1.25 (m, 10H; H-4 to H-8) , 1.20 (d, 3H, J=6.3 Hz; H- 1), 0.96 (t, 3H, J=7.4 Hz; H-13). IRλ max cm^"1: 2950 (s) , 2860 (s) , 1755 (s) , 1465 (m) , 1370 (m) , 1250 (s, broad), 1030 (broad), 972 (m) . MS m/z (rel. abundance): 180 (5, M*-CH₃COOH) , 138 (5), 124 (6), 110 (9), 96 (17), 95 (17), 82 (45), 68 (55), 55 (38), 43 (100), 41 (57).

2S-(E)-10-tridecen-2-ol [2S-6] , [α]³¹ _D=+5.8+0.1° (c 1.32, CHC1₃) , and 2S-(E)-10-tridecen-2-yl acetate [2S- ⁷] [c_]³¹ _D=+0.8±0.2° (c 0.80, CHCl₃) were prepared in identical fashion from 2S-J5, in 87% yield overall. The e.e. of 2S-6_. was determined as before to be >96.7% (GC temp, 210°C isothermal) . Spectra and chromatographic retention times of 2S-6. and 2S-7 matched those of racemic 6. and exactly.

2R-(E)-10-tridecen-2-yl acetate (2R-2) • Meth- anesulfonyl chloride (0.52 g, 4.5 mmol) was added to an ice-cold solution of 2S-(E)-10-tridecen-2-ol (0.594 g, 3.0 mmol) in 20 ml of 20:1 CH₂CI₂:triethylamine. The solution was stirred at 0° for 1 hr, then washed twice with cold saturated aqueous NaHC0₃, once with brine, then dried and concentrated in vacuo (0.2 mm Hg) for 2 hr, yielding 2S-10 as a yellow oil (0.82 g, 98%), chromatographically homoge¬ neous by silica gel TLC (20% EtOAc in hexane) . The oil was used without further purification.

Cesium proprionate:propionic acid complex (1:1 complex; 500 mg, 1.5 mmol) was added to a solution of mesylate 2S-11 (0.44 g, 1.6 mmol) in dry DMF (15 ml, dried over activated 3 Angstrom molee. sieve) . The mixture was stirred for 33 hr at 40°C under Ar, then poured into water (100 ml) . The mixture was extracted 3 times with hexane, and the combined hexane extracts were worked up as usual. The residue was flash chromatographed (7.5% EtOAc in hexane), yielding propionate 2R- L (0.33 g, 87%).

A mixture of the propionate 2R-11 (0.21 g, 1.22 mmol) and NaOH (25 mg) were stirred in MeOH (10 ml) for 36 hr. Water (0.5 ml) was added, and the mixture was stirred a further 16 hr. The mixture was concentrated, taken up in hexane, washed with water, and worked up as usual. The residue was flash chromatographed (20% EtOAc in hexane) , yielding 2R-tridecen-2-ol (2R-j5, 200 mg, 83%) , [α]³¹ _D=- 5.3±0.3° (c 0.34, CHCl₃) , with an e.e. of >96.4%, deter¬ mined as described for 2S-.6 above.

The purified 2R-6. was acetylated as described above for the 2S enantiomer, yielding 2R-2 (92%) , [c_]³² _D=- 0.5+0.2° (c 0.80, CHC1₃) . Spectra and chromatographic retention times of 2R-6. matched those of racemic _5.

REFERENCES

1. A.C. Oehlschlager, E. Czyzewska, R. Aksela, and H.D. Pierce, Jr. Can. J. Chem. , 64, 1407 (1986). 2. S.R. Abrams and A.C. Shaw. Org. Syn. 66, 127 (1988).

3. C . Henrick, R.L. Carney, and R.J. Anderson, "Some

Aspects of the Synthesis of Insect Sex Pheromones" in Insect Pheromone Technology: Chemistry and Applica¬ tions, eds. B.A. Leonhardt and M. Beroza; American Chemical Society, Washington D.C.; 1982; pp27-60.

4. CA. Brown and V.K. Ahuja. J.C.S. Chem. Comm. 553

(1973) .

5. L. Brandsma. Preparative Acetylenic Chemistry. Elsevier Publishing Co., New York. 1971. 6. W.H. Kruizinga, B. Strijtveen, and R.M. Kellogg. J. Org. Chem. 46, 4323 (1981).

7. B.D. Johnston and A.C. Oehlschlager. J. Org. Chem.

51, 760 (1986).

8. K.N. Slessor, G.G.S. King, D.R. Miller, M.L. Winston, and T.L. Cutforth. J. Chem. Ecology 11, 1659 (1985) . 9. K. Utimoto, C Lambert, Y. Fukuda, H. Shiragami, and H. Nozaki. Tetrahedron Lett. 25, 5423 (1984) .

EXAMPLE 2 Three separate bioassays were performed to determine the attractancy. of the (2S)-(E)-10-tridecen-2-yl acetate compound. These tests are described below, and the test results are collected in Tables 1-3. A. Y-TUBE OLFACTOMETER The Y-tube olfactometer used was similar to that described by Chaudury, Ball, and Jones; Ann. Entomol. Soc. Am.37:385-387 (1972).

The two equivalent arms of a glass Y-tube (2.9 cm diam.) were attached to two straight glass tubes (2.9 cm diam.) which functioned as traps for the respond¬ ing male flies. These glass tubes were attached to two larger tubes (4 cm diam. X 15 cm long) into which the sample being tested and a solvent blank were placed (into one each of the respective arms) . The sample consisted of the appropriate amount of chemi¬ cal or extract in n-hexane absorbed on a quadrant of filter paper (2.5 cm radius); the blank consisted of the same amount of n-hexane absorbed on a similar piece of filter paper. The third arm of the Y-tube was attached to a large glass chamber (19.0 cm long

X 6.3 cm diam.) into which male flies were introduced at the commencement of the test. Air, purified through activated carbon filters and subsequently humidified by being passed through water, was pumped through the olfactometer at a rate of 250 ml/min/arm.

Each test was run for 10 min. At the end of each test, the numbers of males in the sample trap, the blank trap, the Y-tube and the introduction chamber were recorded. Test results are set forth in Table 1. B. WIND TUNNEL

The design of the tunnel used was similar to that reported by Miller and Roelofs; J. Chem. Ecol.4.:187- 197 (1978) . The tunnel was constructed from a sheet of 5 mm diam.

Plexiglass and bent into the shape of a half cylinder (2 long X 60 cm diam.). The air flow (16 meters/min) was provided by a fan (40 cm diam. blade) and was smoothed through 3 screens of stretched cheesecloth before entering the tunnel. Fresh, moistened soil (ca. l cm deep) was placed on the floor of the tunnel in order to preclude male flies from sticking to the Plexiglass floor through elec¬ trostatic forces. The tunnel was illuminated by 6 fluorescent lights situated over the top of the tunnel. The chemical being tested was absorbed onto either a filter paper strip (0.5 cm X 5 cm) or a rubber septum (5 X 9 mm, sleeve type, A.H. Thomas Co.) and suspended approximately 2.5 cm above the level of the soil at the furthest upwind point of the tunnel. Located at the end of the tunnel (furthest downwind), was a steel cone (25 cm diam.) attached to a fan which exhausted chemicals tested in the tunnel to the outside of the building. An individual male fly was released into the tunnel approximately 1.5 meters downwind from the chemical source, and his responses to the source observed.

Test results are set forth in Table 2.

C FIELD CAGE TEST A 2 m X 2 m X 1. 5 m (high) field cage was placed in the middle of a wheat field. Inside the cage were placed four Pherocon (Zoecon Corp.) insect traps suspended just above the top of the wheat plants (approximately 20 cm above the ground) . Two of the traps were charged with 100 μg of the compound absorbed onto a rubber septum and the other two traps contained solvent treated blank rubber septa. Male flies were introduced into the cage at approximately 9 am and 3 pm on day 1 of the trial. The trial was run for 2 days after which the traps were removed from the cage and the number of males caught in the traps determined.

Test results are set forth in Table 3.

EXAMPLE 3 The synthetic sex pheromone (2S)-(E)-10-tride- cen-2-yl acetate may be used to disrupt the mating of male and female Hessian flies. The compound is loaded into controlled release formulation polyethylene capillary tubes (manufactured by Shin Etsu Chemical Co. Ltd.). Not less than 500 discrete point sources are distributed throughout the region where control of the insect pest is desired. A total of 1 to 1000 mg (2S)-(E)-10-tridecen-2- yl acetate/hectare/hour is released. The resultant uniform "cloud" of synthetic sex pheromone contacts the receiver of the pheromone signal, usually the male, and disrupts the ability of the receiver to find the (female) sender of the signal. "Mechanisms of disruption are thought to be: (1) sensory adaptation of pheromone recep¬ tors, (2) leading the male to false "trails", (3) preclud- ing the male from detecting the naturally produced sex pheromone of the female, or (4) distorting the sensory input into the male". Disruption of mating leads to fewer numbers of the insect pest in the subsequent generation, and hence pest control is achieved. The described method of loading the compound in a slow release formulation and release of 5 to lOOO g/ hectare/hour results in continuous disruption of mating of adult Hessian flies for a period of not less than one month. Table 1 Y-Tube Olfactometer Tests

^aRacemic mixture of (E)-10-tridecen-2-yl acetate ^b( 2S ) - (E ) -10-tridecen-2-yl acetate ^c(2R)-(E)-10-tridecen-2-yl acetate

Table 2 Wind Tunnel Tests

SOURCE

BLANK ^a

R-ENANTIOMER (20 ng) ^a'^b

S-ENANTIOMER (20 ng) ^a'^c

S-ENANTIOMER (200ng)^a'^c

RACEMATE (40 ng)^a'^d

S-ENANTIOMER (3 μg)^c'^e

S-ENANTIOMER (10 μg) ^c'^e

S-ENANTIOMER (30 μg)^c'^e

S-ENANTIOMER (100 μg)^c'^e

^aOn filter paper ^b(2R) -(E) -10-tridecen-2-yl acetate ^c ( 2 S ) - ( E) -10-tr idecen-2 -yl acetate d ^αRτacemic mixture of (E)-10-tridecen-2-yl acetate

On rubber septum Table 3

Field Cage Trial

SOURCE NUMBER OFMALES CAUGHT

(2S)-(E)-10-tridecen-2-yl acetate (100 μg) 291 BLANK 117

The foregoing data establish that the synthetic pheromone can be successfully used to attract and trap male Hessian flies when placed in a fly trap in an effec¬ tive fly-attracting amount.

Claims

Claims :

1. A method of attracting and trapping male Hessian flies which comprises exposing said flies to an insect trap charged with a fly-attracting effective amount of (2S)-(E)-10-tridecen-2-yl acetate or a racemic mixture containing (2S)-(E)-10-tridecen-2-yl acetate.

2. The method of Claim 1, wherein said (2S)- (E)-10-tridecen-2-yl acetate is present at a level of up to about 500 micrograms.

3. The method of Claim 2, wherein said (2S)- (E)-10-tridecen-2-yl acetate is present at a level of from about 10 to 100 micrograms.

4. The method of Claim 1, wherein said insect trap is equipped with a rubber septum bearing said (2S)- (E)-10-tridecen-2-yl acetate.

5. The method of Claim 1, wherein said trap is placed in proximity to a wheat field.

6. The method of Claim 1, wherein said (2S)- (E)-10-tridecen-2-yl acetate being synthetic.

7. A method of disrupting mating between male and female Hessian flies which comprises exposing said flies to an effective amount of (2S)-(E)-10-tridecen-2-yl acetate, or a racemic mixture containing (2S)-(E)-10- tridecen-2-yl acetate, released throughout a region populated by Hessian flies.

8. The method of Claim 7, wherein said release of (2S)-(E)-10-tridecen-2-yl acetate is at a rate of up to 1000 mg/hectare/hour.

9. The method of Claim 7, wherein said release of (2S)-(E)-10-tridecen-2-yl acetate is at a rate of about 1 to 500 mg/hectare/hour.