On the basis of experimental studies we analyzed the effect of extreme temperatures on the aquatic free-living phases of the life cycle of Chordodes nobilii (Gordiida, Nematomorpha). Bioassays were performed with eggs, larvae, and adults. Eggs and larvae were exposed to 3°C below zero and 40.5°C; adults were exposed to 3°C below zero and to 38.5°C and 40.5°C. The results showed that egg development was inhibited in both tests. Exposed larvae showed a decrease in their infective capacity, which resulted almost null at 40.5°C. Adults exposed to 38.5°C showed mortality ≤10%, at 40.5°C the mortality was 100% and the adult's mortality at 3°C below zero was 89%. Results indicate that free living stages of Chordodes nobilii are susceptible to extreme temperatures.Facultad de Ciencias Naturales y Muse

Achiorno, Cecilia Luján

Ferrari, Lucrecia

Villalobos, Leonor Cristina de

Acta Parasitologica

English

El Servicio de Difusión de la Creación Intelectual

VERSITA
DOI: 10.2478/sl 1686-008-0052-5
© 2008 W. Stefaiíski Institute of Parasitology, PAS
Acta Parasitológica, 2008, 53(4), 392-396; ISSN 1230-2821
Effect oí extreme temperature on egg development, 
larval and adult survival of Chordodes nobilii Camerano, 1901 
(Gordiida, Nematomorpha)
Cecilia Lujan Achiorno1’2, Lucrecia Ferrari3’4 and Cristina De Villalobos1’4*
*Corresponding author: villalo@fcnym.unlp.edu.ar
'Facultad de Ciencias Naturales y Museo Universidad Nacional de La Plata, Paseo del Bosque S/N, 1900 La Plata; 
"Consejo Nacional de Investigaciones Científicas y Técnicas Av. Rivadavia 1917 CP C1033AA.T Ciudad de Buenos Aires; 
"Programa de Ecofisiología Aplicada, Departamento de Ciencias Básicas, Universidad Nacional de Lujan, Casilla de Correo 221, 
B6700ZBA-Luján; 4Comisión de Investigaciones Científicas de la Provincia de Buenos Aires 526 e/10 y 11; Argentina
Abstract
On the basis of experimental studies we analyzed the effect of extreme temperatures on the aquatic free-living phases of the 
life cycle of Chordodes nobilii (Gordiida, Nematomorpha). Bioassays were performed with eggs, larvae, and adults. Eggs and 
larvae were exposed to 3°C below zero and 40.5°C; adults were exposed to 3°C below zero and to 38.5°C and 40.5°C. The 
results showed that egg development was inhibited in both tests. Exposed larvae showed a decrease in their infective capacity, 
which resulted almost null at 40.5°C. Adults exposed to 38.5°C showed mortality <10%, at 40.5°C the mortality was 100% 
and the adult’s mortality at 3°C below zero was 89%. Results indicate that free living stages of Chordodes nobilii are suscep­
tible to extreme temperatures.
Keywords
Nematomorpha, Gordiida, Chordodes nobilii, life cycle, extreme temperatures
Introduction
Many abiotic factors affect directly and indirectly freshwater 
organism causing no visible detrimental effects (Huggins and 
Harp 1983, Mason and Hominick 1995), temperature is one of 
them. Seasonal changes in freshwater enviromnents such as 
ponds and streams, can reach extreme limits, from complete 
freezing to very hot temperatures in suimner, like in Sierra 
de la Ventana (Argentina), were adults of Chordodes nobilii 
(Gordiida) have been collected during all seasons, the absolute 
maximum and minimum temperatures varies between 38.2- 
39.9°C (summer) and 7.7-9.8°C below zero (winter) (Na­
tional Meteorological Services Information). These seasonal 
changes in temperature probably impacts on freshwater envi­
romnents were free-life stages of Gordiida inhabit.
Although several studies have been developed on the com­
plex life cycle of Nematomorpha over the past years (Schmidt- 
Rhaesa 2001, 2002; Bolek and Coggins 2002; Hanelt and 
Janovy 2003, 2004; De Villalobos et al. 2003; Zanca et al. 
2007), the Gordiida is still a group that has received limited 
ecological or physiological study (Swanson 1982, Chandler 
1985, Schmidt-Rhaesa 1997, Bolek and Coggins 2002). Tem­
perature is a principal factor influencing egg development and 
survival of free stages in Gordiida (Camerano 1897; Dorier 
1925, 1930; Thome 1940; Baer 1951; Cappucci 1976; Whit­
taker and Barker 1983 and Zanca et al. 2007). Camerano 
(1897) and Dorier (1925, 1930) analyzed, with different re­
sults, the thermal tolerances in different species of Gordiida. 
Taking into account the scarce data about the tolerance of 
Gordiida to extreme temperatures, the purpose of the present 
paper is to report results of experiments conducted with eggs, 
larvae and adults of Chordodes nobilii subjected to extreme 
temperatures. Using the information obtained from this study 
we hope to predict periods where gordiids may be susceptible 
to temperature related with their reproduction and mortality.
Materials and methods
Collection and maintenance o/Chordodes nobilii
Adults of Chordodes nobilii were collected in late summer 
from El Negro stream (38°07'28"S, 61°45'32"W), Sierra de 
La Ventana, Argentina. The specimens were placed in 1000 ml 
plastic containers with well aerated water, at room tempera­
Unauthenticated
Download Date | 8/23/19 11:31 PM
Effect of extreme temperature on Chordodes nobilii 393
ture (23 ± 1°C). After copulation the females were separated 
in individual containers. Egg strings were collected from each 
mated pair and rinsed in 1:250 Clorox bleach solution, 
as described previously (Hanelt and Janovy 1999) and placed 
into 50 ml plastic containers.
Bioassays were performed with eggs (mainly in blastula 
stage), larvae and adults. General bioassay conditions were 
selected based on preliminary trial (Achiomo et al. 2008).
Temperature test
Eggs: Twelve pieces of egg strings (3 tmn in length each) from 
one of the females were stored in 12 ml plastic containers with 
well aerated water and observed with light microscope until 
most of them reached the blastula stage. Two exposure tests 
were carried out: one at 3 ± 1°C below zero and another at 
40.5 ± 1°C, for 96 hours. Both tests included control groups 
maintained at room temperature (23 ± 1°C). All tests were car­
ried out in triplicate.
After the exposure time of each test the egg strings were 
maintained at room temperature with weekly observations of 
each replica (n = 100 eggs), during the following 30 days 
under light microscope (LM), in order to evaluate if the egg 
development was normal, retarded, interrupted or if the eggs 
were suffering some deterioration (e.g. collapse, wall rup­
ture).
Larvae: Portions of egg strings from the selected female 
at room temperature (23 ± 1°C) were observed under LM dur­
ing 20-25 days, until the larvae were completely developed 
(inside the egg shell as well as in hatched larvae). In order to 
determine the effect of extreme temperatures (3 ± 1°C below 
zero and 40.5 ± 1°C) during 48 hours on Chordodes nobilii 
larvae, the same test protocols used for the egg strings was fol­
lowed. In order to evaluate the survival of C. nobilii larvae, 
taking into account that larvae do not show constant move­
ment, once the exposure time ends, the larvae are placed at 
control temperature (23 ± 1°C). After 24 hours, experimental 
infections with larvae of Aedes aegypti (Diptera) were per­
formed. Plastic capsules of 3 cm diameter each one containing 
12 ml of well water, wheat germ as sediment and 30 larvae (L2 
and L3 instars) of A. aegypti were used for this analysis. After 
being exposed for 72 hrs, mosquito larvae were fixed in 70% 
ethanol and then dissected under LM to search for C. nobilii 
larvae in the body cavity. This procedure was followed for 
each replicate.
The survival of C. nobilii larvae was determined by eval­
uation of their infective capacity with the Infection Index 
Mean Abundance (IIMA), as the total nmnberof C. nobilii lar­
vae divided by the total number of host (A. aegypti larvae) 
observed (Bushei al. 1997). These bioassays were considered 
valid when IIMA in the control group was >2.
Adults: Two tests were carried out, at 3 ± 1°C below zero 
and at 38.5 ± 1°C, during 96 hrs. The temperature chosen for 
the second test follows the results obtained by Dorier (1930) 
who observed that the movements of adults of Gordius aqua- 
ticus; Gordionus violaceus and Paracltordodes gemmatus 
rapidly decreased when exposed at 37.5°C.
In both tests, forty males of C. nobilii were placed in four 
500 ml glass containers each one with ten specimens. Two of 
the samples were taken as a control group and maintained at 
23 ± 1°C.
In order to test the survival at 38.5°C, adult specimens 
were observed four times, every 24 hrs, during 10-15 min. 
Viability was evaluated by their mobility and compared with 
the control groups. The adults that did not respond to mechan­
ical stimulus were separated from the experimental units and 
placed at 23°C during 24 hrs. After this, the specimens that did 
not recover were considered dead to avoid confusion with 
sublethal effects.
As mortality in the specimens exposed during 96 In’s at 
38.5°C was <10%, the survival specimens were exposed at 
40.5 ± 1°C, during other 96 In’s with daily observations to 
evaluate mobility.
In order to evaluate the survival of adults of C. nobilii 
exposed at 3 °C below zero during 96 hrs, specimens were 
observed during 7 days post exposition at 23°C to determine 
whether they were recovering their normal activity (e.g.
Figs 1 and 2. 1. Non viable embryos in one of the samples from 
exposed eggs (30 days post exposition). Scale bar =15 pm. 2. Free 
living larvae and ready-to-hatch larvae within egg capsules in one 
of the samples from control eggs (30 days post exposition). Scale bar 
= 15 pm
Unauthenticated
Download Date | 8/23/19 11:31 PM
394 Cecilia Lujan Achiomo et al.
swimming, rolling). General bioassay conditions were select­
ed based on a preliminary trial.
Data analysis
The Shapiro-Wilk test and the Levene median test were used 
to assess normality and homogeneity of variance of data, 
respectively.
For the assays with larvae the Student’s t-test, p<0.05 was 
used to check for significant differences between the control 
and treated group (Zar 1999). The null hypothesis (Ho) sup­
posed that the IIMA media of the larvae exposed at 3 °C below 
zero is equal to the IIMA media of the larvae of the control 
group.
Significant differences between the control and treated 
groups were determined for the tests with adults using one­
way ANOVA with time as a covariable followed by Tukey’s 
test after Ln transformation of the data (Zar 1999). The sig­
nificance level was set at p<0.05. Statistical analyses were 
performed using Infostat software.
Results
From the results obtained during the observations of the eggs 
strings post exposition (30 days), both treatments at 3°C 
below zero and at 40.5°C interrupted their embryonic devel­
opment and damaged eggs have been observed (egg mem­
brane rupture and embryo retraction) (Fig. 1). The control 
group continued the egg development normally with over 
50% proportion of free larvae after 30 days (Fig. 2).
The bioassays carried out with larvae showed that in spite 
of their exposure at 3 °C below zero during 48 In’s, the C. no- 
bilii larvae could infect the .1. aegypti larvae, although a sta­
tistically significant decrease was registered with respect to
Fig. 3. Infection Index Mean Abundance (IIMA) ± SD observed for the control and the 3°C ± 1°C below zero in the larvae assays. Value 
expressed as arithmetic mean by treatment
Fig. 4. Infection Index Mean Abundance (IIMA) ± SD observed for the control and the 40°C (± 1°C) in the larvae assays. Value expressed 
as arithmetic mean by treatment
Unauthenticated
Download Date | 8/23/19 11:31 PM
Effect of extreme temperature on Chordodes nobilii 395
23°C(±1°C) —3 below zero°C (±1°C) Days
Fig. 5. Curve percentage of mobility in adults exposed to 3°C below zero (± 1°C) and the control 23°C (± 1°C), fortlie day 0 (pre-exposure) 
and for days after exposure (from day 1 to day 7)
Fig. 6. Curve percentage of cumulative mortality for adults exposed to 38.5°C (± l°C)and40.5°C (± 1°C), respect to exposure time (in hours)
the control group (statistical to 05(2).2 = 4.53304148) (Fig. 3). 
The larvae exposed at 40.5°C showed an important decrease 
in their infective capacity with a statistically significant dif­
ference (statistic to.05(2).2 = 31.38) (Fig. 4).
The experimental studies with adults showed that 28% of 
the specimens exposed to 3°C below zero recovered their mo­
bility 120 hrs post exposition. At day 7 only 11% of the spec­
imens continued with mobility (Fig. 5). The control group 
showed normal movements. In the adult’s bioassays at 38.5°C 
during 96 In’s the specimens were found entangled in a knot 
with no mobility, but after 10 min worms recovered their nor­
mal activity. The mortality was 10%, with no significant dif­
ferences with the control group. But when the temperature 
was increased in two grades (40.5°C). after the first 24 hrs an 
exponential increase of mortality of 50% could be observed, 
reaching 100% at the end of the exposure period (96 hrs) (Fig. 
6). Median Lethal Temperature (TL50) occurs in the range 
between 38.5 and 40.5°C.
Unauthenticated
Download Date | 8/23/19 11:31 PM
396 Cecilia Luján Achiomo et al.
Discussion
The effect of low temperatures on the egg strings of C. nobilii 
was studied by Zanca et al. (2007) showing when maintained 
at 5°C they were capable of continuing their embryonic devel­
opment. In our study we can prove for the first time that 
extreme temperature inhibits the embryonic development.
Dorier (1930) studied the effect of different temperatures 
on the mobility of Gordius aquations larvae. He observed that 
50% of the larvae exposed at 37°C showed no mobility after 
two and a half hours and after thirty hours all of them were 
dead. Our observations of C. nobilii larvae exposed at 40.5°C 
showed that only a few larvae survived and could enter the 
corporal cavity of A. aegypti larvae.
There are previous reports on the effect of low tempera­
tures on the survival of larvae. Hanel and Janovy (1999) found 
that Gordius robustus larvae stored in tap water at 4°C remain­
ed viable for 5 months. Zanca et al. (2007) reported that 
C. nobilii larvae were able to survive 6 months at 5°C. Our 
results are the first to evaluate the effect of the freezing tem­
perature on C. nobilii larvae and allow us to determine that the 
larvae exposed at 3 °C below zero can survive and are able to 
complete their life cycle in contrast to those exposed at 
40.5°C.
The analyses carried out by Camerano (1897) on the ther­
mal tolerances of adults in Gordius aquations, Parachordodes 
tolosanus and P. pustulosus showed that the mobility of the 
specimens decreases at 25°C. stops at 39°C. and at 44°C- 
46°C they die. Dorier (1930) considers that the adults of 
Gordionus violaceus exposed at 37°C die after three days, 
while G. aquations and Parachordodes gemmatus die within 
7-9 days.
In the adults of C. nobilii we observed that for the condi­
tions tested the tolerance to temperatures exceeding 38.5°C 
significantly increased mortality of adults.
Our results indicate that aquatic free-living phases of the 
life cycle of Chordodes nobilii are susceptible to extreme tem­
peratures. especially at 40.5°C.
Acknowledgements. We would like to thank Dr. Juan Garcia from 
the Parasites and Vectors Research Center (CEPAVE) for his kind 
donation oIAedes aegypti eggs. Many thanks also to two anonymous 
reviewers for constructive comments on the manuscript.
References
Achiomo C., de Villalobos C., Ferrari L. 2008. Toxicity of the her­
bicide glyphosate to Chordodes nobilii (Gordiida, Nenia­
toniorpha). Chemosphere, 71, 1816-1822. DOI: 10.1016/j. 
cheniosphere.2008.02.001.
Baer J.G 1951. Gordiacea. Ecology of animal parasites. University 
Illinois Press Urbana, 43^15.
BolekM., Coggins J. 2002. Seasonal occurrence, morphology, and 
observation on the life history of Gordius difficilis (Neniato­
niorpha: Gordioidea) from southeastern Wisconsin, United 
States. Journal of Parasitology, 88,287-294. DOI: 10.1645/ 
0022-3395.
Bush A.O., Lafferty K.D., Lotz J.M., Shostak A W. 1997. Parasitol­
ogy meets ecology on its own tenus: Margolis et al. revisit­
ed. Journal of Parasitology, 83, 576-583. DOI: 10.2307/32 
84227.
Camerano L. 1897. Monografía dei gordii. Memoria Reale Accade- 
mia Science Torino, 47, 339—419.
Cappucci D.T. 1976. The biology of Gordius robustus Leidy with a 
host list and summary of the public health importance of the 
Gordioidea. PhD Thesis, University of California, San Fran­
cisco, California, 240 pp.
Chandler C.M. 1985. Horsehair wonns (Nematomorpha, Gordioi­
dea) from Tennessee, with a review of taxonomy and distri­
bution in the United States. Journal of the Tennessee Academy 
of Science, 60, 59-62.
De Villalobos C., Rumi A., Núñez V, Schniidt-Rliaesa A., Zanca F. 
2003. Paratenic hosts: larval survival strategy in Paragordius 
varius (Leidy, 1851) (Gordiida, Nematomorpha). Acta Para­
sitológica, 48, 98-102.
Dorier A. 1925. Sur la faculté d ’ enky stment dans 1 ’ eau de la larve du 
Gordius. Compte Rendu de l’Académie des Sciences, Paris, 
181, 1098-1099.
Dorier A. 1930. Recherches biologiques et systématiques sur les Gor- 
diacés. Travaux du Laboratoire d’Hydrobiologie et de Pisci­
culture de TUniversité de Grenoble, 22, 1-183.
Hanelt B., Janovy J., Jr. 1999. The life cycle of a horsehair wonn, 
Gordius robustus (Gordioidea: Nematomorpha). Journal of 
Parasitology, 85,139-141. DOI: 10.2307/3285720.
Hanelt B., Janovy J., Jr. 2003. Spanning the gap: identification of nat­
ural paratenic hosts of horsehair wonns (Nematomorpha: 
Gordioidea) by experimental detennination of paratenic host 
specificity. Invertebrate Biology, 122,12-18.DOI: 10.1111/j. 
1744-7410.2003.tb00068.x.
Hanelt B., Janovy J., Jr. 2004. Life cycle and paratenesis of American 
gordiids (Neniatoniorpha: Gordiida). Journal of Parasitol­
ogy, 90,240-244. DOI: 10.1645/GE-78R.
Huggins J.A., Harp GL. 1983. Aquatic Macroinvertebrates of the 
Heatt Prairie Region Franklin Country Arkansas. Proceedings 
of the Arkansas Academy of Science, 37, 92-94.
Mason J.M., Hominick W.M. 1995. The effect of temperature on 
infection, development and reproduction of heterorhabditids. 
Journal of Helminthology, 69, 337-345.
Sclmiidt-RliaesaA. 1997. (Eds. J. Schwoerbel and P. Zwick) Nema­
tomorpha. Süßwasserfauna von Mitteleuropa. Vol. 4/4. Gus­
tav Fischer Verlag, Stuttgart, Gennany, 124 pp.
Sclmiidt-RliaesaA. 2001. The life cycle of horsehair wonns (Nenia­
toniorpha). Acta Parasitológica, 46, 151-158.
Sclmiidt-RliaesaA. 2002. Australian species a\'Chordodes (Neniato­
niorpha) with remarks on the genus and its life history. Jour­
nal of Natural History, 36,1569-1588. DOI: 10.108Ó/00222 
930110059664.
Swanson C.J. 1982. Neniatoniorpha. In: (Ed. S.P. Parker) Synopsis 
and Classification of Living Organisms. Vol. 1. McGraw-Hill, 
New York, 931-932.
Thome G. 1940. The hairwonn Gordius robustus Leidy as a parasite 
of the mormon cricket Anabrus simplex Haldeman. Journal of 
the Washington Academy of Sciences, 30,219-231.
Whittaker F.H., Barker R.L. 1983. Some observations on the egg 
string of a neniatoniorph wonn Paragordius sp. Transactions 
of the Kentucky Academy of Science, 44, 76-77.
Zanca F, de Villalobos C., Rumi A. 2007. Larval survival strategy 
during winter of Chordodes nobilii Camerano, 1901 (Gor­
diida Nematomorpha). Acta Parasitológica, 52, 382-385. 
DOI: 10.2478/S11686-007-0055-7.
Zar J.H. 1999. Biostatistical analysis. Fourth edition. Prentice Hall, 
Englewood Cliffs, New Jersey, 663 pp.
(Accepted September 2,2008)
Unauthenticated
Download Date | 8/23/19 11:31 PM


Effect of extreme temperature on egg development, larval and adult survival of Chordodes nobilii Camerano, 1901 (Gordiida, Nematomorpha)

http://sedici.unlp.edu.ar/bitstream/handle/10915/83305/Documento_completo.pdf?sequence=1

Effect of extreme temperature on egg development, larval and adult survival of Chordodes nobilii Camerano, 1901 (Gordiida, Nematomorpha)

Abstract

Similar works

Full text

Available Versions

El Servicio de Difusión de la Creación Intelectual