WO1994013141A1

WO1994013141A1 - Polyphenol-based insecticide compositions

Info

Publication number: WO1994013141A1
Application number: PCT/FR1993/001226
Authority: WO
Inventors: Catherine Regnault-Roger; Aimé Menassa
Original assignee: Elf Atochem S.A.
Priority date: 1992-12-16
Filing date: 1993-12-10
Publication date: 1994-06-23
Also published as: CN1089774A; FR2699051B1; AU5653894A; FR2699051A1

Abstract

Insecticide composition comprising an insecticide substance other than a polyphenol, characterized in that it includes a polyphenol. The polyphenols include catechines, flavanones, flavones, flavanonols, flavonols and other flavonoids with monomer forms or combined to form dimers of polymers. In a preferred embodiment of the composition according to the invention, the insecticide substance other than a polyphenol is a terpene.

Description

Polyphenol-based insecticide compositions

The present invention relates to insecticide compositions.

We already know that certain polyphenols have an insecticidal action. Now, it has now been found that an insecticidal composition comprising an insecticidal substance other than a polyphenol is much more active when it is added with a polyphenol.

It has in fact been found that a polyphenol not only has a delayed or delayed insecticidal activity, but also a nocdown or insect immobilization type effect and above all an attractive effect, so that the composition comprising, at the same time, an insecticidal substance other than a polyphenol and a polyphenol has a synergistic effect, the polyphenol attracting insects and immobilizing them near the other fast-acting insecticide. The attractive effect makes it possible to mask the repellent effect of other insecticidal substances. To this direct insecticidal activity (toxicity on adults) is added an anti-nutritional activity, as well as an inhibition of reproduction by reduction of fertility, ovicidal and larvicidal effect limiting the renewal of generations, all the effects combining to reduce the flow of insects and improve their control. As polyphenols, advantageously those of formula

in which

R ₁ R ₂ and R ₃ , which are the same or different, are a hydrogen atom, hydroxy or lower alkoxy. at least two of R _{1 #} R ₂ and R ₃ being other than a hydrogen atom. is a hydrogen atom. is a hydrogen atom, a hydroxyl, an alkoxy or a glycoside or

R ₄ and R ₅ together form an additional valence bond between the carbon atoms which carry them,

R ₆ is a hydrogen atom,

R ₇ is hydroxyl, lower alkyl or phenyl, optionally mono-, di- or trisubstituted by lower alkyl, lower alkoxy or hydroxyl radicals, or

R ₆ and R ₇ together form a bivalent radical of formula

linked by the oxygen atom to the carbon atom carrying R ₄ . By alkyl or lower alkoxy is meant linear or branched radicals having from 1 to 6 carbon atoms and, preferably, from 1 to 4 carbon atoms.

Among these polyphenols, there may be mentioned in particular catechins, flavanones, flavones, flavanonols, flavonols and other flavonoids of monomeric forms or associated in dimers or polymers. Mention may in particular be made of caffeic acid, ferulic acid, gallic acid and other phenol acids derived from cinnaic acid or benzoic acid, catechin, quercetin, rutin, naringin. Rutin, caffeic acid and naringin are very attractive and cause a strong inhibition of the natural motor skills of insects and that is why they are particularly preferred. The attractive effect of polyphenols is such that they increase the consumption by insects of the toxic mixture, allowing the effective concentrations of each of the insecticidal compounds to be reduced.

These polyphenols are natural substances of vegetable origin which are found in the daily diet and which are, by definition, in effective doses on insects which are non-toxic to mammals and biodegradable. Polyphenols therefore make it possible, combined with another insecticidal substance which is also biodegradable and non-toxic and preferably natural, to constitute an insecticidal composition which does not harm the environment. This is why, according to a preferred embodiment of the composition according to the invention, the insecticidal substance other than a polyphenol is a terpene. Terpenes are hydrocarbons of the aliphatic and cyclanic series, the constitution of which is expressed by formulas obtained by assembly of isoprenic links. One can use acyclic terpene hydrocarbons in ^C 1 ₀ ^H 16 having the structure of 2,6-dimethyl-octane, true terpene hydrocarbons in ^C ιo ^H l ₆ ^and sesquiterpene hydrocarbons ^c i5 ^H 24 * ⁰ⁿ particularly preferred monocyclic terpenes and bicyclic terpenes. Among the terpenes, mention may be made of menthane, li onene, cyene, terpinenes, eugenol, pinene, sabinene, carina. Terpenes can carry an alcohol function, such as linalool, menthol, terpineol, a ketone function, such as enthone, carvone, thujone, camphor, an aldehyde function such as safranal, geranial, cynamaldehyde, cuminaldehyde or a phenol function such as thymol, carvacrol, possibly methoxylated such as anethole, eugenol, estragol, borneol. Particularly preferred are eugenol, terpineol and carvacrol and, to a lesser degree, thymol, linalool, anethol, arminaldehyde, cynamaldehyde and cymene.

However, it is also possible to combine polyphenol with a conventional insecticidal substance, such as fatty acids and derivatives which are carboxylic acids whose aliphatic chain is long enough to give them a lipophilic character, this chain generally consisting of 10 to 20 carbon atoms. and be saturated or mono- or poly-unsaturated. The fatty acids can be used in the free form, in the salified form, the cation possibly being an alkali metal or an alkaline earth metal, in esterified form, generally with an aliphatic alcohol, or in the form of a glyceride such as 'a mono-, di- or triglyceride. It is also possible to combine with polyphenol, as an insecticidal substance, a carba ate, a pyrethroid, an organophosphorus compound or an organochlorine compound. Preferably, another insecticide is combined with the polyphenol and terpene couple.

Preferably, the weight ratio between the insecticide substance (s) other than polyphenol and polyphenol is between 1/1000 and 1/10. The composition is obtained by mixing the constituents. The insecticide composition according to the invention makes it possible to fight not only against the insects themselves, but more generally relates to the whole sub-reign of the metazoans and, in particular, the branching of the arthropods, among which are the arachnids, for example, Tetranycus urticae, family Trombididae, mite order. But the preferred target class is that of insects among which appear (classification according to BALACHOWSKY) 1962 the order of Blattidae, in particular: - genus Blatella species B. germanica, B. orientalis (cockroaches), genus Ectobius species E. lapponicus (cockroach forest).

The order of Hymenoptera, in particular - * family Formicidae (ants), genus Camponotus, species C. femoratus, C. lignaperda

(carpenter ant), genus Formica, species F. polyctena (red ant), F. fusca, * family Myrcidae, genus Myrmica, species M. rubra (red ant), genus Monomorium, species M. pharaonis (pharaoh ant).

But above all

* the order of Diptera, with the families of

Drosophilidae, genus Drosophila (example: species D. melanogaster, vinegar fly, D. auraria), - family Muscidae, genus Musca, species M. domestica

(housefly), family Trypetidae, genus Ceratitis, species C. capitata (Mediterranean fruit and vegetable fly) family Culicidae, genus Culex, C. pipiens (mosquito) or other mosquitoes example: Aedes aegypti vectors of the yellow fever.

* the order of Beetles, sub-order Polyphaga, with the super-families. - Cucujoidea including the families of Coccinellidae, under the family of Epilachninae (phytophagous larvae of fruits and vegetables), species E. chrysomelina, E. varivestis, E. similis,

- family of Mordellidae, genus Mordellistena, M. parvula (sunflower pest, hemp), family Tenebrionidae, genus Tribolium, species Tribolium castaneum, T. confusum (grain and flour pests such as wheat, barley), genus Tenebrio, species T. molitor, T. obscurus F (mealworms)

- Superfamily Bostrychoidea including the family of Bostrychidae,

(genus Rhizoperta, R. dominica (grain capuchin),

Superfamily Scarabaeoidae, for example family Scarabaeidae, subfamily Rutelinae, genus Popillia japonica (Japanese chafer),

Superfamily Phytophagoidea, of which: family Bruchidae, subfamily Bruchinae, * genus Acanthoscelides, species A, obtectus (bean weed)

* genus Bruchus, species Bruchus lentis (lentil bruch),

* genus Callosobruchus, species C. maculatus (4-spotted beetle), C. chinensis (Chinese beetle), subfamily Amblycerinae

* genus Zabrotes, species Z. fasciatus (leguminous weed), family Chrysomelidae subfamily Crysomelidae, genus Leptinotarsa, species L. decemlineata (Colorado potato beetle), family Curculonidae, subfamily Tanymecinae, genus Tanymecus, species T. palliatus (polyphagous weevil), subfamily Curculioninae, tribe Trichiini, genus Tychius, species T. quinquepunctatuβ

(legume cheat), T. Fasciatus, Calandini tribe, genus Sitophilus, species S. granarius, S. oryzae, S. zeamais (wheat weevil, rice and corn).

Lepidoptera Order: Heteroneura Suborder

- Heterocera sub-division

*** of which superfamily: Pyraloidea for example: family Pyralidae

- subfamily Pyraustinae genus Ostrinia species: Ostrinia nubilalis Hb (corn borer) genus Loxostege, species L. Sticticalis (beet moth) genus Evergestis fru entalis (cabbage moth)

- subfamily Galleriinae genus Ephestia species E.Cautella, E.kuenhniella (borer of dried fruit and flour)

- superfamily (Noctuoidea) for example: family Noctuidae group Trifides - subfamily Amphipyrinae genus Sesamia species Sesamia nonagrioides Lef. (corn sesame) genus Spodoptera species: Spodoptera litura Fab. Spodoptera littoralis Bois du Val (fruit and vegetable pest) subfamily Melicleptriinae genus Helicoverpa (or Heliothis) species H. zea Hb.

Tineoidea superfamily: for example: Gelichiidae family of which: genus Sitotroga species Sitotroga cerealla OL. (cereal alucite).

Preferably, the weight ratio between the insecticide substance (s) other than polyphenol and polyphenol is between 1/1000 and 1/10. The composition is obtained by mixing the constituents. The composition according to the invention can be used to protect crops in the open field. The composition according to the invention is applied at a rate of 100 to 1000 grams per hectare.

The compositions can also be formulated for household use, an example of which is given below: an atomizer of 650 ml of total volume, filled to 500 ml useful, has a net weight of 300 grams and contains:

- propellant (butane) 250 grams

- polyphenol 0.9 gram - terpenes 0.1 gram

- 0.5 gram scent

- surfactant 1.5 grams

- viscosifying agent 0.025 gram

- 50% ethyl alcohol: 47 grams, this composition is prepared in the following manner: a 50% by weight hydroalcoholic solution is produced in which the active-tensions are dissolved (ethoxylate 10 EO of undecylenic acid and ethoxylate 10 EO of ricinoleic acid), then polyphenols, terpenes and perfume; the mixture is emulsified, we then add an aqueous viscosifying gum solution.

The atomizers are filled with 50 grams of this emulsion to which 250 g of butane or another propellant are added. (OE stands for ethylene oxide). One can also use the compositions for the external or internal protective coatings (all fields for example: electricity, light construction for terrestrial or aquatic use) and the packaging all fields, in particular food intended for food but also agronomic: encapsulation of biopesticides, buckets for plant plants, films of biodegradable polymers with multiple destinations.

The following experiments illustrate the invention.

1st experiment: attractive power of naringin on R. dominica. (grain capuchin)

Two separate compartments with a volume of 465 cm ³ each are connected to each other by a glass tube with a section of 1.5 cm and a length of 10 cm (volume: 12 cm ³ ). In the first compartment, we place the product whose activity we want to test, in the second, insects whose sensitivity we want to experience. The circulation of insects and gases is ensured by the glass tube described above. In a first experiment, 0.5 g of naringin (ie a mass of 8.6 10 ~ ⁴ M) contained in a small box is placed in the first compartment. In the second compartment evolves a population of 20 adult individuals of Rhizoperta dominica. After three hours, 7 insects are counted in compartment 1, 11 after 5 hours, 17 after 24 hours. If, instead of naringin, a Whatmann paper impregnated with 1 μl of eugenol (ie 0.6 10 ^{"* 6} M or 1.07 mg) was deposited, no insect is counted in compartment 1 at after three hours and only one after 24 hours. The naringine exerts a certain attractive effect, with the opposite of the effect shown by eugenol. We note, moreover, that the insects (18/20) took refuge, agglutinated, at the place furthest from the eugenol deposit. The combination of eugenol and naringin, in the same quantities, makes it possible to attract R. dominica more significantly than eugenol alone, since after twenty-four hours 10 insects are found in the compartment with products. Only four insects stay away from associated products. At a non-lethal concentration for R. dominic, the polyphenol / terpene association exerts a very significant attractive power on the insect and masks the repellent effect exerted by the terpene. 2nd experiment: comparison of the attractiveness of different polyphenols and of a polyphenol / terpene association on Acanthoscelides obtectus, bean weevil.

Populations of 20 insects in each experiment are deposited in the upper part of a two-stage apparatus. To reach the lower compartment, insects must thread their way through small holes perforating a glass tube connecting the two compartments. In the lower compartment is contained 0.5 g of a tested polyphenol. After two hours, 35% of the insects have migrated into the lower compartment in the presence of caffeic acid, 60% in the presence of rutin and 85% in the presence of naringin. After twenty hours, the percentage rises for the three compounds to 90 and 100%, while it remains only 50% for paracoumaric acid. The attractiveness of the three compounds, caffeine acid, rutin and naringin, is therefore very highly significant. If the experiment is carried out with 1 μl of eugenol (1.07 mg), it is noted that the insects remain in the upper compartment, while certain insects (10%) gain the lower compartment in the control experiment (without product in the lower compartment). Eugenol confirms its repellency. On the other hand, if we put in the presence of naringin and eugenol, 65% of insects are found in the lower compartment after twenty hours. The combination of naringin & eugenol has made it possible to significantly inhibit the repellency of eugenol.

3rd experiment: inhibition of natural motor skills by polyphenols and their toxicity on Acanthoscelides obtectus, bean weevil.

Experimental batches of 10 adults are placed in experimental chambers with a volume of 106 cm ³ in the presence of 0.5 g of polyphenol. In the presence of naringin, rutin and caffeic acid, there is a very significant decrease in natural motor skills after the sixth day (for example for caffeic acid, on a workforce of 30 adults, the sixth day is noted 50% of insects knock down, the others being dead) and a mortality of 96% after eight days. Other polyphenols (ferulic acid, vanillic, flavone, quercetin, etc.) exhibit activities of the same type, but to varying degrees, although they are all significantly different from the control batch (P ≈ O). In a confined atmosphere, polyphenols therefore manifest a "delay" type toxicity which is expressed firstly by a strong attractive power, a knock down effect followed by the death of the insect.

4th experiment: toxicity of different terpene molecules on Acanthoscelides obtectus Say and inhibition of reproduction. Experimental batches of 20 insects are placed in experimental chambers with a volume of 106 cm ³ in a confined atmosphere in the presence of increasing quantities (1 μl, 2.5 μl, 5 μl, 7.5 μl, 10 μl of solution 6 , 5 M) of terpenes deposited on Whatmann paper contained in a small box provided with a gauze preventing contact between the insect and the product. The toxicity observed is therefore of inhalation type. After 24 and 48 hours, the dead are counted: for eugenol, there are thus, after 24 hours, 13% of dead for a quantity of 6.5 10 ~ ⁶ M, 72% for 3.25 10 ^"5 M, 84% for 4.9 10 ^{" 5} M. The total lethal effect (100% of deaths) is reached at a concentration of 8.56 mg / dm ³ of air and the LC ₅₀ , calculated by the probits method is 3.5 mg / dm ³ for this product. Similarly, the 100% lethal effect of carvacrol is evaluated at 9.8 mg / dm ³ and terpineol at 9.3 mg / dm ³ .

The inhibition of reproduction is studied by the following experiment. In the experimental chamber described above, a population of 20 adult insects and bean seeds (Phaseolus vulσaris L.) are brought together for the control batch. The terpenes are added to the medium, deposited (1.6 10 ~ ⁶ M and 6.5 10 ~ ⁶ M) on hatmann paper incorporated in a small box so that no contact takes place with the insect. Every day, there are the dead and the eggs laid over a period of ten days. At the end of this period, note the number of larvae that have entered the seeds, then the emerging number, the number of imagos, after about forty days. We note for example that, in the presence of 1.6 10 ~ ⁶ M of carvacrol, 14 adults died, 43 eggs are laid after 10 days (2 dead for the control and 259 eggs laid for the control), 10 larvae only entered the seeds and 6 adults emerged (instead of 210 and 192 for the control). In the presence of 6.5 10 ~ ⁶ M carvacrol, all insects die after 2 days and no eggs are laid.

Carvacrol very strongly inhibits the reproduction of A. obtectus Say, both by an activity on fertility and by a larvicidal activity: only 23% of the larvae enter the seeds and 60% of the adults emerge from them, while the rates are respectively 81% and 91% for the witness. The same inhibitory activity is observed for eugenol, terpineol and, to lesser but nevertheless significant degrees, for other monoterpene terpenes. 5th experiment: impairment of the natural motor skills of Sitotroga cerealella (cereal alucitis) by the eugenol / naringin association (knock-down effect) and toxicity of the polyphenols / terpenes association.

In the experimental device described above (experiment 1), the following manipulations are carried out.

A first experiment, carried out with 1 μl of eugenol (6.5 10 ^"6 M), counts after 20 hours a dead alucite in compartment 1 and three dead alucites in compartment 2 on an initial population of 18 alucites (ie a mortality of 22%), the other twirls quite normally. Under the same conditions, 1 μl of terpineol (ie 0.93 mg) causes the death of 20% of insects. If the same experiment is carried out presence of naringin (mass of 1.7 10 ~ ³ M), note the presence of 3 dead alucites in compartment 1, 7 dead alucites in compartment 2, the other alucites no longer having any natural motor skills (knock effect The combination of the compounds caused the death of 55% of the population and inhibited the natural motor skills of the survivors.

A second series of experiments is carried out in the presence of a combination of polyphenolic compounds (caffeic acid, naringin and rutin: 0.5 g of each of the compounds, or respectively masses of 2 10 ^"" 3M, 8.6 10 ~ ⁴ M and 7.5 10 ~ ⁴ M), after 20 hours, 10 alucites (50%) are dead, the surviving insects having good motor skills. If, on the other hand, the preceding compounds are combined with 20 μl of a mixture of terpineol and eugenol (v: v), the insects die in less than four hours. 6th experiment: attractive effect and inhibition of the motor activity of naringin on Ceratitis capitata (Mediterranean fruit and vegetable fly) and toxicity of the polyphenol / terpene association.

If, in the device with two compartments described above (total volume approximately 950 cm ³ ), 1.1 g of naringin are placed in the compartment and, in compartment 2, a population of 64 ceratites, after 20 hours 28 ceratites , or 43%, are found in compartment 1 and, after 24 hours, 39, or 60% who are, moreover, deprived of natural motor skills. None of the insects died. If we associate with the same amount of naringin 1 μl, or 1.07 mg of eugenol, there are, for the same duration, 42% of dead insects, this percentage increasing to 69% if we put 5 μl (5 , 35 mg) of eugenol with naringin. After 28 hours, 80% of the insects were attracted to naringin, 10% died and 65% no longer have normal motor skills, 85% died in the presence of the naringin / eugenol combination (1 μl) and 83% in the presence of the naringin / eugenol combination (5 μl). It is therefore noted that, if the naringine attracts and deprives insects of their natural motor skills, the association with eugenol lets appear the expression of a more rapid toxicity. The increase in the concentration of eugenol makes it possible to obtain a significant increase in the percentage of mortality observed for a period of between 20 hours and 26 hours only.

7th experiment: toxicity of caffeic acid incorporated into the Ceratitis capitata diet. (Mediterranean fruit and vegetable fly) Or a population of 60 ceratites, in a semi-aerated environment, fed with crushed apple flesh. Three experimental batches are carried out: a control batch, a batch comprising, in two separate boxes, apple and 0.5 g of caffeic acid and a third batch, for which the caffeic acid is mixed with the apple. We note, after four days, that 20% of the insects died in the first batch, 42% in the second batch and 59% in the third batch. After eight days, the percentages are 32%, 60% and 92%, respectively. Caffeic acid thus manifests a significant toxic activity for ceratitis and its effectiveness is all the greater when it is integrated into the usual diet of the fly and consumed regularly. An anti-nutritional effect is also noted with rutin. δth experiment: toxicity of the polyphenols / terpenes association on Ostrinia nubilalis (European corn borer) at the last larval stage.

Are experimental batches each comprising five larvae of borer in a confined environment (volume 106 cm ³ ). Various masses of polyphenol (rutin or naringin) or (/ and) terpenes (terpineol and eugenol) are deposited in the experimental chamber. Observations are made over 7 days. In the presence of polyphenol alone, the larvae see a decrease in their reactivity after excitation but, although having consumed the product, remain alive. In the presence of a eugenol-terpineol mixture (5 μl and 10 μl) out of contact, there are 20% of deaths. If, on the other hand, the same quantity of terpenes is placed in the presence of 0.5 g of naringin, 100% of larvae die. Similarly, the association of caffeic acid (0.5 g) and eugenol (5 μl, or 5.35 mg) causes the death of all the larvae in 72 hours.

9th experiment: effect of a polyphenols / terpenes association on Sesamia nonagroides (Sesamia) at the last larval stage. The experimental device is that described in Experiment 6. Firstly, there is a very high consumption of polyphenol by sesamies. In the presence of 0.5 g of naringin, after four days, 20% died, the others having a sharp decrease in their body volume. At the same time we observe, in the presence of a mixture of terpineol and eugenol (10 μl, v: v, or 6.5 10 ^{"* 5} M), the same mortality. If we put a mixture of rutin-naringin (0.2 g for each) and terpineol-eugenol (40 μl, v: v, ie 2.6 6.5 10 ^{"" 4} M)), it can be seen that, initially, the sesame larvae are very excited by the combination of the compounds: they exhibit activity frantic, twisting in all directions, crawling in the containers containing the polyphenols, wallowing in and consuming them, while they stay away from where the terpenes are. At the end of the four days, there are 60% of the dead larvae and the rest being knock-down, the volume of their body weight having sharply decreased. 10th experiment: potentiation of the activity of conventional commercial insecticides (active ingredients: malathion and pyrethroids) by the polyphenols association / terpenes on Acanthoscelides obtectus.

Two different series of experiments are carried out in 900 cm ³ experimental chambers (confined medium), the first with malathion in solution of 250 g / 1, the second in the presence of an insecticide containing 0.1 g of pyrethroids, 0.2 g of rotenone and 1.5 g of piperonyl butoxide as a synergist.

Different experimental batches are carried out: in addition to the control batch containing only a population of 20 weevils, a first batch contains an insecticide whose toxicity is examined (1 μl for malathion, 100 μl for pyrethroids), a second the same quantity of insecticide in the presence of one gram (17 10 M) of naringin, a third batch contains the same amount of insecticide, but this time in the presence of 5 μl (5.35 mg) of eugenol and a fourth batch contains both insecticide, eugenol and naringin.

Commercial insecticides are tested at doses lower than LD ^{50 in} order to note any synergies between compounds. We previously determined that the Naringin alone does not have a lethal effect after 24 hours and an average concentration of eugenol is chosen.

At the end of 24 hours, there are dead insects in the experimental batches, the control batch having live insects having normal motor skills.

In the presence of pyrethroids, it can be seen that the first batch (insecticide alone) is not assigned to the dose tested; the second batch either. On the other hand, the third batch presents 25% of deaths and the fourth batch 40% of deaths. In the presence of malathion alone, only one insect (5%) died. The percentage rises to 25% in the presence of the malathion-naringin combination (lot 2), to 70% in the presence of the malathion-eugenol combination (lot 3) and to 100% when the association includes insecticide, naringin and eugenol (lot 4).

It is therefore noted, in the first case, that there is no toxicity of the insecticide alone, nor in the presence of the only polyphenol which - it has been established elsewhere (third experiment) - has a lethal effect of delay type. It is noted that, as it was shown previously (4th experiment), the inhalation toxicity of terpene is expressed quickly. The synergistic effect, underlined in the previous experiments between polyphenol and terpene, exists and allows to significantly increase the lethal effect from 25 to 40%.

The second case, which supports the previous observations, differs from the previous one, however. Indeed, we note that naringin - which has no immediate effect in the presence of a dose which is itself inactive of pyrethroids - enhances the low toxicity of malathion and causes a 20% increase in the lethal effect. The combination of the three compounds causes total mortality of the insect population, while each of the compounds, taken separately or in binary association (insecticide / polyphenol or terpene), have a much lower efficacy. This result demonstrates the potentiation of the insecticidal activities of the different compounds by the synergistic effect resulting from the association of various insecticidal molecules, especially d polyphenols / terpenes couple.

Claims

CLAIMS 1. Insecticidal composition comprising an insecticidal substance, other than a polyphenol, characterized in that it comprises a polyphenol.

2. Composition according to claim l, ² characterized in that the polyphenol corresponds to the formula

in which

^R l and

which are identical or different, are a hydrogen atom, a hydroxy or a lower alkoxy, at least two of R- ^, R- _> and R _T being other than a hydrogen atom,

R ₄ is a hydrogen atom, R ₅ is a hydrogen atom, a hydroxyl, an alkoxy or a glycoside, or R ₄ and R ₅ together form an additional valence bond between the carbon atoms which carry them,

R ₆ is a hydrogen atom,

R ₇ is a hydroxyl, lower alkyl or phenyl optionally mono-, di-, or trisubstituted by lower alkyl, lower alkoxy or hydroxyl radicals, or R ₆ and R ₇ together form a bivalent radical of formula

linked by the nitrogen atom to the carbon atom bearing

R ₄ •

3. Composition according to claim 2, characterized in that the biphenol is naringin, rutin or caffeic acid.

4. Composition according to one of the preceding claims, characterized in that the insecticidal substance, other than a polyphenol, comprises a terpene.

5. Composition according to claim 4, characterized in that the terpene is eugenol, terpineol, carvacrol, thymol, linalool, anethole, cuminaldehyde, cynamaldehyde or cymene.

6. Composition according to one of claims 1 to 4, characterized in that the insecticidal substance, other than a polyphenol, comprises a pyrethroid, a carbamate, a chlorinated organic compound, an organic phosphorus compound or a fatty acid.

7. Composition according to one of the preceding claims, characterized in that the weight ratio of the insecticidal substance, other than a polyphenol, to polyphenol, is between 1/10 and 1/1000.