Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Reexamination Certificate
2000-03-06
2003-05-27
Levy, Neil S. (Department: 1616)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
C424S405000, C424S409000, C424S683000, C514S770000
Reexamination Certificate
active
06569440
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention fits in the agricultural sector and, in particular, in the control of insect plagues detrimental to crops.
More specifically, the present invention provides new emitters of semiochemical substances, with controlled emitting speed, useful for the control of insect plagues in agricultural crops and the process for the preparation thereof.
PRIOR ART OF THE INVENTION
Insect plagues cause a drastic reduction of crops and insecticides are the traditional method to combat them. However, the use of insecticides has problems such as:
Their toxicity for humans and superior animals, which causes governments to impose more restrictive regulators for the use thereof.
The lack of selectivity, that converts into the destruction of beneficial insects, or of natural predators of the plague that is to be fought
The resistance developed by the insects, which makes it necessary to increase more and more the dosage to maintain the effectiveness thereof.
All of these problems oblige insecticide manufacturers to dedicate more and more resources to R+D in order to obtain better products, but the problem continues to exist.
On its part, society demands respect for the environment but at the same time it requires quality of the agricultural food products, which requires the development of new plague control systems based environmental methods.
It is well known that the communication among insects is basically done by means of a specific type of substances, called “semiochemical substances” (or simply “semiochemicals”), that their organisms naturally emit.
The knowledge of said semiochemical substances as well as the knowledge of the information that the same transmit to the insects permits the development of environmental methods in order to control the behavior of the insects.
In accordance with the above, it is possible to transmit a specific message to a specific species of insects, inducing a specific response by means of the artificial emission of synthetic semiochemicals. Hence, for example, if the message is of attraction, the response of the insect will be directed towards the emitter.
Taking advantage of this inducing capacity the behavior of insects, techniques that permit the control thereof have been developed. Hereinafter a summary of the most important ones is going to be made:
Control, whose purpose is to prevent the occurrence of plagues, to follow their development and to confirm their extinction by means of a count of the captures that are produced in traps provided with an emitter of an attracting semiochemical.
Sexual confusion, that seeks to prevent the reproduction of insects by means of the emission of amounts of a semiochemical that saturates the receptor organs of the insect preventing it to find members of its same species and of the opposite sex.
Massive captures, that seek to significantly reduce the insect population, by means of captures, in traps, with an attracting semiochemical. Aside from the attractant, a toxic agent for the insect, a sexual sterilizer, an entomopathogenic microorganism or simply glue where the insect is adhered and dies, may also be placed in the traps.
The low toxicity of semiochemicals, their high specificity (generally, their action is directed towards a single species), the difficult occurrence of resistances and their non-existent polluting impact, represent outstanding advantages in contrast to conventional insecticides.
So that the use of these semiochemical substances is effective it is necessary to have physical supports capable of emitting the semiochemicals in a controlled manner for a sufficient amount of time, in such a way that a concentration in the air capable of cause the desired response in the insect in a continued manner is achieved.
The cited supports must comply with a series of requirements so that their use is effective:
Provide an adequate emitting speed of the semiochemical.
Permit prolonged duration of the emission
Avoid degradation of the semiochemicals
Not produce contaminating residues
Be economical and allow easy application of the semiochemical
Although there is a large variety of emitting supports on the market such as rubber septa (Aldrich Co., UK; The West Co., Pennsylvania; Arthur H. Thomas Co.; Maavit Products, Tel Aviv, Israel), polyethylene pipes (Shin Etsu Chemical Co., Tokyo, Japan), porous plastic laminates (Hercon Lab. Co., New Jersey, USA); capillary fibers (Albany International, Massachusetts, USA), microcapsules (ICI Agrochemicals, Berks, UK), none of these emitting supports comply with all the above mentioned requirements.
Therefore, there is still the need of emitters of semiochemical substances with supports that acceptably satisfy said requirements and, precisely, this has been the purpose that the applicant's scientific research has sought. This research has allowed the attainment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Just as it is stated in its title, the present invention refers to new emitters of semiochemical substances with a controlled emitting speed, to a process for the preparation thereof and to the applications thereof for the control of insect plagues in agriculture.
The emitters of the present invention, that comprise a support and a semiochemical substance adsorbed in the support, are characterized in that said support is a sepiolite and in that the retaining capacity between said sepiolite and said semiochemical substance is regulated in such a way that a controlled emission kinetics of said semiochemical substance is obtained.
Natural sepiolites are crystalline magnesium silicates. Structurally, they are formed in laminae of silica tetrahedrons connected by Mg
2+
cations, in octahedral coordination (see FIG.
1
). The laminae form fibers of a length between 0.5 and 1.5&mgr; and in turn, the fibers are connected together by means of Si—O—Si bridges and carbonates, forming beams with a thickness of about 200 Å
The specific surface of natural sepiolite is around 200-300 m
2
/g, and can be modified to values between 80 and 600 m
2
/g (according to the B.E.T. method) by means of adequate treatments, wherein the Si—O—Si bridges are broken.
The size of the channel of natural sepiolite is relatively small and there is a high polarity inside it, caused by the water from crystallization and the end hydroxyl groups.
Due to this, the regular molecules of semiochemicals have difficulties in entering inside the channels, due to the size thereof and the lack of polarity, and consequently, the adsorption to the sepiolite support is superficial, in most of the cases.
The retaining capacity between the sepiolite and the semiochemical can be carried out from two aspects:
1.—Modification of the sepiolite
2.—Modification of the degree of compacting between the sepiolite and the adsorbed semiochemical.
Within the first group of modifications the following ones can be mentioned:
Modification of the surface cations of the sepiolite
Modification of the specific surface of the sepiolite
Within the second group of modifications the following ones can be mentioned:
Modification of the compacting pressure
Modification of the surface/weight ratio of the finally obtained form
Each one of these modifications will now be analyzed in a more detailed manner.
1. The modification of the surface cations of the sepiolite allows modification of the number of adsorption centers and the retaining force of the semiochemical on the part of the same. An illustrative example of this fact is constituted by the use of different sepiolites modified superficially wherein a specific percentage of surface octahedral magnesium has been replaced by mono or bivalent cations of groups IA and IIA or by protons. The modification of the surface cations of the sepiolite can be done by treatment of the natural sepiolite with acids (for example, sulfuric acid) or with bases (for example, sodium hydroxide).
2. The modification of the specific surface of the sepiolite is especially interesting, taking into account that the fixation of the molecul
Canos Avelino Corma
Muñoz Pallares Juan
Primo Yufera Eduardo
Consejo Superior De Investigaciones Cientificas
Klauber & Jackson
Levy Neil S.
LandOfFree
Emitter of semiochemical substances supported on a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Emitter of semiochemical substances supported on a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Emitter of semiochemical substances supported on a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3017190