Transcript However, it is unclear if all snail species are equally

North American and African Nematomorph Host Specificity in Six Species of Aquatic Snails.
Austin Kubat and Matthew G. Bolek, Department of Zoology, Oklahoma State University.
ABSTRACT
RESULTS
METHODS
North American Paragordius varius
A
A
B
C
D
E
F
Fig. 2 Laboratory reared snails, (A) Physa gyrina; (B) Biomphalaria sudanica; (C)
Biomphalaria glabrata; (D) Gyraulus parvus; (E) Planorbella trivolvis; (F) Stagnicola elodes.
100
B
C-width
L-width
C-length
L-length
D
60
40
A
B
0
Biomphalaria
sudanica
Biomphalaria
glabrata
Gyraulus
parvus
P lanorbella
trivolvis
Cyst Length + 1 SD
70
Fig. 1 (A) Cricket definitive host; (B) free living mature worm laying eggs; (C)
free living larvae; (D) snail paratenic host; (E) mature infective cyst from snail.
Mean Abundance + 1 SD
C
C
150
125
100
75
Cyst Length + 1 SD
B
Stagnicola
elodes
Snails Species
C
175
150
125
100
75
25
25
0
P hysa gyrina
60
Biomphalaria
sudanica
Biomphalaria
glabrata
Gyraulus
parvus
P lanorbella
trivolvis
Stagnicola
elodes
Snails Species
55
Biomphalaria sudanica
70
A
P lanorbella
trivolvis
50
0
Physa gyrina
Are all snail species susceptible to nematomorph
Gyraulus
parvus
65
50
Question
Biomphalaria
glabrata
200
50
A
Biomphalaria
sudanica
225
175
B
P hysa gyrina
Stagnicola
elodes
Snails Species
200
RESULTS
40
0
225
Fig. 3 (A) snail infection; (B) snail necropsy; (C) cyst morphology.
60
20
C
E
80
20
P hysa gyrina
B
100
Prevalence (%)
I wonder what worm
species he has?
Prevalence (%)
80
C
A
Mean Abundance + 1 SD
Freshwater snails are commonly infected with horsehair worms
cysts (Nematomorpha). However, it is unclear if all snail species are
equally susceptible to nematomorph infections. In this study we tested
the host specificity of 6 species of North American (NA), South American
(SA) and African (AF) snails from 3 different families to infections with a
North American horsehair worm, Paragordius varius, and an undescribed
African horsehair worm, Paragordius sp. Two groups of 10 individual
laboratory reared snails including Physa gyrina (Physidae, NA),
Biomphalaria sudanica (Planorbidae, AF), Biomphalaria glabrata
(Planorbidae, SA), Planorbella trivolvis (Planorbidae, NA), Gyraulus
parvus (Planorbidae, NA), and Stagnicola elodes (Lymnaeidae, NA) were
each exposed to approximately 500 laboratory reared larvae of
Paragordius sp. and P. varius. After exposure, nematomorph larvae were
allowed to develop to the cyst stage for 5 days, and each snail was
crushed and examined for the presence of nematomorphs and
abundance of nematomorph cysts. Our results indicate, that independent
of horsehair worm continent of origin, based on prevalence, mean
abundance and cyst development, Physa gyrina (NA), Biomphalaria
sudanica (AF), Biomphalaria glabrata (SA) were classified as suitable
hosts for nematomorphs with high prevalence (90-100%) and/or high
mean abundance (3-114), whereas Gyraulus parvus (NA), Stagnicola
elodes (NA), and Planorbella trivolvis (NA) were classified as not suitable
or less suitable hosts for nematomorphs with low prevalence (0-50%) and
low mean abundance (0-4). Our study is the first to document host
specificity of snails to any horsehair worm species.
African Paragordius sp.
Biomphalaria glabrata
Fig. 5 (A) Origin; (B) prevalence; and (C) mean
abundance + 1 SD of Paragordius various cysts in
six species of snail hosts.
P hysa gyrina
Biomphalaria
sudanica
Biomphalaria
glabrata
Gyraulus
parvus
P lanorbella
trivolvis
Stagnicola
elodes
Snails Species
Fig. 6 (A) Origin; (B) prevalence; and (C) mean
abundance + 1 SD of Paragordius sp. cysts in six
species of snail hosts.
D
65
60
55
50
infections?
Physa gyrina
Biomphalaria sudanica
Biomphalaria glabrata
Fig. 4 (A) Typical mature cyst; (B) cyst from Biomphalaria glabrata. Note the abnormal cyst
shape; (C) mean cyst length in µm of Paragordius varius from three species of snails; (D)
mean cyst length in µm of Paragordius sp. from three species of snails.
CONCLUSION
Our results indicate that not all snail species
are equally susceptible to nematomorph
infections.
ACKNOWLEGMENTS
We thank Dr. Ben Hanelt, UNM for collecting
snails infected with cysts from Kenya, Africa
and Nebraska, North America.