FR2665610A1 - ANTI-OVIPOSITION PHEROMONE COMPRISING AT LEAST ONE ALKYL ESTER OF FATTY ACID, AND ITS APPLICATION TO THE FIGHT AGAINST PEST INSECTS. - Google Patents

Abstract

An oviposition-preventing pheremone preparation obtainable from a methanol extract of European corn borer eggs, and including a mixture of methyl esters of palmitoleic acid, palmitic acid, linoleic acid, oleic acid and stearic acid, an oviposition-preventing composition, designed particularly for countering the European corn borer, and including, as the active principle, at least one C1-3 alkyl ester of a C14-20 fatty acid, and use in controlling crop-destroying insects are described.

Description

 The invention relates to the purification and characterization of an anti-oviposition pheromone, as well as to a chemical composition having the anti-oviposition properties of said pheromone, and to the application of said pheromone and said composition to the fight against insect pests.

 Anti-oviposition pheromones are intra-specific chemical signals deposited by certain female insects on and / or in the vicinity of their eggs after oviposition. The sites thus marked are then rejected by other females of the same species as nesting sites.

 It has therefore been proposed to use the deterrent effect of these pheromones in the fight against insect pests.

 However, although the existence of such pheromones has been described in many insects for review, see the publication of ROITBERG and PROKOPY, 1 [Bioscience, 37, 400-406 (1987)], very few have actually been purified, and their chemical nature remains mostly indeterminate.

 Currently, only two compounds of this type have been chemically characterized; it is the kiromone of the lepidopter Ephestia kuehniella, which consists of a mixture of 16 triketones [MUDD, J. chem.

soc. Perkin trans., 1 2357-2362 (1983)], which is not strictly speaking a pheromone antioviposition, but a kairomone present in the mandibular glands of the larvae of this lepidopteran, and which has an attracting effect on its parasite, Venturia canescens.

The other is the anti-oviposition pheromone of the dipteran Rhagoletis cerasi, which is a derivative of palmityl glucopyranoside; the synthesis of the four possible stereoisomers of this derivative was carried out [ERNST and WAGNER,
Helv. Chim. Acta, 72, 165-171, (1989)], in order to determine which corresponded to the natural active form of the pheromone.

Previously, it had been shown that a partially purified preparation of this pheromone obtained from the secretions collected at the laying sites, reduced by 90% the infestation of plants by
R. cerasi [KATSOYANNOS and BOLLER, Z. Angex. Entomol., 89, 278-281 (1980)].

 The existence and efficacy of anti-oviposition pheromones has also been demonstrated in other insects, but their chemical composition has not been determined. For example, KLIJNSTRA [Entomol.

exp.appl., 41, 139-146, (1986)] showed that a methanolic solution obtained by washing the eggs of Pieris brassicae significantly reduced the spawning of females of this species on the plants treated with said solution.

 It is clear that, whatever may be the potential interest of anti-oviposition pheromones in the fight against insect pests, their effective application is only conceivable if it is possible to synthesize them chemically, in order to obtain them in quantity. sufficient.

 Among the insect pests, one of those currently causing significant damage, resulting in significant economic losses is the corn borer, (Ostrinia nubilalis). It is a moth, which sticks its clumps in the form of plates (ooplates) on the surface of the leaves of different plants, then covers them with mucus. This lepidopteran is a maize pest in which it causes significant crop losses, which can reach 40 in some particularly susceptible hybrids [KLENKE et al., Crop Science, 26, p. 859 (1986)]. In addition, the damage caused by this insect is now spreading to other crops, such as vegetable crops and cotton.

 The means of struggle currently advocated against this insect use pesticides, mainly synthetic pyrethroids. Now these pyrethroids are increasingly suspected of promoting the spread of aphid populations, and diseases, especially viral, inoculated by sucking biting insects.

 The existence of anti-oviposition substances in excrement extracts of corn borer larvae has been shown [DITTRICK et al., J. Insect. Physiol., 29, p. 119 (1983)], but their chemical composition has not been determined; it was simply suggested that they were polar substances. In addition, the actual biological role played by these substances may be questioned, as larval droppings are rarely present at the laying sites of corn borer. As had previously been shown that plant-derived substances from plant wounds had anti-oviposition activity, DITTRICK et al. hypothesized that the observed anti-oviposition activity could be due to a substance from the plant, released into larvae excrement.

 Until now, the existence of an anti-oviposition pheromone associated with corn borer moths has not been demonstrated.

 The inventor is the first to extract such a substance from the corn borer eggs. Analysis of the extract thus obtained revealed that it was a complex mixture, as shown in the chromatograms of Figures 1 and 2.

 The inventor has furthermore been able to select and identify in this mixture, constituents which, surprisingly, possess an anti-oviposition activity comparable to that of the total extract.

 The present invention relates to an anti-oviposition pheromone preparation, which preparation is characterized in that it is capable of being obtained from a methanolic extract of corn borer eggs, and in that it comprises a mixture of the methyl esters of palmitoleic, palmitic, linoleic, oleic and stearic acids.

 According to a preferred embodiment of the present invention, said preparation comprises: between 10 and 20 parts of methyl palmitoleate, between 10 and 20 parts of methyl palmitate, between 10 and 20 parts of methyl linoleate, between 10 and 20 parts of methyl oleate, for 1 to 2 parts of methyl stearate.

 The identification of active components has allowed the formulation of simple compositions reproducing the effect, on the reduction of spawning of corn borer, of the anti-oviposition pheromone preparation according to the invention.

 The subject of the present invention is furthermore an anti-oviposition composition, active in particular on the corn borer, and characterized in that it comprises, as active principle, at least one C13 alkyl ester and of acid fat in C1420.

 According to a preferred embodiment of an anti-oviposition composition according to the invention, it comprises, as active principle, at least one methyl ester of a C1618 linear chain fatty acid.

 According to a particularly advantageous arrangement of this embodiment, said linear chain fatty acid methyl ester is chosen from the group which comprises: methyl palmitoleate, methyl palmitate, methyl linoleate, methyl oleate, methyl stearate, and mixtures thereof.

 According to a preferred embodiment of this arrangement, an anti-oviposition composition according to the invention comprises: between 10 and 20 parts of methyl palmitoleate, between 10 and 20 parts of methyl palmitate, between 10 and 20 parts of methyl linoleate, between 10 and 20 parts of methyl oleate, for 1 to 2 parts of methyl stearate.

According to another preferred embodiment of this provision, said composition comprises at least 0.08 mg / ml of methyl palmitoleate, 0.1 mg / ml of methyl palmitate, 0.08 mg / ml of methyl linoleate, 0.1 mg / ml methyl oleate, 0.008 mg / ml methyl stearate
Advantageously, a composition according to the invention comprises: between 0.3 and 0.4 mg / ml of methyl palmitoleate, between 0.4 and 0.5 mg / ml of methyl palmitate, between 0.3 and 0.4 mg / ml of methyl linoleate, between 0.3 and 0.4 mg / ml of methyl oleate and between 0.03 and 0.04 mg / ml of methyl stearate.

 The anti-oviposition compositions according to the invention can be obtained simply and inexpensively from alkyl esters of fatty acids which are readily available commercially. They can therefore be used on a large scale in the treatment of crops.

 The present invention therefore also relates to the application of a composition, or a purified pheromone anti-oviposition preparation, as defined above, to the protection of plants against insect pests, particularly corn borer.

 In particular, the subject of the present invention is a method for protecting plants against insect pests, particularly the corn borer which method is characterized in that the plants to be treated are brought into contact with a pheromone composition or preparation. anti-oviposition according to the invention.

 The present invention will be better understood using the additional description which follows, which refers to examples of preparation and use of the compositions according to the invention. it goes without saying, however, that these examples are given solely by way of illustration of the subject of the invention, of which they in no way constitute a limitation.

EXAMPLE 1: OBTAINING A PHEROMONE PREPARATION
ANTI-OVIPOSITION FROM BRIDGES OF THE
PYRAL OF MAIZE
Females of Ostrinia nubilalis are encouraged to lay on a chemically inert substrate (glass plates rinsed with methanol). 1580 ooplates were obtained in this way. The plates bearing the ooplates were soaked for 12 hours in 200 ml of cold methanol (purity> 99.9%). The extract obtained was then concentrated by evaporation on a Dufton column to a volume of 20 ml.

 The different concentrations used subsequently are obtained by dilution of the extract thus concentrated.

EXAMPLE 2 CHEMICAL CHARACTERIZATION OF THE PREPARATION
PURIFIED ANTI-OVIPOSITION PHEROMONE
COMPLIANT WITH THE INVENTION
10 μl of the extract obtained in Example 1 are used for each analysis.

1 / gas chromatography
The characteristics of the equipment used are as follows: column injector, capillary column, DB5 id 0.53 (equiv., SE52) and CPWAX58 id 0.32 (Carbowax equivalent) (id = internal diameter).

 - The initial temperature is increased linearly from 70 "C to 240 C.

 The chromatography profiles obtained under these conditions are shown in FIGS. 1 and 2.

 Figure 1 shows the profile obtained on column CPWAX58. Figure 2 shows the profile obtained on DB5 column.

 The compounds thus identified by each of these methods were compared, on the basis of their retention time, with standards.

 The determination of the constituents was obtained by gas chromatography.

The selected components were identified by infra-red spectrometry, coupled with FOURIER transform analysis
Table I below gives the list of these components as well as the quantities dosed and the chemical characteristics.

TABLE I.

<Tb>

<SEP> MOLECULE <SEP> QUANTITY <SEP> PM
<tb> Methyl <SEP> palmitoleate <SEP> 0.22 <SEP> 268.44
<tb> Methyl <SEP> palmitate <SEP> 0.29 <SEP> 270.46
<tb> Methyl <SEP> linoleate <SEP> 0.22 <SEP> 294.48
<tb> Methyl <SEP> oleate <SEP> 0.26 <SEP> 296.49
<tb> Methyl <SEP> stearate <SEP> 0.02 <SEP> 298.51
<tb> * Measured in Rg / equivalent ooplaque (average obtained from 1580 ooplaques)
EXAMPLE 3 - PREPARATION OF A COMPOSITION
ANTI-OVIPOSITION COMPLIES WITH THE INVENTION
Methyl palmitoleate, methyl palmitate, methyl linoleate, methyl oleate, and methyl stearate (SIGMA) are mixed in the proportions indicated in Table I above.The mixture is dissolved in methanol
EXAMPLE 4 - COMPARISON OF THE EFFECTIVENESS OF THE COMPOSITIONS
ANTI-OVIPOSITION AND THE PREPARATION OF HORMONE HORMONE ANTI-OVIPOSITION, CONFORMING TO
THE INVENTION ON THE REDUCTION OF THE LAW
THE PYRAL OF MAIZE
The study of spawning behavior was performed in altuglass cages in which was deposited a oviposition substrate for laying, consisting of a plastic grid on which is deposited a sheet of wax paper.

 Each oviposition substrate was divided into two zones: one is impregnated with the test solution (egg extract prepared according to the procedure described in Example 1, composition prepared according to the procedure described in Example 3, or solvent alone) at the desired concentration, the other is not impregnated.

 For each solution tested, the deposition is performed with the precision syringe. 90 drops of 2.5 l each are deposited on the test area.

 In the case of the extract, the concentrations used are expressed in ooplaque equivalents / drop, and are 0.7, 2, and 4.

 The anti-oviposition composition prepared according to the procedure described in Example 3 is used at a concentration of 1.616 mg / ml of the mixture of methyl fatty acid esters, which corresponds to 4 equivalents ooplaques / drop.

 After evaporation of the solvent, the treated oviposition carriers were placed in the cages. 2-day old corn borer females were left in the presence of the supports for 2 consecutive nights, after which the ooplates deposited on the treated areas, on the one hand, and on the untreated control zones, on the other hand, have been enumerated.

 The results obtained, which represent the average of 3 experiments, are illustrated in Figures 3 and 4.

 FIG. 3 represents the results obtained with the preparation extracted from eggs: on the ordinate, the number of ooplates deposited on the treated zone (in% of the total number of ooplates deposited on the support), and, on the abscissa, the concentration of the extract in ooplaque equivalents / drop.

 These results show that the number of ooplates deposited on the treated zone decreases very significantly when the concentration of the preparation deposited on the support increases.

 FIG. 4 shows the comparison of the efficiency of the preparation of the borer egg extract and the composition prepared as described in Example 3, on the reduction of the laying of the corn borer.

 On the ordinate axis is the reduction of the% of ooplates on the treated area compared to the untreated zone. This clearly shows that the effectiveness of the anti-oviposition composition obtained according to Example 3 is of the same order as that of the anti-oviposition pheromone preparation obtained from the corn borer eggs.

As is apparent from the above, the invention is not limited to those of its modes of implementation, implementation and application which have just been described more explicitly; on the contrary, it embraces all the variants that may come to the mind of the technician in the field, without departing from the scope or scope of this
Invention.

Claims (10)

 1) Preparation of anti-oviposition pheromone, which preparation is characterized in that it is obtainable from a methanolic extract of the corn borer eggs, and in that it comprises a mixture of methyl esters of palmitoleic, palmitic, linoleic, oleic and stearic acids.  2) An anti-oviposition pheromone preparation according to claim 1, which preparation is characterized in that it comprises: between 10 and 20 parts of methyl palmitoleate, between 10 and 20 parts of methyl palmitate, between 10 and 20 parts of methyl linoleate, between 10 and 20 parts of methyl oleate, for 1 to 2 parts of methyl stearate.  3) An anti-oviposition composition, active in particular on the corn borer, and characterized in that it comprises as active ingredient, at least one C13 alkyl ester and C1420 fatty acid.  4) anti-oviposition composition according to claim 3, characterized in that it comprises, as active ingredient, at least one methyl ester of a C1618 linear chain fatty acid.  5) anti-oviposition composition according to claim 4, characterized in that it comprises at least one linear fatty acid methyl ester selected from the group which comprises: methyl palmitoleate, methyl palmitate, linoleate methyl, methyl oleate, methyl stearate, and mixtures thereof.  6) Anti-oviposition composition according to Claim 5, characterized in that it comprises between 10 and 20 parts of methyl palmitoleate, between 10 and 20 parts of methyl palmitate, between 10 and 20 parts of methyl linoleate, between 10 and 20 parts of methyl oleate for 1 to 2 parts of methyl stearate.  7) anti-oviposition composition according to any one of claims 5 or 6, characterized in that it comprises at least 0.08 mg / ml of methyl palmitoleate, 0.1 mg / ml of methyl palmitate, 0, 08 mg / ml methyl linoleate, 0.1 mg / ml methyl oleate, 0.008 mg / ml methyl stearate  8) Anti-oviposition composition according to Claim 7, characterized in that it comprises between 0.3 and 0.4 mg / ml of methyl palmitoleate, between 0.4 and 0.5 mg / ml of methyl palmitate, between 0.3 and 0.4 mg / ml of methyl linoleate, between 0.3 and 0.4 mg / ml of methyl oleate and between 0.03 and 0.04 mg / ml of methyl stearate.  9) Application of an anti-oviposition pheromone composition or preparation according to any one of claims 1 to 8 to the protection of plants against insect pests, particularly corn borer.  10) A method of protecting plants against insect pests, particularly corn borer, which method is characterized in that the plants to be treated are brought into contact with an anti-oviposition pheromone composition or preparation according to one of the following: any of Claims 1 to 8.