A species of weevil in the genus Aclees (Curculionidae, Molytinae) was found on several fig farms (Ficus carica) in the Haenam-gun district of Jeonnam Province, Korea on the late of July, 2020. The weevil was subsequently identified as Aclees taiwanensisKôno, 1933 (Coleoptera: Curculionidae). This is first reported the weevil belonging to the genus Aclees in Korea and considered to be an invasive alien species.

Taxonomic account

Family Curculionidae (바구미과)

Subfamily Molytinae (참바구미아과)

Tribe Hylobiini

Genus Aclees Schoenherr

Aclees taiwanensisKȏno, 1933 무화과곰보바구미(신칭) (Fig. 1)

Aclees taiwanensisKȏno, 1933: 182. [TL: Taiwan]

Diagnosis: Adult. Body length (excluding rostrum) 16 mm. Antennal club visibly two-segmented. Pronotum strongly wrinkled-punctate, with a weak median oblong glossy callus before the middle. Third and fourth sternites as smooth as two upper ones and metasternum, with large punctures at sides. Tarsal groove with two rows of outer setose fringes (Morimoto, 1982).

Material examined: 1♂, 3♀♀, 3 larvae, 1 pupa, Gungok-ri, Songji-myeon, Haenam-gun, Jeonnam Province, 22.VII.2020, in the wood at the base of the trunk of fig tree (Ficus carica), K.J. Hong leg.

Distribution: Southern part of Korean Peninsula (new record - introduced); Taiwan, China (Fujian, Guizhou, Guangxi, Hubei, Hunan, Jiangsu, Sichuan, Xizang, Yunnan, Zhejiang), Myanmar, Indonesia (Java, Borneo); introduced to France (Mouttet et al., 2020 as Aclees sp. cf. foveatus Voss) and Italy (Ciampolini et al., 2005 as A. cribratus; Benelli et al., 2014, as Aclees sp. cf. foveatus Voss)(Alonso-Zarazaga, 2013; Meregalli et al., 2020).

Host plant: Fig tree (Ficus carica).

Biological information observed and listened in the fig farms: The fig trees are cultivated under eco-friendly farming practices in the plastic houses. Observations made in the field showed that this Aclees weevil attacked Ficus carica. Larvae feed on the wood at the base of the trunk, mostly under the soil surface (Fig. 2). We had found one larva from diameter 1-2 cm and five to seven larvae from diameter 10 cm at the basal part of trunk. As a consequence of the destruction of the wood at the collar of the trees by the larvae, the aerial parts show growth reduction, yellowing, dieback and eventually tree death. Adults feed on the fig shoots and fruits (Fig. 3). According to the famer’s listening, the damage by this weevil has been observed from 2-3 years ago in Haenam-gun, Jeonnam Province and caused to be abandoned several fig farms in Yeosu-si and Wando-gun, Jeonnam Province in 5 years ago. And also, it is said that such damage on fig trees occurred in Busan-si prior to the occurrence of Jeonnam Province.

Discussion

This weevil seriously damaged the trunk of fig tree, was identified as Aclees taiwanensisKôno, 1933 (Coleoptera: Curculionidae). This weevil probably of subtropical and tropical Asian origin including China, was also introduced in Italy and France where it is responsible for serious damages on fig trees (Ciampolini et al., 2005).

We think that this fig weevil is an invasive alien species to the Korean Peninsula based as follows - firstly, Aclees hirayami Kôno distributed the northernmost part of Asian region among members of genus Aclees, was only found to Kuroshima (30.5°N), Japan (Morimoto, 1982), but even Seogwipo-si, Jeju Is. located the southernmost part of Korea, is 33.1°N; Aclees weevil had not been confirmed from Hong et al. (2000), and from the survey data by taxonomists interested in the Korean weevil fauna and a corresponding author in the Korean Peninsula until now; the fig tree is not native in Korea, but commercially cultivated under the plastic houses, and imported the huge amount of saplings for planting from many foreign countries since 2000s; symptoms caused by this weevil, were known from only 4 or 5 years ago according to the listening from farmers; lastly, this fig weevils are only found on fig trees cultivated under the plastic houses.

The fig trees are cultivated under eco-friendly farming practices in the plastic houses in Korea. Especially, it is considered a serious pest because it is difficult to eradicate on the farms where fig trees are cultivated with nutrient broth in rectangular boxes under the plastic houses. Since the proper control method for this weevil pest is not known until now and fig trees are cultivated using eco-friendly farming practices, the most effective management methods are recommended as follows; planted the healthy trees, picked the adult weevils up on the aerial parts using a flashlight in the night with 2 or 3 days interval, fitted the screen at the door of the plastic houses, forbidden the transplanting of saplings to other farms, and incinerated saplings and agricultural materials that used in the damaged farms.