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Parasitología al día

versión impresa ISSN 0716-0720

Parasitol. día v.23 n.1-2 Santiago ene. 1999

http://dx.doi.org/10.4067/S0716-07201999000100003 

TRABAJO DE INVESTIGACION

ANTI-TICK EFFECT OBSERVED IN MATURE PLANTS OF
TROPICAL LEGUMES Stylosanthes humilis and
Stylosanthes hamata

 

CARLOS CRUZ-VAZQUEZ *, MANUEL FERNANDEZ-RUVALCABA **,
JAIME SOLANO-VERGARA*** and ZEFERINO GARCIA-VAZQUEZ **

*Instituto Tecnológico Agropecuario No. 20 (DGETA - SEP).AP 1439, C. Camionera. C.P. 20270 Aguas calientes, Ags. México.
** Cenid-Parasitología Veterinaria (INIFP - SAG.R).AP. 206, Civac. C.P. 62500 Juitepec, Morelos, México.
***Centro de Bachillerato Tecnológico Agropecuario No. 194 (DGETA. - SEP).A.P. 18. Centro. C.P. 62000 Miacatlan Morelos, México.

ABSTRACT

The anti-tick effect of Stylosanthes humilis and Stylosanthes hamata was evaluated for mature plants on plots experimentally infested with larvae of the cattle tick Boophilus microplus. Cenchurus ciliaris was used as control grass. The effect was evaluated counting the total number of live tick larvae recovered by the double flannel flag technique from the experimental plots during a four week period. The effect observed in both Stylosanthes species did not show significant differences (p > 0.05) between them and the larval survival percentage was 5.1 % for S. humilis and 7.5 % for S. hamata. In the first specie the anti-tick effect was lower than the one reported for young plants, but in S. hamata this effect was similar in young and mature plants. Further studies are necessary to complement the knowledge about this plant and to establish their use in field conditions..
Key words: Stylosanthes humilis; Stylosanthes hamata; mature plants; anti-tick effect; Boophilus microplus


INTRODUCTION

The southern cattle tick, Boophilus microplus, is an important constraint for cattle production in tropical and subtropical regions, where control is usually carried out by regular acaricide applications.1 The use of anti-tick grasses and legumes can be an alternative biocontrol method for tick infestations in these regions.2

The tropical pasture Stylosanthes spp is a legume native of Latin American and is cultivated locally in several countries such as Brasil and México and in others outside the region, such as Australia, for its highly nutritious characteristics; the genus has 25 species, some of these have anti-tick properties, i.e. can repel, trap and kill larvae of the tick B. microplus, because the stems and leaves of these plants are covered with glandular trichomes which produce a sticky secretion with a characteristic odour and a volatile toxic agent.2,3 In a previous study developed in México, the anti-tick effect of S. humilis and S. hamata has been demonstrated in young plants.4

The objective of the present study was to evaluate the anti-tick effect in mature plants of these two Stylosanthes species.

MATHERIALS AND METHODS

The study was carried out at the experimental station of the Centro de Bachillerato Tecnológico Agropecuario No. 194 (DGETA-SEP), located in the municipality of Miacatlán, Morelos, México. The site is at an altitude of 1054 m above sea level, with an annual mean precipitation of 800 mm with rainfall ocurring primarily in summer thus producing a tropical, subhumid climate.

The experimental area (15m X 18m) was on shallow soil, light brown in colour and containing a high percentage of stones. The area was wire fenced to exclude grazing animals. The experimental design used in the study was a random block of three treatments with eight replicates.5 The treatments were: 1. S. humilis, cv. Patterson; 2. S. hamata, cv. Verano; 3. Cenchurus ciliaris, cv. Biloela. Treatment three was used as control. The area of each experimental plot was 4.8 m2 (3m X 1.6m), and each plot was separated by a vegetation free barrier that was 0.5 m wide.6,7 On 4 July 1995, the experimental plots were seeded at a rate equivalent to 6 kg/ha in the case of Stylosanthes species studied and a rate of 12 kg/ha in the case of C. ciliaris.8 The plots were fertilized after seeding. All plots were clipped to a height of 25 cm at 1.5 months intervals to simulate the effects of grazing and clippings were collected and removed. The plots were irrigated weekly from January to April. The number of plants per plot (using a quadrant of 50cm X 50cm) and the estimated percentage of ground covered were recorded on 3 April, 1996.

A colony of B. microplus ticks ("Zapata" strain), free of Babesia spp and susceptible to acaricides, was established by bovine passage at the CENID-Parasitología Veterinaria laboratory. Batches of 0.5 g of eggs (10,000 larvae) were held in glass vials and incubated at 28ºC and 95% R.H. until larvae eclosion. Larvae were 15 days old at the time the infestation was iniciated. The experimental plots were clipped to 25 cms in height one week before experimental larval infestation; on 13 April 1996, the plots were infested with 10,000 larvae (one vial per plot) by lineal distribution outline and seven days after larval infestation the vegetation in each plot was sampled using a double flannel flag technique.7 Sampling was repeated at weeks 2, 3 and 4. The live tick larvae recovered in each sample were counted under a stereoscopical microscope and the mean values were calculated.

The data were analysed by Analysis of Variance (ANOVA) and differences among the means were determined by Tukey´s test.5

RESULTS

The anti-tick effect of S. humilis and S. hamata in mature plants is shown in Table 1. The total mean values of live tick larvae recovered from both tropical legumes did not show significant differences (p> 0.05) between them, but did with the control grass (p< 0.05). The larval survival percentage was 5.1 % for S. humilis, 7.5 % for S. hamata and 18.9 % for C. ciliaris, when the effect was calculated based on the initial infestation level (10,000 larvae).

The number of plants per plot showed significant differences (p < 0.05) between the three treatments. In constrant, the ground cover percentage did not show differences (p > 0.05) within legumes, but there was a significant difference (p < 0.05) between legumes and grass (Table 2).

Table 1.- Anti-tick effect of Stylosanthes, humilis and Stylosanthes, hamata in mature plants1. Mean values of live Boophilus, microplus recovered in each sampling


Treatments

Weekly sampling

Total

 

 

1

2

3
4
 

 

 

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD


1. S. humilis

408.1a

± 12.1

92,5a

±   4.8

11.2a

± 2.5

1.1a

+ 1

512.9a

± 12.6

2. S. hamata

665.2a

±   9.9

75.5a

±   8.4

12.1a

± 5.1

1.7a

+ 1.1

754.5a

± 10.5

3. C. Ciliaris

1695.7b

± 25.9

183.2b

± 12.2

6.5a

± 2.8

1.7a

+ 1.2

1897.1b

± 25.6


Values within a column followed by same letter are not significantly different at p < 0,005

1 Determinated 283 days after seeding

 

Table 2. Agronomical characteristics of experimental
plots with mature plants of Stylosanthes, humilis,
Stylosanthes, hamata and Cenchurus. ciliaris


Treatment

Nº plants/plot

ground cover

 

 

(%)


1. S. humilis

187 c

  5.5 b

2. S . hamata

283 b

  8.8 b

3. C. ciliaris

346 a

65.6 a


Valus within a column followed by the same letter are not
significantly different at p < 0.05
1 Determined on 3 april 1996, 273 days after seeding

DISCUSSION

Some Stylosanthes species have anti-tick properties, with S. viscosa, S. guaianensis and S. scabra being reported to have the greatest impact.3,9,10 Recently, has been reported 4 anti-tick effect in S. humilis and S. hamata, in young plants near first flowering.

In our study the total mean values of live tick larvae recovered do not show differences between Stylosanthes species (Table 1) , this fact is in constrat with previous observations in young plants, where S. humilis has a better effect.4 The number of plants and ground cover percentage in S. humilis was lower than reported for young plants because this plant is an annual species, these factors can influence the larval survival.6 The agronomic characteristics observed in S. hamata tick effect in young mature plants. Stylosanthes dominated pastures are less suitable for tick propagation because they provide an open canopy which leaves ticks more exposed to disecation and possible predation.6 The grass control has a larval survival and agronomic characteristics similar to those previously reported under the same conditions in México.4,7

The use in the field of Stylosanthes plants will depend on plant age and ground cover percentage of legume.2 In the present study S. humilis is influenced in its anti-tick properties by the plant age and its annual cycle which have an impact on ground cover and number of plants, the potential use in the field has to be limited to young plants. In the case of S. hamata, this study does not detect that these factors influenced its anti-tick properties and its potential use in the field may be most feasible in perennial pastures, specially if it is mixed in adequate proportion with other grasses. Further studies are necessary to complement the knowledge about this plants, to establish their use in field conditions and to take advantage of their anti-tick properties and other potential benefits such as those that improve cattle nutrition and soil fertility through nitrogen fixation.

RESUMEN

El efecto anti-garrapata de plantas maduras de las leguminosas tropicales Stylosanthes humilis y Stylosanthes hamata , fue evaluado en parcelas experimentalmente infestadas con larvas de garrapata Boophilus microplus, utilizando al pasto Cenchurus ciliaris como tratamiento testigo. El efecto fue evaluado contando el número total de larvas vivas recuperadas de las parcelas experimentales por la técnica de bandera de doble recorrido durante un periodo de cuatro semanas. El efecto anti-garrapata observado en ambas especies de Stylosanthes no mostró diferencias entre ellas (p<0.05), el porcentaje de sobrevivencia de larvas fue del 5.1% para S. humilis y 7.5% para S. hamata. En la primera especie el efecto anti-garrapata fue menor que el reportado en plantas jóvenes, pero en S. hamata este efecto fue similar en plantas maduras y jóvenes. Es necesario realizar más estudios para complementar el conocimiento que se tiene acerca de estas plantas y establecer su uso en condiciones de campo.

REFERENCES

1.- PEGRAM RG, TATCHELL RJ, DE CASTRO JJ, et al.,. Tick Control: New concepts. World Anim. Rev., 74-75: 2-11, 1993.         [ Links ]

2.- KAAYA GP. Non-Chemical agents and factors capable of regulating tick populations in nature: a mini review. Insect Sci. Applic., 13:587-594, 1992.        [ Links ]

3.- SUTHERST RW, JONES RJ, SCHNITZERLING HJ. Tropical legumes of the genus Stylosanthes immobilize and kill cattle ticks. Nature, 295: 320-321, 1982.        [ Links ]

4.- FERNANDEZ-RUVALCABA M, CRUZ-VAZQUEZ C, SOLANO-VERGARA J, GARCIA-VAZQUEZ Z. Anti-tick effect of Stylosanthes humilis and Stylosanthes hamata on plots experimentally infested with Boophilus microplus larvae in Morelos, Mexico. Exp. Appl. Acarol. 22, 1998. (in press).        [ Links ]

5.- PAGANO M, GAUVREAU K. Principles of Biostatistics, p. 145-167; 257-271. Duxbury Press. USA. 1993        [ Links ]

6.- WILSON LJ, SUTHERST RW, Oviposition sites of Boophilus microplus (Canestrini) (Acarina:Ixodidae) in Stylosanthes and grass pastures. J. Aust. ent. Soc., 29: 101-105, 1990.        [ Links ]

7.- FERNANDEZ RM. Comparison of four sampling techniques for Boophilus microplus larvae under field conditions in controlled infestation. Tec. Pecu. Mex. 34: 175-182, 1996        [ Links ]

8.- HUMPHREYS LR. A guide to better pastures for the tropics and subtropics, p. 46-50. Wright Stepheson Co. Australia. 1980.        [ Links ]

9.- SUTHERST RW, REID LJ, KERR, R. A survey of the ability of tropical legumes in the genus Stylosanthes to trap larvae of cattle tick, Boophilus microplus (Ixodidae). Aust. J. exp. Agric., 28: 473-479, 1988.

10.- ZIMMERMAN RH, GARRIS IG , BEAVER, SJ. Potential of Stylosanthes plants as component in an integrated pest management approach to tick control. Prev. Vet. Med., 2: 579-584, 1984.