Table 1.
Populations of Aphelenchoides characterized in the present study.
| Species | Location | Host | Sample code | GenBank accession number | Source | ||
|---|---|---|---|---|---|---|---|
| SSU | LSU | COI | |||||
| A. bicaudatus | Wimauma, Florida, USA | Fragaria × ananassa | N18-1001-3 | OK644201 | OK644281 | OK644199 | C. Oliveira |
| OK644282 | |||||||
| A. rutgersi | Wimauma, Florida, USA | Fragaria × ananassa | N18-00206 | OK644202 | OK644283 | OK644295 | C. Oliveira |
| OK644203 | |||||||
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.
Table 2.
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 Substrate | Florida Monilinia fructicola | Japan Paddy field | Illinois Pyrenochaeta terrestris | Taiwan Alternaria citri | South Korea Botrytis cinerea | Pakistan Raphanus sativus | South Africa Pennisetum clandestinum |
|---|---|---|---|---|---|---|---|
| Reference | Present paper N18-01001-3 | Imamura (1931) | Siddiqui and Taylor (1967) | Jen et al. (2012) | Kim et al. (2016) | Israr et al. (2017) | Shokoohi and Moyo (2022) |
| Character n | 10♀♀ | 18♀♀ | 50♀♀ | 50♀♀ | 7♀♀ | 2♀♀ | 8♀♀ |
| L | 494.1 ± 32.0 | 499 ± 67.9 | 517.9 ± 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) | |
| A | 31.2 ± 3.6 | 33.0 ± 2.4 | 28.3 ± 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) | |
| B | 8.0 ± 0.5 | 9.0 ± 0.7 | 7.3 ± 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) | |||||
| C | 13.2 ± 0.9 | 11.9 ± 0.9 | 11.3 ± 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 ± 0.5 | 4.6 ± 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) | |||
| V | 68.7 ± 1.5 | 68.5 ± 1.2 | 66.0 ± 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) | |
| OV | 27.8 ± 2.0 | - | - | 15.2 ± 2.7 | - | - | |
| (23.9–30.9) | (11.0–22.0) | (12.0–12.5) | |||||
| Max. body diameter | 15.9 ± 1.3 | - | - | - | - | 15.6 ± 1.5 | |
| (13.5–17.8) | (25.0–26.2) | (14.0–17.0) | |||||
| Body diameter at anus | 8.6 ± 0.8 | - | - | - | - | 8.8 ± 0.7 | |
| (7.2–9.9) | (11.8) | (8.0–9.0) | |||||
| Anterior genital tract length | 136.9 ± 10.4 | - | - | - | - | 179.3 ± 18.0 | |
| (121.7–150.1) | (84.0–95.0) | (167.0–200.0) | |||||
| Lip region width | 4.9 ± 0.3 | - | - | - | 5.7 ± 0.1 | ||
| (4.5–5.5) | (5.0–5.2) | (4.0–4.3) | (5.6–5.8) | ||||
| Lip region height | 2.8 ± 0.2 | - | - | - | 2.8 ± 0.9 | ||
| (2.4–3.0) | (2.5–2.9) | (2.0–2.0) | (2.0–4.0) | ||||
| Stylet length | 10.9 ± 0.4 | - | 10.4 ± 0.6 | 11.2 ± 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 cone | 5.1 ± 0.3 | - | - | - | - | - | 4.7 ±0.3 |
| (4.5–5.8) | (4.5–5.0) | ||||||
| Stylet knob height | 1.4 ± 0.2 | - | - | - | - | - | - |
| (1.2-1.7) | |||||||
| Stylet knob width | 1.9 ± 0.3 | - | - | - | - | - | - |
| (1.2–2.3) | |||||||
| Median bulb length | 12.1 ± 0.7 | - | - | - | 11.2 ± 0.7 | ||
| (10.9–13.3) | (12.8–12.9) | (10.0–10.0) | (11.0–12.0) | ||||
| Median bulb width | 9.6 ± 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 length | 4.1 ± 0.4 | - | - | - | - | - | - |
| (3.6–4.9) | |||||||
| Median bulb valve width | 2.9 ± 0.2 | - | - | - | - | - | - |
| (2.5–3.2) | |||||||
| Pharynx length | 62.1 ± 2.7 | - | - | - | - | 88.3 ± 11.2 | |
| (59.0–68.7) | (90.0–92.0) | (76.0–98.0) | |||||
| Pharyngeal overlap | 57.0 ± 2.1 | - | - | - | - | - | |
| (53.0–59.7) | (50.0–75.0) | ||||||
| Ant. end to pharyngeal gland lobe | 118.8 ± 3.3 | - | - | - | - | - | - |
| (4.5–5.8) | |||||||
| Anterior end to excretory pore | 66.9 ± 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 vulva | 349.3 ± 22.3 | - | - | - | - | - | |
| (311.0–392.7) | (242.0–248.0) | ||||||
| Post end to vulva | 144.8 ± 26.5 | - | - | - | - | - | - |
| (89.3–170.4) | |||||||
| Tail length | 37.4 ± 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/L | 4.5 ± 0.4 | - | - | - | - | - | |
| (3.7–5.2) | (6.1–6.6) | ||||||
| PUS/BWV | 1.6 ± 0.2 | - | - | - | - | - | - |
| (1.1–1.8) | |||||||
| PUS/VA | 18.1 ± 1.1 | - | - | 18.9 ± 4.5 | - | - | |
| (16.0–20.5) | (9.2–33.8) | (22.4–24.0) | |||||
| Lateral field width | 2.7 ± 0.4 | - | - | - | - | - | |
| (2.1–3.4) | (2.2) |
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.
Table 3.
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 Substrate | Florida Monilinia fructicola | Florida Pyrenochaeta terrestris | Florida Botrytis cinerea for 2 weeks | Florida B. cinerea for 7 weeks | Pakistan Triticum sp. | South Africa Aristida canescens seeds |
|---|---|---|---|---|---|---|
| Reference | Present study (N18-00206) | Hooper and Myers (1971) | Hooper and Myers (1971) | Hooper and Myers (1971) | Erum and Shahina (2010) | Girgan at al. (2018) |
| Character n | 20♀♀ | 20♀♀ | 20♀♀ | 20♀♀ | 12♀♀ | 3♀♀ |
| L | 507.6 ± 71.0 | 535.0 ± 20 | 480.0 ± 25 | 360.0 ± 20 | 440 ± 30 | 556.0 ± 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) | |
| A | 29 ± 2 | 27.0 ± 1.8 | 25.0 ± 1.7 | 27.0 ± 1.7 | 26.7 ± 1.4 | 34.1 ± 0.8 |
| (25.8–33.5) | (23–30) | (23–29) | (24–31) | (24.0–31.7) | (33.5–34.9) | |
| B | 8.4 ± 1.0 | 10.7 ± 0.4 | 9.3 ± 0.4 | 7.60 ± 0.16 | 5.7 ± 1.3 | 4.6 ± 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 ± 0.6 | 5.0 ± 0.5 | 4.1 ± 0.4 | 3.5 ± 0.3 | 4.4 ± 0.8 | - |
| (3.0–5.2) | (4.2–6.2) | (3.6–4.6) | (3.1–4.0) | (4.1–5.0) | ||
| C | 15.4 ± 1.7 | 16.9 ± 0.6 | 16.3 ± 1.0 | 14.1 ± 0.8 | 8.0 ±0.4 | 15.8 ± 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 ± 0.4 | 3.0 ± 0.2 | 2.9 ± 0.1 | 3.3 ± 0.2 | 5.7 ± 0.4 | 3.6 ± 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) | |
| V | 70.3 ± 1.0 | 71.0 ± 1.0 | 72.0 ± 0.9 | 70.0 ± 0.7 | 64.5 ± 0.9 | 69.0 ± 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 diameter | 17.6 ± 3.1 | - | - | - | - | 16.0 ± 0.9 |
| (12.8–22.7) | (16.0–17.0) | |||||
| Body diameter at anus or cloacal opening | 10.0 ± 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/L | 24.8 ± 6.4 | 60.0 ± 7.1 | 50.0 ± 4.6 | 24.0 ± 2.8 | - | - |
| (15.4–40.9) | (50–77) | (42–60) | (18–29) | |||
| Anterior genital tract length | 127.2 ± 44.0 | - | - | - | - | 220.0 ± 5.6 |
| (70.0–242.5) | (215.0–226.0) | |||||
| Lip region width | 6.3 ± 0.5 | - | - | - | 5.6 ± 0.4 | |
| (5.0–6.9) | (4.8–5.6) | (5.0–6.0) | ||||
| Lip region height | 2.9 ± 0.2 | - | - | - | 3.2 ± 0.5 | |
| (2.5–3.0) | (2.4–3.2) | (3.0–4.0) | ||||
| Stylet length | 11.0 ± 0.5 | - | - | 10.7 ± 0.6 | 11.0 ± 0.4 | |
| (10.1–11.9) | (10.0) | (10.0–12.0) | (11.0–12.0) | |||
| Stylet cone | 5.4 ± 0.4 | - | - | - | - | - |
| (4.8–6.0) | ||||||
| Stylet knob height | 1.5 ± 0.2 | - | - | - | - | - |
| (1.2–1.9) | ||||||
| Stylet knob width | 2.3 ± 0.3 | - | - | - | - | - |
| (1.9-2.8) | ||||||
| Median bulb length | 13.7 ± 0.7 | - | - | - | 12.0 ±0.5 | |
| (12.3–14.9) | (12.8–13.6) | (12.0–13.0) | ||||
| Median bulb width | 10.3 ± 0.7 | - | - | - | 10.0 ± 0.5 | |
| (9.0-11.9) | (9.6–10.4) | (9.0–10.0) | ||||
| Median bulb valve length | 4.0 ± 0.4 | - | - | - | - | - |
| (3.1–4.5) | ||||||
| Median bulb valve width | 3.0 ± 0.2 | - | - | - | - | - |
| (2.5–3.4) | ||||||
| Pharynx length | 60.4 ± 2.1 | 44 ± 2 | 46 ± 2 | 27.0 ± 1.7 | - | |
| (54.4–66.3) | (42–47) | (42–49) | (24–31) | (58.0) | ||
| Pharyngeal overlap | 67.5 ± 12.5 | - | - | - | - | - |
| (45.5–95.8) | ||||||
| Ant. end to pharyngeal gland lobe | 127.8 ± 13.7 | - | - | - | - | 122.0 ± 1.5 |
| (99.9–162.1) | (121.0–124.0) | |||||
| Anterior end to excretory pore | 66.6 ± 5.4 | - | - | - | - | 76.0 ±1.9 |
| (58.4–76.2) | (75.0–76.0) | |||||
| Postuterine sac | 26.1 ± 4.5 | - | - | - | 42.6 ±2.2 | 40.0 ± 4.1 |
| (15.8–41.0) | (36.0–55.0) | (37.0–43.0) | ||||
| Vulva anus distance | 117.7 ± 19.2 | - | - | - | - | - |
| (76.2–149.4) | ||||||
| Ant. end to vulva | 356.9 ± 50.3 | - | - | - | 386.0 ± 13.6 | - |
| (266.3–437.5) | (374.0 401.0) | |||||
| Post end to vulva | 150.7 ± 21.7 | - | - | - | - | - |
| (104.9–191.9) | ||||||
| Tail length | 33.0 ± 3.6 | - | - | 35.0 ± 2.1 | - | |
| (26.7–42.5) | (30.5) | (33.0–37.0) | ||||
| Spermatheca length | 14.1 ± 3.9 | - | - | - | - | - |
| (9–21) | ||||||
| Spermatheca width | 9.9 ± 1.6 | - | - | - | - | - |
| (8–13) | ||||||
| PUS/VA | 22.1 ± 3.8 | - | - | - | - | - |
| (16.1–27.5) | ||||||
| Lateral field width | 3.0 ± 0.2 | - | - | - | - | - |
| (2.5–3.4) | ||||||
| PUS/L | 5.1 ± 0.8 | - | - | - | - | - |
| (3.8–6.4) | ||||||
| PUS/BDV | 1.5 ± 0.2 | - | - | - | - | - |
| (1.0–1.9) | ||||||
| Spikes | 1 | 1 | 1 | - | 1 | - |
Table 4.
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 Substrate | Florida Monilinia fructicola | Florida Botrytis cinerea | Pakistan Triticum sp. |
|---|---|---|---|
| Reference | Present study N18-00206 | Hooper and Myers (1971) | Erum and Shahina (2010) |
| Character n | 2♂♂ | 20♂♂ | 7♂♂ |
| L | 538.8 ± 20.5 | 440.0 ± 35 | 400.0 ± 30.0 |
| (518.3−559.2) | (380.0−490.0) | (360.0−470.0) | |
| A | 29.7 ± 0.3 | 29.0 ± 2.8 | 28.7 ± 2.5 |
| (29.4−30.0) | (21−32) | (24.0−31.7) | |
| B | 8.9 ± 0.4 | 8.7 ± 0.9 | 5.3 ± 1.3 |
| (8.5−9.3) | (7.1−11.0) | (3.9−7.2) | |
| b’ | 4.0 ± 0.1 | 4.0 ± 0.1 | 4.5 ± 1.0 |
| (4.0−4.1) | (3.6−4.4) | (4.2−5.5) | |
| C | 15.9 ± 1.2 | 14.3 ± 0.8 | 13.7 ± 1.6 |
| (14.7−17.2) | (13.0−15.4) | (10.6−16.0) | |
| c’ | 2.6 ± 0.3 | 2.9 ± 0.2 | 2.7 ± 0.3 |
| (2.3−2.9) | (2.4−3.3) | (2.4−3.1) | |
| Max. body diameter | 18.2 ± 0.9 | - | - |
| (17.3−19.0) | |||
| Body diameter at cloacal opening | 13 ± 1 | - | - |
| (12−14) | |||
| Testis | 240.5 ± 8.5 | - | - |
| (232−249) | |||
| Testis/L% | 44.7 ± 0.1 | 72.0 ± 6.2 | - |
| (44.5−44.8) | (58.0−78.0) | ||
| Lip region width | 6.5 ± 0.2 | - | - |
| (6.3−6.6) | |||
| Lip region height | 3 | - | - |
| Stylet length | 11.9 | 10.0 ± 1 (9.5−11.0) | 10.6 ± 0.4 |
| (10.0−11.2) | |||
| Stylet cone | 6 | - | - |
| (5.9−6.0) | |||
| Stylet knob width | 2.4 ± 0.1 | - | - |
| (2.3−2.4) | |||
| Stylet knob height | 1.8 ± 0.1 | - | - |
| (1.7−1.8) | |||
| Median bulb width | 10.0 ± 0.5 | - | - |
| (9.5−10.5) | |||
| Median bulb length | 14.2 ± 0.7 | - | - |
| (13.5−14.8) | |||
| Median bulb valve length | 4.5 | - | - |
| Median bulb s valve width | 3 | - | - |
| Pharynx length | 60.6 ± 0.2 | 45 ± 3 | - |
| (60.4−60.8) | (38.0−51.0) | ||
| Pharyngeal overlap | 72.8 ± 3.5 | - | - |
| (69.3−76.2) | |||
| Ant. end to pharyngeal gland lobe | 133.7 ± 2.9 | - | - |
| (130.8−136.6) | |||
| Anterior end to excretory pore | 67.8 ± 3.5 | - | - |
| (64.3−71.2) | |||
| Tail length | 33.9 ± 1.3 | - | - |
| (32.6−35.2) | |||
| Spicule length | 18.2 ± 0.6 | 15.5 ± 1.0 | 14.2 ± 1.7 |
| (16.6−19.8) | (14−17) | (13.0−17.0) | |
| Lateral field width | 3 | - | - |
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.
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.
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.
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.
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).