Research Article |
Corresponding author: Runzhi Zhang ( zhangrz@ioz.ac.cn ) Academic editor: Miguel Alonso-Zarazaga
© 2015 Chunyan Jiang, Runzhi Zhang.
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:
Jiang C, Zhang R (2015) The genus Gymnetron from China with description of pre-imaginal stages of G. miyoshii, G. auliense and G. vittipenne (Coleoptera,Curculionidae). ZooKeys 534: 61-84. https://doi.org/10.3897/zookeys.534.5967
|
There are four species of Gymnetron in China recorded to date including G. miyoshii Miyoshi, 1922, G. villosipenne Roelofs, 1875, G. auliense Reitter, 1907 and G. vittipenne Marseul, 1876, of which the last two are new country records. The pre-imaginal stages including eggs, mature larvae and pupae of G. miyoshii, G. auliense and G. vittipenne are described and illustrated. In addition, their diagnostic characters (larvae and pupae) are discussed and differentiated, and notes on some of their biological parameters are provided. Potential ecological impacts between Gymnetron weevils and their host Veronica spp. also are provided.
Gymnetron, larva, pupa, Mecinini, Curculioninae, gallmakers, China, protective chemicals, environmental stress
Gymnetron Schoenherr, 1825 belongs to the tribe Mecinini Gistel, 1848 in the subfamily Curculioninae Latreille, 1802 (
The aim of the present study is to describe for the first time all developmental stages of three species of Gymnetron living in China in order to provide further characters for the identification of these taxa.
Six last instar larvae and ten pupae of Gymnetron miyoshii, five last instar larvae and one pupa of G. villosipenne, and ten last instar larvae and ten pupae of G. vittipenne were examined. Descriptions were made and photographs of pupae were taken with a Canon-5D camera mounted on a Nikon SMZ 1500 microscope. Images of adults were photographed with a CCD Qimagine MicroPublisher 5.0 RTV mounted on a Zeiss SteREO Discovery. V12 microscope; Microscopic slides were studied with a Leica DM 2500 microscope and photos were taken with a Nikon CoolPix 5400. Drawings were made from the original photographs by using the software Adobe Illustrator CS6; photos in the field were taken with Canon G15 and 5D Mark II cameras.
Nomenclature of the larval chaetotaxy mainly follows van
After description, all larvae and pupae were mounted using nail polish, a mixture of butyl acetate, ethyl acetate, multipolymer of adipic acid, neopentyl glycol, trimellitic acid and acetyl tributyl citrate. All slides remain together with the adult specimens in the museum of the Institute of Zoology, Chinese Academy of Sciences.
Gymnetron miyoshii Miyoshi, 1922: 253
Gymnetron villosulum var. orientale Voss, 1955: 139
Adult (Figures
Egg: oval, yellowish, nearly pellucid. Measurements (mm): diameter: 0.11–0.12 (n = 3), length: 0.28 (n = 3).
Mature larva (Figure
Head (Figures
Mouthparts (Figures
Thorax (Figure
Abdomen (Figure
Pupa (Figures
CHINA: Hunan: Food and Drug Administration of Changsha (28°11.85'N; 113°0.36'E, 43m), 18-VIII-1975, Veronica anagallis-aquatica L.(8); same except: Hunan Medical University (28°18.05'N; 112°52.14'E, 48m), VII-1979, Veronica spp.(3); Institute of Plant Protection of Hunan (28°12.01'N; 113°04.86'E, 45m), 1973, Veronica anagallis-aquatica L. (2); 1975 (6); 24-V-1976, Veronica anagallis-aquatica L., leg Yangchang Zhao (10); 21-V-1976, Veronica anagallis-aquatica L., leg Qiong Zhu (2); 16-V-1976, Veronica anagallis-aquatica L. (5). Inner Mongolia: Hohhot (40°49.28'N; 111°38.82'E, 1289m), 15-VI-1965, Veronica undulata Wall., leg Hongchang Li (5); Molidawanqi, Hulun Buir (48°28.53'N; 124°30.18'E, 335m), 23-VII-1940 (1). Hebei: Manzuxiang, Dongling, Zunhua, Tangshan, (40°10.90'N; 117°54.49'E, 120m), 8-VII-1963, Veronica spp., leg Wenzhen Ma (1). Beijing: Badaling, (40°20.49'N; 115°58.88'E, 669), 20-VI-1963, Veronica anagallis-aquatica L., leg Tiesheng Li (9); Sanpu, Yanqing (40°19.65'N; 116°02.18'E, 593m), 28-VII-1980, Veronica undulata Wall. (18); 1980-VI-29, Veronica undulata Wall., leg Shengqiao Jiang (10); 7-VII-1980, Veronica anagallis-aquatica L., leg Subai Liao (29); Beizhaicun, Qiaozizhen (40°19.77'N; 116°33.34'E, 73m), 1-VI-2013, Veronica anagallis-aquatica L., leg Chunyan Jiang (26); 24-V-2014, Veronica anagallis-aquatica L., leg Chunyan Jiang (4); 14-VI-2014, leg Chunyan Jiang (5 eggs, 13 larvae, 6 adults). Jiangsu: Yinqiao, Suyang, Changzhou (31°25.94'N; 119°29.73'E, 8m), 5-VI-1981 (1); Wujin (31°40.16'N; 119°55.93'E, 4m), 12-V-1955 (1); Hangzhou (30°15.33'N; 120°12.50'E, 6m), 1982, leg Guangsheng Li (1). Heilongjiang: Harbin (45°45.94'N; 126°38.70'E, 116m), 18-V-1945 (1).
Veronica anagallis-aquatica L. has been collected with galls on 14-VI-2014 which have been reared in the laboratory. Fifteen pupae were found on 21-VI-2014.
Gymnetron melinum var. auliense Reitter, 1907: 30.
Gymnetron auliense:
Adult (Figures
Egg: unknown.
Mature larva: measurements (mm): body length: 2.40–2.50 (n = 4), width: 1.20–1.45 (n = 4); capsule length (in dorsal view): 0.50–0.55 (n = 3), width: 0.46–0.50 (n = 3). It differs from G. miyoshii by: Mouthparts: epipharynx (Figure
Pupa: Measurements (mm): length: 2.80 (n = 1); width: 1.00 (n = 1).
Mesonotum with three pairs of msns on scutellum; Pro-, meso- and metafemora of legs apically bearing one slightly outcurved fes, apex with grey circular pigmented area.
CHINA: Xinjiang: Kaerjiaocun, Jimunai (47°13.03'N; 86°24.12'E, 1224m), 3-VII- 2014, leg Chunyan Jiang (6).
After collecting specimens of Veronica oxycarpa Boiss. on 3-VII- 2014, for rearing in the laboratory, 5 larvae were obtained on 9-VII-2014 and 1 pupa on 12-VII-2014.
This species has been recorded from Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan. This species is a new record for China.
Gymnetron vittipenne Marseul, 1876: 383.
Gymnetron apicale
Gymnetron vittipenne var. suturiferum
Adult (Figures
Egg: unknown.
Mature larva: measurements (mm): body length: 5.00–5.20 (n = 2), width: 1.60–2.00 (n = 2); capsule length (in dorsal view): 0.70–0.86 (n = 4), width: 0.57–0.68 (n = 4).
It differs from G. miyoshii by: General appearance (Figure
Pupa (Figures
It differs from G. miyoshii by: General appearance: size greater. Head: head yellow-gray with indistinct yellow stripes in middle, two pairs of pas, pas1 situated in middle of frons, pas2 situated at middle margin of eyes. Thorax: prothorax bearing a lightly pigmented tubercle, apically deeply bifurcate. Pronotum with three as, two sls, one ds and two pls. As and sls1, pls subequal, strong and long, pls1 and pls2 in one transverse row, sls2 and ds short; Mesonotum with three msns on scutellum. Abdomen: segment I-VII with tergite bearing two setae. Spiracular area with two ss; Legs: pro-, meso- and metafemora apically bearing one pair of slightly outcurved fes, apex with grey circular pigmented area.
CHINA: Xinjiang: Talaticun, Qinghe (46°40.53'N; 90°27.74'E, 1285m), 28-VII-2013, Veronica oxycarpa Boiss., leg Chunyan Jiang (33); Hualin Park (47°51.75'N; 88°07.18'E, 886m), 5-VIII-2013, leg You Li (1).
After collecting the host plants Veronica oxycarpa Boiss. with galls on 28-VII-2013, 10 larvae and 20 pupae were obtained on 1-VIII-2013.
This species has been recorded from Armenia, Bulgaria, Croatia, Greece, Iran, Iraq, Kazakhstan, Lebanon, Palestine, Slovakia, Syria, Tajikistan, Turkey, Turkmenistan and Uzbekistan. This species is a new record for China.
Gymnetron villosipenne Roelofs, 1875: 149.
Adult (Figures
CHINA: Jilin: Dahuanggou, Antu, Yanbian (42°55.18'N; 128°37.53'E, 918m), 13-VIII-1963 (1). Heilongjiang: Xigou, Aihui, (49°51.45'N; 127°13.30'E, 154m), 20-VII-1963, leg Hongxing Li (1); Daxiangcun, Great Khingan (52°57.65'N; 122°31.67'E, 600m), 19-VII-1970 (1).
Key to adults of Gymnetron from China
1 | Metathoracic episterna covered with broad scales | 2 |
– | Metathoracic episterna covered with narrow scales | G. vittipenne |
2 | Metasternum and urosternite one covered with narrow scales | 3 |
– | Metasternum and urosternite one covered with broad scales | G. miyoshii |
3 | Elytra completely black | G. villosipenne |
– | Elytra reddish with only interstria one and ten black | G. auliense |
Key to larvae of Gymnetron from China (details in Table
1 | Labrum without middle seta and sensilla, nearly all sclerotic | 2 |
– | Labrum with middle seta and sensilla, partly sclerotic | G. vittipenne |
2 | Epipharyngeal setae stout, sensilla absent | G. miyoshii |
– | Epipharyngeal setae slender, two pairs of sensilla | G. auliense |
Diagnostic features of the mature larvae of Gymnetron from China (Characters of G. miyoshi identical in G.auliense/G. vittipenne are not repeated, but indicated by “-”).
Trait | Character | Gymnetron miyoshii | Gymnetron auliense | Gymnetron vittipenne |
---|---|---|---|---|
Length (mm) | 3.25–3.90 | 2.4–2.5 | 5.00–5.20 | |
Head | Dorsal | 3 fs, 1,3 absent; 4 des, 4 absent; 3 minute pes; 2 les; ventral 1 seta; oc present | - | - |
Antenna | 1 aseg, longer than wide, with 4 sa | - | 2 sa | |
Mouthparts | Mandible | 2 teeth 1 flange, 2 ms, 1 sensillum | - | - |
Labrum | 2 pairs of cls; 3 pairs of lrms; nearlly all sclerotic | - | 2 pairs of cls, 1 pair of sensilla; 3 pairs of lrms, 1 mds; partly sclerotic | |
Epipharynx | 2 pairs of als, 3 pairs of ams, stout setae | 2 pairs of als, 3 pairs of ams, 2 pairs of sensilla, slender setae | 2 pairs of als, 3 pairs of ams, 1 pair of mes, stout setae | |
Maxilla | 1 stps, 2 sensilla; 2 pfs; 4 vms, short, 5 dms; mxp 2 segments, 1 mxps, 1 sensillum | - | 3 pfs; 1 mxps, 2 sensilla | |
Labium | lbp 1 segment, 1 sensillum; 2 ligs; pmsc “U” sclerotic, 1 prms, 1 sensillum; plb partly sclerotic, 2 plbs | - | - | |
Thorax (one side) | Th I | 2 prns; 4 dpls; 2 vpls; 4 pda setae; 2 msts | 4 prns | 6 prns; 5 pda setae |
Th II | 2 prs; 2 pds; 4 as; 1 dpls; 1 vpls; 4 pda setae; 2 msts | - | 1 prs; 2 pds; 1 dls; 5 pda setae | |
Th III | same as Th II | - | same as Th II | |
Abdomen (one side) | Abd I-VII | 2 prs; 1 pds; 2 ss; 1 dpls; 1 vpls; 1 lsts; 3 msts; 7 s | - | 1 prs; 2 pds |
Abd VIII | 1 prs; 1 pds; 2 ss; 1 dpls; 1 vpls; 1 lsts; 2 msts | - | 2 pds | |
Abd IX | 1 prs; 1 pds; 1 pls; 3 sts | - | - | |
Abd X (anus) | 1 seta, transverse | - | - |
Key to pupae of Gymnetron from China (details in Table
1 | Pronotum with one pair of apical setae, one pair of sublateral setae, two pairs of posterolateral setae and discal setae absent | 2 |
– | Pronotum with three pairs of apical setae, two pairs of sublateral setae, two pairs of posterolateral setae, one pair of discal setae | G. vittipenne |
2 | Pro-, meso- and metafemora apically bearing two setae | G. miyoshii |
– | Pro-, meso- and metafemora apically bearing one seta | G. auliense |
Diagnostic features of pupae of Gymnetron from China (characters of G. miyoshii identical in G. auliense are not repeated, but indicated by "-").
Traits | Gymnetron miyoshii | Gymnetron auliense | Gymnetron vittipenne |
---|---|---|---|
Head | 1 pair of pas | - | 2 pairs of pas |
Thorax (one side) | Prothoracic tubercle shallowly split, 1 as, 1 sls, 2 pls; 2 msns; 2 mtns | 3 msns; 2 mtns | Prothoracic tubercle deeply split, 3 as, 2 sls, 2 pls; 3 msns; 2 mtns |
Abdomen (one side) | Abd I-VII, tergum 1 seta, 1 ss, 1 dpls, 1 vpls,1 lsts, 2 msts; Abd VIII, tergum with posterior tubercle, 1 seta, Sternum 2 setae; Abd IX, with pc; Abd X, anus transverse cleft, subterminal | - | Abd I-VII, tergum 2 setae, 2 ss |
Legs | 2 fes | 1 fes | 1 fes |
Host plants of Veronica in which larvae of the three species live are widely distributed in China (
The adults of G. miyoshii feed on stems near the axils of their host (Figure
Gymnetron miyoshii. 41 Adult feeds on stems of Veronica anagallis-aquatica L. 42 Adult makes holes on bud of host plants 43 Adult lays eggs in buds 44 Egg in ovary surrounded by ovules 45 Egg visible through ovary wall 46 Adult seals the hole with fecal material 47 Dry fecal material 48 Galls of ovaries and normal flowers 49a–b Larva 50 Pupa.
Gymnetron auliense, like G. miyoshii, also lays eggs in ovaries of host plants (Figure
Gymnetron vittipenne was collected in Veronica anagallis-aquatica L., as reported by
Lee et al. (1998) described the larva of G. miyoshii, but after further study, distinct major differences are observed in the head (ocelli, setae and clypeus), mouthparts (labrum, labium and maxillary palpus), setae of thorax and abdomen, and number of spiracles, with comparison in Table
Trait | Character | Description (Lee et al. 1998) | Review |
---|---|---|---|
Head | Ocellus | 2 pairs | 1 pair |
Setae | des1, 3, 5 long, equal, des4 short, des2 absent; les, ves absent; 2 pes; 2 cls, different length | des3 longest, des5 long, des1, 2 short equal, des4 absent; 2 les; 1 ves; 3 pes; 2 cls, equal | |
Mouthparts | Labrum | posterior margin extended medially into clypeal zone; rods as brownish patches | posterior margin indistinct; rods absent |
Labium | 3 plbs | 2 plbs | |
Thorax (one side) | 6 prns; 3 pds; 1 as; pedal lobe 2 segment, 6 setae | 2 prns; 2 pds; 4 as; pedal lobe 1 segment, 4 setae | |
Abdomen (one side) | 8 spiracles; airtube longer than diameter of peritreme; 3 folds; 1 prs; 2 pds; 1 ss; 2 msts | 7 spiracles; airtube subequal as diameter of peritreme; 2 folds; 2 prs; 1 pds; 2 ss; 3 msts |
In addition, setae on the alar area are found to be variable. There are usually four setae of different lengths on the alar area on each side of each larva. Five setae can be found on the alar area of the metathorax of G. miyoshii. Thus, the setae of the alar area are not useful diagnostic characters. There is only one middle seta on the labrum of G. vittipenne pupae, it is special, and we name it mds. The features of the larva of the genus Gymnetron are as follows: (1) Frontal suture not extending to mandibular membrane; (2) Antennae contiguous with frontal suture; (3) Postoccipital condyles indistinct; (4) meso-, metathorax and abdomen with two tergal folds; (5) Alar area without sclerotized or pigmented areas; (6) Spiracles bicameral; (7) Head brown with pale stripes at side and ecl of head; (8) Accessory sensory appendage of antenna short; (9) Anus, transverse cleft; (10) Living in galls of seeds or stems of Scrophulariaceae or Plantaginaceae.
Parasites of Gymnetron are few (
While collecting these species from the field, three kinds of host plants only were found, living only in flowing water with little pollution or human disturbance. In spring, there are many host plants in the habitats, but only those with Gymnetron living on them can survive as they begin to flower and seed. We collected plants for rearing weevils in the laboratory, and observed the same phenomenon. Plants with galls of Gymnetron lasted long after seven days, but those without galls began to wilt on the second day and died on the 7th day. The host plants were reared five times under the laboratory conditions. Based on this study, we formulate the hypothesis that Gymnetron feed on Veronica causing them to produce more protective chemicals, which can help the plants to resist environmental stress. Species of Veronica with Gymnetron galls living near water cannot live in unclean polluted water for long, so we can use these two organisms as environmental indicators. So, during the co-evolution of insects and plants, there are relationships not only of plant-herbivores-predator, but herbivores and plants can also help each other to live harmoniously.
We are very thankful to Dr. Ning Liu, Dr. Zhiliang Wang, Dr. Li Ren and Dr. Jing Xu from the Institute of Zoology, Chinese Academy of Sciences for their providing partial support for this research; our thanks also to the following: Dr. Charles O’Brien from the U.S.A., Dr. Roberto Caldara from Italy and Dr. Muhammad Haseeb of the Center for Biological Control, Florida A&M University for review of earlier version of this paper; Dr. Jens Prena from Germany and Dr. Roberto Caldara for identifying some specimens; Dr. Zhenyu Li from the Institute of Botany, Chinese Academy of Sciences for identifying host plants; Mr. Jian Wang from Altay Forestry Research Institute for his help in specimen collections; Dr. Marek Wanat from Wroclaw University in Poland for sending specimens of Mecinini; Dr. Kyungduk Han from Korea University and Youssef M Omar from Assiut University in Egypt for field collecting and literature; Dr. Miguel Alonso-Zarazaga from Museo Nacional de Ciencias Naturales in Madrid, Spain and Dr. Christopher H. C. Lyal from The Natural History Museum in London, UK for their guidance in this research project. This research was supported by National Natural Science Foundation of China (31210103909/31172130/J1210002) and National Special Program for Basic Science and Technology (2013FY110300).