COMBATTING PEST INSECTS

Abstract: The present invention relates to the use of the sex pheromone, E8, E10-dodecadien-1-ol in combination with one or more behaviour antagonists for inhibiting the codling moth, Cydia pomonella, by confusion.

Description: COMBATTING PEST INSECTS DESCRIPTION Teςhnical field The present invention relates to the use of a combination of the sex pheromone, E8,E10-dodecadien-1-ol, and a behaviour antagonist for combatting the codling moth, Cydia pomonella, in fruit orchards. The object of the present invention is to obtain an efficient method for combatting codling moth in fruit orchards by utilizing the sex pheromone of said insect in com¬ bination with a behaviour antagonist. Background of the invention Biological methods of inhibiting pest insects have been faced with great interest during later years and in particular the use of pheromones, i.e. specie specific scent substances by means of which animals, such as insects, communicate and which substances trigger (provoke) a certain behaviour or a biological activity. Since se¬ veral years pheromones are marketed for inhibiting certain pest insects on a com¬ mercial basis, as well. The advantage of using pheromones for this purpose is the very high selectivity and the very great environmental advantage. Contrary to che¬ mical inhibiting agents the activity of the pheromones is directed solely towards the insect specie intended and as pheromones are substances that appear naturally they do not give rise to resistance problems. Pheromones are further, active in very small amounts and are biologically degradable. They are not toxic to any part of the ecological system. Sex pheromones of butterflies (in particular night moths and torthricides) are the most well known sex pheromones. In one inhibiting method, the confusing method, the pheromone is spred from sources provided with a synthetic sex pheromone substance in such a way that the whole area will become reeking with the substan¬ ce. The males will then not find the females to any greater extent. The method is efficient. The confusing method is today commercial with regard to a dozen moth species (Carde & Minks, 1955, Ridgway et al, 1990). The most important obstacles for a rapid development of the confusing technique are within the fields of biology and chemistry. One does simply not know how and whv the confusing technique works. The dominant hypothesis for the male pheromone attraction of the females was formulated in 1978 by Roelofs. It is called the treshhold hypothesis and states that the complete and proportinally natural pheromone blend is always a better stimulus of the complete behaviour than any other blend of the components. It will also re¬ lease the behaviour at lower concentrations than any other blend. The hypothesis has governed and still governes, in principle, all pheromone studies. In a review of successful and commercial cases using confusion, Minks & Carde conclude (1988) : "the natural blend achieves disruption of mating at lower appli¬ cation rates than either partial or off-ratio blends". A sex pheromone may consist of up to 10 different, but biosynthetically closely related substances (Baker, 1989). Different species within a family utilize different combinations of such a theme. The specie separation can be strengthened by the fact that specie A has specific sensoric neurons for the main component of specie B as well, but responds with a negative, escaping behaviour on such a signal. As an example the pine hymenopteran of the family Neodiprion (Lδfqvist, 1986) will be mentioned. The main component of the sex pheromone of N. sertifer has three chiral carbon atoms. The substance can thus appear in eight different enantiomers. Only one of them is active as a sex attractant. Another one thereof is a very strong behaviour antagonist. Only 1-2% of this together with the attractant is enough to completely block the attraction. Description of the present invention It has now surprisingly been shown possible to be able to inhibit the codling moth, Cydia pomonella, by confusion by means of the use of the sex pheromone E 8.E10- dodecadien-1-ol in a combination with one or more behaviour antagonists. Further characteristics are evident from the accompanying claims. Suitable behaviour antagonists are one or more of the geometric isomers of delta8,delta10-dodecadien-1-yl acetate. Further, the behaviour antagonist can be one or more of the substances of the group Z8-dodecen-1-yl acetate, E8-dodecen- 1-yl acetate, Z10-dodecen-1-yl acetate and E10-dodecen-1-yl acetate. The codling moth, Cydia pomonella, lives in habitate with a great number of other species. The competition in the communication channel using pheromones has led to the fact that the main component of the sex pheromone of one specie simultan¬ eously is a behaviour antagonist of another specie. A number of such are known with regard to the codling moth, but the effect of them together with the sex phero¬ mone has never been investigated before. However, the confusing method based upon the own sex pheromone of the codling moth, has been developed into a com- mercial product (Charmillot, 1990; Pfeiffer, et al, 1993) which product, however, has a restricted use to low population densities and high amounts of compound. The main component of the sex pheromone of the codling moth, E8,E10-dodecadi- en-1-ol was identified already in 1971 by Roelofs et al. Several research groups then worked with the identification of the composition of the pheromone. A relatively complete composition was published by Einhom et al (1984) and Arn et al (1985). Already Roelofs et al (1972) found that the EE-isomer of the geometric isomers was very attractive while the other three inhibited the attraction of this. The commercial product thus consequently consists of 99% EE-isomer. The family Cydia consists of a great number of species. In many thereof, e.g. the pear moth, Clydia pyrivora, the main component of the sex pheromone is E8.E10- dodecadien-1-yl acetate, i.e. the same substance as of the codling moth, with the difference that the substance is present as an acetate ester, i.e. the end group is an acetate in stead of an alcohol. It has turned out that the acetate is a behaviour anta¬ gonist of the codling moth, which will be evident from the tests shown below. Pheromone traps were loaded with the pheromone, E8,E10-dodecadien-1-ol of the codling moth, (FIG 1A). In other traps the alcohol was combined with the corre- sponding acetate (FIG 1 B). At a blend of 20% of the acetate the catch decreased to 1/8 (dark coloumn). In further tests the other three isomers (EZ (FIG 1C), ZE (FIG 1 D), and ZZ (FIG 1 E)) (FIG 1C-1 E) were tested. They were all behaviour antago¬ nists to the codling moth. The ZZ-isomer was the most powerful of the four isomers. In another test a confusion test was carried out in 100 m2 quadratic test areas in a fruit orchard. In each test four dispensing means, loaded with a behaviour antago¬ nist, were placed in each of the four corners of the respective test area. In the res¬ pective centre of each square a pheromone trap loaded with the sex pheromone, E8,E10-dodecadien-1-ol of the codling moth, was placed. The confusing effect was calculated as the number of males trapped in the trap compared with the number trapped in a trap in a non-treated control square, i.e. without any behaviour anta¬ gonist in the respective corner. Both the alcohol and the the corresponding acetate had a strong confusing effect. However, the combination thereof had a clearly higher effect. The own sex pheromone of the codling moth, the alcohol, is as already mentioned, in commercial use. The inhibiting results are however, not always satisfying, Carde & Minks, (1995), (Control of moth pests by mating disruption. Successes and con¬ straints. Ann. Rev. EntomoL 4j£: 559-585) in particular not in fruit orchards having high trees and a high population density. It has turned out that in such cases, the males are attracted to the tree tops. Probably, the concentration of pheromone from located dispensing means so low there, that the attracting power of the pheromone dominates its confusing effect. Males circulating in the tree topsmay also be caught in lower placed trapswhich indicates a lacking confusing effect. However, if dis- pensing means in which the sex pheromone (the alcohol) is combined with a be¬ haviour antagonist (acetate) is placed out no males are observed flying around in the tree tops. Several of the males caught in pheromone traps in such treated squares can be seen flying some metres above the ground and straight into the trap. They, did never arrive from the top of the trees. The combination of the sex pheromone and a behaviour antagonist can thus be regarded a superior inhibiting method.

Claims: CLAIMS 1. The use of the sex pheromone, E8,E10-dodecadien-1-ol in combination with one or more behaviour antagonists for inhibiting the codling moth, Cydia pomonella, by confusion. 2. The use according to claim 1 characterized in that the behaviour antagonist is one or more of the geometric isomers of derta8,delta10-dodecadien-1-yl acetate. 3. The use according to claim 1 , characterized in that the behaviour antagonist is one or more of the substances of the group Z8-dodecen-1-yl acetate, E8-dodecen- 1-yl acetate, Z10-dodecen-1-yl acetate and E10-dodecen-1-yl acetat.

Inventors: BENGTSSON MARIE, LOEFQVIST JAN, WITZGALL PETER, BENGTSSON, MARIE, LOEFQVIST, JAN, WITZGALL, PETER
Applicants: BENGTSSON MARIE, LOEFQVIST JAN, WITZGALL PETER, BENGTSSON, MARIE, LOEFQVIST, JAN, WITZGALL, PETER
Application year: 1996
Main classification: A01N31
IPC codes: A01N31