NO138235B - PREPARATION FOR ATTRACTION OF SPRINE BARKET BEETLES - Google Patents

Description

The most significant pest in Northern Europe's spruce forests is the spruce bark beetle. (Ips typographus) which bores into the tree and kills it when the attack is carried out by a sufficient number of beetles.

One way to combat such bark beetles is the use of pesticides, but these have limited use for two reasons.

Firstly, it is difficult to achieve a good effect because the beetles, most of the time, live hidden under bark, and secondly, you want to avoid using chemicals that can create disturbances in the ecosystem in the forest as far as possible.

In the fight against bark beetles, people have therefore been looking for new methods. During the last 10-15 years, research, especially in the USA, has found new paths. Considerable funds have been invested in attacking the bark beetle problems with new weapons. It has been found that you can appropriately disrupt the bark beetles' communication system, which is primarily of a chemical nature. Under certain conditions, the beetles produce substances, i.a. from what in the attacked trees. The substances are released into the environment because they affect other individuals of the same species. Such signal substances, which have been named pheromones, are very widespread in nature and can be registered by animals even in very small quantities. When the signaling substance is picked up, it stimulates certain reactions in the receiving individual. Some signaling substances will be attractive, while others, e.g. will appear exciting or alarming.

To find out the individual pheromone components,

analyzes have been carried out especially of sawdust from the beetles. This consists, among other things, of of the beetles' excrement. After the analyzes had been carried out, the effect of the individual pheromones was mapped and these were synthesized. This work is, among other things, described in Science,

c28.- October 1966, vol. 15.4, no. 3748, pp, 509-510. During this work, it was found that the following compounds are the main components of the signal system of several bark beetles: cis-verbenoi (m.p. 69°C, b.p. - approx.-JL20°C/15 mm Hg) . " _u ^ dpsdienol)

(b.p.: 54-59°C/0.15 mmHg)

2-Diethyl-6-methylene-7-okieji-4-ol (ipsenbl}.

In order to further clarify the spruce bark beetle's signaling system and possibly find, for example, more signaling substances than those previously known, we have now subjected the spruce bark beetle's intestinal contents to closer examination. During this work, the gut contents of the spruce bark beetles were analyzed using combined gas chromatography-mass spectrometry. The gas chromatography column, 20 cm x 2.5 mm, was packed"Tned 10% YFKP ^free fatty acid—polyester) on "Varapbrt 30" and held at 70-230°C. "MS source 250°C and 70 eV. Retention time and mass spectra of the active compounds were found to be in full agreement with the corresponding findings for authentic material.

<:rr>In these analyses, it was found that the guts of the spruce bark beetle also contain a compound that has not previously been shown as a signaling substance in such beetles or other insects, namely 2-methyl-3-buten-2-ol (methylbutenol)-, b.p. 99°C.

For a closer examination of the effect of the individual signal substances, individually and in combination, olfactometers with the following construction were used: The main component is a large aluminum funnel with a diameter of 80 cm and a depth of 65 cm. It is placed on

three legs of aluminum tubes, so that the outer edge reaches 170 cm above the ground. Above the opening of the funnel, two 30 cm high plexiglass plates are placed vertically in a cross, and in the center of the plexiglass plates a cardboard cylinder, 40 cm high and 15 cm in diameter, is folded down. The cylinder is closed at the upper end and is perforated.

Below the cylinder is an electrically powered fan which blows air up into the cylinder. On the wall inside the cylinder hangs a polyethylene tube where the test substances are stored in 50 mm long glass capillary tubes with an inner diameter of 1.4 mm.

In some experiments, the polyethylene tube was replaced with a piece of wood in which 40 male beetles had drilled for two days, "or with a fresh piece of wood. The air blown into the cylinder transports the test substances which are distributed through all the holes in the walls of the cylinder. The amount of the test substances that evaporates during the experiments is relatively small; Normally, the amount of the most volatile substance (methylbutenol) that evaporated was about 0.4 mg/hour, while the amount for the others was about 0.02 mg/hour at 20 25°C.

Five olfactometers were placed in the test area. The samples were moved between the olfactometers after an experiment had been completed. The test period was usually 30 minutes when the swarming activity was good. - On cooler days with less swarming, the time intervals were 60 minutes.

The following tables show the results obtained in 5 test series. The reason why the absolute values are somewhat different is that the experiments were carried out at different times and under different temperature conditions, which has an impact on the swarming of the beetles. The tables show the test substances used and the average number of spruce bark beetles (Ips typographus) that were caught.

As will be seen from the tables, in each case good results are obtained with a mixture of methylbutenol and cis-verbenol, and the best results are obtained when the mixture also contains ipsdienol, while ipsenol appears to have a -negative effect. The compounds a-pinene , 3-pinene and myrceh, which are natural constituents of fir trees, were not found to give any increased attraction.

According to the invention, a preparation is provided

for attracting spruce bark beetles (Ips typographus) containing verbenol, since the preparation is characterized by the fact that it also contains 2-methyl-3-buten-2-ol. In particular, it is preferred that it also contains ipsdienol.

The amount of the active components, iserbenol and methylbutenol, and possibly ipsdienol, in the preparation is ideal so that the preparation emits all the aforementioned active ingredients during its entire useful life, i.e. so that the active ingredients are used up almost simultaneously. Such tailored evaporation can be achieved both by varying the amount of the active ingredients in the preparation and likewise by varying the form of the preparation. E.g. can the preparation consist of a layered impregnated material where the most volatile signaling substance (methylbutenol) is in the innermost layer, e.g. as in the "Hercon" system, or capillary tubes in tape form, as in the "Conrel" system, or the active components cast into a solid, volatile solvent such as wax.

Both geometric isomerism and

optical isomerism (chirality). *

We have synthesized verbenol from the a-pinene found in a

right-hand and a left-hand version respectively the R and S-a pin.

From each of these enantiomeric forms of the α-pinene is formed

then the respective enantiomers of trans-verbenol (via the acetate).

S-a-pinene gives R-trans-verbenol. (R configuration at the OH group.). The bicyclic system itself is not touched in the synthesis, so that the basic configuration does not change. Furthermore, R-a-pinene gives S-trans-verbenol. Cis-verbenol is then synthesized from trans-verbenol. By this method, -

R-trans-verbenol give S-cis-verbenol, and

S-trans-verbenol will yield" R-cis-verbenol.

By choosing the right enantiomer of the a-pinene, one can thus obtain

desired enantiomer of cis-verbenol.

In our experiments, approx. 93% optically pure S-cis-verbenol (93% S 7% R enantiomers). This is produced from a-pinene with corresponding optical purity (93% S or (-)-a-pinene).

Furthermore, the cis-verbenol contained approx. 5-10% R-trans-verbenol;

Ipsdienol is also available in R and S form. Here, a racemic mixture is used in the experiments (equal parts of R and S form).

The preparation according to the invention can be suitably used as part of an integrated control by placing it on trees or artificial traps.

Formulas for the compounds used in the experiments:

Claims (2)

1. Preparation for attracting spruce bark beetles, (Ips typographus) containing verbenol., especially cis-verbenol, - characterized in that it also contains 2-methyl-3-buten-2-ol-(methylbutenol). 2. Preparation as stated in claim 1, characterized in that it contains verbenol, especially cis-verbenol, methylbutenol and ipsdienol.