The invasive phytophagous millipede
Nematodes were discovered to be associated with the phytophagous millipede
Nematodes were imaged at ×40‒60 on an Olympus BX51 microscope with a DP71 camera (Olympus America Inc., Center Valley, PA) equipped with polarization optics. Measurements in micrometers were made with an ocular micrometer on a Zeiss Ultraphot II compound microscope with Nomarski optics on alcohol-distorted specimens before formalin fixation, and images were also directly measured with CellSens ver 1.6 imaging software integrated with the camera (Olympus America LLC, Center Valley, PA). Fixed specimens of Rhabditidae juveniles were processed for permanent slides according to the formalin-glycerine method (Golden, 1990). Imaged specimens of Diplogastridae were subsequently processed for PCR so no vouchers are available. For scanning electron microscopy (SEM)
Specimens of each nematode were mechanically disrupted in 20 µl of extraction buffer (Baldwin et al., 1997) then stored in PCR tubes at –80°C until needed. Extracts were prepared from thawed pools by incubating the tubes at 60°C for 60 min, followed by 95°C for 15 min. to deactivate proteinase K. Two microliters of the extract was used for each 25 µl PCR reaction.
The ribosomal LSU D2-D3 expansion segment was amplified with primers D2A 5′-ACAAGTACCGTGAGGGAAAGTTG-3′ and D3B 5′TCGGAAGGAACCAGCTACTA-3′ (Nunn et al., 1996) using previously published amplification procedures (Baldwin et al., 1997 for
The 18S sequences reaction components included, per 25 µL reaction: 17.55 µL H2O, 2.5 µL 10X PCR buffer, 0.5 µL dNTP mix (10 mM each dNTP), 0.75 µL MgCl2, 50 mM, 0.75 µL 18S-G18S4 primer, 10 µM, 0.75 µL 18S-18P primer, 10 µM, 0.2 µL Taq (Invitrogen platinum, 1 unit), 23 µL of the above mix + 2 µL template DNA; cycling conditions were 94 C – 2 min, 94 C – 30 sec, 50 C – 30 sec, 68 C – 2 min, repeat 40 times: steps 2 through 4, 68 C – 10 min, 4 C – Hold, with primers of Thomas et al. (1997) used for PCR and sequencing.
PCR products were visualized and purified within the Lonza FlashGelTM DNA system (VWR International, Radnor, PA), and sequence was generated with an ABI BigDye Terminator v3.1 kit with sample sequence data analyzed on an ABI 3130XLAutomated DNA sequencer (Applied Biosystems, Foster City, CA, USA). The 28S sequence was determined on both strands using D2A and D3B primers.
The 28S rDNA sequences related to
Nematode 28S rDNA sequences for selected taxa in Figure 3.
Species | Isolate | Locality | Accession |
---|---|---|---|
|
DF5075 | The UK | EU195992 |
|
DF5010 | Spain | EU195965 |
|
DF5091 | Fiji | EU195966 |
|
USA | FJ547239 | |
|
China | EF503691 | |
|
Tumian154 | China | EU273599 |
|
SB169 | Germany | EU195968 |
|
DF5020 | The USA | AY602176 |
|
SB218 | Australia | This paper |
|
YNb59 | China | AY177182 |
|
Japan | This paper | |
|
DF5006 | France | AY602177 |
Nematode 18S rDNA sequences for selected taxa in Figure 4.
Species | Isolate | Locality | Accession |
---|---|---|---|
|
N2 | The UK | AY268117 |
|
1206 | – | FJ040430 |
|
RS9003 | Germany | KJ877235 |
|
RS9002 | The USA | KJ877234 |
|
Luc1 | Japan | AB597232 |
|
EJR2014 | Japan | KF924399 |
|
100D10 | Japan | This paper |
|
wb31 | Belgium | GU943512 |
|
MonEStr | – | AY593924 |
|
FDL-2015 M63_39 | Italy | LN827618 |
|
VS-2014 RS5441 | France | KJ877210 |
|
VS-2014 RS9007 | Mexico | KJ877209 |
|
VS-2014 RS9008 | New Caledonia | KJ877211 |
|
NK126 | Japan | AB326310 |
|
VS-TU-2014-2 | Germany | KJ877207 |
|
VS-TU-2014-3 | Germany | KJ877208 |
|
RS9011 | Ghana | KJ877231 |
|
RS9012 | South Africa | KJ877232 |
|
wb3 | Belgium | EU306343 |
(Fig. 1)
This juvenile of
The small distance tree based on a 175 base pair (bp) MAFFT alignment (Fig. 3, Table 1) demonstrated that
N = 10 heat-killed hermaphrodite specimens, body length = 1,661 ± 220 (1,340–2,120) µm, body width = 130 ± 24 (100–180) µm, a = 13.0 ± 1.8 (8.7–15.1), b = 7.5 ± 0.7 (6.1–8.8), c = 14.3 ± 1.6 (12–17.4), c' = 2.6 ± 0.2 (2.3–2.9), V = 50 ± 2 (47–54)% , stoma length = 23 ± 1 (21–25) µm, stoma width = 5.7 ± 0.5 (5–6) µm, stoma length/stoma width = 4.5 ± 0.5 (3.3–4.9).
The original description (Sudhaus and Schulte, 1989) is supplemented by these measurements of adult females made from specimens cultured on
(Fig. 2)
Female body N = 1 (Fig. 2A) length = 890 µm, body width = 44.2 µm, stoma length = 14.9 µm, pharynx (Fig. 2B) length = 139 µm, anterior pharynx/posterior pharynx ratio = 1.7, vulva-anus distance = 278.8 µm, tail length = 254.0 µm, V = 40%, a = 20.1, b = 6.4, c = 3.5, c′ = 11, Paired gonads = 24.4% body length, anterior gonad = 116, posterior gonad = 101.
Male body n = 1 (Fig. 2C) length = 642 µm, body width = 29.2 µm, stoma length = 13.6 µm, tail length = 192 µm, spicule length = 26.2 µm, a = 22, b = 6.6, c = 3.4, c′ = 7.5.
Stoma of male and female with eight prominent cheilostom striations visible laterally defining seven plates, anterior esophagus about 1.7 × the posterior esophagus. Vulva-anus distance = 1.2 × tail length, long female tail ending in a thread. Pharynx, intestine, gonad, and genital papillae of male poorly defined.
The specimens from the millipede come closest to
The DNA sequences were submitted to GenBank: for
Three primary groups of nematodes have been reported as associates of millipedes: Rhigonematomorph millipede gut parasite species (Hunt, 1996; Malysheva and Spiridonov, 2013), Oxyuridomorph, Thelastomatoidea and Coronostomatoidea (Adamson and van Waerebeke, 1982; Jex et al., 2005; Phillips et al., 2016), and Rhabditida:
The
The nematode family Diplogastridae is one of the most phenotypically diverse within Rhabditida (Susoy and Herrmann, 2012). It is especially difficult to diagnose genera such as