BR102020014572A2 - Anticidal baits based on sodium alginate microspheres and clays for use in the control of leaf-cutting ants and production processes - Google Patents

Abstract

The present invention consists of baits formed through the interaction between a biodegradable biopolymer, a clay mineral and agrochemicals, to be used as a management technique in the control of leaf-cutting ants, being an industrial product with application in the agronomic area. The present invention also relates to the production processes of ant baits.

Description

FORMICIDE BAITS BASED ON SODIUM ALGINATE MICROSPHERES AND CLAYS FOR USE IN THE CONTROL OF HARVESTING ANTS AND PRODUCTION PROCESSES TECHNICAL FIELD OF THE INVENTION

01. The present invention consists of baits formed through the interaction between a biodegradable biopolymer, a clay mineral and agrochemicals, to be used as a management technique in the control of leaf-cutting ants, being an industrial product with application in the agronomic area. The present invention also relates to the production processes of ant baits.

STATUS OF THE TECHNIQUE

02. In Brazil there is a diversity of ant species, which are important in the food chain. Leaf-cutting ants, of the genera Atta (saúvas) and Acromyrmex (quenquéns) are the main severe pests of national agriculture, causing significant losses in plantations for small, medium and large producers.

03. A single Atta anthill is capable of consuming 1 ton of leaf mass per year, equivalent to 86 eucalyptus trees (MENDES FILHO, JM de A. – Fight against ants at CAF. Technical Circular. IPEF, Piracicaba (76) : 1-9, Nov. 1979). Adult colonies can have from thousands to millions of workers according to gender. It is during the process known as foraging that these insects cut leaves in order to subsist on the colony. During this process, they also collect feces, branches or any other type of attractive organic matter, which are later used to nourish symbiotic fungi (AUTUORI, M. Investigation on the biology of the anteater. Cienc. Cult, v. 1, p. 4). -13, 1950; VILELA, EF, DELLA LUCIA, TMC (1987) Insect pheromones; biology, chemistry and use in pest management. Viçosa, MG, Universidade Federal de Viçosa. 155p; FISHER, PJ, STRADLING, DJ, PEGLER , DN Leaf cutting ants, their fungus gardens and the formation of basidiomata of Leucoagaricus gongylophorus. Top. Catal, v. 8, p. 128–131, 1994).

04. In order to minimize the damage and impacts caused by these insect pests, management techniques were developed. The most commonly used techniques to combat ants are: mechanical, biological, cultural and chemical control (ARAÚJO, MS; DELLA LUCIA, TMC; SOUZA, DJ Alternative Control Strategies. Bahia Agrícola, Salvador, v. 6, n. 1, pp. 71-73, 2003).

05. The chemical control of these insects is efficient and can be carried out with different products and in different ways of application, using more expensive techniques such as thermal fogging or cheaper techniques such as the use of ant baits and chemical powder (ZANETTI, R.; CARVALHO , GA; SANTOS, A.; SOUZASILVA, A.; GODOY, MS Integrated management of leaf-cutting ants. Lavras: UFLA, 2002. 16 p). The ant baits are the most common because they have low cost, localized application and high yield, in addition to dispensing equipment for their application.

06. The chemical group of organochlorines, dodedachlor, was the first active ingredient used in ant baits (BRITTO, JS DE; FORTI, LC; OLIVEIRA, MA DE; ZANETTI, R.; WILCKEN, CF; ZANUNCIO, JC; LOECK, AE; ; CALDATO, N.; NAGAMOTO, NS; LEMES, PG; CAMARGO, S. Use of alternatives to PFOS , its salts and PFOSF for the control of leaf-cutting ants Atta and Acromyrmex. Int. J. Res. Environ. Stud. , v. 3, p. 11–92, 2016). This chemical group has had its use banned in Brazil since 1985 because of its toxic and cumulative nature (Kasemodel MC, Porto ALM & Nitschke M. Bacterial biodegradation of organochlorine compounds. Quimica Nova, 37(8): 1351–1356, 2014), being authorized only in public health campaigns (Decree no. 329 of 09/02/85 of the Ministry of Agriculture).

07. The commercial product Mirex-s ® (sulfuramide, 0.2%) is one of the usual brands in Brazil for chemical control of these insect pests. These baits are in the form of pellets and are made up of dehydrated orange pulp, vegetable oil (soybean) and active ingredient of the insecticide (sulfuramide, chlorpyrifos and fipronil) (PEREGRINE, DJ; CHERRETT, JM Toxicant spread in colonies of leaf-cutting). Proceedings of the Association of Applied Biologists, p. 131-132, 1976; FORTI, LC; NAGAMOTO, NS; PRETTO, DR Control of leaf-cutting ants with granulated bait. In: Symposium on leaf-cutting ants in Mercosur countries. Piracicaba: FEALQ, 1998, p. 113-132). During this process, known as foraging, the ants are contaminated by trophallaxis and end up dead due to the action of the insecticide present in the bait. This insecticide inhibits the metabolic process of oxidative phosphorylation, which acts on the respiratory chain, causing the blocking of electrons in the mitochondria and interrupting the production of adenosine triphosphate (ATP), affecting the energy storage process for the insect's vital activities, thus causing its death by asphyxia (SCHNELLMANN, RG, MANNING, RO Perfluorooctane sulfonamide: A structurally novel uncoupler of oxidative phosphorylation. Bioenerg, v. 1016, p.344–348, 1990). Its use is efficient as a management technique, however these baits cannot be applied in humid environments, because the baits end up falling apart, thus losing their attractiveness and, as a consequence, inefficiency (JUSTI JUNIOR, J.; IMENES, SL; BERGMANN , EC; CAMPOS, FAEC; ZORZENON, FJ Formigas Cortadeiras. Technical Bulletin of the Biological Institute, São Paulo, n. 4, p. 31, 1996; ZANUNCIO, J. C; COUTO, C; SANTOS, G. P; ANUNCIO, T.V; Efficiency of granulated bait Mirex-S, based on sulfluramid, in the control of leaf-cutting ants Atta laevigata (F. Smith, 1858) (Hymenoptera: Formicidae) Revista Árvore, v. 16, n. 3, p 247 - 372, 1992; DELLA LUCIA, TMC, FOWLER, HG, ARAÚJO, MS Leaf-cutting ant varieties. In: Della Lucia, TMC (ed.) Leaf-cutting ants. Viçosa: Folha de Viçosa. p. 43-53, 1993) .

08. In 1995, granulated ant baits containing the active ingredient chlorpyrifos were developed (Neto, OC "Formiçida granulated bait formulated based on the active ingredient chlorpyriphos covering formulations from 0.7000 grams per kilo to 5.000 grams per kilo". PI 9401591- 0) The baits were produced in a similar way to the commercial product Mirex-s ®, in which it was also synthesized with orange pulp and essential oil and vegetable oil, which attract ants and give the granular structure to the product. efficient as a management technique, however they are not efficient in humid environments coming to decompose, losing their attractiveness.

09. In order to solve the problems caused by these insect pests and the inefficiency of baits that easily decompose in a humid environment, the present invention was developed, biodegradable ant baits and its production process, which aims to kill and /or mitigate the damage caused by these insects to crops. Thus, the inventors of the current patent application carried out extensive studies with the objective of synthesizing and characterizing hybrid organic-inorganic materials formed from alginate and kaolinite microspheres for incorporation of different agrochemicals used to control leaf-cutting ants, and to carry out bioassays of efficacy and behavior in the field and laboratory.

10. The organic-inorganic hybrid materials are a class of materials that would provide an alternative to increase the physical resistance of these baits, the synergism between organic and inorganic components can create new materials with properties not found in conventional materials (FERNANDES, FM; BARADARI, H.; SANCHEZ, C. Integrative strategies to hybrid lamellar compounds: An integration challenge. Appl. Clay Sci, v. 100, p. 2–21, 2014; SANCHEZ, C., SHEA, KJ, KITAGAWA, S. Recent progress in hybrid materials science. Chem. Soc. Rev, v.40, p. 471–472, 2011).

11. The baits formed have clay minerals in their composition, helping to increase the physical resistance of the baits.

12. The synthesized microspheres (baits) are formed by solubilizing the sodium alginate biopolymer followed by the addition of clay and agrochemicals at predetermined periods.

13. The invention has the advantage of using various agrochemicals, allowing the chemical control of these insects, either by respiratory and/or neurological routes, depending only on the active ingredient of the insecticide.

DESCRIPTION OF THE FIGURES

14. Figure 1: Amount of boron in solution as a function of time in “in vitro” release studies for microspheres: (a) control with borate (T2); (b) 2.5 g borate and B. bassiana (T6); (c) 5 g borate and B. bassiana (T7) and (d) borate and chlorpyrifos (T8). It presents the results of the “in vitro” release of common salt in all microspheres. The maximum rate of release of the micronutrient into the solution occurred in a period of 1 h, reaching 100% release. This study was carried out for 48 h and the microspheres remained in the initial physical condition.

15. Figure 2: Percentage of ants alive during the evaluation days. Treatments – T0: Witness, T2: Micro. borate control, T6: Micro. 2.5 g borate and B. bassiana; T7: Micro. 5 g borate and B. bassiana, T8: Micro. Borate and chlorpyrifos and T9: Mirex®. It presents the results of the bioassay in which there was a significant interaction (treatments versus days evaluated after application of treatments) for the variable percentage of live ants (p<0.01). This figure illustrates the mortality profile of these insects after confinement in a closed container containing the baits and artificial diet. At the end of 5 days all insects were dead, it is worth mentioning that one of the synthesized baits showed better performance within the treatments used, which contained commercial bait already consolidated in the market. Mortality data were corrected with the control following the Abott formula (1925), and submitted to analysis of variance and Tukey's mean test (p<0.05) with the aid of Sisvar software (FERREIRA, DF SISVAR : A Computer Statistical Analysis System Sisvar : a computational system for statistical analysis. Ciênc. Agrotec, v.35, n.6, p.1039– 1042, 2011).

16. Figure 3: Schematic representation of the synthesis of control microspheres.

17. Figure 4: Photographic image of control microspheres applied at an approximate distance of 20 cm from the spot.

18. Figure 5: Photographic images of the microspheres used for bioassay 2: (e) Control with sodium borate (T2); (f) 2.5 g of Sodium Borate and B. bassiana (T6); (g) 5 g of Sodium borate and B. bassiana (T7) and (h) Sodium borate and chlorpyrifos (T8). It presents photographic images of the microspheres formed after the synthesis process. These baits had a variable mean mass of 35.6 ± 9.1 (mg/bait) depending on the bait synthesized. This variation is due to the decrease in viscosity that is dependent on the amount of precursor materials used during the synthesis, which increases the flow rate and formation of the baits after dripping into the solution containing the metal ion. The thickness and diameter also varied, 1.66 ± 0.36 (mm) and 5.59 ± 0.35 (mm), respectively.

DETAILED DESCRIPTION OF THE INVENTION

19. The present invention deals with ant baits formed through the interaction between a biodegradable biopolymer, a clay mineral and agrochemicals, to be used as a management technique in the control of leaf-cutting ants and their production processes.

20. The microspheres were adapted and synthesized by the complex coacervation method (ZHANG, Y.; LIANG, X.; YANG, X.; LIU, H.; YAO, J. An eco-friendly slow-release urea fertilizer based on waste mulberry branches for potential agriculture and horticulture applications. ACS Sustain. Chem. Eng, v.2, n.7, p.1871–1878, 2014).

21. Figure 3 illustrates the processes for obtaining the microspheres.

Procedure 1: control microspheres

22. In this method, a gel was formed by mixing 50 ± 0.5 mL of water with 0.5 ± 0.05 g of the biopolymer sodium alginate after 60 ± 10 min under vigorous stirring with the aid of a stirring plate and magnetic stirrer, or similar, until complete solubilization and homogenization (step 1). Then, 2.5 ± 0.005 g of the kaolin clay mineral was weighed with the aid of an analytical balance and transferred quantitatively with the aid of a spatula to the suspension, which was kept under agitation for another 60 ± 10 min at room temperature (25 ± 3°C). In this step, any type of silicate clay can be used, such as: bentonite, montmorillonite, illite and vermiculite (step 2). Step 3 consists of adding 2.5g to 5.0g of sodium tetraborate until complete solubilization.

23. After completion of step (3), in which the homogeneous mixture was obtained containing biopolymer sodium alginate, water, clay mineral and agrochemical, it was transferred to a burette with a capacity of 50 ± 0.5 mL (step 4) and poured “drop by drop” with a flow rate of approximately 1 drop∙s-1 , into a solution containing 5 ± 0.05% CaCl2 (m/v) (step 5). The resulting material (microspheres) was dried in an oven with air circulation for 5 h ± 30 min at a temperature of 25 ± 3ºC and placed in a clean and dry flask. This bait was named T2 treatment.

24. With the objective of producing materials with different compositions, more baits were produced using the methodology described above with some modifications during the stages.

Procedure 2: Microspheres containing Beauveria bassiana spores

25. In step 3, after the suspension was formed by the addition of clay mineral, 2.5g to 5.0g of sodium tetraborate and 0.1 to 1 ml of B. Bassiana spores were added. This bait was named as T6 treatment. The other steps followed as shown in procedure 1.

Procedure 3: Microspheres containing agrochemical solution

26. Similar to procedure 1 described above, other microspheres were produced, in which the gel was formed by means of a solution of the active ingredients of insecticides such as chlorpyrifos, sulfluramid and fipronil. In step 1 the water was replaced by a 600 mg solution. L -1 (50 ± 0.5 mL) of chlorpyrifos insecticide, this bait was named as T8 treatment. The other steps followed as shown in procedure 1

27. The baits produced in all stages are placed on the trails at about 20 ± 2 cm from the scout (colony nest hole) according to the total area, which consists of the dosage of 8.0 g∙m-2 anthill (Figure 4).

28. The tetraborate salt inhibits the characteristic odor of the biopolymer sodium alginate, making the bait attractive, causing these insects to collect these baits and take them to the interior of the nest, where they end up being contaminated by trophallaxis during the journey and killed due to the insecticide present in the microspheres.

DEMONSTRATION EXPERIMENTS

29. Toxicity bioassays were conducted at the Lamellar Compounds Laboratory (LCL). The experimental design was completely randomized with 6 treatments and 5 replications. In each treatment, five plastic pots with holes in the lid (61 x 101 mm) with 5 cm of clay soil were used, containing 6 ants per pot. Inside the pot, cotton wool moistened with 1.5 mL of liquid diet was placed, containing 100 mL of milli-q water with 5% (m/v) glucose, 0.1% (m/v) yeast extract. and 1% (m/v) of bacteriological peptone (BUENO, OC; MORINI, MSC; PAGNOCCA, FC; HEBLING, MJA; SILVA, OA Survival of workers of Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae) isolated from the anthill and fed with Artificial Diets. An. Soc. Entomol, v. 26, n. 1, p. 107-113, 1997). The mixture was solubilized with a glass rod and autoclaved for 15 min at a temperature of 120 °C and 1 atm of pressure, the diet was placed in a clean and dry flask for later use. The diet was replaced every 24 h. Fifteen microspheres containing the treatments (T0: Control, T2: Micro. borate control, T6: Micro. 2.5 g borate and B. bassiana; T7: Micro. 5 g borate and B. bassiana, T8: Micro. borate and chlorpyrifos and T9: Mirex®) were released onto the soil so that they were evenly distributed. The evaluations were carried out daily, at the same time of day, recording the number of live ants. Mortality data were corrected with the control (ABBOTT, WS A Method of Computing the Effectiveness of an Insecticide. Journal of Economic Entomology, v. 18, n. 2, p. 265–267, 1925), and subjected to analysis of variance. and Tukey's mean test (p<0.05).

30. In the field, anthills were measured using measured steps (width versus length) to determine apparent nest size, 3 nests of young anthills ranging from 1 to 4 m2 for each treatment. The application of the baits was at a distance of 20 cm from the scout and consisted of the dosage of 8.0 g∙m-2 apparent anthill (MARICONI, FAM As saúvas. Circular Técnica, n. 77, IPEF, São Paulo, 1979. )

31. Foraging activity was evaluated for 5 minutes between 3 pm and 6 pm, on the day of bait application, after 24 h, 4, 7, 14, 21, 35 and 60 days. A 5 x 8 factorial scheme (five treatments x eight days of evaluations after application of treatments) in a completely randomized design with three replications. The data were submitted to analysis of variance and the means were compared by the Tukey test at 5% of probability, with the aid of the Sisvar software (FERREIRA, DF SISVAR: A Computer Statistical Analysis System Sisvar: a computer system for statistical analysis. Ciênc. Agrotec, v.35, n.6, p.1039–1042, 2011).

32. The baits allowed a sustained (slow) release of the agrochemicals as shown in Figure 1. The baits showed excellent physical resistance after 48 h immersed in water, a factor caused by the synergism of the microsphere obtained through the interaction between the organic material (alginate sodium) and inorganic (kaolinite).

33. After application of the baits, good mortality results were observed after bioassay in the laboratory, leading to the death of these insects within 5 days, some within 24 hours, as can be seen in Figure 2.

34. Field bioassays confirmed the chemical control of these insects, so that after 60 days of evaluation, a decrease in forage activity and/or total colony death was observed, thus showing the efficiency of the baits in the pasture and in plantations of eucalyptus.

CONCLUSION

35. Based on the results, it is concluded that the synthesis of alginate and clay mineral microspheres containing the agrochemicals, resulted in products with ant-killing potential, presenting good physical resistance in contact with water and attractive to these insects, being efficient as a management technique, a since it presented excellent percentages of mortality within the period of days studied in the bioassays in the laboratory and in the field.

Claims (13)

Formicidal baits characterized by comprising biodegradable biopolymer, clay mineral and agrochemicals. Formicidal baits, according to claim 1, characterized in that it comprises the biopolymer sodium alginate, clay mineral, selected from a group of silicate clay that comprises kaolinte, bentonite, montmorillonite, illite and vermiculite; and agrochemicals, selected from a group comprising sodium tetraborate, chlorpyrifos, sulfluramid, fipronil, Beauveria bassiana. Production process of the baits described in claims 1 and 2, characterized in that it comprises the following steps:

• a) Mixing water and the biopolymer;
• b) Stir;
• c) Adding clay mineral to the mixture obtained in steps a and b;
• d) shake,
• e) Adding the solid sodium tetraborate salt;
• f) Homogenize;
• g) Transfer the mixture to a burette;
• h) Dry the microspheres obtained.

Production process of the baits described in claims 1 and 2, characterized in that it comprises the following steps:

• a) Mixing water and the biopolymer;
• b) Stir;
• c) Adding clay mineral to the mixture obtained in steps a and b;
• d) Add the fungal spores;
• e) Shake;
• f) Adding the solid sodium tetraborate salt;
• g) Homogenize;
• h) Transfer the mixture to a burette;
• i) Dry the microspheres obtained.

Production process of the baits described in claims 1 and 2, characterized in that it comprises the following steps:

• a) Mix the agrochemical and biopolymer solution;
• b) Stir;
• c) Adding clay mineral to the mixture obtained in step a;
• d) shake,
• e) Adding the solid sodium tetraborate salt;
• f) Homogenize;
• g) Transfer the mixture to a burette;
• h) Dry the microspheres obtained.

Production process, according to claims 3 and 4, step a, characterized by mixing 50 ± 0.5 ml of water with 0.5 ± 0.05 g of the sodium alginate biopolymer. Production process, according to claim 5, step a, characterized by mixing 50 ± 0.5 ml of agrochemical solution, selected from a group comprising chlorpyrifos, sulfluramid, fipronil, in a pre-established concentration of 600 ppm, with 0.5 ± 0.5 g of the sodium alginate biopolymer. Production process, according to claim 4, step d, characterized in that 0.1 to 1 ml of fungal spores of Beauveria bassiana are added. Production process, according to claims 3, 4 and 5, step b, characterized in that the mixture obtained in step 1 is vigorously stirred for 60 ± 10 min with the aid of a stirring plate and magnetic stirrer, or similar, until complete solubilization and homogenization. Production process, according to claims 3 and 5, steps c and d, and claim 4, step c e e, characterized by the addition of 2.5 ± 0.005g of the clay mineral under stirring for 60 ± 10 min at room temperature 25 ± 3 ºC. Production process according to claims 3 and 5, step e, and claim 4, step f, characterized in that 2.5 to 5.0 g of solid sodium tetraborate salt are added. Production process, according to claims 3 and 5, step g, and claim 4, step h, characterized in that the mixture is transferred to a burette with a capacity equal to 50 ± 0.5 mL and poured “drop by drop” with a flow rate of approximately 1 drop∙s-1 , in a solution containing 5 ± 0.05% CaCl2 (m/v). Production process, according to claims 3 and 5, step h, and claim 4, step i, characterized in that the microspheres obtained are dried in an oven with air circulation for 5 h ± 30 min at a temperature of 25 ± 3°C and packed in a clean, fresh bottle.

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