PROCESS FOR INHIBITING PINE SHOOT BEETLES AND COMPOSITION THEREFOR

Abstract: The present invention relates to a method for inhibiting the larger and/or smaller pine shoot beetles, Tomicus piniperda, and Tomicus minor, respectively, by preventing aggregation and/or colonization of pine, wherein one applies an inhibitory active amount of (+) and/or (-)-verbenone on cut pine wood, as well as a composition hereto.

Description: Process for inhibiting pine s oot beet es an compo¬ sition therefor. DESCRIPTION Technical field The present invention relates to a method for inhibiting the larger and smaller pine shoot beetle, Tomi cus piniperda, and Tomicus mi nor, respectively, as well as a composition hereto. The object of the p resent • i nvent i on is to obtain a possibi lity to inhibit invasion of the larger and smaller pine shoot beetle 0 in pine . A further object is to obtain a composition hereto. Background of the invention The interest for biological methods for in ibiting pest insects has steadi ly increased during the last decade. Thi s i s particu¬ larly due for pheromones, the specie specific signal substances which some animals, and then in particular insects, communica¬ te with, inter alia to find a partner prior to mating. Pheromo- ^ ne based inhibiting methods against pest insects are characte¬ rized in that 1) they are highly specie specific, 2) the chemi¬ cal compounds used are relatively simple, and biologically ac¬ tive in very small amounts to the target organism, often nano- gram amounts, and 3) the insects have great difficulty in deve- loping resi stance against these natural signal compounds. The high specie specificity of the pheromones means that phero- mone based inhibiting agents are di rected almost only against individuals of one single specie. Sometimes, furthermore, against closely related species. The chemical composition of the pheromones is as a rule of such a type that they wi ll quite easi ly decompose by UV-light and micro organisms after an app¬ lication. Then they are decomposed to compounds whi ch are com¬ pletely harmless to other organi sms. This i s natural as the pheromones as behaviour signal shall be short living. They are thus not accumulated in higher organisms in a nutritional chain. The development of resistance in the insects against specie specific pheromones is extremely improbable. In spite of a considerable use of pheromones in the inhibition of e.g. a cotton fly in California for a whole decade, no resistance has developed. No change whatsoever in the composition of the phe- romone has been demonstrated. For the reason given above pheromone based inhibiting methods against pest insects are particularly harmless to the environ¬ ment. Furthermore, they have proved to be extremely efficient. Inhibition of forest damaging insects is an area where phero¬ mone based inhibiting methods already are of great importance as great economical values are at stake hereby. These is parti¬ cularly due for bark beetles which every years cause great los- ses both in form of ki lled trees, growth losses and numerous damages of e.g. blueing fungus. The Larger and smaller pine shoot beetles, Tomi cus piniperda, and Tomi cus minor attack pines. Pi nus sylvestr s. As most borer beetles the larger pine shoot beetle multiply in the nutritio¬ nal phloeme between the outer bark and the wood whi le the smal¬ ler pine shoot beetle lives on blueing fungus. The females ini¬ tiate an attack and are then rapidly followed by the males. Byers et al (1985) showed that T. piniperda is strongly attrac- ted by a mixture of monoterpenes consisting of the two enantio- mers of a-pinene, and the (+)-3-carene and terpinolene, which are characte istic components of the pine resin. Wind broken, top broken or in any other way damaged trees are colonized by the pine shoot beetles. Healthy trees are however, seldom at- tacked. The pine shoot beetles orient apparently by means of the resin compounds released from the fracture surface from broken branches, roots, tops or other bark damages and which thereby indicates a weakened tree. Early in spring-time when the temperature raises above 12 C the pine shoot beetles aggre- gate in large numbers on damaged pines, particularly on wind- fallen trees and stores of trees being cut during the winter. This has caused a regulation of the extract from the forest of cut trees, which, when pine is concerned, shall have been ended prior to July 1. This means a transport problem which, during certain years can be particularly troublesome. The pine shoot beetles gnaw paths in the phloeme under the out¬ er bark and lay thei r eggs in these. The larvae live of the nu¬ tritionally rich phloeme (T^ pi ni perda) or of hyfes of blueing fungus (T. mi nor) and after the pupal stage the new generation of pine shoot beetles is born in July. The leave the log and fly up to healthy crowns of pine where they gnaw into the new shoots and live of the marrow in these during the summer. Du¬ ring autumn they relocalize down to the layer of forest litter (T. minor) or bore themselves into the thick outer bark at the base of the pines (T. pin perda), where they hibernate Those shoots as the pine shoot beetles have lived in and of du¬ ring the late summer blow off during the autumn and winter which, at more massive attacks can cause considerable growth losses of the pines. The blueing fungus causes a technical da¬ mage on the wood by discolouring, which leads to a Lower price, Even if pine shoot beetles usually multiply in weakened trees these respond on these borings by a rich resin flow, which can drown those arriving fi rst. Pine shoot beetles thus usually use an aggregation pheromone by means of which the pine shoot beet¬ les first arrived attracts a lot of animals. The resin flow be¬ comes then at such a massive attack supportable to one and each of them. In an attempt to isolate the aggregation pheromone from the larger pine shoot beetle Byers et al (1985) combined chemical fract ionat ion made by preparative gas chromatography with a be¬ haviour test in which the attraction of the pine shoot beetles was studied. No indication of such a pheromone could be disco- vered neither in these tests nor in field trials with attrac¬ tion to infested wood. The larger pine shoot beetle thus uses as signal substance for attraction only monoterpenes from resin of the pine, particularly the above mentioned. Description of the present invention It has now surprisingly been shown possible to be able to pre- vent attack on cut pine by applying an inhibiting amount of verbenone on such wood, preferably in a combination with an in¬ ert carrier. Just as important as it is that the pine shoot beetles can ori- ent their flying to a certain tree in the initial stage, just as important is it of course that they cease to aggregate on the tree when this becomes filled. In other cases many lar-vae will die of lack of nutrients. It has now turned out that (-)- verbenone which together with several other compounds is pro- duced, when pine shoot beetles of both sexes gnaw the path's underneath the bark (Lanne et al, 1987) inhibits pine shoot beetles of both sexes to an attrahent consisting of the above mentioned three monoterpenes (FIG. 1). The behaviour test as such, has previously been described more carefully by Byers et al (1985) and Lanne et al (1987). Both (+) and (-)-enantiomeres of verbenone reduces the attraction of the pine shoot beetles to baits consisting of the three monoterpenes (Table 1). It has also been determined the naturally released amount of verbenone during a week time from pine shoot beetles bored into a log (FIG. 2) and it has been found that the amounts correspond to those which in a laboratory (FIG. 1) and field (Table 1) test lead to an inhibition. Verbenone is thus already in these small amounts a very effective inhibitor preventing pine shoot beet¬ les to attract to baits simulating the attraction ability of damaged pines. TABLE 1 Attraction of Tomi cus pi ni perda to tube traps loaded with at¬ tracting, synthetic monoterpenes and inhibitory amounts of enantiomeres of verbenone (V). The traps were placed in a pine forest. Total catch of the tube traps Chemi ca Is released Ma les Fema les May 14-20 Control Monoterpenesb,'c 30 29' Monoterpenes + (+)-V 9 3 Monoterpenes + (-)-V 0 3 April 17-29 Cont ro I 1 Monoterpenes 83 ( 65 v Monoterpenes + (+)-V 35 16 Monoterpenes + (-)-V 19 19 a The compounds were released in a constant amount (alfa- pinene 14 mg/day, 3-carene 6 mg/day, terpinolene 2.5 mg/day) each from glass tubes melted together in one end (2 x 0.07 cm) and containing 0.05 ml of compound in pure form. (+) and (-) alfa-pinene, (+)-3-carene and terpinolene c The release of verbenone was in all tests 0.25 mg/day (about 174 ng/min) d According to the Wi lcoxon test the monoterpenes loaded traps catch significantly more pine shoot beetles than the control traps or simi lar traps which all released verbenone (p<0.05) . The effect of verbenone to protect cut wood against attack of pine shoot beetles was studied in a field trial in which race ic verbenone in pure form was applied by spraying directly onto 1.5 m long pine logs in a dosage of 15 ml/log. The result is evident from Table 2. TABLE 2 Direct application of verbenone. 8 replicates (groups of logs) with two logs in each group (one treated and one untreated). Treatment Attacks/log Total number Inhibition Mean value of attacks effect Verbenone 8 61 79% Cont ro I 37 295 It has thus been shown that either of or both enantiomers to¬ gether of verbenone can be used to prevent the both sexes of T^ piniperda and T. minor to colonize cut pine log. As the pine shoot beetles have difficulty in colonizing living trees, which defend themselves with a rich resin flow they wi ll tire them¬ selves out in fruitless attempts to find a suitable spawning place or they wi ll die in the resin when they try to attack a healthy pine. At the use of verbenone in this aim verbenone is applied in an absorbent, such as si lica, zeolites., or porous polymers, such as of polyethylene, po lycarbami de, or dextrose derivatives, or e dispersed in an emulsion of a cellulose derivative, such as CMC, hydroxymethyL cellulose, other starch glues or gum forming po lysacchari des, so that the compound is released with an even amount for a long time. The absorbent is sprayed over the store of wood in the forest. As the wood does not become attacked the transport out of the forest can be spread during a longer time period and can be made during the autumn. In the same way, sum¬ mer cutting can take place which means a more rational handling within forestry. FIG. 1 shows the importance of increasing amounts of (-)- verbenone on the attraction response in a behaviour test carried out as a laboratory test using males and females of ^ piniperda to a 1 :1 :1 :1 mixture of the resin monoterpenes (-) -a-pinene, (+)-a-pinene, (+) -3-ca rene, and terpinolene, each being released in an amount of 2.2 x 10 g/min. Points (N=30) marked with the same letter are not significantly separated (a = 0.05 X ) . Vertical lines denotes the upper and lower 95 percent confidence inte rva I . FIG. 2 Release of verbenone from pine logs with 1.) 50 females (fi lled ci rcles), 2.) 50 females and 50 males (unfi lled circles) of T^ piniperda and 3.) only 50 artificially bored (triangles). The quantification was carried out using gas ch romatog raphy /mas s spectrometry using Z7- tridecanyl acetate (500 ng) as internal standard.

Claims: CLAIMS . 1. Method for inhibiting the larger and/or smaller pine shoot beetles, Tomi cus pi ni perda, and Tomi cus minor, respectively, by preventing aggregation and/or colonization of pine, charactei— ized in that one applies an inhibitory active amount of (+) and/or (-)-verbenone on cut pine wood. 2. Method according to claim 1, characterized in that one adds so much of verbenone that one obtains a release of at least 2.5 -9 x 10 g of verbenone per minute. 3. Method according to claim 1, characterized in that one adds so much of verbenone that one obtains a release of at least 2.5 —8 x 10 g of verbenone per minute. 4. Method according to claim 1 ,. characterized in that one ob¬ ttaaiinnss aa rreelleeaassee ooff aatt least 2.5 x 10 to 2.5 x 10 g of verbenone per minute. 5. Composition for inhibiting T^ piniperda and/or T^ minor on pine and/or cut pine wood according to claims 1 to 4, charac¬ terized in that it consists of (+) and/or (-) verbenone as an active component together with an absorbent and/or a fi lm form¬ ing cellulose derivative. 6. Composition according to claim 5, characterized in that it consists of a silicon based absorbent and (+) and/or (-) verbenone . 7. Composition according to claim 5, characterized in that it consists of a cellulose derivative and (+) and/or (-) verbenone . 8. Composition according to claim 5, characterized in that it consists of a porous polymer and (+) and/or (-) verbenone.

Inventors: BYERS JOHN, LANNE BOEL, LOEFQUIST JAN, SCHLYTER FREDRIK, BYERS, JOHN, LANNE, BOEL, LOEFQUIST, JAN, SCHLYTER, FREDRIK
Applicants: BYERS JOHN, LANNE BOEL, LOEFQUIST JAN, SCHLYTER FREDRIK, BYERS, JOHN, LANNE, BOEL, LOEFQUIST, JAN, SCHLYTER, FREDRIK
Application year: 1989
Main classification: A01N31
IPC codes: A01N35