IE59071B1 - Methods for controlling cockroaches - Google Patents

Abstract

Cockroach populations are controlled using the (S)-(+) enantiomer of hydroprene (Ethyl (2E, 4E)-3,7,11-trimethyl-2,4-dodecadienoate), which has superior juvenile hormone activity to the (R)-(-) enantiomer. Compositions for this purpose comprise (a) (S)-(+) hydroprene; (b) a diluent; and (c), where the diluent is a solvent, a propellant, a surfactant or a thickener.

Description

This invention relates to methods for controlling cockroach populations using the (S)~(*) enantiomer of hydroprene.

Hydroprene is ethyl (2E,4E)-3,7,ll-trimethyl-2,4-dodecadienoate. It is known to have juvenile hormone activity on insects e.g. cockroaches such as Blattella germanica (see i.a. J. Econ Entom (1975) 58;45-48) There is an asymmetric carbon atom at C-7 in hvdroprene and, accordingly, there are R and S enantiomers of the compound. J. Aqrjc Food Chem (1987) 26:542-550 reports comparative juvenile hormone activity tests on (S)-(*) hvdroprene, (R)-(-) hydrprene and the racemic mixture on Aedes aeovoti. Galleria mellonella. Tenebrio molitor, Musca domestica and Heliothis virescens.

It has now surprisingly been found that (S)-(<-) hvdroprene exhibits unexpectedly superior juvenile hormone activity on cockroaches relative to racemic hydroprene.

Accordingly, the invention provides a method of cockroach population control comprising administering a cockroach reproduction inhibiting amount of (S)-(*) hydroprene to the locus infested by said pupulation.

The term (S)-(-s-) hydroprene as used herein is intended to relate to hydroprene comprising substantially more than 50% by weight of the (S)(--)-enentiomsr Preferably the hydroprene used in the invention is composed predominantly of (S)-(*) hydroprene, i.e. comprises more than 75% by weight of (S)-(+) hydroprene. More preferably, the hydroprene contains less than 10%, particularly less than 5% by weight of the (R) enantiomer and is most preferably substantially free of the (R) enantiomer (i.e. contains less than 2% by weight of the (R) enantiomer) Pest controlling compositions suitable for use in the invention comprise: a) (S)-(*) hydroprene b) a diluent and c) where the diluent is a solvent, at least one adjuvant selected from a propellant, a surfactant and a thickener.

The term diluent as used herein means any liquid or solid agriculturally acceptable material which may be added to the active ingredient to bring it in an easier or improved applicable form. It includes carriers and solvents and can for example be calcium carbonate, talc, kaolin, clay, diatomaceous earth, resins (such as polyvinyl chloride, polyester urethane ethylene vinyl acetate, polypropylene), polyethylene, xylene, a petroleum solvent (including ligroin, benzin, naphta, a hydrocarbon such as pentane, hexane, octane), an alkanol such as isopropanol, a chlorinated hycrocarbon(e.g. CHgClg, CClgCHg), glycol monoalkvlecher, water and the like.

The term propellant relates to an agriculturally acceptable liquified gas which is self pressurised in a container having a valve and comprising a pest controlling composition, which gas forces the contents from the container when the valve is activated.

The term surfactant relates to an agriculturally aceptable material which imparts emulsiflability, spreading, wetting, dispersibility or other surface-modifying properties of the past controlling composition.

The term thickener relates to a material which increases the viscosity of a liquid. (5)-(+) hydroprene may be obtained in a manner known per se by resolving hydroprene into the (S) and (R) enantiomers or by synthesizing it from a resolved starting material.

(S)-(->) hydroprene exhibits a unique combination of properties vis-a-vis other juvenoids that makes it remarkably effective as a cockroach population control agent.

It is persistent in the enviroments that cockroaches inhabit. It is sufficiently volatile to translocate from one surface to another and thus penetrate into cockroach harborages, redistribute therein and remain accessible to resident cockroach populations. Further, (S)-(<·) hydroprene is effective in inducing sterility in cockroaches as well as having other juvenoid activities. This property is essential to effective cockroach eradication. Finally, (S)-(*) hydroprene has a high level of activity. Its superior activity relative to racemic hydroprene means that it is much more economical to use and provides less contamination of food and the human habitat than the racemic mixture.

In this regard, substantially pure (S)-(v) hydroprene has been found to provide German cockroach reproduction control in the laboratory at distribution levels as low as a few tenths of a microgram per square meter. Higher distribution levels may be required to control populations of other cockroach species such as the American cockroach (Periolaneta americana) and the oriental cockroack (Blatta oriental is). Also, in actual use in the field higher distribution levels than were used in the laboratory are used. Thus, depending on the nature of the surfaces in the habitat, the roach species, the mode of application etc., the distribution level of (S)-(4·) hydroprene in actual use will conveniently be in the range of 0.3 mg/m to 4 mg/m , more preferably of 3 mg/m2 to 30 mg/m2.

(S)-(O hydroprene is typically applied in composition form suitable for use in cockroach control. Examples of compositions suitable for such use comprise aerosols (in aerosol dispensers or foggers), roach baits, roach dusts, emulsifiable concentrates, ready to use sprays, ultra low volume sprays, aroma disks, roach strips and the like: such compositions may be obtained in conventional manner. The composition is conveniently applied to cockroach habitats, which habitats include human lodgings, sites where food is stored or prepared and industrial facilities.

For uss of (S)-(*) hydroprene in aerosol form, the active ingredient is conveniently formulated with an innocuous, volatile solvent and a propellant.

Examples of suitable volatile solvents are chlorinated alkanes such as methylene chloride or 1,1,1-trichloroethane.

Examples of suitable propellants are low boiling alkanes such as propane or butane or fluorinated hydrocarbons.

For use of (S)~(*) hydroprene in spray form, e.g. as emulsifiable concentrate or ready to use spray, the active ingredient will conveniently be formulated with an emulsifying agent and a solvent.

Examples of suitable emulsifiers are sorbitol, fatty acid esters, polyethoxylated fatty acid esters of alcohols or phenols, calcium dodecyl benzoate and the like.

Examples of suitable solvents are aromatic hydrocarbons such as xylene.

Solid compositions such as dusts or powders comprise (S)~(+) hydroprene and a solid carrier.

Examples of suitable solid carriers are calcium carbonate, diatomaceous earth, clay and the like.

(S)-(*) hydroprene may also be applied in solid composition form by evaporation from a solid carrier, e.g. in the form of aroma disks and strips, particularly the latter.

Solid compositions such as aroma disks and strips will comprise (S)-(+) hydroprene, a polymer and preferably a placticizer.

Examples of suitable polymers (resins) are polyvinylchloride, polyethylene, polyurethane, polypropylene, acrylics, nylon, in particular polyvinylchloride.

For use of (S)-(+) hvdroprene in bait form, the active ingredient will conveniently be formulated with a foodstuff.

Suitable foodstuffs for use in such baits are corn meal, dog food, corn syrup and the like.

(S)-(-j·) hvdroprene may also be used in microencapsulated form. Such microcapsules are conveniently of the gelatin of nylon type? compositions comprising microcapsules contain conveniently a thickener such as xanthan gum.

The (S)-(->) hvdroprene formulations may contain conventional additives such as U.V. stabilizers, heat stabilizers, antioxidants, pigments etc. They may also contain conventional insecticides such as organophosphates and pyrethroids to provide an initial knockdown of a portion of the cockroach population or other insects at the application site. They are prepared in a manner known per se. Suitable compositions comprise conveniently from 0.01 to 80% by weight of (5)-(^-) hvdroprene.

Conveniently aerosols will comprise from 0.01 to 10% by weight, emulsifiable concentrates and ultra low volume spray from 0.3 to 80% by weight, ready to use sprays from 0.5 to 10% by weight and roach baits or strips from 1 to 15% by weight of (S)-(->) hvdroprene.

The invention is further illustrated by the following examples. These examples are not intended to limit the invention in any manner. Parts are by weight.

FORMULATION EXAMPLE I.- Aerosol A B C (S)(-!-) hydroprene (100%) 0.021 0.054 0.1 5CH2C12 17.546 15.935 15.9 cci3-ch3 54.333 55 55 propane/isobutane to 70 psi 28 28 28 2. Emulsifiable concentrate 10 (S)-(-s-) hydroprene (100%) 10 antioxidant 0.2 (butylated hydroxytoluene) emulsifier polyoxyethylene sorbitol ester) 30.8 15 solvent (aliphatic hydrocarbon) 59.0 3, Readv fo use sorav (S)-(+) hydroprene (100%) 0.4 20 water 91.86 antioxidant 0.44 (butylated hydroxytoluene) emulsifier (polyoxyethylene sorbitol ester) 2.0 25 chelating agent (NaEDTA) 5.0 buffering agent (citric acid) 0.3 4. Bait (S)-(*) hydroprene (100%) 1.0 30 CH2C12 5.0 corn meal 94.0 5,, Dust (S)~(+) hydroprene (100%) 10.0 35 Ethylene glycol 4.5 antioxydant (butylated hydroxy toluene) 0.5 silica 85 _ 7 .

Test I Foggers comprising 15 mg and 45 mg of (S)-(-s-) hvdroprene resp,, formulated according to Formulation Examples IA and IB resp. are discharged in a 85 m fogger chamber. At the time of discharge the chamber contained cigarette papers and three different test substrates (treated vinyl tile, glass and unpainted plywood) placed at distances of 1.8, 2 7 and 3.7 m from the fogger. This mist is allowed to settle for 20 minutes and the papers and substrates are removed. The papers are extracted and the extracts analysed to determine the amount of (S)-(*) hvdroprene (in ug/cm substrate) deposited at the three distances. The depositions are in the range of 0.005 to 0.053 ug/cm .

After removal from the chamber the treated test substrates are placed in a laboratory under ambient conditions. Within one hour of removal, ten to twelve fifth to sixth instar German roaches are confined to each of the treated substrate sufaces. Food, water and harborage is supplied.

The containers are examined daily for the first ten days. At the examination times food and water are replenished as needed. All roaches molting to the adult stage are removed and destroyed during the first ten days of the test- (Roaches in the last ten days of the last instar before molt are not sensitive to juvenoids).

After day ten the containers are examined every seven to fourteen days and the following status information recorded.

Total number of surviving roaches.

Adult or nymph status of each roach.

Sex of all adult roaches.

JH effect on adult roaches if any.

Ootheca carried.

Viability of ootheca dropped.

F1 progeny produced.

The final reading is taken at week 12 after the ten-day post-treatment period.

Based on these readings the treatments are scored for overall juvenile hormone (JH) effects.

The overall JH response of (S) hydroprene was significantly better than the racemic mixture which was used as Standard. More importantly, the results of the readings on total F^ nymphs produced and F^ nymphs produced per female roach having the opportunity to mate and produce young indicate the reproduction control activity of (S)-(+) hydroprene was about 7-fold higher than the racemic mixture.

Test 2 Serial dilutions of (5)-(+) hydroprene or racemic hydroprene in acetone are applied to glass and plywood plates by dribbling the solution onto the plates from a syringe. The plates are used as floors for test cages. Each cage is supplied with harborage, water and food and 50 4th instar German cockroaches. The cages are maintained at 27°C, 15 hours light cycle, 50% relative humidity for about two months. Control efficacy is scored based on morphological effects and 100% inhibition of reproduction. In these tests S(+) hydroprene provided 100% control 2 of reproduction at a distribution of 0.1 ug/cm , whereas the lowest distribution Giving 100% control with racemic hydroprene was 10 ug/cm 2 on glass and 1 ug/cm on plywood.

Claims (5)

1. - A method of controlling a cockroach population comprising administering a cockroach reproduction inhibiting amount of (5)-(+) hydroprene to the locus infested by said population.

2. Ihe method of Claim l f wherein the distribution of (S)(+) hydroprene to said locus is in the range of 0.3 to 40 mg/m .

3. The method of Claim 1 or 2, wherein the (S)(+) hydroprene is administered in aerosol or spray form.

4. « The method of Claim 1 or 2, wherein the (S)»(+) hydroprene is administered by evaporation from a solid carrier.

5. A method of controlling a cockroach population as claimed in claim 1 substantially as hereinbefore described with reference to the Examples.