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ORIGINAL ARTICLE / ARTÍCULO ORIGINAL
MORPHOMETRIC AND CYTOGENETIC DESCRIPTION OF
BLATTICOLA
CHYDAEUS
SP. N. (NEMATODA, THELASTOMATIDAE),
A PARASITE OF
ANUROGRYLLUS MUTICUS
(DE GEER, 1773)
(ORTHOPTERA, GRYLLIDAE) IN ARGENTINA
DESCRIPCIÓN MORFOMÉTRICA Y CITOGENÉTICA DE
BLATTICOLA
CHYDAEUS
SP. N. (NEMATODA, THELASTOMATIDAE), UN PARÁSITO DE
ANUROGRYLLUS MUTICUS
(DE GEER, 1773) (ORTHOPTERA, GRYLLIDAE)
EN ARGENTINA
Nora B. Camino
1,2,3*
; Carolina Casanovas
1,2
& Sergio Rodríguez Gil
1,4
ISSN Versión Impresa 2218-6425 ISSN Versión Electrónica 1995-1403
DOI: https://dx.doi.org/10.24039/rnh20231721655
Volume 17, Number 2 (jul - dec) 2023
Este artículo es publicado por la revista Neotropical Helminthology de la Facultad de Ciencias Naturales y Matemática, Universidad Nacional Federico
Villarreal, Lima, Perú auspiciado por la Asociación Peruana de Helmintología e Invertebrados Af nes (APHIA). Este es un artículo de acceso abierto,
distribuido bajo los términos de la licencia Creative Commons Atribución 4.0 Internacional (CC BY 4.0) [https:// creativecommons.org/licenses/by/4.0/
deed.es] que permite el uso, distribución y reproducción en cualquier medio, siempre que la obra original sea debidamente citada de su fuente original.
Centro de Estudios Parasitológicos y de Vectores, CEPAVE, Argentina.
2
Universidad Nacional de La Plata, UNLP, Facultad de Ciencias Naturales y Museo, Argentina.
3
Investigador CIC, Comisión de Investigaciones Científ cas de la provincia de Buenos Aires, CIC, Argentina.
4
Consejo Nacional de Investigaciones Científ cas y Técnicas, CONICET, Argentina.
* Corresponding author: nemainst@cepave.edu.ar
Nora B. Camino:
https://orcid.org/0000-0003-4910-3986
Carolina Casanovas:
https://orcid.org/0009-0003-9774-6078
Sergio Rodríguez-Gil:
https://orcid.org/0000-0003-4608-1961
ABSTRACT
Blatticola chydaeus
n. sp. (Nematoda, T elastomatidae), parasitizing
Anurogryllus muticus
(De Geer, 1773) (Orthoptera,
Gryllidae) in Argentina is morphometric and cytogenetic described. It is characterized by the female with cuticle
annulated up to the middle of the body, the mouth surrounded by eight cephalic papillae, the stoma short with two
plates and one tooth, the amphid pore shaped, the esophagus divided into three parts, anterior cylindrical corpus,
isthmus distinct, and basal bulb valvated, the excretory pore located posterior to the basal bulb, the nerve ring situated at
the beginning of the esophagic isthmus, the intestine broadest anteriorly, the egg oval, smooth shell, in apical view show
a triangular section. T e tail appendage is short and conic and presents anal alae. T e vulva is protruding, the vagina is
long and posterior. T e male has one preanal papilla, one simple papilla, and one pair of postanal papillae. One spicule,
short and simple, without gubernaculum. T e tail appendage is short, conic, and pointed. T e cytogenetic study revealed
very small acrocentric chromosomes, this new species shows 3 and 3+X bivalent chromosomes, the sexual determination
is not given by haplodiploidy, the sexual chromosome was assumed to be X.
Keywords
:
Blatticola chydaeus
sp. n. – T elastomatidae – cricket – morphometric – cytogenetic – Argentina
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et al.
RESUMEN
Blatticola chydaeus
n. sp. (Nematoda, Telastomatidae), es un parásito de
Anurogryllus muticus
(De Geer, 1773)
(Orthoptera, Gryllidae) en Argentina, se describe al parásito morfométrica y citognéticamente. Se caracteriza porque la
hembra posee una cutícula anillada hasta la mitad del cuerpo, boca rodeada por ocho papilas cefálicas, estoma corto con
dos placas y un diente, anfdio piriforme, esófago dividido en tres partes, corpus anterior, istmo y bulbo basal valvado.
El poro excretor ubicado posterior al bulbo basal, el anillo nervioso situado al comienzo del istmo esofágico, el intestino
más ancho anteriormente, huevos ovales de cáscara lisa en vista apical muestran una sección triangular. Apéndice caudal
corto y cónico, con ala anal. Vulva protuberante, vagina larga y posterior. El macho tiene una papila preanal, una papila
simple y un par de papilas postanales. Una espícula, corta y sencilla, sin gubernáculo. El apéndice caudal corto, cónico
y puntiagudo. El estudio citogenético reveló cromosomas acrocéntricos muy pequeños. Esta nueva especie muestra
cromosomas bivalentes 3 y 3 + X, la determinación sexual no se da por haplodiploidía, el cromosoma sexual es X.
Palabras claves:
Blatticola chydaeus
n. sp. – Telastomatidae – grillo – morfometría – citogenética – Argentina
INTRODUCTION
During the day,
Anurogryllus muticus
(De Geer, 1773)
crickets stay in the galleries they make under the ground,
feeding on grass roots, and on warm nights, they often
leave their caves to feed on the surface. Te most serious
damage caused by crickets is to the grass, where they
can destroy the root system. Due to the signifcant loss
of root mass, a yellow spot can be observed (Rusconi,
2007). Tat is why it is necessary to fnd some biocontrol
agent, such as nematodos, which promise to be efective.
It is necessary to search for some biocontrol agent, such
as nematodes. Nematodes of the family Telastomatidae,
which belongs to the genus
Blatticola
, were found during
a feld survey. Te genus
Blatticola
Schwenk, 1926, who
was designated for
B. blatticola
as its type species. In 1932,
Chitwood considered this species a synonym of
B. blattae
(Graefe, 1860). Te confusion in the taxonomy of the
genus and type species was clarifed by Dale in 1966.
Earlier emended diagnosis of the genus was modifed
(Adamson & van Waerebeke, 1992) to accommodate
the species described by Chitwood (1932) in a revision
of the thelastomatid group. Te genus
Blattellicola
Basir, 1940 and
Blatellicoloides
Farooqui, 1966 agree
with
Blatticola
in all essential respects and they are
considered synonymous. All the species described up to
the present are parasites of cockroaches from all major
regions of the world. While conducting feld surveys on
agricultural pests in Argentinian areas of La Plata, Buenos
Aires province, we found cricket nymphs parasitized by
species of this thelastomatid group. Achinelly & Camino
(2007) described a new species,
Blatticola cristovata
, and
then Camino & Schargorodsky (2009) described
B.
biannulata
. Tese records represent the frst and second
reports of parasitized crickets in Argentina. Rodriguez-
Gil
et al.
(2017) described the morphology of another
new species of the genus and carried out a cytogenetic
study on
Blatticola ancoracauda
, also from Argentinian
crickets. In the present study, we found a new species of
the genus
Blatticola
.
MATERIALS AND METHODS
Twenty-fve crickets were collected from the lawn in 66
th
Av., between 1
st
Av. (34° 55’ 13.318’’ S, 57° 55’ 42.994’’ W)
and 2
nd
St. (34° 55’ 16.612’’ S, 57° 55’ 46.432’’ W) in La
Plata, Buenos Aires province, from October 2017 to March
2018. Considering the biological cycle of the crickets,
were captured during the warm months of the Southern
Hemisphere, in coincidence with their reproductive season.
Te adults were found from October to December, and
between January and March, mostly nymphs. Te crickets
were captured using a tensioactive solution (detergent and
water) that causes an obstruction in their respiratory tract,
making them come out of the subterranean galleries they
inhabit. Te methodology followed consisted frstly on the
identifcation of the holes that were compatible the cricket’s
caves. Ten, each hole was flled with the tensioactive
solution until the crickets came out. Every single insect was
recollected in a jar and immediately carried to the laboratory
to execute its dissection by previously refrigerating it to
asleep. If the dissection couldn’t be done on the same day
of the recollection, the insects were kept in the refrigerator
at -4°C until the next day. Te dissection was carried
out under stereoscopic binocular lens, with the help of
dissection needles, tweezers, a Westcott pair of scissors and
under immersion in physiological solution. Te incision
begins at the anus, continuing by the cricket pleura until
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the thoracic region, then transversely by the sterno and it
fnishes by the other pleura, opening a window from where
the mid and posterior gut was retired. Te cricket was kept
in an 80% ethyl alcohol solution for posterior taxonomic
identifcation. Later on, the gut was opened side to side,
caring not to hurt the potential parasites, to make evident
their presence. Te nematodes were extracted and fxed in
diferent solutions for its posterior treatment, depending
on the study to be carried out. Each treatment is described
below.
Morphometric and systematic analysis of nematodes
For the morphological studies and systematic analysis TAF
(formalin 7%, triethanolamine 2 % and distilled water 91%)
was used as fxer (Courtney
et al.,
1955). 20 nematodes
were fxed. Te nematodes were killed by placing them
in distilled water at 60 °C for 2 minutes. Ten they were
moved to a 50% TAF solution in water for 48 hours, and
fnally they were placed in pure TAF. Fixed specimens were
photographed with a camera mounted on a Zeiss compound
microscope. All measurements are in µm, and presented as
the mean and standard deviation, with ranges in parenthesis.
Cytogenetic analysis
For cytogenetic studies, 139 crickets were analyzed, 22
of which were parasitized with at least one nematode.
16 nematodes adults were selected and placed in
distilled water for 30 minutes and then fxed in regular
Carnoy’s solution (six parts pure ethyl alcohol, three parts
chloroform and one-part acetic acid) and in a modifed
one (six parts pure ethyl alcohol, one-part chloroform
and one part acetic acid). Te cytogenetic preparations
were made using the squash technique and stained with
45% acetic orcein (Adamson, 1981; Lacadena, 1996;
Rodríguez-Gil
et al
., 2007). Te representative cells
of each stage were photographed with an Olympus
microscope with digital camera DP 71, using the program
DP Controller 3.3.1.292, the images were processed with
the programs Pixillion V Demo 6.08, and the karyotypes
were done with DRAWID (Kirov
et al
., 2017).
Te TCL, which represents the total length of a haploid
cell, was obtained summing the average of each one of the
homologous chromosomes.
Ethic aspect
: Te ethical biosafety standards established
for laboratory animals and good animal experimentation
practices were followed.
RESULTS
We recognized our new species belonging to the genus
Blatticola
Schwenk, 1926, which is characterized by the
female with cuticle annulated up to the middle of the
body, the mouth opening subtriangular surrounded by
eight cephalic papillae, the stoma short and telostoma
with two plates and one tooth in the telorhabdion (Fig. 1
A), the amphid small pore shaped, the oesophagus divided
into three parts, anterior cylindrical corpus, isthmus
distinct, and basal bulb valvated (Fig. 1 B), the excretory
pore located posterior to basal bulb, the nerve ring
situated at the beginning of the esophagic isthmus, the
intestine broadest anteriorly, the egg oval, smooth shell,
in apical view show a triangular section. Te basal bulb is
muscular and strong, and is inserted into the frst part of
the intestine. Te tail appendage is short and conic, and
presents anal alae (Fig. 1C). Te vulva is protruding, the
vagina is long and posterior with V = 70% (Fig. 1D). Te
male has one preanal papilla, one simple papilla and one
pair of postanal papillae (Fig. 2B). It also has a spicule,
short and simple, without gubernaculum (Fig. 2A). Te
tail appendage is short, conic and pointed.
Table 1
.
Blatticola chydaeus
n. sp. Mean and standard deviation of the diferent measurements, with ranges (minimum
and maximum) µm in parenthesis.
Total length5,500 ± 368.62 (5,200 – 6,300)1,125 ± 320 (1,000 – 1,800)
Diameter of head at level of cephalic papillae24 ± 5.2 (20-32)14.28 ± 4.6 (11-20)
Stoma length16 ± 0.6 (15-17)5.2 ± 0.2 (5- 6)
Stoma width8.8 ± 0.2 (8-9)3.5 ± 0.2 (3-4)
Width of body at level of nerve ring164.70 ± 42.1 (122-210)40.22 ± 3.8 (38-45)
Maximum body diameter282.35 ± 45.9 (222-318)47.36 ± 2.2 (46-50)
Width of body at level of posterior end 129.41 ± 13.6 (116-142)40 ± 3.8 (36-42)
Width of body at level of vulva241.17 ± 33.9 (220-290)
---
Distance anterior end to nerve ring 358.82 ± 45.4 (320-410)125.71 ± 18.6 (109-145)
(Continued Table 1)
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Oesophagus length620 ± 45.6 (550-660)194.98 ± 68.3 (120-260)
Distance from anterior end to excretory pore1,400 ± 305 (1,000 – 1,600)337.14 ± 642.5 (290-382)
Vagina length300 ± 60.9 (260-355)
---
Vagina width47.05 ± 4.3 (42-52)
---
V (distance anterior end to vulva/body length x 100)68.98 ± 1.6 % (68-71)
---
Spicule length ---32.35 ± 2.8 (29-35)
Spicule width---4.41 ± 0.6 (4-5)
Length of eggs88.23 ± 2.6 (85-90)
---
Width of eggs41.17 ± 1.5 (40-43)
---
Tail appendage length45.29 ± 2.8 (42-48)26.47 ± 1.02 (25-27)
(Continued Table 1)
A
B
C
D
Figure 1
. Blatticola chydaeus n. sp. Te female. A) Anterior end. B) Oesophagus and anterior end of intestine. C) Tail
appendage. D) Posterior end of the body showing the vulva. Bars = A, C: 100 µm; B, D: 200 µm.
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