EP0984683A2 - Means amd method for pest control - Google Patents

Abstract

This invention relates to a pest control agent. The pest control agent includes one or more flavour-masking compounds and/or scent-disrupting/confusing compounds and/or irritating/repelling compounds selected from the following compounds namely suitable phenolic compounds, suitable naphthalenic compounds, suitable mono-terpenoid compounds, suitable aliphatic alkene and alkyne compounds C6 to C14 and suitable ketones and methyl ketones of aliphatic compounds C6 to C14.

Description

TITLE: MEANS AND METHOD FOR PEST CONTROL

INTRODUCTION

This invention relates to a means and method for pest control. More particularly, this invention relates to an agent or composition, and a method for controlling Lepidoptera pests, such as false codling moths, codling moths, etc., and Diptera pests, such as fruit flies, flies, mosquitos, etc.

BACKGROUND TO THE INVENTION

The false codling moth (Cryptophlefaia Leucotreta) (hereinafter referred to as "FCM") is a serious indigenous pest which destroys citrus, peach, plum and various other fruit crops both in South Africa and in other countries in the world. Losses is suffered as a result of infestations by this pest are massive when direct losses of infected fruit are considered together with

costs resulting from expensive insecticides that are used at present, for example on citrus fruit and trees. The cost to the industry in a country like South Africa includes a ban on fruit exports to countries such as the United States of America, as a result of insecticides used such as Alsystin or Nomolt which are the trade marks or trade names for teflubensuron and triflumuroπ, respectively. The aforementioned two chitin-inhibiting insecticides are presently registered for use on citrus in South Africa.

However, chitin-inhibiting pesticides such as Nomolt and Alsystin are losing their efficacy as a result of FCM developing resistance against them. Hence there are presently no alternative means of chemical control, and high losses of ruit in orchards will therefore result when FCM cannot be effectively controlled.

A more recent technique that has been adopted to control pests such as FCM is the use of smell or odour-disrupting substances. The FCM depends strongly on its olfactory senses for performing vital life functions such as feeding and mating.

The FCM as a nocturnal insect, is largely dependent on its olfactory sense for orientation in its living sphere. The male moth locates the female entirely by following through the air, a trail of sex pheromone exuded by the female, and the female also locates the proper host plant to feed upon and

to lay its eggs upon, through its olfactory senses. The tatter are located on the two antennae upon its forehead. If the olfactory sensors of night-living insects such as FCM can be put out of action or neutralised, they will become disoriented in their living space, so that the male will not be able locate the female to mate with, and the female will also not be able to find the host plant to feed upon or to lay its eggs upon. In the case of FCM. citrus trees of the right cultivar and not others must be located and then the fruit must also be located between the leaves, in the dark.

The types of substances that could usefully be exploited are:

(a) Attractive substances for example sex pheromones or food odours;

(b) Repellent substances for example Di-ethyl toluamide used against blood-sucking insects: and/or

(c) Odour-masking and odour-neutralizing substances for example those used in deodorants.

To date, certain smell-disrupting chemicals have been used to inactivate or neutralize the olfactory sensors of FCM. Such smell disruption has been utilised to achieve mating disruption of FCM. To this end, alterations in the normal ratio of (E)-7-Dodecenyl acetate, (E)-8-Dodecenyl acetate, (Z)-8-Dodecenyl acetate which constitute the sex pheromone mix of FCM,

will repel the male FCM from the female. However, these compounds are very expensive, rendering the mixture impractical for large-scale orchard

use.

Another, and simpler technique, has been to stock orchards densely with synthetic sex pheromone traps, making it very difficult for male FCM to

locate females. However, the FCM sex pheromone is also very expensive,

rendering impractical for large scale orchard use, so that this technique has

been somewhat limited.

Other examples known as insect repellents are for example Naphthalene (moth balls), used to repel cloth moths from wardrobes and Di-ethyl

toluamide (trade name or trade mark - Mγiol) to repel blood-sucking insects

from humans.

A known technique used to identify FCM flavour active substances is to

provide smell-disrupting compounds in standard (sex pheromone) traps.

These traps are pest specific indicators. The procedure followed has been

to treat one set of traps with experimental smell-disrupting compounds and

to compare it with an untreated i.e. control set of traps. All the traps are then placed in an environment well populated by the target pest - FCM - in

this case. Using this technique smell-disrupting compounds can be identified. OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide a pest control agent or composition and a method which is effective against Lepidoptera pests, such as FCM and codling moths (hereinafter referred to as "CM" ), and Diptera pests, such as Natal fruit flies. Also to identify substances which are non-poisonous to humans, are environmentally acceptable, and which are relatively inexpensive.

It is also an object of the present invention, to provide a novel and improved pest control agent or composition and method, accordingly, which avoids, at least partly, the shortcomings and the disadvantages of the prior art.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a pest control agent including one or more flavour-masking compounds and/or scent-irritating and/or scent-disrupting compounds selected from the

following compounds namely suitable phenolic compounds, suitable naphthyl or naphthalenic compounds, suitable mono-terpenoid compounds, suitable aliphatic alkene and alkyne compounds (C₆-C₁₄), and suitable ketones and methyl ketones of aliphatic compounds (C₆-C-₄). The or each suitable phenolic compound(s) may include :

hydroxy and/or methoxy substituted benzyl compounds including:

aldehydes thereof including 2-hydroxy benzaldehyde, 2- hydroxy 3-methoxy benzaldehyde (o-Vanillin), 4-hydroxy 3- methoxy benzaldehyde (standard Vanillin), 2-hydroxy 4- methoxy benzaldehyde, 2-hydroxy 5-methoxy benzaldehyde, 2,5-dihydroxy benzaldehyde (gentisic aldehyde), 2,4-dihydroxy benzaldehyde, 2,3-dihydroxy benzaldehyde;

alcohols, acids, and esters of the aforementioned compounds including 2-hydroxy benzyl (salicyi) alcohol, salicylic acid. methyl salicylic acid, methyl p-hydroxγ benzoic acid, methyl salicylate. ethyl salicylate, benzyl salicylate, phenety! salicylate, iso-amyl salicylate and hexenyl salicylate, but excluding methyl salicylate per se.

The or each suitable naphthyl or naphthalenic comρound(s) may include -

naphthalene but excluding naphthalene per se:

methyl naphthyl or naphthalenic compounds, including

1 -naphtal-dehyde, methyl naphtyl ketone and 2-methoxy naphtalene. The or each suitable mono-terpenoid compound(s) may include:

closed ring structures including (bi) cyciohexyl compounds. including limonene, iso-firrtonene, terpenene, phellandrene, sabinene, carvone, ionone , thujone, pulegone. menthol, menthone, diosphenol (buchu), and perilla aldehyde' and its corresponding alcohol;

closed ring structures including (bi) cyclo heptyl compounds including verbenol, myrtenal, myrtenol, fenchone, pinene, pinenal, camphene, carcene cineole and borneol;

- open ring dimethyl octyl compounds including ipsenol, nerol, geraniol, linalool, tagetone, allo-ocimen, neo allo-ocimen, myrcene, citral, citronelial, citronellene and iso— citronellene but excluding citroπellol per se;

C₂ up to C₅ alkyl esters of mono-terpenoids including acetate, propionate, (iso) butyrate and valerate esters.

The or each aliphatic compound(s) of C_e, C₇, C₈, C9 C₁₀, C,,, C₁₂- C₁₃, and

C₁₄ (C_β up to C₁₄)

unsaturated alkenes and alkynes as mono- di- or tri -ene group compounds including 1 -decene, 1 -decyne, 1 ,5,9-decatriene, 1 -undecene, 1 -dodecene, 1 -tridecene, 1 -tetradecene, 1 ,7 octadiene. 1 ,5 hexadiene, 1 -heptene, 1 -octene, and 1 -nonene; ketones and methyl ketones occurring mostly as alarm pheromones/allomones in Formicidea (-ants) and including 2,6 dimethyl 4-heptanone, 2-undecanone, 2-dodecanone, 2-tridecanone, 4-methyl 3-heptanone, 4-methyl 3-hexanone, 4,6-dimethyl 4-octen 3-one, 6-methyl 3-octanone, 6-methyi,

5-hepten 2-one, 4-methyl 4-heptan 3-one, 4-methyl 2-hexanone 2-methyl 4-heptanone, 4-methyl 4-hexen 3-one, 3-octanone, 3-decanone and 3-πonamone.

The invention extends to a pest control agent as herein described, whenever provided in a composition or form adapted to be sprayed.

The invention also extends to a pest control agent as herein described, whenever provided in a composition or form adapted to provide a retarded and even release of volatile compound(s).

According to another aspect of the present invention, there is provided a pest control composition, including an effective amount or concentration of a pest control agent as herein described.

According to yet another aspect of the present invention, there is provided a method of controlling pests, including the step of using or applying an effective amount of a pest control agent to a pest habitat or location, the pest control agent including one or more flavour-masking compounds and/or scent-disrupting compounds selected from the following compounds namely suitable phenolic compounds, naphthalenic compounds, suitable mono- terpenoid compounds, suitable unsaturated aliphatic compounds, alkenes and alkynes - C₆ up to C₁₄ and suitable aliphatic ketones and methyl ketones

- C₆ up to C₁₄ compounds.

The method may include the step of providing the pest control agent in a composition or form suitable for spraying, and spraying a solution of the agent to a pest habitat or location.

In another form of the invention, the method may include the step of providing the agent in a composition adapted to effect a retarded and even release of volatile compound(s), and providing such composition in or near a pest habitat or location.

The method may include the step of or be adapted for treating pests which eat and/or spoil fruit and/or vegetables and/or plants or trees.

The pests to be treated may include Tortricid moths, such as (ordinary) codling moths. (Laspeyresia pomonella) Eastern fruit moths (Grapholita molesta), false codling Moths (Crytophlebia leucotreta) and fruit flies (Pterandrus rosa). In a preferred form of thejnventioπ, the pest control agent may include a mixture of efficient and safe odour active substances from all of the critical chemical groups in order to disrupt as many as possible insect smell acceptors.

In a preferred form of the invention, spray additives may be provided in the composition to effect a retarded and more even release of all flavour active substances.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described by way of the following non-limiting examples to illustrate the nature of the invention more clearly and in greater detail.

EXAMPLE 1 :

In order to identify Vanilla as a flavour active (i.e. disruptive or repellant) substance, pure i.e. undiluted commercial Vanilla essence at 2ml per sex pheromone trap was applied inside the traps and placed in a FCM infested

Navel orange orchard. Control sex pheromone traps were placed in the same FCM infested orchard far enough not to be influenced by odours from the treated traps. Other experimental flavour-masking compounds- (-see below) were tested in the same manner.

FCM male moths were effectively repelled from the Vanilla-treated traps i.e. not attracted by the pheromone in such traps for at least 1 ,5 weeks or as long as the Vanilla flavour was perceptible in the traps. No male moths were caught in the Vanilla- treated traps for at least 1 ,5 weeks against 10 to 12 moths per week in the untreated control traps. This was confirmed in citrus orchards located on a different farm in a citrus-growing area of the Cape region (of South Africa).

The other flavour-masking compounds that were tested are dealt with hereunder.

Expecting that flavour activity may reside in botanical relationships, and because of the safety of such natural compounds, flavour extracts from two other aromatic plants belonging to the Rutaceae family (as does Citrus) were tested in the same way in FCM sex traps. These plants were Buchu (Agathosma betulina) and Rue (Ruta graveolens).

Buchu extract (of which the active ingredients are the monoterpenoids puiegone and diosphenol) repelled i.e. did not attract FCM males for approximately 5 days from/to a treated trap in a FCM infested orchard but thereafter FCM moths were caught. The Rue treatment had no significant effect.

This suggests or indicates that, although other flavour-masking compounds may be useful for the intended purpose. Vanillin has a considerable odour- masking or odour-disrupting effect on the sex pheromone, sufficient to some extent to disorient and/or confuse i.e. not to attract male FCM. However under higher population pressures, the apparent repellant action may not be strong enough.

EXAMPLE 2:

After the above repellant action of Vanillin was identified, FCM infected

Navel orange orchards were sprayed with a 0,2% to 0,25% by volume solution of commercial Vanilla essence in water, on two farms both being in a citrus-growing area of the Cape region. Medium spray volumes per tree were used, giving a good wetting but not sufficient for the solution to drip off.

WORK DONE ON FIRST FARM

The results of a spray program with Alsystin and Vanillin are summarized and illustrated in the graph annexed hereto as Fig. 1 .

Alsystin which was sprayed at a concentration of 15ml/ 100! reduced fruitfall one month after spraying by one half ( 1 ,6 to 0,8 fruits per day) but in the two consecutive weeks fruitfall increased till near the original level i.e. 1 ,4 fruits per day.

Alsystin as chitin inhibitor inhibited the hatching of part of FCM eggs only for one week while lethal levels of it were effective and before it reached sub-lethal levels because of natural breakdown. Alsystin resistance by FCM had previously been encountered in the particular orchard tested.

The first Vanillin spray was applied the beginning of March 1997, followed by two follow-up sprays as indicated.

One month after spraying, fruitfall reduced from 1 ,4 fruits per day to between 0,9 and 0,45 fruits per day. The first Vanillin sprays were not applied in the specific orchard where the FCM sex traps were located. FCM male moths caught in these traps at the beginning of May 1997 varied between 7 to 8 per week .

After the second and third Vanillin sprays applied to the orchard where the traps were placed, no (0) FCM male moths were caught in the traps. WORK DONE ON SECOND FARM

Pilot experiments on this farm indicated the following:

(a) FCM moth populations as monitored by sex traps (males) and fruitfall (females) are fairly mobile and easily migrate from place to place over time according to various (influencing) factors;

(b) Control blocks (non-sprayed with Vanillin) must be sufficiently far removed (about 100m to 200m) away and up-wind not to be affected by Vanillin vapour drift.

In tests done on this farm, FCM moth counts in sex traps varied from 6 to 10 and 12 moths per week in orchards sufficiently removed (between about

100m to 200m) from sprayed plots while in the Vanillin sprayed and adjacent possibly affected "control" blocks were about one FCM caught per week. Even on the same tree where 12 FCM moths were caught during a previous week, no FCM moths were caught the subsequent week in the same traps.

With particular reference to the annexed graph, it should be pointed out that the considerably reduction in FCM trap yield prior to Alsystin spraying is probably a normal seasonal tendency with FCM population changes, with maximum population in mid-summer and a reduction thereafter. When compared with prevailing norms, a trap yield of approximately 57 moths per week is exceptional. Normal trap yields of about 10 moths per week is the indicated level above which control measures are recommended and applied. Yields of between about 10 and 20 moths per week between week number 4 and week number 8 on the graph are normal for high yields. It should also be pointed out that spraying of Alsystin or Vanillin does not usually have an immediate effect on trap yield and/or fruitfall, but requires approximately 30 days or one month to take effect. Both compounds operate to impair egg-laying of FCM. After FCM eggs have been laid on the fruit and have hatched, it takes approximately thirty days for the worms to damage the fruit sufficiently for the fruit to fall. Consequently the first Vanillin spray at the beginning of March 1997 should have, and in fact showed its overall effect at approximately the end of March 1997, as seen in the graph. The second and third Vanillin sprays were applied because of an increasing fruitfall at those times, resulting from previously laid eggs.

It was therefore seen that the Vanillin odour had the effect of substantially reducing FCM populations, especially female FCM, by its odour-masking effect. In addition, and as proof of the aforementioned, no FCM or very few were caught in traps on trees sprayed with the aforementioned composition, as long as the Vanillin odour lasted, indicating the odour or smell-masking or disrupting effect of Vanillin. This is confirmed by the results shown in the attached graph.

As mentioned above, one or more additives could be provided in the solution which will result in a retarded and more even release of the Vanillin odour.

Vanillin is seen as a useful, safe and inexpensive additive to smell disruption mixtures. However in follow-up experiments, possible under higher population pressures, it seems to need help from other flavour active substances regarding efficiency.

Ways and means of effecting a retarded and more even release are necessary for all flavour-active substances. The aforementioned tests were expanded to identify other volatile substances to which the codling moth family or group were sufficiently sensitive so that such substances could be used to irritate, confuse and/or repel such moths thereby suppressing their activity on agricultural plants. These latter tests were commenced on FCM in citrus (orchards) as the initial target insect and were expanded to ordinary codling moths in apple orchards.

EXAMPLE 3:

1 . Orchard tests in respect of FCM on citrus:

The test was commenced with Vanillin. In respect of FCM, a pilot test was conducted on a block of 10 x 10 full-bearing Navel orange trees on a farm in a citrus-growing area of the Cape region (of South Africa). The block of trees was demarcated and the outer two rows were provided with a plurality of cloth strips which had been dipped in hot wax wherein 4% Vanilla had been dissolved. The cloth strips were suspended from branches of the trees in these rows.

FCM sex pheromone trap counts were recorded weekly in five traps in the block of trees - one in each corner and one in the centre of the block. In the untreated part of the orchard approximately 20m around the demarcated block and along each of its four sides, four traps were monitored.

After two weeks an average of 5 FCM were caught within the block as opposed to 12 in the traps located outside the block. Shortly afterwards the natural FCM population in the orchard had decreased to such an extent that the test was terminated. Low and erratic FCM trap counts made it difficult to conduct further accurate tests with Vanillin and other flavour-masking and/or scent-disrupting substances or compounds. Therefore tests were commenced with more readily controllable pot or container tests.

2. Orchard tests in respect of Coddling moths on apples:

A test block (A) of 9 x 9 apple trees was selected in an orchard in an apple-growing area of the Cape region (of South Africa). In every other row 3 Vanillin dispensers, as used in the test described immediately above, were suspended in the branches of each tree. Five sex pheromone traps were positioned in the block, one at each corner and one at the centre of the block.

A second test block (B) was provided with 4 traps suspended from trees in the adjacent area i.e. in 2 rows of threes outside and around test block A. After 4 weeks of trap counts, the size of block A was increased and expanded to increase the area of (formerly untreated) block B.

After the aforementioned expansion had taken place, the new surrounding

(untreated) area of 2 rows was established as block C A third set of 4 traps was placed therein, 1 trap in each of the 4 (double) rows.

A marked concentration of codling moths was observed in area B surrounding the Vanillin-treated block A during the first month. Cumulative average weekly trap counts increased in the following manner: 2 - 27 - 34 -

39. The comparable weekly increase in the adjacent Vanillin-treated area A was: 1 - 7 - 10 - 12.

After the Vanillin treatment was expanded to area B, the trap counts thereafter decreased rapidly with average weekly counts for the next month being: 1 ,0 - 1 ,3 - 0 - 0. Comparable counts for the original Vanillin-treated block A were: 1 ,0 - _ 1 ,0 - 0 - 0. However, in contrast to the aforementioned, the comparable weekly counts in the new border area C immediately after Vanillin application in the adjacent area B, were: 7,5 - 0.8 - 1 ,0 - 1 .0. Trap counts in the following month decreased throughout the areas A, B, and C, and in each of these areas on average was fewer than

1 per week.

It was noticeable that trap counts in the untreated area around the Vanillin- treated blocks or areas increased sharply especially during the first week of placing of the cloth strips i.e after placing of the strips on both occasions, in comparison with counts in the treated blocks themselves. The comparative figures were: 24,3 versus 5,8 for the first date and 7.5 versus 1 ,0 for the second date. In contrast herewith, the weekly average trap counts in the high population area B in the week immediately after Vanillin treatment decreased from 4,5 to 1 ,0, whilst at the same time there was an increase in the new border area C of from 4,0 to 7,5.

Traps were also placed for fruit flies, and it was observed that fruit fly trap counts at the end of the season averaged approximately 2 flies per trap per week outside the vanillin treated area while no catches were recorded in the vanillin treated block.

EXAMPLE 4:

Pot or container tests in respect of FCM:

Because of low and erratic FCM trap counts on citrus in the Citrusdal area this season, tests were conducted in respect of FCM under more controlled conditions. For this purpose artificially or laboratorium bred FCM obtained from the Good Hope Citrus Co-operative insectarium, were used. Recently hatched FCM moths, at an average count of about 20 moths per 750 ml canned fruit jar with screw tops, in which the odour test compounds were placed, served as test units.

Regarding the other pest insects, artificially bred common codling moths and Natal fruit flies were obtained from the Entomology Section, Infruitec Research Institute, Steilenbosch.

Evaluating the effect op smell perception of test insects in reaction to odour substances.

In the initial tests with FCM, the test compounds were placed at an amount between 0,15 and 0,2g per jar and applied to the inside of the screw top on aluminium foil. Moths were placed in the scaled jars for varying periods.

Thereafter they were exposed to the standard sex pheromone ampoule to determine whether their reaction (attraction of males), had been influenced. When it appeared that the reaction of the moths was related to their apparent health and life expectancy in the jars, survival time of the moths was mainly used as an important first sifting or elimination criterion to identify the most effective smell disrupting compounds, leading also to the identification of compounds which would shorten the life of moths. As was the case with the FCM, the same substances also shorten the lives of common codling moths (CM) and Natal fruit flies (NFF). A summary of the effect of the 5 main groups of flavour active substances on the lifespan of

FCM, CM and NFF appears in Table 1 .

The behaviour of insects effected by the odour active substances further suggest an irritation/unwanted effect of their chemosensilla which they try to get rid of by rubbing it off. The reaction of the fruit flies to most of the odour active substances is an incessant and active rubbing of their foreheads and extended mouthparts (probiscus) with its associated chemosensilla with their front legs. The same was also seen in the case of the garden crickets stroking their antennas with their front legs and even pulling it through their mouthparts when exposed to salicylaldehyde vapour.

The first effect of all flavour active substances upon the 3 types of test insects used, was a change from a immobile resting stance to rapid moving as if being irritated as soon as the vapours reach them from the inside of the jartops. Movements include running around, sitting on the one place and fluttering of wings, flying short distances and inducing copulation behaviour in males. After being effected, they lye on their sides and backs and rub their legs together.

EXAMPLE 4.1 :

Phenolic compounds:

Initially various forms/isomers of Vanillin namely standard Vanillin, iso-Vanillin and ortho Vanillin, which are all hydroxy/methoxy benzaldehyde compounds, were used. It was found that these and other flavouring compounds were injurious to the moths as measured by the shortening of their normal lifespan of approximately 10,5 days (250 hours). The LD₅₀ periods for the untreated control and iso-Vanillin was approximately 160 hours, for standard Vanillin approximately 130 hours and for ortho- Vanillin only approximately 7,5 hours. By way of explanation, the LD_S0 period is the time taken from the commencement of exposure of insects, in this case moths, to a relevant or suitable compound until 50% of the insects or moths are dead.

It was also found that FCM that were kept in the jars for approximately 4 days, were much more sensitive than younger FCM in response to standard Vanillin, as measured by significantly shortened lifespan relative to comparable controls. In view of the structural similarity between ortho-Vanillin and methyl salicylate (Wintergreen) in respect of the 2-hydroxy benzyl (salicylic) structure, it was decided in the selection of experimental phenolic compounds to concentrate on the salicylic (2-hydroxy benzyl) group. It was found that 2-hydroxy benzaldehyde (salicylic aldehyde) and methyl salicylate (Wintergreen) were two particularly toxic compounds for FCM. These were found to have LD₅₀ periods of about 0,25 hours and 0,5 hours, respectively, for comparable doses. See the graphs attached hereto as Fig.2 and Fig 3. These graphs show the relative effectivity of inter alia the aforementioned phenolic compounds.

Table 1 - Relative sensitivity of false codling moth (FCM), codling moth (CM) and Natal fruit fly (NFF) to flavour active substances.

Substance FCM CM NFF

Time (hours) to 50/100% mortality

1. Phenolic substances (dosage 0,01 g/container):

Salicyl aldehyde 0.22 - 0,33 0,5 -0,75 0,18 -0,33

Methyl salicylate 0,45- 1,17

Ortho-vanillin 7,5 - 22,0 - 55,0 - 180 Vanillin 130 - 220

Control-untreated 160 - 250 150 -230 140 - 220

2. Naphtalenic substances (Dosage 0,01 g/container)

Naphtalene 2,2 - 3,75 - 9,5 - 17,75

Methyl naphtalene 1,6 - 6,25 3. Monoterpenoids (Dosage 0,005 g/container)

Citronellal 0,66 - 1,5 0,5 - 0,67 0,2 - 0,33

Thujoπe 0,8 - 1,5

Carvone 0.9 - 1.58 0,37 - 0,58

Myrtenal 1,25 - 1,8 0,44 - 0,58

Citral 1.0 - 2,33 0,41 - 0,67

( neral + geranial)

Verbenone 1.6 - 2,53 0,17 -0,30

Limonene 2.0 - 4,73 0,26 - 0,50

Terpinylacetate 3,0 - 13,9

Myrcene 5,25 - 10,25

Allo-ocimen 5.4 - 16,1

Geranioi 36 - 55

4. Unsaturated aliphatic alkene and alkyne substances (Dosage - 0,01 g/container)

1-Decene 3,58 - 6,58 4,5- 5,25 0,55 - 1,75 1 -Decyne 4,5 - 8,25 1,5,9-Decatriene 8,5 - 49,5 3,75 - 6.75 0,33 - 0,92 1-Dodecene 10 -48

5. Aliphatic ketones and methylketones (Dosage 0,01 g/container)

2,6 Dimethyl 4 hβpatanone 0,8 -2,5 0,6 - 1,0 0,38 - 1,25

2-Undecanone 2,5 - 11,75

(-methyl nonylketone) trans 6,10-Dimetiel 5,9

Undecadienone 13,0 - 36,75

2-Dodecanone 13 -78 Insect allomone compounds i.e. chemical defence and repulsive compounds which were taken as an indication of desired activity, and which are classified in the phenolic group, include methyl p-hydroxy benzoate, p- hydroxy benzaldehyde, hydroquinone, toluquinone and benzoquinone.

The immediate reaction of FCM to the above and other effective compounds, is that they become hyperactive in the jars until the compounds began to affect them deleteriously. In a free condition, this would be seen as a flight instinct in reaction to an irritation. This process was indicated to a greater or lesser extent in the abovementioned tests with vanilla strips used in orange and apple orchards respectively.

EXAMPLE 4.2: (See Table 1 )

The naphthalene group compounds:

Naphthalene per se i.e. when used on its own is a recognised moth repellent but is also strongly toxic in respect of FCM as was also the case with methyl nephtalene. See the graphical representation above in Fig. 3 and Table 1 .

EXAMPLE 4.3:

The mono-terpenoid group compounds:

Certain mono-terpenoid compounds were identified as flavouring and/or scent disrupting and/or irritating compounds, such as citronellal, myrtenal, verbenone, ips-dienone, thujone and terpene compounds. After it was established that these compounds are strongly toxic to FCM, it was attempted to establish their relative toxicities by reducing the dose per pot from the standard dose of 0, 15 g per pot in initial tests to 0,01 g, 0,005 g and 0,001 g per pot. _ The most effective compounds of this group identified to date include thujoπe, citronellal, carvone and myrtenal which kill FCM in the time-frame of 1 ,0 to 1 ,5 hours, followed by citral and verbenone ⁽2 to 3 hours), and iimonene (4 to 5 hours). Terpeπyl acetate, geraniol, allo-octimeπ and eucalyptol (cineole) require higher doses to be effective in such short periods. See Table 1 and the graphical representation in Fig. 3 of the effectivity of mono-terpenoids in respect of FCM . See also Table 1 .

At 0, 15 to 0.2 mi per jar, the following plant extracts with their associated mono terpenoids kill all FCM within about 5 hours in pot or jar tests:

Buchu (Agathosma betuiina and A. crenuiata) especially diosphenol and pulegone;

Wild Wormwood or Absinth/Lanyana (Artemesia spp.) i.e. Thujone;

Lippia javanica - especially ips-dienone and myrcene;

Kakiebos (Tagetes minuta) - Tagetenone;

As a group, the mono-terpenoid compounds were found to be highly effective in the pot tests, whilst these compounds are relatively safe in respect of humans. Endogene mono-terpenoids in citrus include Iimonene. pheilandrene, cymene, linaloie, geraniol, citral, terpenene, citronellol, nerol, carvone, pinene, myrcene, sabiπene, carene, and carnphene.

Mono-terpenoids which are used by certain insects as allomone/repellents against inter alia other insects include citronellal and pinene. EXAMPLE 4.4:

Aliphatic C_Λ0 to C₁₄ compounds:

The chemical structure of sex pheromone compounds of the Tortricid moths, which include about 450 species worldwide, falls in the C₁₀ (deca) to C₁₄ (tetradeca) aliphatic groups . Since very sensitive smell acceptors are associated with these pheremones, suitable odour-active substances can be expected to be effective at very low dosages. Particularly the C,₂ (dodeca) group is physiologically very important with moths of inter alia the Tortricid group, within which many of the important South African fruit pest insects fall, such as the common codling moth (Laspeyresia pomonella), false codling moth {Cryptophlebia leucotreta) and the Eastern fruit moth (Graphofita molesta). Physiologically sensitive substances in this group include the sex pheremone compounds and plant wound hormones (traumatien), both of which are part of the Dodecenyl group, and the youth hormones and farnasene feeder plant marking compounds, both of which are part of the Dodecatriene group.

First experimental results of compounds in this group with regard to the effect on FCM life cycle are shown in the attached Fig. 4. The most effective compounds in this group which has been identified this far, and which has killed ail test moths within 2 days, is dodecene, followed by dodecanethiol, dodecanone and dodecanoyl ( = lauryl) chloride which require between 2 and 3 days. Insect allomone compounds that are defence and deterrent compounds which fall within this group, and which appear in the poison glands of certain ant types, include n-alkanes, n-alkenes and ketones of the C₁₀ to C₁₄ group such as dodecene, undecene, decanone and tridecanone. Positive results with C₁₂ alkenes and ketones in this first test series led to further experiments in this group, revealing much beπer sensitivities of ail test insects (FCM, CM and NFF) in the C₁₀ alkene group like 1 -decene, 1 -decyne and 1 ,5,9-decatriene and in the ketone group 2-undecanone and especially 2,6-dimethyl 4-heptanone. (See Table 1 ) .

EXAMPLE 4.5:

Insect allomone compounds:

These are defence and deterrent compounds which are used by insects against their natural enemies, including other insects. The usefulness of compounds in this group against FCM was investigated in the pot tests.

Insect allomone compounds are represented in most groups mentioned herein above, that is phenol, mono-terpenoides and the C₁₀ to C,₄ aikane and alkene series. The toxicity versus FCM of certain insect allomone compounds has been reported before such as hydroxy and methyl hydroxy benzoate in the phenol group, citroneitol and citral in the mono-terpenoid group and dodecene and dodecanone in the C₁₀ to C₁₄ groups. A special sub group of the insect allomone compounds which required investigation is ketones and/or methyl ketones of the C_β to C₁₄ n-alkane and n-alkene series. Tests with this sub group compounds on FCM, CM and NFF are presently being conducted as well as with other allomone compound groups.

EXAMPLE 5:

Orchard experiments with some of the more effective odour substances.

In an endeavour to investigate the applicability of the pot tests in an orchard environment, a spray mixture was prepared of the following substances and fruit bearing naval orange trees were treated therewith; salicyl aldehyde - 25ml, citronellal -25ml, and dodecene -25ml.

Since these substances are insoluble in water, they were first emulsified by means of 10ml Nufilm 17 and 10ml domestic liquid soap. The total mixture was emulsified in 10 litre water whereafter the trees were sprayed up till before rundown. Immediately after the spraying process, mesh screen tubes of 10cm diameter by 25cm length, in which 20 FCM were placed, positioned in the crown of the sprayed trees. The progress of moth deaths versus time in the tubes were monitored. No toxidity symtems were detected on the sprayed trees. Cumulative moth deaths (% of total) over time (hours) were as follows: 1 ,75 hour - 61 ,7%; 18,75 hours - 76.6%; 21 .75 hours - 82,0%; and 25,3 hours - 90%.

Although certain aspects of the invention only have been described herein, it will be appreciated by any person skilled in the art that other modifications and variations of the invention are possible. Such modifications and/or variations are therefore to be considered as falling within the spirit and scope of the invention as herein described and as defined in the appended claims.

Claims

CLAIMS:

1 . A pest control agent including one or more flavour-masking compounds and/or sceπt-disrupting/confusing compounds and/or irritating/repelling compounds selected from the following compounds namely suitable phenolic compounds, suitable naphthalenic compounds, suitable mono-terpenoid compounds, suitable aliphatic alkene and alkyne compounds C₆ to C_n4 and suitable ketones and methyl ketones of aliphatic compounds C₆ to C₁₄.

2. A pest control agent as claimed in claim 1 , the or each suitable phenolic compouπd(s) including:

hydroxy and/or methoxy substituted benzyl compounds including aldehydes thereof including 2-hydroxy benzaldehyde, 2-hydroxy 3-methoxy benzaldehyde (o-Vanillin), 4-hydroxy 3-methoxy benzaldehyde (standard Vanillin), 2-hydroxy 4-methoxybenzaldehyde,2-hydroxy5-methoxybenzaldehyde;

esters of the aforementioned compounds and esters of 2-hydroxy benzyl (salicyl) alcohol, salicylic acid, methyl salicylic acid, methyl p-hydroxy benzoic acid, methyl salicylate, ethyl salicylate, benzyl salicylate, phenetyl salicylate, iso-amyl salicylate and hexenyl salicylate.

3; A pest control agent as claimed in either claim 1 or claim 2, the or

each suitable naphthyl or naphthalenic compound(s) including:

naphthalene and methyl naphtalene; methy naphtyl or naphthalenic compounds including 1 -naphthaldehyde, 2-methoxy naphtalene and methyl naphtyl ketone.

4. A pest control agent as claimed in any one of claims 1 to 3, the or each suitable mono-terpenoid compound(s) including:

(a) closed ring structures including (bi) cyclo hexγi compounds including Iimonene, iso-limonene, terpenene, phellandrene, sabinene, carvone, ionone, thujone, pulegone, menthol, menthone, diosphenol (buchu), and perilla aldehyde and its corresponding alcohol;

(b) closed ring structures including (bi) cyclo heptyl compounds including verbenal, verbenol, myrtenal, myrtenol, fenchone, pinene, pinenal, camphene, camphor, carene, cineole, and borneol;

(c) open ring dimethyl octyl compounds including ipsenoi, nerol, myrcene, geraniol, linalool, tagetone, allo-ocimen, citral, citronellal, neo allo-ocimen, citronellol, citronellene, and iso- citronellene but excluding citronellol per se:

(d) C₂up to C_s alkyl esters of mono-terpenoids including acetate, propionate, (iso) butyrate and valerate esters.

5. A pest control agent as claimed in any one of the preceding claims, the or each suitable aliphatic alkene and alkyne compounds including unsaturated alkenes and alkynes as mono-, di- or tri -ene groups of compounds including 1 -decene, 1 -decyne, 1 ,5,9-decatriene, 1 - undecene, 1 -dodecene, 1 -trideceπe, 1 -tetradecene, 1 ,7-octadiene, 1 ,5-hexadieπe. 1 -heptene, 1 -octene and 1 -nonene;

6. A pest control agent as claimed in any one of the preceding claims, the or each selected arthropod allomone compound(s) including:

(a) insect natural chemical defense compounds, excluding methyl salicylate and citronellol per se.

(b) ketones and methyl ketones of aliphatic compounds as alkanes and alkenes of the series C_e to C₁₄ occurring mostly as alarm pheromones/allomones in Formicidae (- ants) and including 2,6-dimethyl 4-heptanone, 2τundecanone, 2-dodecanone, 2- tridecanone, 4-methyl 3-heptanone, 4-methyl 3-hexanoπe, 4,6- dimethyi 4-octen 3-one, 6-methyl 3-octanone, 6-methyl 5- hepten 2-one, 4-methyl 4-hepten 3-one, 4-methyl 2-hexanone and 2-methyl 4-heptanone, 4-methyl 4-hexeπ 3-one, 3- octanone, 3-decanone and 3-nonanone.

7. A pest control agent as claimed in any one of the preceding claims, whenever provided in a composition or form adapted to be sprayed.

8. A pest control agent as claimed in any one of claims 1 to 6, whenever provided in a composition or form adapted to provide a retarded and even release of volatile compound(s).

. A pest control agent, substantially as herein described and/or exemplified.

10. A pest control composition, including an effective amount or concentration of a pest control agent as claimed in any one of the preceding claims.

1 1 . A pest control composition, substantially as herein described and/or exemplified.

12. A method of controlling pests, including the step of using or applying an effective amount of a pest control agent to a pest habitat or location, the pest control agent including one or more flavour- masking compounds and/or scent-disrupting compounds and/or irritating/repelling compounds selected from the following compounds namely suitable phenolic compounds, suitable naphthyl compounds and naphthalenic compounds, suitable mono-terpenoid compounds, suitable aliphatic alkene and alkyne compounds, and suitable aliphatic ketones and methyl ketones.

1 3. A method as claimed in claim 12, including the step of providing the pest control agent in a composition or form suitable for spraying, and spraying a solution of the agent to a pest habitat or location.

14. A method as claimed in claim 12, including the step of providing the agent in a composition adapted to effect a retarded and even release of volatile compound(s), and providing such composition in or near a pest habitat or location.

5. A method as claimed in any one of claims 12 to 14, for treating pests which eat and/or spoil fruit and/or vegetables and/or plants or trees.

16. A method as claimed in claim 1 5, the pests including the Lepidoptera family such as false codling moth (Crystaphlebia leucotreta) and

(ordinary) codling moths, ⁽Laspeyresia leucotreta) and the Diptera family such as fruit flies (Pterandrus rosa) .

1 7. A method as claimed in claim 16, the Tortricid moths including false codling moths (Crytophlebia leucotreta) and codling moth (Laspeyresia pomonella) and fruit flies (Pterandrus rosa).

18. A method of controlling pests, substantially as herein described and/or exemplified.