Biodiversity Data Journal :
Taxonomy & Inventories
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Corresponding author: Xiaosheng Chen (xshchen@scau.edu.cn)
Academic editor: Enrico Ruzzier
Received: 26 Sep 2023 | Accepted: 31 Oct 2023 | Published: 16 Nov 2023
© 2023 Jiamin Zhuang, Lizhi Huo, Mingjie Tang, Xiufeng Xie, Xiaosheng Chen
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:
Zhuang J, Huo L, Tang M, Xie X, Chen X (2023) First report of Diomus guilavoguii Duverger, 1994 (Coleoptera, Coccinellidae, Diomini) predating on papaya mealybug Paracoccus marginatus from China. Biodiversity Data Journal 11: e113291. https://doi.org/10.3897/BDJ.11.e113291
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Diomus guilavoguii Duverger, 1994, an adventive species, is recorded from Guangzhou (Guangdong Province), China for the first time. Larvae of D. guilavoguii were collected in association with an invasive mealybug, Paracoccus marginatus Williams & Granara de Willink, 1992, infesting papayas, cassava and several ornamental plants. However, little has been known about the biology of D. guilavoguii, especially the morphology of their larvae since their original descriptions.
Diomus guilavoguii Duverger, 1994, native to Conakry, Guinea (Africa), is recorded as established in Guangdong Province for the first time. However, it is unclear when and how D. guilavoguii spread from Africa to Guangzhou, Guangdong Province. Both the adult and larva feed on the invasive mealybug Paracoccus marginatus Williams & Granara de Willink (Hemiptera, Pseudococcidae) that infests papaya and ornamental plants. In this paper, the external morphology and male genitalia of adults are re-described. The detailed descriptions of larva and pupa are also provided for the first time. The status of D. guilavoguii and D. hennessyi Fürsch, 1987 are discussed.
Coccinellidae, new record, larva, pupa, Diomus hennessyi
Diomus was originally established by
Diomus guilavoguii Duverger, 1994 was described from Guinea by
The papaya mealybug, P. marginatus is a globally invasive pest that causes significant yield losses in various crops (
Although the papaya mealybug is native to Mexico and Central America, it is not a pest there due to the presence of its natural enemies keeping it under control. However, when it invaded other countries or regions, it was considered a serious pest mainly due to the lack of natural predators (
In this paper, Diomus guilavoguii Duverger, 1994 is recorded as being well established in Guangzhou for the first time. Detailed descriptions and illustrations of the adult, pupa and larvae are provided. Diagnostic characters for the genus and species are also given.
Specimens examined were collected from Guangdong Province, China and deposited in the Department of Entomology, South China Agricultural University, Guangzhou, China (SCAU). The terminology used in the descriptions of larva follows
Measurements were taken using a micrometer attached to a SteREO Discovery V20 dissecting stereoscope and are defined as follows: (TW) total width, across both elytra at widest part; (TH) total height, at highest part of elytra in lateral view; (TL) total length, from apical margin of clypeus to apex of elytra; (PL) pronotal length, from the middle of anterior margin to the base of pronotum; (PW) pronotal width at widest part; (EW) elytral width, equal to TW; (EL) elytral length, along suture from base to apex including scutellum; (HW) head width, at widest part including eyes.
Male and female genitalia were dissected, cleared in a 10% solution of sodium hydroxide (NaOH) by boiling for several minutes and placed on slides for further study. Photographs of the adult were taken with a digital camera (EOS 5D Mark IV, Canon) and photographs of their genitalia were taken using digital cameras (ZEISS Imager M2 and Axiocam 506 Color) attached to the microscope.
Larvae were reared in 500 ml plastic dishes in rearing chambers at 25 ± 1℃, 70% ± 10% R.H. and 12:12 h L:D. The food, Paracoccus marginatus, was supplied daily to maintain the population stock (Fig.
For morphological studies, the larvae were soaked in 75% alcohol for conservation. The larvae were photographed using digital cameras (EOS 5D Mark IV, Canon), attached to a focus stacking rail (WeMacro Rail). The software Helicon Remote and Helicon Focus were used to capture and render images respectively from the camera. Mouthparts, head and tarsal claw of the larvae were dissected, cleared in a 10% NaOH solution, boiled for half an hour, washed in distilled water and placed on slides. Colour images were captured with digital cameras (ZEISS Imager M2 and Axiocam 506 Color) attached to a dissecting microscope using ZEN 2.3 software. All photographs were edited using Adobe Photoshop CC 2018 and Adobe Illustrator 2020.
Scymnus (Diomus) Mulsant, 1850: 951. Type species: Coccinella thoracica Fabricius, 1801, by subsequent designation by
Diomus: -Weise (1895: 144); Gordon (1976: 319); Gordon (1999: 13); Pang and Ślipiński (2009: 646).
Nephus (Diomus) by Iablokoff-Khnzorian (1976: 377) (
Amidellus Weise, 1923 - Weise (1923: 141) (
This genus can be separated from other genera within the tribe Diomini by the following characters: antennae composed of 11 or 10 antennomeres; slightly shorter than head capsule with pedicel narrower than scape; antennomere 3 elongate; antennal club indistinct and multi-segmented (Fig.
Main characters of Diomus guilavoguii Duverger, 1994, adult: a adult in front view; b prothorax, ventral view; c mandible; d antenna; e maxilla; f labium; g hind leg; h front leg; i tarsus of front leg; j abdomen in ventral view. Scale bars: a = 0.2 mm; b, g, j = 200 μm; c, d, e, f, h, i = 50 µm.
Worldwide, but certainly more diverse in the Southern Hemisphere like Neotropical and Australian Regions (
Most species of the genus have a wide range of host preferences that mainly feed on mealybugs (Fig.
Diomus guilavoguii Duverger, 1994: 121.
Adult. TL: 1.53-1.54 mm, TW: 1.16-1.21 mm, TH: 0.57-0.63 mm, TL/TW: 1.27-1.32, PL/PW: 0.31-0.32, EL/EW: 1.00-1.03, HW/PW: 0.61-0.65, PW/EW: 0.73.
Male: Body oval, weakly convex; usually winged; dorsum uniformly hairy. Head transverse, dorsally not covered by pronotum (Fig.
Adult of Diomus guilavoguii Duverger, 1994. a male, dorsal view; b male, front view; c male, lateral view; d female, dorsal view; e female, front view; f female, lateral view; g abdomen; h tegmen, inner view; i tegmen, lateral view; j penis; k penis capsule. Scale bars: a-f = 0.5 mm; g, j = 200 μm; h-k = 100 μm. Black lines: outlines of apical penis guide.
Male genitalia: Penis slender, extremely long (Fig.
Female: Externally identical to male, but head black and elytra black with the apex more or less finely yellowish (Fig.
Four instar larva (Figs
Larval characters of Diomus guilavoguii Duverger, 1994, fourth instar larva; a head; b antenna; c labrum; d mandible; e tarsal claw; f maxilla; g labium; h maxillary palp; i labial palp. Scale bars: a = 100 µm; b, c, f, g, h, i = 50 µm; d, e = 25 μm. Black lines: outlines of structures; red dots: boundaries of segmentation of maxillary palp and labial palp.
Pupa (Fig.
This species is similar to most members of the genus Diomus in general habitus and colour pattern, but can be distinguished from those species by the extremely long penis and the robust penis capsule with a bifurcate inner arm.
Guinea (Conakry), China (Guangdong) new record.
Diomus guilavoguii is recorded from China for the first time. The specimens examined in the present paper show some minor variation in antennae however, their external appearance of adult and male genitalia were in agreement with the detailed descriptions and illustrations given by
D. guilavoguii closely resembles D. hennessyi Fürsch, 1987 from Zaire, Africa in external appearance and male genitalia.
There have been no deliberate introductions of D. guilavoguii in China. When and how did this species spread to Guangdong Province, China? As aforementioned, P. marginatus is native to Mexico and Central America. Although this invasive pest has also been reported in Africa, we suspect that D. guilavoguii was likely spread to Guangdong, China from Central America along with P. marginatus. However, its diffusion path remains to be further studied.
We sincerely thank Prof. Shaobin Huang for the identification of the species Paracoccus marginatus. Our sincere thanks are extended to the editors and reviewers for their critical comments and suggestions on this manuscript. The present study was supported by National Natural Science Foundation of China (32000327), Guangzhou Collaborative Innovation Center on Science-Tech of Ecology and Landscape (202206010058) and the Characteristic Innovation Projects of Regular Universities in Guangdong Province (2019GKTSCX056).
X. Chen managed the project and led the writing of the manuscript. L. Huo found the species of ladybird beetle. J. Zhuang, M. Tang and X. Xie collected the specimens. J. Zhuang performed the laboratory work and wrote the manuscript. X. Chen conceived and designed the experiments. J. Zhuang and L. Huo contributed equally to this work.