Eastern Cambodia Research Articles

Households or Hotspots? Defining Intervention Targets for Malaria Elimination in Ratanakiri Province, Eastern Cambodia.

BackgroundMalaria “hotspots” have been proposed as potential intervention units for targeted malaria elimination. Little is known about hotspot formation and stability in settings outside sub-Saharan Africa.MethodsClustering of Plasmodium infections at the household and hotspot level was assessed over 2 years in 3 villages in eastern Cambodia. Social and spatial autocorrelation statistics were calculated to assess clustering of malaria risk, and logistic regression was used to assess the effect of living in a malaria hotspot compared to living in a malaria-positive household in the first year of the study on risk of malaria infection in the second year.ResultsThe crude prevalence of Plasmodium infection was 8.4% in 2016 and 3.6% in 2017. Living in a hotspot in 2016 did not predict Plasmodium risk at the individual or household level in 2017 overall, but living in a Plasmodium-positive household in 2016 strongly predicted living in a Plasmodium-positive household in 2017 (Risk Ratio, 5.00 [95% confidence interval, 2.09–11.96], P < .0001). There was no consistent evidence that malaria risk clustered in groups of socially connected individuals from different households.ConclusionsMalaria risk clustered more clearly in households than in hotspots over 2 years. Household-based strategies should be prioritized in malaria elimination programs in this region.

Efficacy and Safety of Pyronaridine-Artesunate plus Single-Dose Primaquine for Treatment of Uncomplicated Plasmodium falciparum Malaria in Eastern Cambodia.

In Cambodia, multidrug-resistant Plasmodium falciparum undermines the treatment of uncomplicated malaria, and new therapeutic options are needed. Pyronaridine-artesunate has not previously been evaluated in eastern Cambodia. We conducted a single-arm, open-label, prospective study between July and December 2017 at the Koh Gnek (Mondulkiri) and Veun Sai (Rattanakiri) health centers in eastern Cambodia. Eligible patients were aged ≥7 years (females, ages 12 to 18 years, were excluded), weighing ≥20 kg, with microscopically confirmed P. falciparum monoinfection and fever. Oral pyronaridine-artesunate was administered once daily for 3 days, dosed according to body weight, plus a single dose of primaquine on day 0. Sixty patients were recruited to Koh Gnek, and 61 patients were recruited to Veun Sai. The primary outcomes, i.e., the day 42 PCR-adjusted adequate clinical and parasitological responses (ACPRs), were 98.3% (95% confidence interval [CI], 88.4 to 99.8) in Koh Gnek and 96.7% (95% CI, 87.3 to 99.2) in Veun Sai (Kaplan-Meier). In a per-protocol analysis, the proportions of patients with day 42 PCR-adjusted ACPRs were 98.3% (57/58; 95% CI, 90.8 to 100.0) at Koh Gnek and 96.7% (58/60; 95% CI, 88.5 to 99.6) at Veun Sai. The Kelch13 (C580Y) mutation was present in 70.0% (77/110) of isolates. The copy numbers were increased in 61.3% (73/119) of isolates for Pfpm2 and in 1.7% (2/119) for Pfmdr1 There was no relationship between outcome and the 50% inhibitory concentration of pyronaridine. Adverse events were consistent with malaria, and there were no serious adverse events. Pyronaridine-artesunate has high efficacy in eastern Cambodia and could be used to increase the diversity of antimalarial therapy in the region. (This study is registered in the Australian New Zealand Clinical Trials Registry [ANZCTR] under no. ACTRN12618001300268.).

Surveillance for Sri Lankan cassava mosaic virus (SLCMV) in Cambodia and Vietnam one year after its initial detection in a single plantation in 2015.

Cassava mosaic disease, one of the ten most economically important crop viral diseases in the world, was first reported in Southeast Asia from a single plantation in Cambodia in 2015. To determine the presence and incidence of Sri Lankan cassava mosaic virus (SLCMV) one year after first detection, a total of 6,480 samples from 419 fields were systematically collected from cassava production areas across Cambodia (3,840 samples; 240 fields) and Vietnam (2,640samples; 179 fields) in the 2016 cropping season. Using PCR-based diagnostics, we identified 49 SLCMV-infected plants from nine fields, representing 2% of the total number of fields sampled. Infected fields were geographically restricted to two provinces of Eastern Cambodia, while no infection was detected from any of the other sampled sites in either country. Symptom expression patterns in infected plants suggested that SLCMV may have been transmitted both through infected planting materials, and by Bemisia tabaci, the known whitefly vector of SLCMV. In addition, 14% of virus infected plants did not express typical symptoms of cassava mosaic disease on their leaves, highlighting that molecular-based validation is needed to confirm the presence of SLCMV in the field. None of the owners of the SLCMV-infected fields indicated acquired planting materials from the plantation in Ratanakiri where SLCMV was first reported. The surveillance baseline data generated for both countries is discussed in light of future options to control and manage cassava mosaic disease.

Utilization of waterholes by globally threatened species in deciduous dipterocarp forest of the Eastern Plains Landscape of Cambodia

AbstractDeciduous dipterocarp forests throughout Asia provide crucial habitat for several globally threatened species. During the dry season water availability in these forests is primarily limited to perennial rivers and waterholes. Such water sources form an essential part of these dry forests and are used by multiple species, including large mammals and birds, but little is known regarding how waterhole characteristics affect wildlife use. We investigated waterhole utilization by six globally threatened dry forest specialists: banteng Bos javanicus, Eld's deer Rucervus eldii, giant ibis Thaumatibis gigantea, green peafowl Pavo muticus, lesser adjutant Leptoptilos javanicus and Asian woolly-necked stork Ciconia episcopus. We camera-trapped 54 waterholes in Srepok Wildlife Sanctuary, eastern Cambodia, during the dry season of December 2015–June 2016. We measured nine waterhole and landscape characteristics, including indicators of human disturbance. Waterhole depth (measured every 2 weeks) and the area of water at the start of the dry season were the main environmental factors influencing waterhole use. Additionally, waterholes further from villages were more frequently used than those nearer. Our study reaffirmed the importance of waterholes in supporting globally threatened species, especially large grazers, which are critical for maintaining these dry forest ecosystems. The results also suggested that artificially enlarging and deepening selected waterholes, particularly those further from human disturbance, could enhance available habitat for a range of species, including grazers. However, this would need to be conducted in coordination with patrolling activities to ensure waterholes are not targets for illegal hunting, which is a problem throughout South-east Asian protected areas.

Rediscovery of Lestes nigriceps Fraser, 1924 (Odonata: Lestidae) in eastern Cambodia.

Lestes nigriceps Fraser, 1924 was described from a male (later the lectotype) and two non-conspecific females collected in 1922 at Pusa, Bihar State, India, and has never been reported since. In June 2018 a population of L. nigriceps was unexpectedly found in eastern Cambodia, Mondulkiri Province. The Cambodian males, their variation and, for the first time, the true female of L. nigriceps is described.

Common Illnesses in Tropical Asia and Significance of Medical Volunteering.

This study was conducted to provide practical information for actual preparation of medical volunteering in tropical Asia, mainly the distribution of common illnesses encountered during mission. From 2012 to 2017, we visited two rural areas of Eastern Cambodia for medical volunteering missions, Cham Lak and Khsoem. Neither area has electricity or public water. We classified the common cases encountered during missions into six groups (upper respiratory infection, gastroenteritis, vaginitis and/or cystitis, dermatitis, work-related pain and parasite prevention) and assessed the distribution. In Cham Lak and Khsoem, 558 and 371 people were treated, respectively. The most commonly encountered cases in children under age of 18 were upper respiratory infection, followed by parasite control and dermatitis, in both areas. There was no significant difference in distribution between the two areas. For adults, the most common illnesses in Cham Lak area were vaginitis and/or cystitis, followed by gastroenteritis and work-related pain. In Khsoem area, the common illnesses were work-related pain followed by gastroenteritis, and upper respiratory infection. The distribution between the two areas differed significantly (p <0.001). The difference might be due to the water source and main crops of agriculture. Successful preparation of a medical volunteering needs deep understanding of the destination community.

An adaptable but threatened big cat: density, diet and prey selection of the Indochinese leopard (Panthera pardus delacouri) in eastern Cambodia.

We studied the Indochinese leopard (Panthera pardus delacouri) in eastern Cambodia, in one of the few potentially remaining viable populations in Southeast Asia. The aims were to determine the: (i) current leopard density in Srepok Wildlife Sanctuary (SWS) and (ii) diet, prey selection and predation impact of leopard in SWS. The density, estimated using spatially explicit capture–recapture models, was 1.0 leopard/100 km2, 72% lower than an estimate from 2009 at the same site, and one of the lowest densities ever reported in Asia. Dietary analysis of 73 DNA confirmed scats showed leopard consumed 13 prey species, although ungulates comprised 87% of the biomass consumed (BC). The overall main prey (42% BC) was banteng (Bos javanicus), making this the only known leopard population whose main prey had adult weight greater than 500 kg. Consumption of wild pig (Sus scrofa) was also one of the highest ever reported (22% BC), indicating leopard consistently predated on ungulates with some of the largest adult weights in SWS. There were important differences in diet and prey selection between sexes, as males consumed mostly banteng (62% BC) in proportion to availability, but few muntjac (Muntiacus vaginalis; 7% BC), whereas females selectively consumed muntjac (56% BC) and avoided banteng (less than 1% BC). Predation impact was low (0.5–3.2% of populations) for the three ungulate species consumed. We conclude that the Indochinese leopard is an important apex predator in SWS, but this unique population is declining at an alarming rate and will soon be eradicated unless effective protection is provided.

Experimental estimation of snare detectability for robust threat monitoring.

Hunting with wire snares is rife within many tropical forest systems, and constitutes one of the severest threats to a wide range of vertebrate taxa. As for all threats, reliable monitoring of snaring levels is critical for assessing the relative effectiveness of management interventions. However, snares pose a particular challenge in terms of tracking spatial or temporal trends in their prevalence because they are extremely difficult to detect, and are typically spread across large, inaccessible areas. As with cryptic animal targets, any approach used to monitor snaring levels must address the issue of imperfect detection, but no standard method exists to do so. We carried out a field experiment in Keo Seima Wildlife Reserve in eastern Cambodia with the following objectives: (1) To estimate the detection probably of wire snares within a tropical forest context, and to investigate how detectability might be affected by habitat type, snare type, or observer. (2) To trial two sets of sampling protocols feasible to implement in a range of challenging field conditions. (3) To conduct a preliminary assessment of two potential analytical approaches to dealing with the resulting snare encounter data. We found that although different observers had no discernible effect on detection probability, detectability did vary between habitat type and snare type. We contend that simple repeated counts carried out at multiple sites and analyzed using binomial mixture models could represent a practical yet robust solution to the problem of monitoring snaring levels both inside and outside of protected areas. This experiment represents an important first step in developing improved methods of threat monitoring, and such methods are greatly needed in southeast Asia, as well as in as many other regions.

Robust estimation of snare prevalence within a tropical forest context using N-mixture models

Hunting with snares is indiscriminate and wasteful, and this practice is currently one of the gravest threats to terrestrial vertebrates in the tropics. However, as snares are difficult to detect and often dispersed widely across large, inaccessible areas it is problematic to reliably estimate their prevalence and no standard survey methods exist. Conservation managers need reliable, timely, information on the spatio-temporal patterns of hunting and on responses to interventions, and we present an innovative sampling and analysis framework that allows for the rigorous estimation of snare detectability and ‘abundance’, but which can be feasibly implemented in challenging field contexts. This new approach was used to undertake a large-scale systematic snare survey in Keo Seima Wildlife Sanctuary, in Eastern Cambodia, and the resulting data were analysed using a novel application of N-mixture models. A range of environmental and management factors were examined as potential determinants of snare abundance and detectability, and proximity to the Vietnamese border was shown to be overwhelmingly the most influential factor. Snares were more common in the wet season rather than the dry season, and the detection probability of snares was shown to be low (~0.33), as predicted. No clear relationships between snaring levels, anti-poaching patrol effort and ungulate densities were evident from these data. There was clear evidence that certain factors, such as the percentage of dense forest cover, will exert confounding effects on both detectability and abundance, highlighting the critical need to take account of the imperfect detection when designing threat monitoring systems.

Coeliccia rolandorum sp. nov. from eastern Cambodia and southern Vietnam, the eastern relative of C. kazukoae Asahina, 1984 (Odonata: Platycnemididae).

Coeliccia rolandorum sp. nov. is described from the eastern Cambodia (holotype: Cambodia, Mondulkiri Province, Buu Sraa Waterfall environs, 12°34' N 107°24' E, ~780 m a.s.l., 16 June 2014, RMNH) and southern and central Vietnam. It is related to C. kazukoae, which is known from the Cardamom and Sankamphaeng Mts., and replaces it in eastern Indochina. New distributional data on C. kazukoae are presented and its characters are discussed with respect to their change with age.

Phytoplasma infection of a tropical root crop triggers bottom-up cascades by favoring generalist over specialist herbivores.

Global interest on plant-microbe-insect interactions is rapidly growing, revealing the multiple ways in which microorganisms mediate plant-herbivore interactions. Phytopathogens regularly alter whole repertoires of plant phenotypic traits, and bring about shifts in key chemical or morphological characteristics of plant hosts. Pathogens can also cause cascading effects on higher trophic levels, and eventually shape entire plant-associated arthropod communities. We tested the hypothesis that a Candidatus Phytoplasma causing cassava witches’ broom (CWB) on cassava (Manihot esculenta Grantz) is altering species composition of invasive herbivores and their associated parasitic hymenopterans. We conducted observational studies in cassava fields in eastern Cambodia to assess the effect of CWB infection on abundance of specialist and generalist mealybugs (Homoptera: Pseudococcidae), and associated primary and hyper-parasitoid species. CWB infection positively affects overall mealybug abundance and species richness at a plant- and field-level, and disproportionately favors a generalist mealybug over a specialist feeder. CWB phytoplasma infection led to increased parasitoid richness and diversity, with richness of ‘comparative’ specialist taxa being the most significantly affected. Parasitism rate did not differ among infected and uninfected plants, and mealybug host suppression was not impacted. CWB phytoplasma modifies host plant quality for sap-feeding homopterans, differentially affects success rates of two invasive species, and generates niche opportunities for higher trophic orders. By doing so, a Candidatus phytoplasma affects broader food web structure and functioning, and assumes the role of an ecosystem engineer. Our work unveils key facets of phytoplasma ecology, and sheds light upon complex multi-trophic interactions mediated by an emerging phytopathogen. These findings have further implications for invasion ecology and management.

A framework for assessing readiness for tiger Panthera tigris reintroduction: a case study from eastern Cambodia

Reintroduction is a viable conservation strategy for large carnivores however such reintroductions require robust feasibility assessments, considering ecological, management, and social factors, prior to implementation. Plans are being developed in a number of tiger range countries, including Cambodia, for tiger Panthera tigris reintroductions in response to local and national extinctions. We provide a framework for undertaking feasibility assessments for tiger, and other large carnivore, reintroductions and present a number of methodological tools, and appropriate indicators, for conducting such assessments. We apply the framework to plans by the Royal Government of Cambodia for tiger reintroduction into Srepok Wildlife Sanctuary (formally Mondulkiri Protected Forest), eastern Cambodia. Srepok Wildlife Sanctuary forms part of a large (>13,000-km2) trans-boundary conservation landscape with potential to support a tiger source population. Current ungulate prey densities, assessed through robust line-transect sampling, at approximately 5.0 individuals per km2 may be sufficient to support a breeding tiger population. However levels of protected area management and law enforcement fall below global standards for tiger recovery. Local communities, though supportive of conservation efforts, also identified a number of concerns regarding reintroduction. Therefore current ecological, social, and management conditions within SWS are not currently suitable for tiger reintroduction. However with improved and more effective law enforcement, combined with robust monitoring of the indicators within our framework, such conditions could be met. We recommend that our framework for assessing landscape suitability for reintroductions offers an effective road map for reintroduction-based recovery of tiger populations across tiger range countries.

Endangered leopards: Range collapse of the Indochinese leopard (Panthera pardus delacouri) in Southeast Asia

The Indochinese leopard (Panthera pardus delacouri) is a genetically distinct subspecies that historically occurred throughout mainland Southeast Asia, but might have experienced recent declines in numbers and distribution. This study aimed to determine the current distribution of the Indochinese leopard, and estimate its population size, by reviewing data from camera trap and other wildlife surveys conducted during the past 20years. Our results showed the Indochinese leopard likely now occurs only in 6.2% of its historical range, with only 2.4% of its distribution in areas of confirmed leopard presence. The leopard is extirpated in Singapore, likely extirpated in Laos and Vietnam, nearly extirpated in Cambodia and China, and has greatly reduced distributions in Malaysia, Myanmar, and Thailand. There are plausibly only two major strongholds remaining, which we consider priority sites: Peninsular Malaysia, and the Northern Tenasserim Forest Complex. We also identified a small isolated population in eastern Cambodia as a third priority site, because of its uniqueness and high conservation value. We estimate a total remaining population of 973–2503 individuals, with only 409–1051 breeding adults. Increased poaching for the illegal wildlife trade likely is the main factor causing the decline of the Indochinese leopard. Other potential contributing factors include prey declines, habitat destruction, and possibly disease. We recommend a separate IUCN assessment for the Indochinese leopard, and that this subspecies be classified as Endangered. Our findings provide important information that can help guide where conservation actions would be most effective in preventing the extinction of this subspecies.

Fungal Biodiversity in Cardamom Protected Forests and Seima Biodiversity Conservation Area of Cambodia

Mushroom surveys and collections were conducted in the western and eastern forest areas in Cambodia, and then fungal biodiversity was analyzed by identifying mushrooms. One thousand and three hundreds eighty three specimens were identified by morphological and genetical characteristics, and were classified into 238 species, 160 genera, 52 families, 15 orders, and 3 phylums. The collected mushrooms were immersed in 70% ethyl alcohol for DNA extraction, and the rest of them were dried in the portable mushroom dryer for 12 hrs. Among these mushrooms, the genera Mycena (8.7%), Ganoderma (5.6%), Microporus (5.3%), Marasmius (4.2%), Marasmiellus (3.0%), Phellinus (2.5%), Trametes (2.5%), Hygrocybe (1.9%) and Pycnoporus (1.5%) were dominant. In the western Cambodia, 1,061 specimens were collected from Koh Kong forests, while 263 specimens were collected from the eastern Cambodia, Seima and Mondulkiri forests. Elevations of surveyed sites were ranged from 0 to 750 m above sea level. The number of species observed in the elevation of 251-500 m was the highest as compared to the other ranges of elevation. Daldinia concentrica, Microporus vernicipes, Microporus xanthopus, Pycnoporus coccineus, Stereum hirsutum, and Stereum ostrea were commonly distributed in all ranges of elevation, while the distribution of Ceratomyxa fruticulosa, Panus fulvus, Schizophyllum, Trametes versicolor, and Tyromyces chioneus were limited under 500 m. One hundred and forty one species including Amauroderma sp., Bjerkandera adusta, Trichaptum abietinum, and Tyromyces chioneus were collected only in Cardamom, while 20 species including Auricularia auricula-judae, Coriolopsis sanguinaria, Rigidoporus microporus, and Xylaria polymorpha were collected only in Seima. Ganoderma sp., Mycena sp., Marasmius sp., Microporus xanthopus, Phellinus sp., and Russula sp. were dominant species in both the western and eastern Cambodia. Species diversity indices in the eastern and western survey sites were 1.83 and 1.77, respectively, while evenness indices were 0.92 and 0.90. The species similarity index between two survey sites was 0.42.

Abundance estimates for the endangered Green PeafowlPavo muticusin Cambodia: identification of a globally important site for conservation

SummaryThe catastrophic decline of the endangered Green peafowlPavo muticusacross its former range is well known, yet there are only a handful of reliable population estimates for this species from its remaining range, making global assessment challenging. We present the first rigorous population estimates for this species from Cambodia, and model the distribution and the relationships between this species and several environmental covariates from the Core Zone (187,900 ha) of Seima Protection Forest (SPF), eastern Cambodia. Using distance sampling the abundance of Green Peafowl in SPF in 2014 is estimated to be 541 (95% CI [252, 1160]). Density surface modelling was used to predict distribution and relative abundance within the study area, and there was some evidence that the species prefers areas of deciduous forest, non-forest, and to a lesser extent semi-evergreen forest. These results highlight the importance of the central and northern sections of SPF for this species. Furthermore, the analysis suggested that Green Peafowl abundance is higher in closer proximity to water, yet decreases in closer proximity to human settlement.

Asiagomphus reinhardti sp. nov. (Odonata, Gomphidae) from eastern Cambodia and southern Laos

Asiagomphus reinhardti sp. nov. is described by two males from Annamense Mountains in eastern Cambodia (holotype: Cambodia, Mondulkiri Province, the left tributary of the main river downstream from Buu Sraa Waterfall, 12°34'01-19'' N 107°24'50''-25'03'' E, ca 450 m a.s.l., 15 vi 2014, RMNH) and southern Laos. The species is characterised by a large caudal lobe on S10 in males and a blunt medial lateroventral projection at cercus.

Prodasineura hoffmanni sp. nov. (Odonata, Platycnemididae, Disparoneurinae) from eastern Cambodia.

Prodasineura hoffmanni sp. nov. is described from Annamense Mountains in eastern Cambodia (holotype: Cambodia, Mondulkiri Province, 4.2 km SE of Dak Dam village, 12°23'10-18'' N 107°19'22-30'' E, 877-878 m asl, 14. VI. 2014, RMNH). The species has a blue pattern, and the male is characterised by medium-broad blue stripes on synthorax and blue colour at the end of the abdomen confined to a tiny spot on S9, dorsum of S10 and cerci. A female of P. doisuthepensis Hoess, 2007 is described. Based on original descriptions, the following synonymy is proposed: Prodasineura fujianensis Xu, 2006 = Prodasineura huai Zhou et Zhou, 2007, syn. n.

Artificial deepening of seasonal waterholes in eastern Cambodia: impact on water retention and use by large ungulates and waterbirds

Natural seasonal waterholes (trapeang in Khmer) are an important feature of the deciduous dipterocarp forests of eastern Cambodia and are utilised by a number of globally threatened species of large ungulates and waterbirds. However at the end of the dry-season (April) only a small proportion of waterholes retain water. In 2011, we artificially deepened six waterholes in the core area of Mondulkiri Protected Forest, eastern Cambodia, removing 3m3 to 24m3 of earth (mean 16.5m3) from each. Surveys prior to deepening demonstrated that only one of these waterholes, and 10% of all waterholes surveyed in the study area (n=50), held water at the end of the dry-season. Following modification five of the six deepened waterholes (83%) held water at the end of the subsequent dry-season. From four camera traps over 448 trap-nights, 23 species including two globally threatened large ungulates, Banteng Bos javanicus and Eld’s Deer Rucervus eldii, and two Critically Endangered Ibises (Giant Thaumatibis gigantea and White-shouldered Ibis Pseudibis davisoni), were photographed foraging and drinking at the deepened waterholes between March and June 2012. Our results suggest that artificial deepening of natural waterholes does not cause damage, and makes these waterholes suitable for use throughout the dry-season. In the face of changing climate it is suggested that management plans should have a programme for the survey and determination of the status of waterholes every year and improve the use of water resources by artificial deepening. Â

Onychargia priydaksp. nov. (Odonata, Platycnemididae) from eastern Cambodia

Onychargia priydak sp. nov. is described from eastern Cambodia. The new species co-occurs with the widespread Onychargia atrocyana Selys, 1865 in the same region. Its males differ from those of O. atrocyana by a larger paraprocts, which are longer than the cerci, and a bright white pruinescence on thorax, femora and the two first abdominal segments. This is the second species in the genus Onychargia Selys, 1865. Onychargia vittigera Selys, 1865 is synonymised with O. atrocyana; Onychargia indica Sahni, 1964 does not belong in the genus Onychargia.http://zoobank.org/urn:lsid:zoobank.org:pub:CCE4986F-905D-48E4-ABFD-217BF835BDC0

The breeding behaviour, advertisement call and tadpole of Limnonectes dabanus(Anura: Dicroglossidae).

Fanged frogs (Limnonectes) are a group of dicroglossid frogs from Asia that often have reversed sexual dimorphism with larger males. Limnonectes dabanus is a poorly known species of fanged frog from forested habitats in southern Vietnam and eastern Cambodia. Adult males exhibit an extreme degree of megacephaly and possess bizarre head ornamentation. L. dabanus breeds in shallow, non-flowing or very slow-flowing pools, puddles, and drainage ditches. Eggs are laid as a widely spaced array, and the larvae have a morphology typical of pond-dwelling tadpoles. Although males of the species lack vocal sacs, they produce a low-pitched (0.4-0.6 kHz), single-note advertisement call that sounds like a drop of water falling into water. Given the spacing of calling males, presence of multiple females near breeding sites, and reversed sexual dimorphism, the mating system of L. dabanus may be an example of resource-defense polygyny, and the massive head of the male is likely used in male combat.