WO2018011826A1

WO2018011826A1 - Nanogels, methods and devices thereof, for managing holotrichia consanguinea

Info

Publication number: WO2018011826A1
Application number: PCT/IN2017/050290
Authority: WO
Inventors: Subham BHATTACHARJEE; Santanu Bhattacharya; Deepa BHAGAT
Original assignee: Indian Institute Of Science; National Bureau Of Agricultural Insect Resources
Priority date: 2016-07-15
Filing date: 2017-07-13
Publication date: 2018-01-18
Also published as: EP3484941A4; EP3484941A1

Abstract

The present invention relates to a novel approach for controlling the Holotrichia consanguinea. Specifically, the instant disclosure provides a nanogel comprising a gelator and a volatile active agent wherein said gelator is obtained by attaching poly(benzyl-ether) dendron with oligo(p- phenylenevinylene) via hyadrazone linkage. The present disclosure further discloses a method of preparing the nanogel, a device for controlling the Holotrichia consanguinea and uses thereof.

Description

"NANOGELS, METHODS AND DEVICES THEREOF, FOR MANAGING HOLOTRICHIA CONSANGUINEA "

CROSS-REFERENCE

This application claims the benefit of Indian Patent Application no.201641024309 filed on July 15, 2016, which application is incorporated herein by reference in its entirety and is similar in scope with said priority application.

TECHNICAL FIELD:

The present disclosure relates to the field of nanotechnology and pest management.

BACKGROUND OF THE ART:

Holotrichia consanguinea, popularly known as white-grubs belongs to family Scarabaeidae. Holotrichia consanguinea causes severe damage to kharif or monsoon crops including groundnut, bajra, moong bean and vegetables and so on. The larvae of this insect reside underground and on application of pesticides they tend to penetrate the ground further, thereby making the application of pesticides or insecticides ineffective in order to control such species. Accordingly, for controlling the damage caused by this insect, the adult form of the same is targeted.The adult form of Holotrichia consanguinea appear from the soil at the beginning of the monsoon rain. The adult Holotrichia consanguinea congregate in host trees such as neem, ber, khejari, guava trees for feeding and mating. Considering the aforesaid problem, the life cycle of the Holotrichia consanguinea is stopped by killing adult Holotrichia consanguinea. Method of controlling Holotrichia consanguinea are provided in the art. The first method involves spraying of insecticides which includes imidacloprid, monocrotophos, quinalphos, and carbaryl.ln thie method, trees are spread with insecticides and studies have shown that spraying of a single host tree from a group of trees within a radius of ~1 5 meters is generally required for effective action. Subsequently, a piece of sponge and a small piece of stone are connected at the two ends of a small wire followed by soaking of the sponge with few drops of the pheromone. The pheromone loaded sponge also known as pheromone dispenser has been placed on the host tree in the evening time preferably between 7.15 to 7.45 PM. The adult beetles (Holotrichia consanguinea) are attracted by the sex pheromone. They gather in the host tree, feed and die soon either due to the body contacts with the insecticides or by the stomach action of the insecticides.

However, there are several disadvantages of the above technique. For instance, the pheromone, being volatile, diffuses in air within a few minutes after delivery, making the surrounding air encompassing with high concentration of the pheromone. Therefore, the sponge requires a frequent loading of the pheromone in the same evening. Moreover, in a small agricultural field, it may still be possible for a farmer to repeat this process over and over again. In contrast, for a large field, which is the real situation in Indian sub-continent, spraying in a larger number of host trees with insecticides, placing of the pheromone soaked sponge in all the host trees within this short time interval is really very difficult by a farmer. That requires a large amount of pheromone, insecticides as well as a good number of labours, which makes the overall process inefficient and economically not viable. The sprayed insecticides also pollute the environment to a great extent. The disadvantages of this method are numerous, Further, the non-specificity of the compounds towards Holotrichia consanguinea makes its difficult to get a control on the same .

Another method known in the art for controlling the Holotrichia consanguinea is trapping the beetles in a device using sponge soaked in pheromone. This method also suffers from multiple drawbacks. As the pheromone is volatile, as mentioned already, this method also requires frequent loading of the pheromone in the dispenser within a short time interval. Therefore, it is practically impossible to load the pheromone every evening after the first monsoon rain by a farmer or her/his family.

Yet another method known in the art discloses highly viscous and thickened hydrogels to deliver pheromones, fragrances and other water insoluble actives. The resulting material is a semi-solid and that is also hydrophilic in nature. One of the significant disadvantage of the method is water-solubility causes the hydrogels to swell and shrink with changes in humidity, so they cannot be used during all seasons. Thus, there exists a need within the art to develop a simple, safe, efficient and practical approach for controlling Holotrichia Consanguinea. SUMMARY :

The present disclosure provides a novel approach for controlling the Holotrichia consanguinea. Specifically, the instant disclosure provides a nanogel comprising a gelator and a volatile active agent wherein said gelator is obtained by attaching poly(benzyl-ether) dendron with oligo(p-phenylenevinylene) via hyadrazone linkage. The present disclosure further discloses a method of preparing the nanogel, a device for controlling the Holotrichia consanguinea and uses thereof.

BRIEF DESCRIPTION OF DRAWINGS

So that the manner in which the recited features of the invention can be understood in detail, some of the embodiments are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

FIG.1 shows GC-MS studies of the pheromone released from the nanogel according to an embodiment of the invention.

FIG.2a shows plots of the nanogel melting temperature (T_gei) vs. concentration of the gelator, according to one example of the invention.

FIG.2b shows plots of the nanogel melting temperature (T_gei) vs. concentration of the gelator, according to another example of the invention.

FIG.3 shows Amplitude and frequency-sweep studies of the nanogel , according to an embodiment of the invention.

FIG.4 shows plots of percent weight losses as a function of time,

according to an embodiment of the invention.

FIG.5 shows a device for controlling Holotrichia consanguinea, according to an embodiment of the invention.

FIG.6 shows a plot representing averages of number of adult

beetles, for a pheromone immobilized in nanogel and a

pheromone alone (control) during a field trial, according to an

example of the invention. DETAILED DESCRIPTION:

The present invention is described by the following specific embodiments. Those with ordinary skill in the art can readily understand the other advantages and functions of the present invention after reading the disclosure of this specification. Various details described in this specification can be modified based on different viewpoints and applications without departing from the scope of the currently disclosed invention.

The present invention provides a nanogel comprising a gelator and a volatile active agent, wherein said gelator i.e. OPV-cored poly (benzyl-ether) dendron conjugates based gelator is obtained by linking poly (benzyl-ether) dendron to oligo (p- phenylenevinylene) [OPV]. Further, the present invention provides a method of preparing the nanogel composition and a device for capturing the Holotrichia consanguinea.

The volatile active agent is selected from group consisting of pheromones, kairomones, para-pheromones, allomones, synomones and combinations thereof.

Pheromones are promising tools for controlling the pests/beetles in the agricultural field. However, the drawbacks of the existing technologies involves a use of large amount of insecticides as well as frequent loading of pheromone in the dispenser within a short duration along with multiple other problems such as causing environmental pollution, toxicity to animal kind, lack of efficient control of Holotrichia consanguinea. The present invention involves the immobilization of the active pheromone within the three-dimensional nano-pockets of the nanogel by utilizing various non-covalent interactions. A convenient and solvent-free method has been employed for the preparation of the nanogel composition comprising the active pheromone without having chemical cross-linking among the pheromone and gelator. The resultant nanogel composition releases the pheromone not only in a highly controlled manner but also for a prolonged time in the range of several weeks. Such time period is adequate to deal with the White grub beetles. The high thermal stability of the nanogel composition (gel melting temperature; T_gei ~ 90 °C) and the resistance to undergo swelling/shrinking with changes in temperature or humidity, makes it ideal to use the same in a hot climate zone. Since, the nanogel composition comprising gelator of the present invention is insoluble in water, the sample can be used in the field even during the monsoon, a period when the adult beetles of H. consanguinea showed maximum activity and crop damages are found to be in the greatest extent.

With the deployment of nanogel loaded with the active pheromone, there will be a less need to use genetically modified crops. The pheromone immobilized nanogel is a highly viscous semi-solid in nature with a significantly high mechanical strength. Therefore, this could be transported in a trouble-free manner without refrigeration or without requiring any special precaution. Once the nanogel composition in the vial dries up after the evaporation of all the pheromones, this could be reused to make a fresh batch of nanogel sample comprising the active volatile agent for the next monsoon.

It is important to note that, the earlier methods reported could not be implemented in a large-scale due to the high cost of such methods as already discussed above. The use of pheromone dispenser along with insecticides sprayed host trees are also not an eco-friendly process. In the present invention, therefore we have been able to overcome the limitations of the methods that were reported in the art by providing a simple, practical and low-cost green chemical approach which has a significant potential for kharif or monsoon crop protection, long lasting activity, excellent efficiency and favorable safety profiles. The present invention also provides the basis for the fabrication of other nano-composites with various volatile molecular scaffolds, such as perfumes, fragrances, flavoring agents, co-attractants and there off.

In one aspect, the present invention provides a nanogel for sustained release of a volatile active agent, wherein said nanogel comprises:

a gelator; and

a volatile active agent; wherein, the gelator comprises of poly benzyl-ether dendron and oligo (p- phenylenevinylene) [OPV] for producing OPV-cored poly (benzyl-ether) dendron conjugates based gelator represented by Formula 1 or Formula 2:

wherein R represents aryl group and its derivative or combination thereof; R1 represents n-hexadecyl chains or its analog.

In another embodiment, the concentration of gelator is in the range of about 19 mg/ml of the volatile active agent to about 20 mg/ml of the volatile active agent.

In another embodiment said volatile agent is selected from group consisting of pheromones, kairomones, para-pheromones, allomones, synomones and combinations thereof.

In yet another embodiment said volatile agent is a pheromone. In a further embodiment said pheromones is methoxybenzene (anisole). In an embodiment, said nanogel is a thermally stable over a temperature range of about 50 °C to about 90°C. In an embodiment, the sustained release is a temperature dependent release.

In a further embodiment, the OPV-cored poly (benzyl-ether) dendron conjugates based gelator is prepared by reacting poly (benzyl-ether) dendron and OPV in presence of CHCI3 for 4hr at ambient temperature.

In another aspect, the present invention provides a method for preparation of a nanogel for controlling Holotrichia consanguinea, the method comprising the steps of:

preparing a gelator of the present invention ;

· adding a volatile active agent to said nanogel to obtain a mixture;

heating the mixture to obtain a homogeneous solution; and

cooling the homogeneous solution to obtain said nanogel composition.

In an embodiment, said step of heating is performed at a temperature ranging from about 1 15 °C to about 120 °C for a pre-determined duration of time.

In yet another embodiment, said time duration for heating is in the range of about 1 minute to about 3 minutes. In a further embodiment, the step of cooling is performed at a temperature ranging from about 23 °C to about 25 °C for a pre-determined duration of time.

In an embodiment, said time duration for cooling is in the range from about 3 minutes to about 4 minutes.

In yet another aspect, the present invention provides a device for controlling Holotrichia consanguinea, wherein said device comprises:

- a means (2) for retaining the nanogel of the present invention; - a means for trapping (3a) and collecting (3b) the Holotrichia consanguinea; - a means for retaining (3c) said trapped Holotrichia consanguinea; wherein, means for trapping the Holotrichia consanguinea is coupled to the retaining means through a cap (3d) and together they form a collection apparatus (3).

In an embodiment, the retaining means is a container.

In yet another embodiment, said container is selected from a group comprising of a thin glass plate, a glass film, a plastic film, a thin plastic plate, a vial, a tube and a capsule.

In another embodiment, the collection apparatus is at least one selected from a group consisting of a bottle, a flask, a tumbler, a beaker, a bowl, a bag, a can, a canister, a carton, a jar, a jug, a kettle and a packet.

In a further embodiment, the device is positioned proximal to a horticultural produce having high risk of infestation.

In another embodiment, the device can be used for preventing the crops from the damages caused by Holotrichia consanguinea.

In yet another embodiment, the device can be used for trapping the Holotrichia consanguinea. The "gelators" described herein include but are not limited to oligo (p- phenylenevinylene) and its derivatives based gelators, dendron based gelators, Low molecular mass organic gelators (LMOGs) and a combination thereof. In one optional embodiment of the invention, poly-benzyl 5 ether is taken in a reaction flask and chloroform is added to the poly-benzyl ether to obtain a mixture. The mixture is stirred for about 4 hours at a temperature in the range of about 25 °C to about 35 °C. The non-covalent interactions lead to the formation of nanoscopic structures. The structures formed include but are not limited to fibrils, rods, tubes, spheres, coils and sheets. The OPV-cored poly (benzyl-ether) dendron conjugates based gelator, described herein is hereinafter interchangeably referred to as 'gelator', the meaning and expression of which does not alter the scope of the invention. Formation of the nanostructures in turn creates micro-domains with solvent pockets and hence these network structures could hold solvents.

The gelator formed is dried under vacuum. The dried gelator is characterized by spectrographic methods including but not limited to 1 H-, 1 3C-NMR spectroscopy, FT-IR and elemental analysis. The all-trans geometry of the two vinyl moieties in the gelator is confirmed by 1 H NMR spectral analysis.

The active pheromone, isolated from the abdominal glands of the female adult beetles of H. consanguinea is an aromatic compound. Gelation of such aromatic motifs generally requires a gelator comprising aromatic unit in its structure, which facilitate ττ-stacking interactions among the gelator and pheromone. This, in turn, increases the chance of obtaining a robust gel to a significant extent. With this objective in mind, the present inventor attached a poly(benzyl-ether) dendron on both sides of a suitably designed OPV-scaffold to obtain OPV-cored poly(benzyl- ether) dendron conjugates as the final gelator (see below). These two structural motifs have been chosen because both of them are rich with aromatic units. To introduce H-bonding as a supramolecular synthon, the dendron and OPV-derivative are linked by means of a hydrazone linkage. Indeed, the carefully designed gelators have been found to rigidity the active pheromone in an efficient manner. Laboratory and field trials were conducted for the gels loaded with the active pheromone. This successfully demonstrated its efficacy and a shelf-life increase as shown in Figures 1 -4 and 6 and Tables 1 -4.

The pheromone entrapped nanogel as obtained by the method described herein above and as characterized is incorporated into a device for determining the efficacy of the pheromone entrapped nanogel in managing Holotrichia Consanguinea. The device includes but is not limited to the pheromone entrapped nanogel, an arrangement to mount the device and a collection apparatus. The pheromone entrapped nanogel can be loaded onto a retaining means. In an embodiment of the invention, the retaining means is a container. The container includes but is not limited to a thin glass plate, a glass film, a plastic film, a thin plastic plate, a vial, a tube and a capsule. Alternatively, the pheromone entrapped nanogel can be layered as a thin film on a suitable material. The material is selected from a group that includes glass, plastic, fiberglass and the like. The collection apparatus includes but is not limited to a bottle, a flask, a tumbler, a beaker, a bowl, a bag, a can, a canister, a carton, a jar, a jug, a kettle and a packet. The collection apparatus is mounted vertically below the container having the pheromone entrapped nanogel. The collection apparatus is configured to entrap the Holotrichia consanguinea, attracted towards the pheromone entrapped nanogel.

FIG.5 shows a device for managing Holotrichia consanguinea, according to an embodiment of the invention. In one example of the invention, The device comprises of a pheromone entrapped nanogel (1 ), a means for retaining the nanogel (2) and a collection apparatus (3) the pheromone entrapped nanogel (1 ) is loaded onto a means for retaining the nanogel (2). In an embodiment of the invention, the means for retaining the nanogel (2) is a container. The container includes but is not limited to a thin glass plate, a glass film, a plastic film, a thin plastic plate, a vial, a tube and a capsule. In one example of the invention, the container is a vail (2a). The collection apparatus (3) is coupled to the means for retaining the nanogel (2). The collection apparatus (3) is mounted vertically below the vail (2a). The collection apparatus includes but is not limited to a bottle, a flask, a tumbler, a beaker, a bowl, a bag, a can, a canister, a carton, a jar, a jug, a kettle and a packet. In one example of the invention, the collection apparatus includes a sheet (3a), a funnel (3b) and a bottle (3c). The sheet (3a) is coupled to the funnel (3b), further the funnel (3b) is coupled to the bottle (3c). The sheet (3a) of around 25 cm and width of around 12 cm is taken. The sheet (3a) is attached in a propeller shaped fashion. The sheet (3a) is coupled to the funnel (3b). The funnel (3b) is coupled to the bottle (3c). The bottle (3c) is of about 25 cm long and about 14 cm diameter. The bottle (3c) has a cap (3d). Two circular holes (not shown) with a diameter of about 4cm and about 0.2 cm are made on the centre of the cap (3d) and on the bottom of the bottle (3c). The stem of the funnel (3b) is inserted in the hole of the screw cap (3d) of the bottle (3c) by using nut and bolt. The device is positioned proximal to a horticultural produce having high risk of infestation. The arrangement of the device prevents stagnation of water within the device, during rain, by allowing the excess of water to automatically drain away from the lower hole of the bottle. The method and the device as described in detail herein above is applied to perform field trail experiments. Examples:

The following examples serve to illustrate certain embodiments and aspects of the present disclosure and are not to be considered as limiting the scope thereof.

Example 1 : Synthesis and characterization of the gelator.

The gelators 1 and 2 were synthesized quantitatively by stirring a mixture of poly- benzyl ether (4/5) and OPV (3) (2:1 molar ratio) in CHCI3 for 4 h at ambient temperature. The robust gel obtained in the reaction flask was then dried under vacuum and characterised by 1 H-, 13C-NMR spectroscopy, FT-IR and elemental analysis. The all trans geometry of the two vinyl moieties in 1 and 2 was confirmed by 1 H NMR spectral analysis.

Synthetic scheme:

1 )

2)

The yield from both the schemes is 100%. Example 2: Preparation of nanogel composition:

18 mg of the gelator obtained is added to 1 ml of volatile active agent to obtain a mixture. The mixture obtained is heated at a temperature in the range of about 1 15 ^eC to about 1 20 ^eC for a time duration ranging from about 1 minute to about 3 minutes to obtain a homogeneous solution.

The homogeneous solution obtained is then cooled at a temperature in the range of about 22 ^eC to about 25 ^eC. The cooling is further achieved over a time period in the range of about 3 minutes to about 4 minutes. Subsequent to subjecting the mixture to the heating and cooling cycle as described herein, a nanogel composition is obtained.

The pheromone entrapped nanogel is then characterized to determine the physical and chemical characteristics. The nanogel formation is confirmed initially through a physical characterisation. FIG. 1 shows a GC-MS spectra of the pheromone released from the nanogel composition, according to an embodiment of the invention. The formed nanogel composition is water insoluble and does not undergo swelling and shrinking with changes in temperature or humidity. Further, the critical gelator concentration (CGC) of the nanogel obtained is in the range of about 0.6 mM to about 1 .4 mM.

The nanogel composition melting temperature (T_gei) of the gelators obtained through the method, as described herein above, is in the range of about 35^eC to about 90^eC. The Tgei increases progressively with increasing concentration of gelator. The density of the gel assembly increases with increasing concentration of the gelator, ensuring participation of a larger number of gelator molecules per unit volume in the thermally induced transitions. FIG.2a shows the variation of T_gei of the nanogel composition with temperature. It shown in the figure that the T_gei reached about 53°C, at the gelator concentration of 1 1 .8mM, which is well above the ambient temperature even during peak summer in India. Thus, the thermal stability of the nanogel is adequate for the agricultural field trials even in hot climates around different geographical regions of the world.

FIG.3 shows amplitude and frequency-sweep studies of the nanogel, according to an embodiment of the invention. The oscillatory amplitude and frequency-sweep studies revealed that the storage modulus G', is much larger in magnitude than the corresponding loss modulus, G", indicating viscoelastic behavior of the nanofibrous gel. The significantly high G' value of ~ 120000 Pa of the nanogel at 1 1 .8 mM concentration indicates the remarkable mechanical strength of the nanogel. The mechanical strength of the nanogel is sufficiently high to provide adequate mechanical stability to prohibit the samples being relaxed (dropped) during its transportation or shipment.

FIG.4 shows plots of percent weight losses as a function of time, according to an embodiment of the invention. The release pattern of the volatile pheromone in terms of its relative rates of evaporation at a particular temperature is determined both for pheromone immobilized in nanogel at a concentration of 20 mg/ml and pheromone alone under identical conditions. The extent of evaporation is investigated by monitoring the weight loss from both the samples in a temperature gradient chamber. The temperature within the chamber is varied in the range from about 20°C to about 50°C. Plots of percent -weight losses measured over the number of weeks, show that the rates of evaporation are always greater from the pheromone alone compared to the pheromone immobilized in nanogel. The calculated slopes from the linear fit of the data at various temperatures showed that the evaporation rate of pheromone increased significantly with increasing temperatures. The graph confirms the sustained release pattern of the pheromone immobilized in nanogel. Thus, the sustainable nature of the pheromone in the nanogel for a significant period of time makes the nanogel composition particularly useful for controlling Holotrichia consanguinea. The dried nanogel formed after evaporation of the pheromone is also re-used to make a fresh gelator again.

Example 3:

The field trial experiment is carried out at a fallow land. The area of the fallow land is about one acre. The experiment is conducted during pre-monsoon for a period of 22 days. Six replications for each sample containing active pheromone in the nanofibrous gels ([1 ] = 1 1 .8 mM; 0.2 mL) and active pheromone alone (0.2 mL) were taken. Samples containing 0.2 mL of pheromone (anisole) immobilized in the nanogel and 0.2 mL of pheromone alone(control) are taken in the vial 2a of the device (as shown in FIG. 5). The device is kept under observation. Due to the presence of pheromone, the adult beetles are attracted towards the hanging vial 2a and are trapped in the bottle 3c of the device (as shown in FIG. 5). The adult beetles from the bottle 3c are counted by opening the screw-cap 3d and are averaged from six bottles under each category.

FIG.6 shows a plot representing averages of number of adult beetles, for a pheromone immobilized in nanogel and a pheromone alone (control) during a field trial, according to an embodiment of the invention. The number of beetles trapped in the control experiments containing only pheromone is significantly lower relative to the number of beetles trapped in pheromone immobilized in nanogel. The pheromone alone is active only for -10 to 15 minutes. Whereas the pheromone immobilized in nanogel is effective throughout the emergence period of the adult beetles. Statistical analysis revealed that the treatment with the pheromone immobilized in nanogel is highly significant than that of the treatment with pheromone alone. Two-factor ANOVA calculations of the transformed data retrieved from the field trials.

The least significant difference (LSD) calculated (with AgRes software) for the treatments (active pheromone alone and active pheromone immobilized in the gelator 1 ), the period of observations (days) and the interaction between the two (t x d) considering the mean values are all presented in the Table 1 . LSD results clearly indicate that the treatment 2 (t2, active pheromone immobilized in the gelator 1 ) is more efficient than the treatment 1 (t1 , active pheromone alone) in trapping White grubs as the critical difference (CD) between the treatments is 0.153 (p < 0.05). This further indicates that there is significant difference between the mean for the treatment 1 (0.98) and treatment 2 (4.95). The differences between the mean values of the periods of observations (days) were estimated using LSD considering the CD = 0.507 (p < 0.05) which showed a descending order of distribution among days (Table 3). The maximum number of White grubs catches was recorded on the first 7 days. As the days progressed, White grubs emergence in the field became gradually lesser in numbers and thus the lowest number of trap catches took place from the 12^th day. LSD calculations were also performed from the mean values for the comparison of the interactions between the treatments and the period of observations (t x d) considering CD = 0.717 (p < 0.05) and the relevant data recorded in Table 1 . Among treatment 1 (active pheromone alone) and treatment 2 (active pheromone immobilized in the gelator 1 ), treatment 2 showed more effectiveness than the treatment 1 . Therefore, active pheromone immobilized in gelator acted as an effective formulation compared to the active pheromone alone for the management of White grubs in the field trial studies. Results of these studies are provided in the below mentioned tables: Table 1 : Mean values of the adult beetles trapped from the six replications per treatment (active pheromone alone and active pheromone immobilized in the gelator)

Table 2: Two-factor ANOVA calculations of the transformed data of White grubs field trials.

Table 3: White grubs catches for each replication (R1 -R6) of the active pheromone containing samples in the field trials. The values showing the number of white grubs trapped in the individual traps. The number of white grubs were collected and counted on the daily basis.

Table 4: Transformation of data (Square root of x + 0.5, presented in Table 3) for the two-factor ANOVA calculations. The data presented in Table 3 has been transformed [(x + 0.5) ½ , x = number of adult beetles trapped in each day per replication] to homogenize variances.

The invention provides pheromones entrapped in nanogel which is an immobile viscoelastic semi-solid mass which is easily handled and transported without refrigeration. Further, due to its slow-release properties, it allows a reduction in the frequency of pheromone recharging in the fields. Such nanogelled pheromones exhibit high residual activity and excellent efficacy in the field, even during rainy seasons. These nanogels have a fibrillar network structure, are environment friendly, non-toxic and act only as an attractant.

The pheromone entrapped nanogel as provided herein can be targeted to various agricultural crops which include but are not limited to groundnut, maize, pulses such as bajra, moong bean and vegetables. With the deployment of nanogel carrier systems, there is less need to use pest resistant genetically modified crops as well. Also, transportation of the pheromone entrapped nanogel is trouble-free due to the significant mechanical strength of the nanogels. The foregoing description of the invention has been set for merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

Claims

laims:

1 . A nanogel for sustained release of a volatile active agent, wherein said nanogel comprises:

a gelator; and

a volatile active agent;

wherein, the gelator comprises of poly benzyl-ether dendron and oligo (p- phenylenevinylene) [OPV] for producing OPV-cored poly (benzyl-ether) dendron conjugates based gelator represented by Formula 1 or Formula 2:

wherein R represents aryl group and its derivative or combination thereof; Ri represents n-hexadecyl chains or its analog.

2. A nanogel as claimed in claim 1 , wherein the concentration of gelator is in the range of about 19 mg/ml of the volatile active agent to about 20 mg/ml of the volatile active agent.

3. The nanogel as claimed in claim 1 , wherein said volatile agent is selected from group consisting of pheromones, kairomones, para-pheromones, allomones, synomones and combinations thereof.

4. The nanogel as claimed in claim 3, wherein said volatile agent is a pheromone.

5. The nanogel as claimed in claim 4, wherein said pheromones is a methoxybenzene (anisole).

6. The nanogel as claimed in claim 1 , wherein said nanogel is a thermally stable over a temperature range of about 50 °C to about 90°C.

7. The nanogel as claimed in claim 1 , wherein said sustained release is a temperature dependent release.

8. The nanogel as claimed in claim 1 , wherein the OPV-cored poly (benzyl- ether) dendron conjugates based gelator is prepared by reacting poly (benzyl-ether) dendron and OPV in presence of CHC for 4hr at ambient temperature.

9. A method for preparation of a nanogel for controlling Holotrichia consanguinea, the method comprising the steps of:

• preparing a gelator as claimed in claim 8;

• adding a volatile active agent to said gelator to obtain a mixture;

• heating the mixture to obtain a homogeneous solution; and

• cooling the homogeneous solution to obtain said nanogel composition.

10. The method as claimed in claim 9, wherein said volatile active agent is selected from a group comprising of pheromones, kairomones, para- pheromones, allomones, synomones and combinations thereof.

1 1 .The method as claimed in claim 9, wherein said step of heating is performed at a temperature ranging from about 1 15 °C to about 120°C for a predetermined duration of time.

12. The method as claimed in claim 9, wherein said time duration for heating is in the range of about 1 minute to about 3 minutes.

13. The method as claimed in claim 9, wherein the step of cooling is performed at a temperature ranging from about 23°C to about 25°C for a pre-determined duration of time.

14. The method as claimed in claim 9, wherein the time duration for cooling is in the range from about 3 minutes to about 4 minutes.

15. A device for controlling Holotrichia consanguinea, wherein said device comprises:

- a means (2) for retaining the nanogel as claimed in claim 1 ;

- a means for trapping (3a) and collecting (3b) the Holotrichia consanguinea; - a means for retaining (3c) said trapped Holotrichia consanguinea; wherein, means for trapping the Holotrichia consanguinea^ coupled to the retaining means through a cap (3d) and together they form a collection apparatus (3).

16. The device as claimed in claim 15, wherein the retaining means is a container.

17. The device as claimed in claim 16, wherein said container is selected from a group comprising of a thin glass plate, a glass film, a plastic film, a thin plastic plate, a vial, a tube and a capsule.

18. The device as claimed in claim 15, wherein the collection apparatus is selected from a group consisting of a bottle, a flask, a tumbler, a beaker, a bowl, a bag, a can, a canister, a carton, a jar, a jug, a kettle and a packet.

19. The device as claimed in claim 15, wherein the device is positioned proximal to an agricultural land having high risk of infestation.

20. Use of the device as claimed in claim 15, for preventing the crops from the damages caused by Holotrichia consanguinea.

21 . Use of the device as claimed in claim 15, for trapping the Holotrichia consanguinea.