SUSTAINED RELEASE PHEROMONE PREPARATION

Abstract

Provided is a sustained release pheromone preparation used for the control of insect pest, which can maintain a high release rate of a pheromone substance during the control period of the insect pest which has, as the pheromone substance, a C.sub.20-35 aliphatic hydrocarbon compound having such a melting point that the aliphatic hydrocarbon is in a solid form at normal temperature. More specifically, provided is a sustained release pheromone preparation comprising a membrane of an ethylene-vinyl acetate copolymer, and a C.sub.20-35 aliphatic hydrocarbon compound which is carried by the membrane, is permeable through the membrane, and has such a melting point that the aliphatic hydrocarbon compound is in a solid form at normal temperature, wherein the preparation targets an insect pest having the aliphatic hydrocarbon compound as a pheromone substance.

Claims

1. A sustained release pheromone preparation, comprising: a membrane of an ethylene-vinyl acetate copolymer, and at least one C.sub.20-35 aliphatic hydrocarbon compound which is carried by the membrane, is permeable through the membrane, and has such a melting point that the aliphatic hydrocarbon compound is in a solid form at normal temperature, wherein the preparation targets an insect pest having the aliphatic hydrocarbon compound as a pheromone substance.

2. The sustained release pheromone preparation according to claim 1, wherein the aliphatic hydrocarbon compound is at least one selected from the group consisting of 2-methyltricosane, 3-methyltricosane, 2-methylpentacosane, 3-methylpentacosane, 3-ethyltracosane, 2-methylhexacosane, 2-methylheptacosane, 3-methylheptacosane, 11-methylheptacosane, 13-methylheptacosane, 4,8-dimethylheptacosane, 2-methyloctacosane, 2-methylnonacosane, 3-methylnonacosane, 11-methylnonacosane, 13-methylnonacosane, 15-methylnonacosane, 11-methylhentriacontane,13-methylhentriacontane, 15-methylhentriacontane, 11,15-dimethylhentriacontane, 13,17-dimethylhentriacontane and 11-methyltritriacontane.

3. The sustained release pheromone preparation according to claim 1, wherein the normal temperature is a temperature of from 5 to 35° C.

4. The sustained release pheromone preparation according to claim 2, wherein the normal temperature is a temperature of from 5 to 35° C.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In the invention, an insect pest to which the sustained release pheromone preparation is applied is not particularly limited insofar as it is an insect pest having, as a pheromone substance, a C.sub.20-35 aliphatic hydrocarbon compound having such a melting point that the aliphatic hydrocarbon compound is in a solid form at normal temperature. Examples of the insect pest include insects belonging to the order Hemiptera such as Pear Psylla (Cacopsylla pyricola, Cacopsylla pyri, or Cacopsylla chinensis).

[0012] The term “normal temperature” means a temperature of from 5 to 35° C. The C.sub.20-35 aliphatic hydrocarbon compound having such a melting point that the aliphatic hydrocarbon compound is in a solid form at normal temperature, has a melting point of preferably 20° C. or more.

[0013] The C.sub.20-35 aliphatic hydrocarbon compound having such a melting point that the aliphatic hydrocarbon compound is in a solid form at normal temperature may have any of linear, branched and cyclic structures. A bond of the aliphatic hydrocarbon compound may be a saturated bond or unsaturated bond. Examples of the aliphatic hydrocarbon compound include substances having one or more methyl groups in the carbon skeleton thereof such as 2-methyltricosane (having 24 carbon atoms), 3-methyltricosane (having 24 carbon atoms), 2-methylpentacosane (having 26 carbon atoms), 3-methylpentacosane (having 26 carbon atoms), 3-ethyltetracosane (having 26 carbon atoms), 2-methylhexacosane (having 27 carbon atoms), 2-methylheptacosane (having 28 carbon atoms), 3-methylheptacosane (having 28 carbon atoms), 11-methylheptacosane (having 28 carbon atoms), 13-methylheptacosane (having 28 carbon atoms), 4,8-dimethylheptacosane (having 29 carbon atoms), 2-methyloctacosane (having 29 carbon atoms), 2-methylnonacosane (having 30 carbon atoms), 3-methylnonacosane (having 30 carbon atoms), 11-methylnonacosane (having 30 carbon atoms), 13-methylnonacosane (having 30 carbon atoms), 15- ethylnonacosane (having 30 carbon atoms), 11-methylhentriacontane (having 32 carbon atoms), 13-methylhentriacontane (having 32 carbon atoms), 15-methylhentriacontane (having 32 carbon atoms), 11,15-dimethylhentriacontane (having 33 carbon atoms), 13,17-dimethylhentriacontane (having 33 carbon atoms), and 11-methyltritriacontane (having 34 carbon atoms).

[0014] The preparation may further comprise, as a pheromone substance other than the C.sub.20-35 aliphatic hydrocarbon compound having such a melting point that the aliphatic hydrocarbon compound is in a solid form at normal temperature, an aldehyde compound, an ester compound, an alcohol compound, a ketone compound, a hydrocarbon compound or the like which has low reactivity toward the aliphatic hydrocarbon compound and does not decompose the aliphatic hydrocarbon compound.

[0015] As a material of the membrane of the sustained release pheromone preparation, an ethylene-vinyl acetate copolymer is selected because it can maintain a liquid form of the aliphatic hydrocarbon compound having such a melting point that the aliphatic hydrocarbon compound is in a solid form at normal temperature. From the standpoint of release performance and workability, a weight ratio of ethylene units to vinyl acetate units of EVA is preferably from 92:8 to 80:20, particularly preferably from 90:10 to 85:15. The vinyl acetate unit content is the content of vinyl acetate-derived repeating units of EVA, while the ethylene unit content is the content of ethylene-derived repeating units of EVA.

[0016] The molecular weight of EVA is not particularly limited. A weight average molecular weight (Mw) of EVA is preferably from 50,000 to 500,000 as measured by gel permeation chromatography (GPC) on basis of polystyrene from the standpoint of the release performance and workability.

[0017] When the membrane of the sustained release pheromone preparation is made of EVA which can maintain a liquid form of the aliphatic hydrocarbon compound having such a melting point that the aliphatic hydrocarbon compound is in a solid form at normal temperature, the aliphatic hydrocarbon compound can permeate the membrane even at a temperature not higher than the melting point. The EVA membrane may be formed into an entire container of the sustained release pheromone preparation such as tube, capsule, ampule or a bag, or may be formed into a part of the container such as a wall portion of the container. When a part of the container comprises the EVA membrane, the aliphatic hydrocarbon compound can be released from the membrane. In addition, when another part of the container comprises, for example, a polyethylene membrane, a pheromone substance other than the aliphatic hydrocarbon compound can be released simultaneously.

[0018] An amount of the compound carried by the membrane in the sustained release pheromone preparation is preferably from 30 to 1000 mg, more preferably from 50 to 500 mg.

[0019] The thickness of the EVA membrane varies depending on the kind of the pheromone substance, release period of time into the air, or the like. The thickness of the EVA membrane is typically from 0.03 to 0.07 mm.

[0020] From the standpoint of preventing UV-caused deterioration of the aliphatic hydrocarbon compound, the sustained release pheromone preparation may comprise an inorganic colorant such as iron oxide, chromium oxide, titanium oxide or carbon black; or an organic colorant such as polycyclic pigment or azo-based pigment; in an amount of preferably 3% by weight or less, more preferably 1% by weight or less.

[0021] Further, from the standpoint of prevention of the polymer deterioration during polymer use, the sustained release pheromone preparation may comprise an antioxidant such as a phenol-based antioxidant, a sulfur-based antioxidant or a phosphor-based antioxidant; and/or a stabilizer such as a benzotriazole-based or benzophenone-based ultraviolet absorbent. From the standpoint of workability improvement, the preparation may comprise an antiblocking agent such as a metal salt of a higher fatty acid or an inorganic powder; and/or a lubricant such as hydrocarbons, alcohols, a higher fatty acid, esters, a partial ester of polyhydric alcohol, a metal salt of higher fatty acid, natural wax, fatty acid amide or a polymer. The preparation may comprise the antioxidant, the stabilizer, the antiblocking agent and/or the lubricant, each in a typical amount of from 0.002 to 1% by weight.

[0022] The sustained release pheromone preparation can be produced by the method comprising the steps of: filling a container formed by blow raiding, extrusion or the like with a pheromone substance in a liquid form, and sealing the container. Alternatively, the sustained release pheromone preparation can be produced by the method comprising the steps of: filling the molded product with a pheromone substance in a liquid form through the same route as that for pushing out the air during the simultaneous molding, and sealing the container.

EXAMPLES

[0023] Example and Comparative Example of the invention will hereinafter be described in detail. It should not be construed that the invention is limited to or by Example.

Example 1 and Comparative Example 1

[0024] In Example 1, a sustained release pheromone preparation having an actual release surface area of 50 cm.sup.2 was produced by forming a 0.05 cm-thick membrane of an ethylene-vinyl acetate copolymer (EVA) having a weight ratio of ethylene units to vinyl acetate units of 85:15 into a 5 cm×6 cm bag having an opening, pouring 100 mg of 13-methylheptacosane melted in a temperature-controlled oven of 60° C. into the bag through the opening, and then sealing the liquid-containing bag at a position 5 cm higher from the bottom side of the bag at a sealing temperature of 240° C.

[0025] In Comparative Example 1, a sustained release pheromone preparation was produced in the same manner as in Example 1 except for use of a 0.05-cm thick membrane of low-density polyethylene (LDPE).

[0026] Then the sustained release pheromone preparations thus produced in Example 1 and Comparative Example 1 were placed for 21 days under an environment of 15° C., and the appearance of the 13-methylheptacosane in each bag was observed.

[0027] The 13-methylheptacosane in the sustained release pheromone preparation of Example 1 was still melted so that the 13-methylheptacosane was being released. On the other hand, the sustained release pheromone preparation of Comparative Example 1 did not release the 13-methylheptacosane because it solidified.