Curculio quelparticola is an endemic species of the Republic of Korea, specifically in the summit area of Halla Mountain on Jeju Island. Its area of occupancy (AOO) and extent of occurrence (EOO) are 8 km², meeting the thresholds for the Critically Endangered (CR) category under criterion B. Regarding sub-criteria (a) and (b), its sole habitat is deteriorating due to the decreasing availability of its host plant, driven by climate change. A single location has been identified for this species. As a result, it qualifies as Critically Endangered.

Curculio quelparticola is a nut weevil species endemic to the Republic of Korea (National Institute of Biological Resources 2015). The distribution of this species is limited to Halla Mountain, Jeju Island, and no additional habitats have been found outside of its type locality, despite the several research on Halla Mountain’s invertebrate diversity and the insect species that inhabit its host.

Due to the limited knowledge of these species’ ecology and the small number of samples, a habitat map covering the entire distribution on Jeju of its only known host plants, Abies koreana (Korean Fir) and A. holophylla (Needle Fir) was used for analyses (National Institute of Biological Resources 2015, Park 2018). Recent work has found that the Korean Fir’s distribution has become mostly restricted to areas with elevations above 1,510 meters (Kim 2022). The genus Abies is mainly classified into alpine/subalpine conifer forest communities, and is affected by temperature rise caused by climate change driving alterations in precipitation, moisture stress (Ahn et al. 2019, Koo and Kim 2020), and competing species (Song 2011, Kim et al. 2015). According to Kim et al. (2024), in 1918, the area of the A. koreana forest was analysed to be 1,168.4 hectares. Through continuous decline, the forest area had shrunk by 562.4 hectares, leaving 606 hectares of forest in 2021 (Kim et al. 2024). The same trends were predicted in the future (Kim et al. 2015, Koo et al. 2016, Koo and Kim 2020, Choo et al. 2023). Koo et al.'s (2016) model predicted that rising temperatures, along with fluctuating weather patterns would decline the distribution of A. koreana and, consequently, cause the risk of extinction due to changes in their current habitat (Koo et al. 2016).

Following the decline of its host trees, this species is suspected to be decreasing throughout time. Currently, the area of occupancy for this species is estimated to be 8 km² based on a 2x2 km grid overlay on the range map. Its extent of occurrence (EOO) is estimated to be 6.6 km² based on total area within a minimum convex polygon around all known and inferred occurrences, but because this is less than the AOO value, the EOO takes the AOO value.

This species' population is suspected to be declining due to the decline of its host plants.

Genus Curculio lays its eggs in the host fruit, and uses it as food for its larvae (Shanovich and Aukema 2022). In order to reduce competition within different Curculio species, most Curculio species have evolved as habitat specialists (ex. mating seasonality and fruit size; Leskey and Wright 2007). This tendency leads for many species to have specific host genus preferences (Kwon and Lee 1990, Kojima and Morimoto 1994, Leskey and Wright 2007, Rahati et al. 2017, Arias-Le Claire 2018, Reut et al. 2021, Zhang et al. 2024). C. quelparticola has been found only on genus Abies (National Institute of Biological Resources 2015). Although the larvae of this species have not been identified, studies suggest that imagos are typically found near its host species (Arias-Le Claire 2018). Accordingly, if the imago was captured exclusively in the Abies genus, it is reasonable to assume that the Abies genus serves as the major or exclusive host species for C. quelparticola. In Jeju’s Halla Mountain, there exists only two species of the Abies genus, which are A. koreana and A. holophylla, and both species are decreasing (Kim et al. 2011, Katsuki et al. 2013). As the insect species are suspected to be strongly dependent on these host plants, the decline of the host species would presumably impact the insect population (Arias-Le Claire 2018).

The decrease of host plants is a dominant threat. As this species is suspected to depend on genus Abies as host plants, this species' population is likely to be influenced by host plant population dynamics (Arias-LeClaire 2018). Climate change significantly impacts the survival of host plants, driving the continuing decline of the host species’ distribution. Specifically, the distribution of conifer has reduced by 34% between 1988 and 2002 (Kim and Lee 2013), and 15.2% during 2006 to 2015 (Koo and Kim 2020). Therefore, this species is suspected to be facing inevitable continuing decline, and has one location defined by climate change.

There is no trade in this taxon.

Conservative actions need to address the decline of this species' host plants, Abies koreana and A. holophylla, due to climate changes. Therefore, actions should be taken to conserve these species. To find proper conservation methods, more research should be conducted on the population size, distribution, and life cycle of this species. Meanwhile, the adults of this species were all found on Abies species, but further investigation into the larvae is needed to confirm whether these trees are definitively used as hosts.