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Morphological and Molecular Analysis of Two Mycophagous Nematodes, Aphelenchoides bicaudatus and A. rutgersi (Nematoda: Aphelenchoididae) from Florida Strawberry

Journal of Nematology
Volume 56 (2024): Issue 1 (March 2024)
By:
Open Access
|Jul 2024

Figures & Tables

Figure 1.

Photomicrographs of Aphelenchoides bicaudatus female from Florida. (A) Anterior body showing the (E) excretory pore and the (PO) pharyngeal overlap. (B) Vulvar region showing (V) vulva and (PB) postuterine branch. (C) Lateral field (LF) marked by two outer visible incisures. The inner incisure is not discernible. (D), (E) Posterior body showing (A) anus and shape variations of the bifurcate tail terminus.
Photomicrographs of Aphelenchoides bicaudatus female from Florida. (A) Anterior body showing the (E) excretory pore and the (PO) pharyngeal overlap. (B) Vulvar region showing (V) vulva and (PB) postuterine branch. (C) Lateral field (LF) marked by two outer visible incisures. The inner incisure is not discernible. (D), (E) Posterior body showing (A) anus and shape variations of the bifurcate tail terminus.

Figure 2.

Photomicrographs of Aphelenchoides rutgersi female and male from Florida. (A) Female anterior body. (B) Pharyngeal region of female showing (M) median bulb and (PO) pharyngeal overlap. (C) Lateral field (LF) marked by three incisures. (D) Vulvar region showing (O) ovary with oocytes, (V) vulva, and portion of the (PB) post-vulvar uterine branch. (E) Posterior body of female showing (A) anus (A) and (N) the tail terminus with a ventral fine mucro. (F): Posterior body of male showing (S) spicules.
Photomicrographs of Aphelenchoides rutgersi female and male from Florida. (A) Female anterior body. (B) Pharyngeal region of female showing (M) median bulb and (PO) pharyngeal overlap. (C) Lateral field (LF) marked by three incisures. (D) Vulvar region showing (O) ovary with oocytes, (V) vulva, and portion of the (PB) post-vulvar uterine branch. (E) Posterior body of female showing (A) anus (A) and (N) the tail terminus with a ventral fine mucro. (F): Posterior body of male showing (S) spicules.

Figure 3.

Phylogenetic relationships of A. bicaudatus and A. rutgersi with some Aphelenchoides species: Bayesian 50% majority rule consensus tree from two runs as inferred from analysis of the 18S rRNA gene sequence alignment under the GTR + I + G model. Posterior probabilities equal to, or more than, 0.7 are given for appropriate clades. New sequences are indicated in bold letters. * - identified as Aphelenchoides sp. in the GenBank.
Phylogenetic relationships of A. bicaudatus and A. rutgersi with some Aphelenchoides species: Bayesian 50% majority rule consensus tree from two runs as inferred from analysis of the 18S rRNA gene sequence alignment under the GTR + I + G model. Posterior probabilities equal to, or more than, 0.7 are given for appropriate clades. New sequences are indicated in bold letters. * - identified as Aphelenchoides sp. in the GenBank.

Figure 4.

Phylogenetic relationships of A. bicaudatus and A. rutgersi with some Aphelenchoides species: Bayesian 50% majority rule consensus tree from two runs as inferred from analysis of the D2-D3 of 28S rRNA gene sequence alignment under the GTR + I + G model. Posterior probabilities equal to, or more than, 0.7 are given for appropriate clades. New sequences are indicated in bold letters. * - identified as Aphelenchoides sp. in the GenBank. ** - identified as an uncultured fungus in the GenBank.
Phylogenetic relationships of A. bicaudatus and A. rutgersi with some Aphelenchoides species: Bayesian 50% majority rule consensus tree from two runs as inferred from analysis of the D2-D3 of 28S rRNA gene sequence alignment under the GTR + I + G model. Posterior probabilities equal to, or more than, 0.7 are given for appropriate clades. New sequences are indicated in bold letters. * - identified as Aphelenchoides sp. in the GenBank. ** - identified as an uncultured fungus in the GenBank.

Figure 5.

Phylogenetic relationships of A. bicaudatus and A. rutgersi with some Aphelenchoides species: Bayesian 50% majority rule consensus tree from two runs as inferred from analysis of the COI gene sequence alignment under the GTR + I + G model. Posterior probabilities equal to, or more than, 0.7 are given for appropriate clades. New sequences are indicated in bold letters.
Phylogenetic relationships of A. bicaudatus and A. rutgersi with some Aphelenchoides species: Bayesian 50% majority rule consensus tree from two runs as inferred from analysis of the COI gene sequence alignment under the GTR + I + G model. Posterior probabilities equal to, or more than, 0.7 are given for appropriate clades. New sequences are indicated in bold letters.

Figure 6.

Symptoms induced by Aphelenchoides bicaudatus on soybean leaves. (A) Seedling showing discoloration and necrosis on the upper surface of the blade adjacent to the petiole 3 d after inoculation of the nematode using pieces of filter paper attached to the leaf Blade. (B) Closeup of the lesion delimited by the veins of the leaflet showing desiccated areas and dark tissues along the veins 14 d after the inoculation of the nematode.
Symptoms induced by Aphelenchoides bicaudatus on soybean leaves. (A) Seedling showing discoloration and necrosis on the upper surface of the blade adjacent to the petiole 3 d after inoculation of the nematode using pieces of filter paper attached to the leaf Blade. (B) Closeup of the lesion delimited by the veins of the leaflet showing desiccated areas and dark tissues along the veins 14 d after the inoculation of the nematode.

Figure 7.

Aphelenchoides bicaudatus inside soybean leaf tissues. (A) A nematode specimen tunneling the mesophyll 7 d after the inoculation of 300 specimens delivered with a piece of filter paper attached to the leaf blade. (B) Posterior body of a specimen showing the bifurcate tail terminus. (C) Anterior body of a specimen showing the stylet. (Scale bar = 24 μm).
Aphelenchoides bicaudatus inside soybean leaf tissues. (A) A nematode specimen tunneling the mesophyll 7 d after the inoculation of 300 specimens delivered with a piece of filter paper attached to the leaf blade. (B) Posterior body of a specimen showing the bifurcate tail terminus. (C) Anterior body of a specimen showing the stylet. (Scale bar = 24 μm).

Populations of Aphelenchoides characterized in the present study_

SpeciesLocationHostSample codeGenBank accession numberSource
SSULSUCOI
A. bicaudatusWimauma, Florida, USAFragaria × ananassaN18-1001-3OK644201OK644281OK644199C. Oliveira
OK644282
A. rutgersiWimauma, Florida, USAFragaria × ananassaN18-00206OK644202OK644283OK644295C. Oliveira
OK644203

Morphometrics of live females of a Florida population of Aphelenchoides bicaudatus from strawberry reared on Monilinia fructicola compared to those in the original (Imamura, 1931) and subsequent re-descriptions by Siddiqui & Taylor (1967), Jen et al_ (2012), Kim et al_ (2016), Israr et al_ (2017) and Shokoohi and Moyo (2022)_a

Population SubstrateFlorida Monilinia fructicolaJapan Paddy fieldIllinois Pyrenochaeta terrestrisTaiwan Alternaria citriSouth Korea Botrytis cinereaPakistan Raphanus sativusSouth Africa Pennisetum clandestinum
ReferencePresent paper N18-01001-3Imamura (1931)Siddiqui and Taylor (1967)Jen et al. (2012)Kim et al. (2016)Israr et al. (2017)Shokoohi and Moyo (2022)
Character n10♀♀18♀♀50♀♀50♀♀7♀♀2♀♀8♀♀
L494.1 ± 32.0 499 ± 67.9517.9 ± 3.8 455.0 ± 64.5
(454.8–552.4)(380.0–470.0)(410.0–550.0)(376–637)(513.6–522.6)(360.0–360.0)(409.0–529.0)
A31.2 ± 3.6 33.0 ± 2.428.3 ± 0.5 29.1 ± 2.0
(27.6–41.1)(31.3–31.7)(25–31)(27.0–38.6)(27.7–28.8)(30.1–32.7)(27.1–31.1)
B8.0 ± 0.5 9.0 ± 0.77.3 ± 0.0 4.6 ± 0.5
(7.2–9.0)(6.8–8.4)(7.3–9.6)(7.5–10.0)(7.3–7.4)(8.8–7.2)(4.1–5.1)
b’4.1 ± 0.2--5.1 ± 0.7- -
(3.7–4.6)(3.6–7.9)(5.6–5.8)
C13.2 ± 0.9 11.9 ± 0.911.3 ± 0.5 16.3 ± 2.0
(11.9–14.8)(9.4–12.6)(9.8–13.7)(10.1–14.8)(10.7–11.9)(11.3–12.0)(14.1–17.8)
c’4.4 ± 0.5--5.4 ± 0.54.6 ± 0.1 3.2 ± 0.6
(3.7–5.3)(4.1–7.1)(4.4–4.8)(2.9–3.7)(2.6–3.6)
V68.7 ± 1.5 68.5 ± 1.266.0 ± 0.2 68.8 ± 1.6
(65.8–71.1)(61.7–90.2)(65.0–70.0)(64.9–71.8)(65.7–66.4)(66.8–67.2)(67.0–71.0)
OV27.8 ± 2.0--15.2 ± 2.7- -
(23.9–30.9)(11.0–22.0)(12.0–12.5)
Max. body diameter15.9 ± 1.3---- 15.6 ± 1.5
(13.5–17.8)(25.0–26.2)(14.0–17.0)
Body diameter at anus8.6 ± 0.8---- 8.8 ± 0.7
(7.2–9.9)(11.8)(8.0–9.0)
Anterior genital tract length136.9 ± 10.4---- 179.3 ± 18.0
(121.7–150.1)(84.0–95.0)(167.0–200.0)
Lip region width4.9 ± 0.3--- 5.7 ± 0.1
(4.5–5.5)(5.0–5.2)(4.0–4.3)(5.6–5.8)
Lip region height2.8 ± 0.2--- 2.8 ± 0.9
(2.4–3.0)(2.5–2.9)(2.0–2.0)(2.0–4.0)
Stylet length10.9 ± 0.4- 10.4 ± 0.611.2 ± 0.5 11.1 ± 1.7
(10.3–11.8)(10–12)(9.0–12.0)(10.4–11.7)(10.0–11.0)(10.0–13.0)
Stylet cone5.1 ± 0.3-----4.7 ±0.3
(4.5–5.8)(4.5–5.0)
Stylet knob height1.4 ± 0.2------
(1.2-1.7)
Stylet knob width1.9 ± 0.3------
(1.2–2.3)
Median bulb length12.1 ± 0.7--- 11.2 ± 0.7
(10.9–13.3)(12.8–12.9)(10.0–10.0)(11.0–12.0)
Median bulb width9.6 ± 0.8--- 9.0 ±0.8
(7.9–11.1)(8.6–8.9)(7.0–8.0)(8.5–10.0)
Median bulb valve length4.1 ± 0.4------
(3.6–4.9)
Median bulb valve width2.9 ± 0.2------
(2.5–3.2)
Pharynx length62.1 ± 2.7---- 88.3 ± 11.2
(59.0–68.7)(90.0–92.0)(76.0–98.0)
Pharyngeal overlap57.0 ± 2.1- ----
(53.0–59.7)(50.0–75.0)
Ant. end to pharyngeal gland lobe118.8 ± 3.3------
(4.5–5.8)
Anterior end to excretory pore66.9 ± 3.0---- 61.3 ± 3.2
(62.3–71.2)(50.0–51.0)(60.0–65.0)
Postuterine sac (PUS)22.3 ± 1.9---- 47.0 ± 2.6
(18.0–24.2)(22.0–24.0)(45.0–50.0)
Vulva anus distance (VA)123.5 ± 10.3---- -
(105.9–137.6)(84.0–85.0)
Ant. end to vulva349.3 ± 22.3---- -
(311.0–392.7)(242.0–248.0)
Post end to vulva144.8 ± 26.5------
(89.3–170.4)
Tail length37.4 ± 0.8- 45.9 ± 2.5 28.0 ± 3.6
(36.6–38.6)(41.8)(34–42)(43.0–48.8)(30.0–31.0)(24.0–31.0)
Body width at vulva (BWV)14.5 ± 0.8------
(13.1–15.8)
PUS/L4.5 ± 0.4---- -
(3.7–5.2)(6.1–6.6)
PUS/BWV1.6 ± 0.2------
(1.1–1.8)
PUS/VA18.1 ± 1.1--18.9 ± 4.5- -
(16.0–20.5)(9.2–33.8)(22.4–24.0)
Lateral field width2.7 ± 0.4-- ---
(2.1–3.4)(2.2)

Morphometrics of live females of a Florida populations of Aphelenchoides rutgersi from strawberry and reared on Monilinia fructicola compared to those in the original description by Hooper and Myers (1971) and populations from Pakistan and South Africa reported by Erum and Shahina (2010) and Girgan et al_ (2018), respectively_a

Population SubstrateFlorida Monilinia fructicolaFlorida Pyrenochaeta terrestrisFlorida Botrytis cinerea for 2 weeksFlorida B. cinerea for 7 weeksPakistan Triticum sp.South Africa Aristida canescens seeds
ReferencePresent study (N18-00206)Hooper and Myers (1971)Hooper and Myers (1971)Hooper and Myers (1971)Erum and Shahina (2010)Girgan at al. (2018)
Character n20♀♀20♀♀20♀♀20♀♀12♀♀3♀♀
L507.6 ± 71.0535.0 ± 20480.0 ± 25360.0 ± 20440 ± 30556.0 ± 22.6
(371.2–614.7)(500.0–570.0)(430.0–530.0)(320.0–405.0)(370.0–500.0)(542.0–582.0)
A29 ± 227.0 ± 1.825.0 ± 1.727.0 ± 1.726.7 ± 1.434.1 ± 0.8
(25.8–33.5)(23–30)(23–29)(24–31)(24.0–31.7)(33.5–34.9)
B8.4 ± 1.010.7 ± 0.49.3 ± 0.47.60 ± 0.165.7 ± 1.34.6 ± 0.2
(6.5–10.0)(9.7–11.6)(8.3–10.1)(6.7–8.9)(4.4–8.4)(4.4–4.8)
b’4.0 ± 0.65.0 ± 0.54.1 ± 0.43.5 ± 0.34.4 ± 0.8-
(3.0–5.2)(4.2–6.2)(3.6–4.6)(3.1–4.0)(4.1–5.0)
C15.4 ± 1.716.9 ± 0.616.3 ± 1.014.1 ± 0.88.0 ±0.415.8 ± 0.5
(12.9–18.9)(15.9–18.1)(15.0–18.7)(12.4–15.5)(7.2–8.6)(15.5–16.4)
c’3.4 ± 0.43.0 ± 0.22.9 ± 0.13.3 ± 0.25.7 ± 0.43.6 ± 0.3
(2.5–4.0)(2.6–3.4)(2.6–3.2)(2.8–4.0)(4.8–6.4)(3.3–3.9)
V70.3 ± 1.071.0 ± 1.072.0 ± 0.970.0 ± 0.764.5 ± 0.969.0 ± 0.8
(68.6–72.0)(69.0–72.0)(70.0–74.0)(69.0–72.0)(63.3–65.5)(69.0–70.0)
Max. body diameter17.6 ± 3.1----16.0 ± 0.9
(12.8–22.7)(16.0–17.0)
Body diameter at anus or cloacal opening10.0 ± 1.4----10.0 ± 0.9
(7.4–13.3)(9.0–11.0)
Body diameter at vulva (BDV)18.1 ± 2.3----16.0 ± 0.8
(15–23)(15.017.0)
OV or Testis/L24.8 ± 6.460.0 ± 7.150.0 ± 4.624.0 ± 2.8--
(15.4–40.9)(50–77)(42–60)(18–29)
Anterior genital tract length127.2 ± 44.0----220.0 ± 5.6
(70.0–242.5)(215.0–226.0)
Lip region width6.3 ± 0.5--- 5.6 ± 0.4
(5.0–6.9)(4.8–5.6)(5.0–6.0)
Lip region height2.9 ± 0.2--- 3.2 ± 0.5
(2.5–3.0)(2.4–3.2)(3.0–4.0)
Stylet length11.0 ± 0.5 --10.7 ± 0.611.0 ± 0.4
(10.1–11.9)(10.0)(10.0–12.0)(11.0–12.0)
Stylet cone5.4 ± 0.4-----
(4.8–6.0)
Stylet knob height1.5 ± 0.2-----
(1.2–1.9)
Stylet knob width2.3 ± 0.3-----
(1.9-2.8)
Median bulb length13.7 ± 0.7--- 12.0 ±0.5
(12.3–14.9)(12.8–13.6)(12.0–13.0)
Median bulb width10.3 ± 0.7--- 10.0 ± 0.5
(9.0-11.9)(9.6–10.4)(9.0–10.0)
Median bulb valve length4.0 ± 0.4-----
(3.1–4.5)
Median bulb valve width3.0 ± 0.2-----
(2.5–3.4)
Pharynx length60.4 ± 2.144 ± 246 ± 227.0 ± 1.7-
(54.4–66.3)(42–47)(42–49)(24–31)(58.0)
Pharyngeal overlap67.5 ± 12.5-----
(45.5–95.8)
Ant. end to pharyngeal gland lobe127.8 ± 13.7----122.0 ± 1.5
(99.9–162.1)(121.0–124.0)
Anterior end to excretory pore66.6 ± 5.4----76.0 ±1.9
(58.4–76.2)(75.0–76.0)
Postuterine sac26.1 ± 4.5---42.6 ±2.240.0 ± 4.1
(15.8–41.0)(36.0–55.0)(37.0–43.0)
Vulva anus distance117.7 ± 19.2-----
(76.2–149.4)
Ant. end to vulva356.9 ± 50.3---386.0 ± 13.6-
(266.3–437.5)(374.0 401.0)
Post end to vulva150.7 ± 21.7-----
(104.9–191.9)
Tail length33.0 ± 3.6 --35.0 ± 2.1-
(26.7–42.5)(30.5)(33.0–37.0)
Spermatheca length14.1 ± 3.9-----
(9–21)
Spermatheca width9.9 ± 1.6-----
(8–13)
PUS/VA22.1 ± 3.8-----
(16.1–27.5)
Lateral field width3.0 ± 0.2-----
(2.5–3.4)
PUS/L5.1 ± 0.8-----
(3.8–6.4)
PUS/BDV1.5 ± 0.2-----
(1.0–1.9)
Spikes111-1-

Morphometrics of live males of a Florida population of Aphelenchoides rutgersi from strawberry reared on Monilinia fructicola compared to those in the original description by Hooper and Myers (1971) and a population from Pakistan described by Erum and Shahina (2010)_a

Population SubstrateFlorida Monilinia fructicolaFlorida Botrytis cinereaPakistan Triticum sp.
ReferencePresent study N18-00206Hooper and Myers (1971)Erum and Shahina (2010)
Character n2♂♂20♂♂7♂♂
L538.8 ± 20.5440.0 ± 35400.0 ± 30.0
(518.3−559.2)(380.0−490.0)(360.0−470.0)
A29.7 ± 0.329.0 ± 2.828.7 ± 2.5
(29.4−30.0)(21−32)(24.0−31.7)
B8.9 ± 0.48.7 ± 0.95.3 ± 1.3
(8.5−9.3)(7.1−11.0)(3.9−7.2)
b’4.0 ± 0.14.0 ± 0.14.5 ± 1.0
(4.0−4.1)(3.6−4.4)(4.2−5.5)
C15.9 ± 1.214.3 ± 0.813.7 ± 1.6
(14.7−17.2)(13.0−15.4)(10.6−16.0)
c’2.6 ± 0.32.9 ± 0.22.7 ± 0.3
(2.3−2.9)(2.4−3.3)(2.4−3.1)
Max. body diameter18.2 ± 0.9--
(17.3−19.0)
Body diameter at cloacal opening13 ± 1--
(12−14)
Testis240.5 ± 8.5--
(232−249)
Testis/L%44.7 ± 0.172.0 ± 6.2-
(44.5−44.8)(58.0−78.0)
Lip region width6.5 ± 0.2--
(6.3−6.6)
Lip region height3--
Stylet length11.910.0 ± 1 (9.5−11.0)10.6 ± 0.4
(10.0−11.2)
Stylet cone6--
(5.9−6.0)
Stylet knob width2.4 ± 0.1--
(2.3−2.4)
Stylet knob height1.8 ± 0.1--
(1.7−1.8)
Median bulb width10.0 ± 0.5--
(9.5−10.5)
Median bulb length14.2 ± 0.7--
(13.5−14.8)
Median bulb valve length4.5--
Median bulb s valve width3--
Pharynx length60.6 ± 0.245 ± 3-
(60.4−60.8)(38.0−51.0)
Pharyngeal overlap72.8 ± 3.5--
(69.3−76.2)
Ant. end to pharyngeal gland lobe133.7 ± 2.9--
(130.8−136.6)
Anterior end to excretory pore67.8 ± 3.5--
(64.3−71.2)
Tail length33.9 ± 1.3--
(32.6−35.2)
Spicule length18.2 ± 0.615.5 ± 1.014.2 ± 1.7
(16.6−19.8)(14−17)(13.0−17.0)
Lateral field width3--
DOI: https://doi.org/10.2478/jofnem-2024-0021 | Journal eISSN: 2640-396X | Journal ISSN: 0022-300X
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Language: English
Submitted on: Apr 29, 2023
Published on: Jul 5, 2024
Published by: Society of Nematologists, Inc.
In partnership with: Paradigm Publishing Services
Publication frequency: 1 times per year
Keywords:
facultative parasitism,
foliar nematodes,
×,
morphology,
morphometrics,
phylogeny,
taxonomy
Related subjects:
Life sciences,
Life sciences, other

© 2024 Clemen J. Oliveira, Sergei A. Subbotin, Johan A. Desager, Paul Dahlin, Silvia Vau, Renato N. Inserra, published by Society of Nematologists, Inc.
This work is licensed under the Creative Commons Attribution 4.0 License.

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