The Common House Gecko, Hemidactylus frenatus, also known as the Asian House Gecko (AHG), is the most significant invasive gecko globally. Detecting this species can be challenging because it closely resembles other geckos, and is often not directly observed, being cryptic and nocturnal. Traces such as scats, however, are more readily observed than the animal itself. Here, we developed and tested a new diagnostic mitochondrial ND2 LAMP (Loop-mediated isothermal amplification) assay to detect and distinguish AHG from other geckos. Testing DNA from twenty-five non-target gecko and skink species present in Western Australia demonstrated the species-specificity of the assay. This new molecular assay showed amplification in under 15 minutes from AHG DNA. Intraspecific variation did not adversely affect the LAMP assay, with all AHG tissue samples successfully amplifying. This included samples from the Cocos (Keeling) Islands territory of Australia which were >6% genetically divergent from mainland Australian samples, representing a genetic group that was previously unknown, referred to here as AHG "clade E". The assay was found to be highly sensitive, capable of amplifying AHG DNA at very low levels, down to 0.0001 ng/µL of AHG DNA, within 25 minutes. The new LAMP assay has been fully optimised for in-field use, including development and testing of a non-destructive DNA extraction method for in-field extractions from both AHG tissue and scat samples, as well as a gBlock gene fragment for use as a synthetic positive control. The in-field protocols were tested on 100 field collected scats, from multiple lizard species in Western Australia, demonstrating the AHG specificity of the assay, with amplification successful on 79% of AHG scats tested in-field. While the assay was highly effective, scat DNA degradation and inhibitors limited detection in 21% of AHG samples, highlighting preservation challenges. This new assay has already been applied operationally in the field, providing early detection of AHG, and preventing potential introduction of this species into new areas.

The Common House Gecko, Hemidactylus frenatus, also known as the Asian House Gecko (AHG), is the most significant invasive gecko globally. Detecting this species can be challenging because it closely resembles other geckos, and is often not directly observed, being cryptic and nocturnal. Traces such as scats, however, are more readily observed than the animal itself. Here, we developed and tested a new diagnostic mitochondrial ND2 LAMP (Loop-mediated isothermal amplification) assay to detect and distinguish AHG from other geckos. Testing DNA from twenty-five non-target gecko and skink species present in Western Australia demonstrated the species-specificity of the assay. This new molecular assay showed amplification in under 15 minutes from AHG DNA. Intraspecific variation did not adversely affect the LAMP assay, with all AHG tissue samples successfully amplifying. This included samples from the Cocos (Keeling) Islands territory of Australia which were >6% genetically divergent from mainland Australian samples, representing a genetic group that was previously unknown, referred to here as AHG “clade E”. The assay was found to be highly sensitive, capable of amplifying AHG DNA at very low levels, down to 0.0001 ng/µL of AHG DNA, within 25 minutes. The new LAMP assay has been fully optimised for in-field use, including development and testing of a non-destructive DNA extraction method for in-field extractions from both AHG tissue and scat samples, as well as a gBlock gene fragment for use as a synthetic positive control. The in-field protocols were tested on 100 field collected scats, from multiple lizard species in Western Australia, demonstrating the AHG specificity of the assay, with amplification successful on 79% of AHG scats tested in-field. While the assay was highly effective, scat DNA degradation and inhibitors limited detection in 21% of AHG samples, highlighting preservation challenges. This new assay has already been applied operationally in the field, providing early detection of AHG, and preventing potential introduction of this species into new areas.

Abstract Artificial light at night (ALAN) is a pervasive driver of ecological change in urban ecosystems, yet little is known about how reptiles respond to illuminated structures. We investigated the use of internally lit advertising banners by the common house gecko Hemidactylus frenatus in five Cambodian cities. Field surveys showed an occupancy rate of 28% across all banners. Generalised linear models revealed that gecko presence was positively associated with banner light intensity, whereas gecko abundance increased significantly with banner surface area. Trends indicated slightly higher numbers shortly after dusk and at brighter banners. Other tested variables, including air temperature, ambient noise, mounting height and anchoring type, had no detectable effects. The explained variance of the models was modest, suggesting that additional unmeasured factors, such as insect availability or the possibility of geckos quickly retreating into the banner structure, may play important roles. These findings demonstrate that illuminated banners provide suitable microhabitats for geckos. By concentrating predators, such structures may influence urban trophic interactions and contribute not only to the success of H. frenatus in anthropogenic environments but also to its invasive potential and the displacement of native species.

Hemidactylus frenatus (Duméril & Bibron, 1836) is an invasive lizard distributed across Europe, Africa, and the Americas. In Colombia, it occupies over 70% of the territory in lowlands and mid-elevation areas, with only one record above 2,500 m above sea level (a.s.l). We provide two new records at 2,800 m a.s.l. which expand the distribution of H. frenatus in the Cordillera Occidental of Boyacá, Colombia. These records are the highest in the Neotropics. We discuss the importance of monitoring invasions and the effects of a warming climate in high-mountain ecosystems.

The predation by the Big-headed Treefrog Polypedates megacephalus on the Common House Gecko Hemidactylus frenatus and a failed predation attempt on the Tokay Gecko Gekko gecko are reported. In addition, for the first time, tadpoles of this treefrog species were observed scavenging on dead Asian Grass Lizard Takydromus sexlineatus, Boie's Wart Frog Fejervarya limnocharis, and unidentified species of the annelid order Haplotaxida. All observations were carried out in urban environments.

Involvement of enkephalinergic system in the reproductive stress response of the gecko Hemidactylus frenatus.

Investigating altitudinal distribution patterns of species richness represents a fundamental research objective in biogeography and community ecology. Hainan Island has tropical rainforests ranging from sea level to >1800 m a.s.l., with various animal species, including reptiles such as geckos. Information on the altitudinal distribution patterns of animal diversity on Hainan Island is limited. Thus, from October 2020 to June 2023, we surveyed Gekkonidae species on Diaoluo Mountain and Jianfeng Ridge in the Hainan Tropical Rainforest National Park using a line transect method. The two study sites were divided into seven altitudinal zones at intervals of 150 m from 31 to 1080 m a.s.l. We tested correlations between abundance and species diversity indices and altitude. Five gecko species were identified. The endemic Gekko similignum mainly occurred at high-altitude areas on both mountains, whereas Hemidactylus frenatus occupied low-altitude areas. Gehyra mutilata had the lowest abundance among all species at all altitudes. Diaoluo Mountain exhibited a higher species diversity and abundance than Jianfeng Ridge. Geckos on Diaoluo Mountain were mainly distributed between 31 and 920 m a.s.l., presenting a bimodal distribution, with peaks appearing in altitudinal zones II (181-330 m a.s.l.) and VI (781-930 m a.s.l.). The gecko distribution on Jianfeng Ridge ranged from 31 to 948 m a.s.l., presenting a unimodal distribution, with a peak in altitudinal zone V (631-780 m a.s.l.).

Widespread dispersal of a human commensal across the Pacific: Reconstructing the human-mediated invasion history of the house gecko (Hemidactylus frenatus)

The Asian house gecko (Hemidactylus frenatus) is a unique species among lizards, commonly found in human habitats and often regarded as a pest. Like all vertebrates, these geckos are susceptible to parasites. In this investigation, a total of 54 H. frenatus specimens were collected from randomly selected households in various locations throughout Dhaka city to examine parasitic infections. The study's results revealed that 61.11% of the geckos were infected with endoparasites. The infection rate for female geckos (63.64%) was higher than that for males (59.38%). A total of 61 parasites were collected from different organs including the body cavity, stomach, intestine, and lungs of the house geckos. Four species of parasites were identified, belonging to the groups trematode (Ganeo kumaonensis), nematoda (Strongyloides cruzi and Neopharyngodon gecko), and pentastomida (Raillietiella frenatus). Notably, the pentastomid Raillietiella frenatus had not been previously recorded in H. frenatus in Bangladesh. The prevalence of the identified parasites was as follows: Ganeo kumaonensis (9.26%), Strongyloides cruzi (7.41%), Neopharyngodon gecko (37.04%), and Raillietiella frenatus (18.52%). Among these, the nematode exhibited the highest prevalence at 44.44%, while the trematode showed the lowest at 9.26%. A significant number of parasites were also collected from the stomach, accounting for 27.78% of the total. Additionally, when examining various length groups, those geckos measuring 9.5-10.49 cm in length showed a higher susceptibility to parasitic infections (88.23%) compared to other length groups. Similarly, in different weight groups, geckos weighting 2.5-3.49 grams were found to have a higher susceptibility to parasitic infections (78.12%). Furthermore, a positive correlation was observed between the host's weight and the parasite burden. The significance of the current study lies in identifying the parasites that infect this unique species within the study area. Bangladesh J. Zool. 53(1): 57-66, 2025

Background matching is a common form of crypsis in animals, resulting from selective pressures imposed by visual systems of predators and/or prey. Therefore, it could be expected that novel backgrounds would pose a barrier to the establishment of invasive species, due to a lack of crypsis. Behavioural flexibility in crypsis—through facultative crypsis and/or choice of matching backgrounds—has been suggested as a trait that may facilitate invasiveness. We assessed background-matching and facultative brightness-change in an Australian population of the invasive Asian House Gecko (Hemidactylus frenatus). This species is currently expanding from urban environments into surrounding tropical woodland, and demonstrates great variability in colour and pattern among individuals. We quantified wild background-matching in terms of both colour and brightness. We then experimentally tested whether geckos facultatively change brightness in the direction expected for a given background. Hemidactylus frenatus consistently brightness-matched across the backgrounds on which they were found, more than would be expected by chance. Experiments showed that H. frenatus rapidly changed in their dorsal brightness, in the direction expected given their background, suggesting that brightness-matching observed in wild geckos is due to facultative brightness-change. Successful invasion may benefit from facultative crypsis; however, it remains to be demonstrated how facultative brightness-change in H. frenatus is linked to predation and invasion success. We outline how recognition of facultative colour-pattern change in invasive species may be important for early detection and management actions.

Hemidactylus frenatus Duméril & Bibron (Gekkonidae) is a fairly common species and has a wide distribution from Asia, Americas, Africa, Australia, and a number of tropical islands worldwide. Although this species is distributed from the North to the South in Vietnam, studies on morphological characters and genetic diversity are limited. In this study, we used two mtDNA sequences, Cytb (Cytochrome b) and ND2 (NADH dehydrogenase subunit 2), to evaluate the genetic relationships of five H. frenatus specimens in Nghe An province. The genetic distances between the studied samples were relatively low, 0.3% and 0.1% for Cytb and ND2 sequences, respectively. Phylogenetic analyses based on Cytb and ND2 sequences showed that all five samples were grouped together with H. frenatus on GenBank with significant support (100%). The genetic divergence between the H. frenatus specimens in Nghe An and the H. frenatus specimens on GenBank were also small, ranging from 0.0% to 0.6%, while high genetic distance between the five H. frenatus specimens and othe species in the genus Hemidactylus was observed, ranging from 29% to 46%. In addition, the morphological characters of H. frenatus species in Nghe An are also described to provide additional biological data for studies on genetic relationships and the invasion process of the species.

La dieta de la rana lechera (Trachycephalus typhonius) consiste principalmente de artrópodos terrestres, auque hay algunas observaciones que involucran pequeños vertebrados como ranas, lagartijas y murciélgos. Reportamos el primer registro de un evento de depredación de T. typhonius sobre un geco casero común (Hemidactylus frenatus) en una zona urbana. La observación ocurrió en la cochera de una vivienda en la ciudad de Chetumal, Quintana Roo, México.

The wall gecko is found in tropical, subtropical, and warm temperate regions. It is a nocturnal species that seeks shelter during the daytime and emerges at dusk to forage throughout the night. This small lizard has become established in areas near human habitation in the tropics, forming a close association with people. Like other vertebrates, wall geckos are susceptible to parasitism. This study investigated the prevalence and intensity of ecto- and gastrointestinal parasites infecting Hemidactylus frenatus (wall geckos) in Akure North Local Government Area, Ondo State, Nigeria. A total of 360 geckos were sampled across six communities and examined for parasites using standard parasitological techniques. Overall, 68.9% of H. frenatus were infected with ectoparasites, while 66.4% harbored gastrointestinal parasites. The most prevalent ectoparasite was Trombicula sp. (35.8%), and Parapharyngodon sp. (37.5%) was the dominant gastrointestinal parasite. Cryptosporidium spp. was detected in 6.9% of the geckos using modified Ziehl-Neelsen staining. Ectoparasites were primarily located on the back and limbs, while gastrointestinal parasites were most abundant in the large intestine. Chi-square analysis revealed no statistically significant differences in parasite prevalence across sampling locations and sex (P > 0.05). These findings highlight the high parasite burden in H. frenatus and the potential public health risks associated with their close proximity to human dwellings.

Tropical reptiles colonizing temperate regions face distinct physiological challenges due to thermal stress. Their long-term survival hinges on physiological acclimatization or adaptation to these novel thermal environments. Previous research on cold tolerance in introduced high-latitude Hemidactylus frenatus revealed that rural populations on Okinawajima Island, Japan exhibited significantly lower critical thermal minimum (CTmin) compared to their urban counterparts. However, whether this variation stems from acclimation or genetically fixed physiological differences remains unclear. To address this issue, we re-examined the cold tolerance of rural and urban populations after subjecting them to 2-week acclimation periods under high and low temperatures. Our experiments revealed that urban geckos exposed to the high-temperature treatment exhibited the highest CTmin, while rural geckos in the low-temperature treatment displayed the lowest CTmin. Urban geckos in the low-temperature treatment and rural geckos in the high-temperature treatment displayed intermediate CTmin values. These findings suggest that both acclimation and genetic differences contribute to the observed variations in cold tolerance among H. frenatus populations. The urban and rural populations are only 10 km apart, highlighting that evolutionary responses to thermal stress can occur rapidly over surprisingly small geographical scales in this species.

Mammals, especially humans, have limited regenerative abilities compared to lower organisms. The common house gecko (Hemidactylus platyurus) exhibits high regenerative capacity and closer evolutionary relationship to mammals than other highly regenerative species. Observing the regeneration process in house gecko reveals insights into the biological mechanisms underlying tissue regeneration after injury. Sonic hedgehog (Shh) pathway is essential for intercellular communication during development and regeneration. In this study, Shh expression and its distribution during the tail regeneration in the common house gecko (Hemidactylus platyurus) were examined to understand the molecular mechanisms regulating regeneration. A total of 28 house geckos were divided into 7 groups based on sampling time. Autotomy procedures were conducted for all groups. The tails were allowed to regenerate, measured using graph paper, and cut to be analyzed. Hematoxylin-eosin and immunohistochemical staining using anti-Shh primary antibody were conducted to observe the microscopic structure and Shh expression. Statistical analyses were conducted to analyze the obtained data. Tail elongation was observed throughout the regeneration process. Shh expression is evident in both original and regenerated tails, commencing on day 1 post autotomy, peaking on day 14, stabilizing until day 21, and gradually decreasing by day 30. Statistical analysis showed significant differences on tail length measurement and Shh expression between groups (p < 0.001). The results showed strong positive correlation between Shh expression and regenerated tail length from day 1 to day 14 (R=0.818; p<0.001). Additionally, strong negative correlation was observed between Shh expression and regenerated tail length from day 21 to day 30 (R=-0.852; p<0.001). Shh protein is detected in a variety of cell types within both original and regenerated tail tissues. It plays critical role in maintaining tissue homeostasis in adult tissues and facilitating the proliferation, migration, and differentiation of blastema cells in response to injury.

Seasonal physiological plasticity (acclimatisation) facilitates homeostasis in changing environments and has been studied extensively with respect to thermal biology and metabolism. Less is known about seasonal changes in evaporative water loss (EWL) in response to changing water availability and humidity. The wet–dry tropics of northern Australia experience moderate seasonal temperature changes, but substantial changes in rainfall and humidity. We studied three gecko species (Amalosia rhombifer, Heteronotia binoei and Hemidactylus frenatus) in the wet and dry seasons with respect to their EWL, preferred body temperatures (Tpref), and their choice between a dry and humid refuge at and below Tpref. EWL was significantly lower in the dry season (66% of wet season values). Tpref for two of the species did not change seasonally, but A. rhombifer selected lower Tpref during the warmer wet season. Given a choice of refugia, the humid refuge at low temperatures was never preferred over the warm microhabitat. When both refugia were at the preferred temperature, only A. rhombifer showed a preference for the humid microhabitat. These results demonstrate that although thermoregulation is prioritised in the short term, hydroregulation (physiological plasticity in EWL) is adjusted in the longer term, with shifts occurring on a seasonal scale. However, it is possible that shifts in EWL may occur in response to prevailing weather conditions on a shorter timescale. Before broad generalisations can be drawn about the phenomenon of EWL plasticity, measurements need to be taken from more species in different climatic regions at ecologically relevant timescales.

The role of the opioid peptide dynorphin during the seasonal and gonadotropin-induced ovarian recrudescence in the gecko.

Cat-eyed snakes from genus Leptodeira, primarily prey on amphibians, but also consume other prey types. However, lizards have not previously been documented as prey for Leptodeira sp. aff. ornata. This snake is native to Costa Rica and Panama, though its precise taxonomic and phylogenetic relationships remain unclear. Its diet primarily consists of anurans, including both eggs and adult individuals. We report the first documented case of predation by this Cat-eyed snake on the Common House gecko, Hemidactylus frenatus. This gecko, native to Asia, has been introduced to numerous regions worldwide and is particularly abundant in urban and semi-urban areas. The Cat-eyed snake ingested the Common House gecko starting from the tail, in contrast to a different event where a Black-banded Cat-eyed snake began ingesting a Yellow-bellied gecko from the head. This finding suggests potential foraging behavior of this Cat-eyed snake in semi-urban areas, highlighting another instance of opportunism in its dietary preferences.

The Caribbean Islands biogeographic region is a biodiversity hotspot with 1,030 species of amphibians and reptiles, 82% endemic to the region (Hedges et al. 2019; Hedges 2025). However, many of these species are locally extirpated or face extinction, primarily by habitat destruction (deforestation), but also by introduced diseases and invasive species (Roy et al. 2023). In particular, St. Eustatius (Caribbean Netherlands; 21 km2) has faced several introductions of non-native herpetofauna, including the Montserrat Whistling Frog (Eleutherodactylus montserratae; Yuan et al. 2022; Hedges 2022; Powell et al. 2015), the Tropical House Gecko (Hemidactylus mabouia; Powell et al. 2015), the Green Iguana (Iguana iguana species complex; Debrot et al. 2022; van den Burg et al. 2018), and the Brahminy Blindsnake (Indotyphlops braminus; Powell et al. 2015). More recently, the establishment of the Common House Gecko (Hemidactylus frenatus) and the Smooth-scaled Tegulet (Gymnophthalmus underwoodi) has been described (Thibaudier et al. 2023). Here, we report another newly introduced species on St. Eustatius, the Cuban Treefrog, Osteopilus septentrionalis.

The Common House Gecko, Hemidactylus frenatus (Gekkonidae), as a Food Source of the Olive Sparrow, Arremonops rufivirgatus (Passerellidae), in Northwestern Costa Rica