Attractant effective in relation to Tribolium Confusum J.

Abstract: An attractant having attraction activity in rela­ tion to Tribolium Confusum J., which contains 2,6-­ dimethyl-1-octanol as a component exhibiting attraction activity. 2,6-dimethyl-1-octanol can be diluted with an appropriate solvent, or carried by an appropriate solid-­ phase carrier in the form of tablets. The attractant can be effectively used in lure trapping.

Description: The present invention relates to an attractant effective in relation to Tribolium confusum J. Tribolium Confusum J. is coleoptera generally known as a noxious insect parasitic on cereals. The coleopteran is parasitic not only on cereals such as flour, but also on secondary processed food (e.g., bread and cakes), and dried herbs, spices, zoological specimens, and the like. The coleopteran is therefore regarded as one of the most prominent indoor noxious insects, and there is a great demand for an effective method of preventing Tribolium confusum J. from living on, and removing it from, cereals, processed food, dried herbs, spices, and zoological specimens,. One of the methods which have been utilized to prevent noxious insects from living on, cereals is fumigation using compounds such as hydrogen phosphite, methyl bromide, DDVP, or the like. These compounds are harmful to humans, too. If they are applied indoors, they will be more harmful to humans than in the outdoor application. Hence, their use is limited to outdoor fumigation. Recently, methods using the pheromones of specific insects, such as lure trapping, confusion and the like, are attracting much attention. These methods can be carried out only by placing a dose of the attractant in a limited region, and are much easier than fumigation which is achieved by filling a limited space with a great amount of compounds. In view of this, the methods are very useful in a workshop or a warehouse where many people are working. Many persons have been studying not only these methods but also the compounds to be used in the methods. The inventors hereof have found that 2,6-dimethyloctyl formate exhibits attraction activity in relation to Tribolium castaneum H., and invented an attractant containing this substance, which is claimed in Japanese Patent Application No. 63-233942. However, no attractant which exhibits attraction activity in relation to Tribolium confusum J. and which can be manufactured economically has yet been realised. The pheromone of Tribolium confusum J. is identified as 4,8-dimethyl decanal (T. Suzuki, Agric. Biol. Che., 44, 2519 (1981)). The structure of this substance, i.e., 4,8-dimethyl decanal, is so unstable that the substance can hardly be used as an attractant. Accordingly, it is an object of this invention to provide a stable attractant which exhibits attraction activity in relation to Tribolium confusum J. and is an economical attractant for achieving lure trapping of this insect This objective can be attained by an attractant containing 2,6-dimethyl-1-octanol which exhibits attraction activity in relation to Tribolium confusum J. The present invention will now be described in detail. The inventors hereof synthesized a number of compounds which have structures similar to that of the pheromone of Tribolium confusum J., and tested them to see whether or not they have attraction activity in relation to this particular kind of insect. Of these compounds, 2,6-dimethyl-1-octanol was found to exhibit important attraction activity in relation to Tribolium confusum J. Although 2,6-dimethyl-1-octanol is a compound generally known in the art (K. Mori et al., Proc. Indian Acad., (Chem. Sci.), 100, 113 (1988)), the present inventors were the first to make the discovery that this compound has attraction activity in relation to Tribolium confusum J. This particular compound is chemically stable and, thus, exhibits attraction activity for a long period of time. This compound, i.e., 2,6-dimethyl-1-octanol, is represented by the following structural formula: The compound can be identified by the following physical properties: Boiling point: 117 to 110°C/26mmHg IR spectrum (cm⁻¹): 3350(s), 1040(s) NMR spectrum (ppm, CCℓ₄): 0.7 to 1.0 (9H,m) 1.0 to 1.9 (10H,m) 3.11 (1H,s,OH) 3.26 (2H,d,J=6Hz) The attractant according to the invention, which is effective in relation to Tribolium confusum J., can either be 2,6-dimethyl-1-octanol itself, or this compound diluted with an appropriate solvent such as hexane, acetone, benzene, ether, methanol, or the like. Alternatively, 2,6-dimethyl-1-octanol can be carried by a solid-phase carrier and used in the form of tablets. The carrier can be polypropylene, pulp, polysulfone nylon, nylon, polycarbonate, polyvinylidene chloride, polyvinyl chloride, polyvinylidene fluoride, polyurethane, cellulose ester, polyvinyl alcohol, epoxy resin, or polyolefine. The weight ratio between 2,6-dimethyl-1-octanol and the carrier is 1:10 to 1:100,000, preferably 1:100 to 1:1,000. The tablets are made by stamping a plate of polypropylene, having a thickness of 3 mm, forming discs having a diameter of 10 mm, and injecting 1 mℓ of ether solution of 2,6-dimethyl-1-octanol (1 wt%) into the discs by means of a syringe. To perform lure trapping of Tribolium confusum J., the attractant is placed within an appropriate trap. The attractant according to the present invention has prominent attraction activity in relation to Tribolium confusum J. Hence, if placed in a trap, the attractant attracts adult Tribolium confusum J. into the trap. Alternatively, it disturbs the ecosystem of adult Tribolium confusum J., thereby preventing the insect from living on foods, dried herbs, spices, and zoological specimens, or driving the insect from these items. Moreover, the attractant according to the invention is chemically stable and, therefore, exhibits attraction activity for a long period of time. Also, the attractant according to the invention can be used to determine how and where Tribolium confusum J. generates, and how many individuals generate. In other words, the attractant helps to provide valuable data for use in deciding whether or not an insecticide be used or when it should be applied, in order to kill Tribolium confusum J. or keep the insect away from foods, dried herbs, spices, and zoological specimens. The present invention will now be described in greater detail, with reference to examples. Example 1 <A> Synthesis of 2,6-Dimethyl-1-Octanol a) First, 31.4 g (0.2 mol) of 1-bromo-3-chloropropane and 14.2 g (0.1 mol) of cuprous bromide were added to 160 ml of dried THF. Then, these components were vigorously agitated by means of a stirrer, while being cooled to -10°C, thereby preparing a cooled solution. In the meantime, 4.8 g (0.2 mol) of metal magnesium and 27.4 g (0.2 mol) of 2-bromobutane were made to react in 160 mol of dried THF, thus preparing Grignard reagent. The Grignard reagent, thus obtained, was dripped into the cooled solution and made to react therewith for about three hours, whereby 17.4 g of 1-chloro-4-methylhexane (1) was obtained at yield of 65%. This reaction is represented by the following formula: (b) First, 4 g (0.1 mol) of NaH in the state of oil was added to 100 ml of dried DMSO, forming a mixture. Into this mixture, 17.4 g (0.1 mol) of diethyl methylmalonate was dripped, while being stirred on an ice bath. Then, 13.4 g (0.1 mol) of 1-chloro-4-methylhexane was added to the resultant mixture and made to react therewith at 70°C for five hours, thereby obtaining 26 g of crude diethyl 4-methylhexylmethylmalonate (II). This reaction is described as follows: (c) First, 8.18 g (0.22 mol) of sodium hydroxide was dissolved in a mixture solution of 28 ml of water and 14 ml of methanol, thus forming a solution. Next, 26 g of the crude product (II), not refined, was added to the resultant solution and made to react with the solution at 20°C for three to five hours, thereby obtaining 18.4 g of 4-methylhexylmethylmalonic acid (III). This reaction is represented as follows: (d) 17 g of 4-methylhexylmalonic acid (III) was stirred on an oil bath, while being heated at 140 to 145°C for 12 hours, and was thus subjected to decarboxylation. As a result of the decarboxylation, 12.5 g of 2,6-dimethyl octanoic acid at yield of 92%. This reaction is represented by the following formula: (e) First, 1.9 g (0.05 mol) of lithium aluminum hydride was suspended in 50 ml of dried ether while being cooled on an ice bath. Then, 8.6 g (0.05 mol) of 2,6-dimethyl octanoic acid was dripped into the resultant mixture, while the mixture was being stirred, and was reacted with the mixture for 20 hours, thereby obtaining 6.32 g of 2,6-dimethyl-1-octanol (V) at yield of 80%. This reaction is described as follows: The boiling point of the product (V), thus obtained, was 52 to 53°C at 0.7 mmHg. The IR- and NMR-spectrum of this product were identical to the data previously acquired. <B> Attraction Activity of 2,6-Dimethyl-1-Octanol in Relation to Tribolium confusum J. In order to evaluate the attraction activity which 2,6-dimethyl-1-octanol exhibits in relation to Tribolium confusum J., the following test was conducted. Different amounts of 2,6-dimethyl-1-octanol were dissolved in acetone, thus preparing solutions having various contents of 2,6-dimethyl-1-octanol. Each solution, thus obtained was applied to a circular sheet of filter paper having a diameter of 21 mm, and acetone was evaporated from both sheets of filter paper, thus making a test sheet. Acetone was applied to a circular sheet of filter paper having the same diameter, and acetone was evaporated from both sheets of filter paper, making a comparative sheet. A test sheet and a comparative sheet were placed in a plastic dish having a diameter of 85 mm, set apart from each other by a distance of 30 mm. Thereafter, 30 adult Tribolium confusum J. were put in the dish, and the dish was closed with a cover. The dish was placed in a room maintained at 28°C and illuminated with red light. After of 5 minutes, the dish was opened, and the individuals of Tribolium confusum J. attracted to the respective sheets of filter paper were counted. The test described above was repeated six times for each test sheet, and the average number of the Tribolium confusum J. attracted to the test sheet, and that of the Tribolium confusum J. attracted to the comparative sheet, were obtained. The results are shown in Table 1: As can be understood from Table 1, 2,6-dimethyl-1-octanol has attraction activity in relation to Tribolium confusum J. Example 2 Various solutions were prepared by dissolving, in hexane, different amount of 2,6-dimethyl-1-octanol prepared by synthesis <A> of Example 1. Each solution was applied to a disc made of polypropylene, having a diameter of 1 cm and a thickness of 3 mm, and this disc was used as test disc. Also, hexane only was applied to a disc made of polypropylene and having the same diameter, and this disc was used as a comparative disc. Further, two rectangular open boxes were made of a thick sheet of paper, measuring 6 cm × 15 cm × 2 cm. The inner surfaces of these boxes were coated with an adhesive. The test disc was placed on the bottom of the first box, thus making a test trap, and the comparative disc was placed on the bottom of the second box, thereby making a comparative trap. The test trap and the comparative trap, thus made, were placed on the floor of a closed test room, measuring 5 m × 5 m × 5 m, spaced apart from each other by 2 m. Then, 100 adult individuals of Tribolium confusum J. were put into the test room. The temperature within the test room was maintained at 28°C, and the room was illuminated with red light. Two days later, both the test trap and the comparative trap were removed from the room, and the Tribolium confusum J. individuals found in these boxes were counted. The test described above was repeated six times, for each test disk. The results were as is shown in the following Table 2: As Table 2 proves, 2,6-dimethyl-1-octanol has attraction activity in relation to Tribolium confusum J. Example 3 Two test traps identical to that used in Example 2, and also two comparative traps identical to that used in Example 2 were prepared. Two test rooms, either sized 5 m × 5 m × 5 m, were also built. A test trap and a comparative trap were put on the floor of either room, spaced apart from each other for 2 m. One hundred adult individuals of Tribolium confusum J. were released into the first test room, thereby performing lure trapping. One hundred adult individuals of Tribolium castaneum H. were put into the second test room, thereby performing lure trapping. The temperature in either test room was maintained at 28°C, and the interior thereof was illuminated with red light. Two days later, the Tribolium confusum J. individuals found in the test trap and comparative trap placed in the first test room were counted, and so were the Tribolium castaneum H. individuals present in the test trap and comparative trap placed in the second test room. The lure trapping described above was repeated six times, for each type of the insect. The results were as is shown in the following Tables 3 and 4: As is evident from Tables 3 and 4, 2,6-dimethyl-1-octanol has attraction activity in relation to Tribolium confusum J. Example 4 Two test traps were prepared which were identical to that used in Example 2, except that the solutions contained 2,6-dimethyl-1-octylformate instead of 2,6-dimethyl-1-octanol. Also, two comparative traps were prepared which were identical to that used in Example 2 and impregnated with hexane only. Using these test traps and these comparative traps, the lure trapping of Tribolium confusum J. and that of Tribolium castaneum H. were carried out in the same way as in Example 3, for each solution having a different content of 2,6-dimethyl-1-octylformate. The results were as is shown in the following tables 5 and 6: As can be understood from Tables 5 and 6, 2,6-dimethyl-1-octylformate, which has been developed as attractant effective in relation to Tribolium castaneum H., exhibited no particular attraction activity in relation to Tribolium confusum J.

Claims: Use of an attractant containing 2,6-dimethyl-1-octanol as a component exhibiting attraction activity in relation to Tribolium confusum J. The attractant according to claim 1, characterized in that said component is carried on a solid-phase carrier. The attractant according to claim 2, characterized in that said solid-phase carrier is one selected from the group consisting of polypropylene, pulp, polysulfone nylon, nylon, polycarbonate, polyvinylidene chloride, polyvinyl chloride, polyvinylidene fluoride, polyurethane, cellulose ester, polyvinyl alcohol, epoxy resin, and polyolefine. The attractant according to claim 2, which is in the form of a tablet. The attractant according to claim 3, characterized in that said solid-phase carrier is a disc having a thickness of 3 mm and a diameter of 10 mm. The attractant according to claim 5, characterized in that said disc is impregnated with 2,6-dimethyl-1-octanol in an amount of 1/10 to 1/100,000 the weight of said disc. The attractant according to claim 6, characterized in that the amount of 2,6-dimethyl-1-octanol impregnated in said disc is 1/100 to 1/1,000 the weight of said disc. The attractant according to claim 5, characterized in that said disc is made of polypropylene. The attractant according to claim 1, which is diluted with a solvent. The attractant according to claim 9, characterized in that said solvent is one selected from the group consisting of hexane, acetone, benzene, ether, and methanol.

Inventors: CHUMAN, TATSUJI, ONO, MIKIO, FUJI FLAVOR CO., LTD., CHUMAN, TATSUJI, C/O JAPAN TOBACCO INC.
Applicants: FUJI FLAVOR CO., LTD., JAPAN TOBACCO INC.
Application year: 1990
Main classification: A01N31
IPC codes: A01N25, A01N49, C07C31, A01N31