Research Article |
Corresponding author: Dao-Hong Zhu ( daohongzhu@yeah.net ) Corresponding author: Zhiwei Liu ( zliu@eiu.edu ) Academic editor: Andreas Köhler
© 2022 Yin Pang, Cheng-Yuan Su, Jun-Qiao Zhu, Xiao-Hui Yang, Jia-Lian Zhong, Dao-Hong Zhu, Zhiwei Liu.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Pang Y, Su C-Y, Zhu J-Q, Yang X-H, Zhong J-L, Zhu D-H, Liu Z (2022) A new species of Andricus Hartig, 1840 (Hymenoptera, Cynipidae) from China, with references to DNA taxonomy and Wolbachia infection. ZooKeys 1134: 52-73. https://doi.org/10.3897/zookeys.1134.89267
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In the present paper, a new species of cynipid gall wasp, Andricus elodeoides Liu & Pang, is described from several provinces in southern China. The new species is closely related to the recently redescribed A. mairei (Kieffer, 1906). In addition to differences in adult and gall morphology, the new species is also readily separated by COI sequences, with a 6.2–8.9% genetic distance between populations of the new species and those of A. mairei. A contrasting difference in sex ratios was also observed between the two species, with A. elodeoides extremely female-biased (95.5–97.8% female) while A. mairei male-biased to more balanced (5.4–43.5% female). PCR screening for Wolbachia infection further revealed contrasting infection rates between populations of A. elodeoides and A. mairei: the Wolbachia infection rate was 0% in A. elodeoides and 100% in A. mairei. Cytoplasmic incompatibility induced by Wolbachia is proposed as a potential mechanism of speciation of the sympatric A. elodeoides and A. mairei.
Andricus elodeoides, gall wasp, phylogeny, Quercus serrata, taxonomy
The genus Andricus Hartig, 1840 (Hymenoptera, Cynipoidea, Cynipidae, Cynipini) is the largest genus of the oak-gall wasp tribe Cynipini, currently comprising approximately 400 known species (
The unusually high diversity of Andricus species among all the genera of the tribe Cynipini may be an artifact, as the genus is not well defined and often has been treated as a “trash can” genus in Cynipini (
One of the genera synonymized with Andricus Hartig, 1840 by
The galls of gall wasps were collected from 12 locations in six provinces in southern China in late spring to early summer from 2012 to 2019 (Table
Collection information, female ratio and Wolbachia infection in A. elodeoides sp. nov. and A. mairei.
Location(code) | Coordinates | Date of gall collection | Date of adult emergence | Insect species | Female: male | Wolbachia infect frequency (%) |
---|---|---|---|---|---|---|
Xinyang, Henan (XY) | 32°02'N, 113°53'E | May, 2012 | May, 2012 | A. mairei | 8: 46 (14.8%*) | 100 (20)† |
A. elodeoides | 64: 2 (97.0%) | 0 (20) | ||||
Jinzhai, Anhui (JZ) | 31°38'N, 115°58'E | May, 2014 | May, 2014 | A. mairei | 64: 318 (16.8%) | 100 (20) |
A. elodeoides | 224: 5 (97.8%) | 0 (40) | ||||
May, 2015 | May, 2015 | A. mairei | 12: 63 (16.0%) | 100 (20) | ||
A. elodeoides | 78: 2 (97.5%) | 0 (20) | ||||
May, 2016 | May, 2016 | A. mairei | 19: 213 (8.2%) | 100 (20) | ||
A. elodeoides | 86: 3 (96.6%) | 0 (20) | ||||
May, 2017 | May, 2017 | A. mairei | 9: 43 (17.3%) | 100 (20) | ||
A. elodeoides | 123: 4 (96.9%) | 0 (20) | ||||
May, 2018 | May, 2018 | A. mairei | 29: 512 (5.4%) | – | ||
A. elodeoides | 128: 6 (95.5%) | – | ||||
May, 2019 | May, 2019 | A. mairei | 46: 612 (7.0%) | – | ||
A. elodeoides | 224: 8 (96.6%) | – | ||||
Shucheng, Anhui (SHC) | 31°21'N, 116°04'E | May, 2016 | May, 2016 | A. mairei | 34: 104 (24.6%) | 100 (20) |
A. elodeoides | 426: 13 (97.0%) | 0 (40) | ||||
May, 2017 | May, 2017 | A. mairei | 6: 46 (11.5%) | 100 (20) | ||
A. elodeoides | 91: 2 (97.8%) | 0 (20) | ||||
May, 2018 | May, 2018 | A. mairei | 16: 65 (19.8%) | 100 (20) | ||
A. elodeoides | 73: 3 (96.1%) | 0 (20) | ||||
May, 2019 | May, 2019 | A. mairei | 9: 56 (13.8%) | 100 (20) | ||
A. elodeoides | 129: 6 (95.6%) | 0 (20) | ||||
Taihu, Anhui (TH) | 30°34'N, 116°04'E | May, 2016 | May, 2016 | A. mairei | 12: 32 (27.3%) | 100 (20) |
A. elodeoides | 94: 3 (96.9%) | 0 (40) | ||||
Wuhan, Hubei (WH) | 30°31'N, 114°31'E | May, 2014 | May, 2014 | A. mairei | 8: 12 (40.0%) | 100 (20) |
A. elodeoides | 166: 6 (96.5%) | 0 (40) | ||||
Changsha, Hunan CS) | 28°25'N, 113°07'E | May, 2016 | May, 2016 | A. mairei | 102: 136 (42.9%) | 100 (20) |
May, 2017 | May, 2017 | A. mairei | 258: 349 (42.9%) | – | ||
May, 2018 | May, 2018 | A. mairei | 121: 157 (43.5%) | – | ||
Suichang, Zhejiang (SUC) | 28°37'N, 119°19'E | April, 2018 | May, 2018 | A. elodeoides | 79: 2 (97.5%) | 0 (30) |
A. mairei | 124: 987 (11.2%) | 100 (20) | ||||
Qingyuan, Zhejiang (QY) | 27°44'N, 119°15'E | April, 2018 | May, 2018 | A. elodeoides | 76: 3 (96.2%) | 0 (20) |
A. mairei | 23: 245 (8.6%) | 100 (20) | ||||
Zhenghe, Fujian (ZH) | 27°23'N, 118°2'E | April, 2018 | May, 2018 | A. mairei | 66: 568 (10.4%) | 100 (20) |
Zhouning, Fujian (ZN) | 27°13'N, 119°20'E | April, 2018 | May, 2018 | A. mairei | 13: 86 (13.1%) | 100 (20) |
Guiding, Guizhou (GD) | 26°37'N, 107°14'E | May, 2017 | Jun, 2017 | A. mairei | 6: 24 (20.0%) | 100 (20) |
Shaoguan, Guangdong (SG) | 24°59'N, 113°01'E | April, 2017 | May, 2017 | A. mairei | 34: 256 (11.7%) | 100 (20) |
Specimens for conventional morphological examination were air dried at room temperature before mounting. Specimens mounted to pinned triangle-card paper were studied under a stereomicroscope (SZX7, Olympus, Japan) and automatically stacked photographs were taken with Leica M205C microscope system (Leica, Germany) equipped with Leica DMC6200 digital camera connected to a computer. Additional specimens were dissected out and transferred to diluted ammonia (5%) and kept overnight to remove debris that might interfere with observation. Cleansed parts were then rinsed in distilled water and dehydrated gradually through 25%, 50%, 75%, and 100% ethanol solutions, and finally stored in 100% ethanol. Dehydrated specimen parts were air-dried before being mounted onto aluminum stub (Ted Pella, Redding, CA, USA) with copper conductive tape (3M). Gold-coated specimens were examined with JEOL JSM-6380Lv SEM (JEOL, Japan) at CSUFT with 15 KV voltage, and selected frames were saved as digitized high-resolution TIFF images.
We follow
Three individuals from each population of two gall wasp species were used for DNA extraction. The insects were washed in sterile water before DNA extraction to avoid surface contamination. Total DNA was extracted from each individual using SDS/proteinase K digestion and a phenol-chloroform extraction. Extracted DNA pellets were air dried, resuspended in 50 µl sterile water, and then stored at 4 °C before being processed for PCR and sequencing.
For phylogenetic analysis, we chose a specific region of the mitochondrial cytochrome c oxidase subunit I gene (COI) and the nuclear large ribosomal subunit gene (28S), which were amplified with the primes HCO-2198 (5′-TAAACTTCAGGGTGACCAAAAAATCA-3′) and LCO-1490 (5′-GGTCAACAAATCATAAAGATATTGG-3′) (
Sequences of mitochondrial COI and nuclear 28S genes used in the phylogenetic analysis.
Gall wasp | COI | 28S D2 | Reference |
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Andricus caputmedusae | DQ012619 | EF030040 |
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Andricus curvator | DQ012621 | AF395155 |
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Andricus coriarius | DQ012620 | DQ012579 |
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Andricus crystallinus | MT179597 | MT183614 |
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Andricus hakonensis | MT179612 | MT183628 |
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Andricus kollari | AF395176 | AF395156 |
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Andricus pictus | DQ012625 | DQ012583 |
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Andricus quercusstrobilana | DQ012617 | DQ012576 |
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Andricus rochai | MT179600 | MT183671 |
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Andricus xishuangbannaus | MT179618 | MT183634 |
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Andricus mairei (ILV92) | MT179620 |
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(ILV90) | MT179616 | ||
(ILV87) | MT179614 | ||
(ILV86) | MT179613 | ||
(ILV32) | MT179604 | ||
(ILV31) | MT179603 | ||
(ILV30) | MT179602 | ||
(ILV91) | MT179617 | ||
Andricus mairei | ON803612–ON803624 | ON911591–ON911603 | Present study |
Andricus elodeoides | ON803625–ON803631 | ON911604–ON911610 | Present study |
Melikaiella bicolor | MT179619 | MT183623 |
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Dryocosmus liui | MG754067 | MN633412 |
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The COI and 28S gene sequences of 11 species of Andricus (including eight populations of A. mairei) and Dryocosmus liui and Melikaiella bicolor (as outgroups) were retrieved from GenBank (https://www.ncbi.nlm.nih.gov/genbank/) (Table
The final dataset was subjected to MEGA 11.0 for evaluation of best fit nucleotide substitution model (
To compare directly with a recent study on A. mairei and related species based solely on COI (
Finally, the pair-wise genetic distance in the COI sequences from all populations of A. elodeoides and A. mairei, and other two Andricus species were calculated, using the MEGA 11.0 (
Wolbachia infections were screened by PCR with the Wolbachia-specific primers wsp-81F and wsp-691R that amplify a 575–625 bp fragment of the wsp gene encoding Wolbachia surface protein (
Holotype ♀; Paratypes: 10♀, 8♂♂. China, Hunan Province, Changsha City (113°07'N, 28°25'E), 2011-V-11–20, leg. Xiao-Hui Yang, deposited in Insect Collection, Central South University of Forestry and Technology (CSUFT), Changsha, Hunan.
The species epithet derived from Elodea, the genus name of the aquatic plants well known as waterweeds, referring to the superficial resemblance of the cluster of galls of the species to these plants.
Same data as holotype, 3♂, 3♀ (Cheng-Yuan Su leg.). Jinzhai (31°38'N, 115°58'E), Anhui province. 3♂, 3♀ (Cheng-Yuan Su leg.). Wuhan (30°31'N, 114°31'E), Hubei province. 3♂, 3♀ (Cheng-Yuan Su leg.). Suichang (28°37'N, 119°19'E), Zhejiang province. 1♂, 1♀ (Cheng-Yuan Su leg.). Xinyang (32°02'N, 113°53'E), Henan province,. 3♂, 3♀ (Cheng-Yuan Su leg.). Taihu (30°34'N, 116°04'E), Anhui province. 3♂, 3♀ (Cheng-Yuan Su leg.), Qingyuan (27°44'N, 119°15'E), Zhejiang province. 3♂, 3♀ (Cheng-Yuan Su leg.), Zhenghe (27°23'N, 118°52'E), Fujian province. 3♂, 3♀ (Cheng-Yuan Su leg.), Zhouning (27°13'N, 119°20'E), Fujian province. 3♂, 3♀ (Cheng-Yuan Su leg.), Guiding (26°37'N, 107°14'E), Guizhou province. 3♂, 3♀ (Cheng-Yuan Su leg.), Shaoguan (24°59'N, 113°01'E), Guangdong province.
The new species is similar to A. mairei (
Female: body length 2.6–2.8 mm (N = 5).
Coloration. Head area of compound eyes and frons black and gena yellow. Antenna uniformly dark brown to black, except for scape, pedicel and F1 brownish yellow. Mandible, maxillar and labial palpi dark brown. Legs uniformly brownish yellow. Mesosoma black; metasoma mostly reddish brown and posteriorly black. Hypopygial spine reddish brown.
Forewing
with distinct veins R+Sc, R1+Sc, R1, Rs, Rs+M (somewhat faint basally), M, 2r, M+Cu1, Cu1, Cu1b and Cu1a; areolet distinct and small; marginal cell about 2.6–3.0 times as long as wide; all visible veins yellow except for the distal half of R+Sc, R1+Sc, 2r, and M. The distal half of M+Cu1 black (Fig.
Head
coriaceous, 1.2 times as wide as high in anterior view, nearly oval, broader than mesosoma in front view and 2.2 times as broad as long in dorsal view. Gena not broadened behind eyes in dorsal view. Height of eye about 3.4 times the length of malar space. Frons glabrate with evenly spaced long setae, with ocellar triangle indistinctly rugose; lower face and malar space glabrate and distinctly setose. Clypeus distinct and impressed; epistomal sulcus distinct; anterior tentorial pits small, but distinct; clypeo-pleurostomal line distinct. Transfacial distance slightly bigger than height of eye; distance between inner margin of eye and outer rim of antennal torulus slightly wider than distance between antennal toruli, but as wide as diameter of torulus (Fig.
Antenna
filiform with 11 flagellomeres, slightly tapering toward apex; pedicel sub-spherical; relative lengths of scape, pedicel and F1-F11: 10:6:11:9:9:8:8:8:7:7:6:6:13; placoid sensillae distinctly visible on F2–F11 (Fig.
Mesosoma
longer than high in lateral view. Pronotum median length two ninth of length of outer lateral margin. Anterior plate of pronotum areolate to rugose and densely setose laterally (Fig.
Metasoma
1.2 times as long as high in lateral view; abdominal tergite II 1.5 times as high as long in lateral view, laterally with anterior patch of short setae; tergite VII dorsally and VIII with long setae. Prominent part of hypopygium slender, distally not pointed; and ventrally with a row of short setae (Fig.
Male: Similar to female, but different as below. Antenna with 12 flagellomeres, length of scape 1.25 times as long as wide; pedicel almost same as long as broad. F1 strongly curved medially. Lengths of scape, pedicel and F1–F12: 10:10:7:8:8:7:7:7:7:7:7:14. Upper face black, lower face yellow (Figs
Galls are monolocular and form clusters of 50–60 galls on twigs of host plant. Galls are covered with very dense resinous white hairs, which become brown at the terminal of the galls as galls mature. Individual galls straight and cylindrical (Fig.
All specimens emerged from galls collected from Quercus serrata. The adults of the new species appeared in early to mid-May (which overlaps with the emergence period of A. mairei). Populations were extremely female-biased at 95.5–97.8% (while that of A. mairei were 5.4–43.5%) (Table
The new species is currently known from China in several provinces in the middle to lower reaches of the Yangtze River, including Henan (Xinyang), Anhui (Jinzhai, Shucheng, and Taihu), Hubei (Wuhan), Hunan (Changsha and Shaoyang), and Zhejiang (Suichang and Qingyuan).
The Bayesian and maximum-likelihood phylogenetic trees of various populations of A. elodeoides, A. mairei, and other Andricus species based on the COI and 28S genes had identical topology while showing minor differences in support level for some nodes. According to the Bayesian trees presented here (Fig.
Bayesian phylogenetic tree of A. elodeoides sp. nov. and other Andricus species based on COI and 28S sequences. Bold font refers to the sequence obtained in this study, and others are downloaded from NCBI. The photograph on the right refers to the gall of adult emergence. The letters in parentheses indicate the sampled populations shown in Table
In the COI tree, all populations of A. mairei from
Bayesian phylogenetic tree for A. elodeoides sp. nov. and A. mairei of different geographic populations using COI sequences. Bold font refers to the sequence obtained in this study, and the others are from
Pair-wise comparison of the COI gene segment used in this study showed interspecific genetic distances ranged from 6.2 to 11.7% among Andricus species. In A. elodeoides and A. mairei, the interspecific genetic distance ranged from 6.2 to 8.9%. The level of intraspecific genetic variation in A. mairei was higher than that in A. elodeoides. The intraspecific genetic distances were 0–1.8% in A. elodeoides and 0–2.6% in A. mairei, while the distance between “A. mairei ILV91” and A. elodeoides, “A. mairei ILV91” and A. mairei were 0.2–1.8%, and 6.5–8.2%, respectively (Table
Pair-wise COI sequence distances in various geographic populations of A. elodeoides sp. nov. and A. mairei.
Species | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 |
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1 A. curvator | 0.010 | 0.011 | 0.011 | 0.011 | 0.011 | 0.011 | 0.011 | 0.011 | 0.011 | 0.011 | 0.011 | 0.011 | 0.011 | 0.011 | 0.014 | 0.011 | 0.011 | 0.011 | 0.011 | 0.011 | 0.011 | 0.012 | 0.012 | 0.011 | 0.011 | 0.011 | 0.011 | 0.011 | |
2 A. hakonensis | 0.070 | 0.013 | 0.013 | 0.012 | 0.013 | 0.012 | 0.012 | 0.012 | 0.013 | 0.012 | 0.012 | 0.012 | 0.013 | 0.012 | 0.015 | 0.012 | 0.012 | 0.012 | 0.012 | 0.012 | 0.012 | 0.014 | 0.014 | 0.013 | 0.013 | 0.013 | 0.013 | 0.013 | |
3 A. mairei (SG*) | 0.080 | 0.096 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | ||||||||||||||||||||
4 A. mairei (CS) | 0.082 | 0.096 | 0.002 | 0.010 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | |||||||||||||||||||
5 A. mairei (WH) | 0.078 | 0.096 | 0.006 | 0.008 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | ||||||||||||||||||
6 A. mairei (TH) | 0.080 | 0.098 | 0.005 | 0.006 | 0.002 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | |||||||||||||||||
7 A. mairei (SUC) | 0.082 | 0.092 | 0.014 | 0.015 | 0.011 | 0.009 | 0.011 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | ||||||||||||||||
8 A. mairei (XY) | 0.080 | 0.094 | 0.008 | 0.009 | 0.002 | 0.003 | 0.012 | 0.010 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | |||||||||||||||
9 A. mairei (ZN) | 0.082 | 0.092 | 0.014 | 0.015 | 0.011 | 0.009 | 0.000 | 0.012 | 0.011 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | ||||||||||||||
10 A. mairei (JZ) | 0.082 | 0.098 | 0.002 | 0.003 | 0.005 | 0.003 | 0.012 | 0.006 | 0.012 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | |||||||||||||
11 A. mairei (SHC) | 0.082 | 0.094 | 0.005 | 0.006 | 0.008 | 0.006 | 0.015 | 0.009 | 0.015 | 0.003 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | ||||||||||||
12 A. mairei (QY) | 0.082 | 0.092 | 0.014 | 0.015 | 0.011 | 0.009 | 0.000 | 0.012 | 0.000 | 0.012 | 0.015 | A. mairei | 0.011 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | ||||||||||
13 A. mairei (GD1) | 0.083 | 0.092 | 0.017 | 0.018 | 0.017 | 0.015 | 0.009 | 0.018 | 0.009 | 0.015 | 0.018 | 0.009 | 0.011 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | ||||||||||
14 A. mairei (GD2) | 0.083 | 0.096 | 0.014 | 0.015 | 0.014 | 0.012 | 0.006 | 0.015 | 0.006 | 0.012 | 0.015 | 0.006 | 0.003 | 0.011 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | |||||||||
15 A. mairei (ZH) | 0.082 | 0.092 | 0.014 | 0.015 | 0.011 | 0.009 | 0.000 | 0.012 | 0.000 | 0.012 | 0.015 | 0.000 | 0.009 | 0.006 | 0.011 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | ||||||||
16 A. mairei ILV92† | 0.091 | 0.099 | 0.022 | 0.024 | 0.024 | 0.024 | 0.011 | 0.026 | 0.011 | 0.020 | 0.022 | 0.011 | 0.020 | 0.015 | 0.011 | 0.013 | 0.013 | 0.012 | 0.012 | 0.013 | 0.012 | 0.012 | |||||||
17 A. mairei ILV90† | 0.082 | 0.092 | 0.012 | 0.014 | 0.012 | 0.011 | 0.002 | 0.014 | 0.002 | 0.011 | 0.014 | 0.002 | 0.011 | 0.008 | 0.002 | 0.009 | 0.011 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | ||||||
18 A. mairei ILV87 | 0.082 | 0.094 | 0.015 | 0.017 | 0.012 | 0.011 | 0.002 | 0.014 | 0.002 | 0.014 | 0.017 | 0.002 | 0.011 | 0.008 | 0.002 | 0.011 | 0.003 | 0.011 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | 0.010 | |||||
19 A. mairei ILV86† | 0.081 | 0.092 | 0.014 | 0.015 | 0.011 | 0.009 | 0.000 | 0.012 | 0.000 | 0.012 | 0.015 | 0.000 | 0.009 | 0.006 | 0.000 | 0.011 | 0.002 | 0.002 | 0.011 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | |||||
20 A. mairei ILV32† | 0.081 | 0.092 | 0.012 | 0.014 | 0.012 | 0.011 | 0.002 | 0.014 | 0.002 | 0.011 | 0.014 | 0.002 | 0.008 | 0.005 | 0.002 | 0.009 | 0.003 | 0.003 | 0.002 | 0.011 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | ||||
21 A. mairei ILV31† | 0.081 | 0.092 | 0.014 | 0.015 | 0.011 | 0.009 | 0.000 | 0.012 | 0.000 | 0.012 | 0.015 | 0.000 | 0.009 | 0.006 | 0.000 | 0.011 | 0.002 | 0.002 | 0.000 | 0.002 | 0.011 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | 0.0 | ||
22 A. mairei ILV30† | 0.087 | 0.096 | 0.016 | 0.018 | 0.014 | 0.013 | 0.005 | 0.016 | 0.005 | 0.014 | 0.018 | 0.005 | 0.013 | 0.010 | 0.005 | 0.016 | 0.005 | 0.006 | 0.005 | 0.006 | 0.005 | 0.011 | 0.011 | 0.010 | 0.010 | 0.010 | 0.010 | 0.0 | |
23 A. elodeoides (SHC) | 0.097 | 0.117 | 0.076 | 0.078 | 0.078 | 0.080 | 0.083 | 0.080 | 0.083 | 0.078 | 0.078 | 0.083 | 0.085 | 0.085 | 0.083 | 0.089 | 0.082 | 0.086 | 0.084 | 0.084 | 0.084 | 0.084 | |||||||
24 A. mairei ILV91† | 0.090 | 0.103 | 0.066 | 0.068 | 0.066 | 0.066 | 0.070 | 0.068 | 0.070 | 0.068 | 0.068 | 0.070 | 0.072 | 0.072 | 0.070 | 0.082 | 0.072 | 0.070 | 0.070 | 0.070 | 0.070 | 0.071 | 0.018 | ||||||
25 A. elodeoides (JZ) | 0.087 | 0.105 | 0.070 | 0.071 | 0.068 | 0.070 | 0.073 | 0.070 | 0.073 | 0.071 | 0.071 | 0.073 | 0.075 | 0.075 | 0.073 | 0.079 | 0.076 | 0.076 | 0.074 | 0.074 | 0.074 | 0.075 | 0.017 | 0.002 | A. elodeoides | ||||
26 A. elodeoides (SUC) | 0.087 | 0.105 | 0.070 | 0.071 | 0.068 | 0.070 | 0.073 | 0.070 | 0.073 | 0.071 | 0.071 | 0.073 | 0.075 | 0.075 | 0.073 | 0.079 | 0.076 | 0.076 | 0.074 | 0.074 | 0.074 | 0.075 | 0.017 | 0.002 | 0.000 | ||||
27 A. elodeoides (TH) | 0.088 | 0.107 | 0.071 | 0.073 | 0.070 | 0.071 | 0.075 | 0.071 | 0.075 | 0.073 | 0.073 | 0.075 | 0.076 | 0.076 | 0.075 | 0.082 | 0.077 | 0.077 | 0.076 | 0.076 | 0.076 | 0.077 | 0.015 | 0.004 | 0.002 | 0.002 | |||
28 A. elodeoides (WH) | 0.087 | 0.105 | 0.070 | 0.071 | 0.068 | 0.070 | 0.073 | 0.070 | 0.073 | 0.071 | 0.071 | 0.073 | 0.075 | 0.075 | 0.073 | 0.079 | 0.076 | 0.076 | 0.074 | 0.074 | 0.074 | 0.075 | 0.017 | 0.002 | 0.000 | 0.000 | 0.002 | ||
29 A. elodeoides (XL) | 0.087 | 0.105 | 0.070 | 0.071 | 0.068 | 0.070 | 0.073 | 0.070 | 0.073 | 0.071 | 0.071 | 0.073 | 0.075 | 0.075 | 0.073 | 0.079 | 0.076 | 0.076 | 0.074 | 0.074 | 0.074 | 0.075 | 0.017 | 0.002 | 0.000 | 0.000 | 0.002 | 0.000 | |
30 A. elodeoides (XY) | 0.087 | 0.105 | 0.070 | 0.071 | 0.068 | 0.070 | 0.073 | 0.070 | 0.073 | 0.071 | 0.071 | 0.073 | 0.075 | 0.075 | 0.073 | 0.079 | 0.076 | 0.076 | 0.074 | 0.074 | 0.074 | 0.075 | 0.017 | 0.002 | 0.000 | 0.000 | 0.002 | 0.000 | 0.000 |
Using PCR screening for Wolbachia infection with wsp gene-specific primers, in all sampled populations of A. elodeoides and A. mairei, we found that all individuals from 12 populations of A. mairei (N = 360) were infected with Wolbachia, whereas no Wolbachia infection was found in the seven studied populations of A. elodeoides (N = 350), including samples collected from Jinzhai and Shucheng populations through four consecutive years (Table
Andricus elodeoides sp. nov. is considered a distinct from A. mairei (Kieffer) based on differences in adult and gall morphology, and phylogenetic reconstruction based on COI sequence data (Fig.
Our phylogenetic analyses of gene sequence data support A. elodeoides and A. mairei as sister species (Figs
Wolbachia (Anaplasmataceae) are maternally inherited endosymbiotic bacteria that infect arthropods and nematodes and has been shown to be associated with multiple effects on the reproduction of their hosts, such as cytoplasmic incompatibility (CI), induced parthenogenesis, feminization of genetic males, and male killing (
A contrasting difference in sex ratio was observed between A. elodeoides and A. mairei. Populations of of A. elodeoides were extremely female-biased, with female rates being 95.5–97.8%, while populations of A. mairei were more male biased to nearly balanced, with female rates being 5.4–43.5%. For two A. mairei populations in Jinzhai and Shucheng, which were investigated for six and four consecutive years, the female rates were 17.3% and 24.6%, or lower, respectively. This is consistent with observations made by other studies.
This study was supported by the National Key Research and Development Program of China (no. 2018YFE0127100).