ASIAN MYRMECOLOGY Volume 10, e010012, 2018 ISSN 1985-1944 | eISSN: 2462-2362 © Benoit Guénard DOI: 10.20362/am.010012 First record of the emerging global pest Brachymyrmex patagonicus Mayr 1868 (Hymenoptera: Formicidae) from continental Asia Benoit Guénard School of Biological Sciences, The University of Hong Kong, Hong Kong SAR *Corresponding author: [email protected] ABSTRACT. The first record of the exotic ant Brachymyrmex patagonicus Mayr 1868 from continental Asia is here presented. Specimens collected from an urban environment in Hong Kong coupled with recent surveys suggest an early stage in the invasion process. The summary of recent records shows that the introduced range of this species is quickly increasing globally and biologists in Asia should remain vigilant to detect it. In Hong Kong, measures to identify its overall spread and to eradicate this species, which is considered as a major pest, should be quickly implemented. Keywords: Brachymyrmex patagonicus, Hong Kong, Tropical Asia, Introduc- tion, Urban Ecosystems, Tramp Ant. The ant genus Brachymyrmex is native to the Guénard et al. 2017). Though the native range New World and widely distributed from south- has sometimes been presented as limited to Ar- ern Canada to the Patagonian region of Argentina gentina or Paraguay (e.g. MacGown et al. 2007, (antmaps.org, Guénard et al. 2017). The genus Hill 2017), its distribution in South America is diversity is relatively modest and currently in- thus more extensive, and ecological results sug- cludes 44 valid species, 17 valid subspecies and a gest that the native range of B. patagonicus could good reservoir of potentially undescribed species extend further. For instance, in a study conducted (Deyrup 2016). However, five species have been within the northern part of the Cerrado ecore- recorded as introduced outside their native rang- gion (Maranhão state, Brazil), B. patagonicus es: B. cordemoyi Forel 1895, B. heeri Forel 1874, was found to be an indicator species of interior B. minutus Forel 1893, B. obscurior Forel 1893, forest, a habitat less exposed to disturbance in and B. patagonicus Mayr 1868. The latter species comparison to forest edges and agricultural fields is arguably the most widespread Brachymyrmex (Brandão et al. 2011). However, it should also be species and its introduced range has quickly ex- noted that within the Neotropical realm, B. pa- panded in the past decade based on recent records tagonicus is frequently encountered within dis- summarized below. Here the first record ofB. pa- turbed open habitats or anthropogenic habitats tagonicus from continental Asia is reported from (Delabie et al. 2009, Santos-Silva et al. 2016, Hong Kong. Golias et al. 2018) suggesting that some popula- Brachymyrmex patagonicus is native to tions could represent more recent introductions. South America and has been reported from the Determining the exact native range of this species southern Argentinean province of Santa Cruz within South America is thus needed at this point. north to Venezuela and the Guiana Shield, and Within the United States, where the spe- from the eastern Brazilian states of Pernambuco cies is non-native, MacGown and collaborators and Paraiba to Ecuador in the west (antmaps.org, reported B. patagonicus from seven states in 2007 2 Benoit Guénard (Florida, Georgia, Alabama, Mississippi, Louisi- single record of B. patagonicus has been reported ana, Arkansas and Texas) but in just 12 years, ad- from the harbor area of Kobe, Hyogo prefecture, ditional records from California (Martinez et al. Japan (Terayama et al. 2014), however further in- 2011), North Carolina (Guénard et al. 2012), Ari- vestigation to determine if this population remains zona (MacGown et al. 2013), New Mexico (Mac- and has been able to survive the cooler climate of Gown et al. 2013), South Carolina (MacGown et the region would be welcome. al. 2013), Missouri (Trager 2014), Nevada and Because of its small size and the lack of Tennessee (Hill 2017) have been reported, with a recent and comprehensive taxonomy, the genus B. patagonicus now widespread within the south- Brachymyrmex has caused much confusion his- ern American states from coast to coast across 15 torically among ant biologists (MacGown et al. states. In the Caribbean region, B. patagonicus is 2007, Deyrup 2016). For instance, early records known from the Bahamas (Wheeler & Wheeler of the Mesoamerican species B. musculus Forel 1978) and was recently reported from Martinique 1899 from the USA and the Bahamas (Wheeler & (Carval et al. 2016). Wheeler 1978) were misidentifications of B. pa- In the Old World, B. patagonicus has tagonicus in (MacGown et al. 2007). Similarly, been reported in Europe from greenhouses of early records of B. brevicornis from Florida (Dey- the Kew Gardens, London (England) since 1909 rup et al. 2000) represent an undescribed species and more recently in the early 2000’s from green- of Brachymyrmex (MacGown et al. 2007), or the houses and zoos in the Netherlands (Vierbergen record of B. aphidicola Forel 1909 from Hawaii 2003, Boer & Vierbergen 2008). However, for (Wheeler 1934) represents a misidentification of both countries, it is uncertain if these populations B. obscurior (Huddleston & Fluker 1968). Recent persist (e.g. see Brangham 1938) and no outdoor taxonomic work initiated by Quirán and collabo- populations have been reported. The situation dif- rators (2004) and later completed by MacGown fers in Spain, where B. patagonicus was recently and collaborators (2007) defined B. patagoni- reported from the coastal city of Almería (Almería cus from the following morphological charac- province) where it was collected both indoors and ters (briefly summarized here): brownish-yellow outdoors (Espadaler & Pradera 2016). In Asia, a scapes exceeding the occipital margin of head by Figure 1: Pictures of a specimen of B. patagonicus collected from Hong Kong showing A) a head, B) a profile and C) a dorsal view. First record of the emerging global pest Brachymyrmex patagonicus Mayr 1868 3 (Hymenoptera: Formicidae) from continental Asia 1/5 of their total length, eyes well-developed and surface was directly exposed to the sun, constant as large as the malar space, decumbent pubes- wind likely cooled the surface. On the afternoon cence on head and gaster sparse with the presence of December 16th (3 to 4:30pm), additional sam- of a few long and scattered erect hairs, prome- pling was performed using baits (cookie crumbs) sonotum with a few erect hairs (3 to 9) on dorsum to collect more workers and other species in the when specimens observed in profile view. These vicinity. Over 60 workers of B. patagonicus were morphological characters are clearly observed on observed, including a few meters away from the the specimens collected in Hong Kong (Figure 1) original sites (within a radius of 5m) on bare from Kowloon, Hung Hom district, waterfront, ground and lawn (Figure 2). A few individu- 22.302074N, 114.191298E, 4 m elev., 11 & 16 als were observed at collecting baits, however December 2018, B. Guénard col. no mass-recruitment was observed despite the The collecting site in Hong Kong is lo- high ground temperature measured (22.7°C to cated at the tip of a zone of reclaimed land and 25.8°C). While workers were observed using a heavily urbanized. The specimens were first ob- similar trail suggesting the potential use of phero- served foraging at the base of two planted Arau- monal communication, the density of workers caria heterophylla (Salisb.), an introduced tree observed was low. Three other ant species were species within a landscaped urban habitat. Forag- observed in the same area, Pheidole megacepha- ing activities were observed on December 11th in la (Fabricius, 1793) which appeared dominant on the morning at 8:45am and around 10:30am. At baits, and more rarely Paraparatrechina sauteri the time of the initial observation, atmospheric (Forel, 1913) and Cardiocondyla minutior Forel, temperature was close to 17°C, and while the bark 1899; the latter is here recorded for the first time Figure 2: Landscape habitat where B. patagonicus was found in Hung Hom, Hong Kong. White arrows indicate areas where the species was found foraging. 4 Benoit Guénard in Hong Kong as well and was recently collect- Within urban settings, B. patagonicus is ed from the nearby territory of Macao (Leong considered to be a major pest due to the nuisance et al. 2017). The presence of B. patagonicus at the species creates in entering buildings (Mac- the basis of a coniferous species is worth noting Gown et al. 2007). For instance, in separate stud- as the association of this ant with pine trees has ies conducted in hospitals, B. patagonicus has been reported previously in its North American been recorded as one of the most frequent and introduced range (MacGown et al. 2007, Hill abundant species found in several room types in- 2017) as well as in its native range in associa- cluding kitchens, offices, and laundry rooms, but tion with exotic pine trees in Patagonia (Corley et also more sensitive areas such as infirmaries and al. 2006). The presence of B. patagonicus within neonatal units (dos Santos et al. 2009, Josens et landscaped habitat and heavily urbanized envi- al. 2014, de Castro et al. 2016). This species also ronment (Figure 2) is similar to observations in colonizes or forages within administrative build- collecting sites in other introduced regions such ings (e.g. schools) as well as households or ho- as southern Spain (Espadaler & Pradera 2016), or tels and was recognized in Mississippi as the pest North Carolina, USA (North Carolina State Uni- causing the most frequent interventions from pest versity Campus: Guénard et al. 2014). control companies due to its high nesting plas- ticity and the difficulties to control populations (MacGown et al. 2007). While the species is not Risks for Hong Kong and Asia anticipated to directly damage building structures or cause health problems, its high abundance In both its native and introduced ranges, B.