Human disturbance affects behavioural time allocation in a fiddler crab (Austruca annulipes) in Southern Thailand

Human disturbances affect the macroinvertebrate populations in coastal regions. They respond to disturbances by altering their density and behaviour. Therefore, many of them are used as bioindicator species of human disturbance. Here, we pioneer the use of fiddler crabs to examine whether they alter their behaviour under human disturbance. Male fiddler crabs possess one large claw used for courting (waving) and fighting, and one small feeding claw, whereas females have two feeding claws. They show several surface activities. This study investigates (1) the effects of human disturbance on density and sex-ratio, and (2) the effects of human disturbance, and sex on behavioural time allocations in Austruca annulipes. Their density, sex-ratio, and time allocations were investigated in human-disturbed area (DA) and nondisturbed area (NDA). They showed feeding, feeding and walking, walking, running, standing/vigilance, inside burrows, burrowing, grooming, fighting, and waving. The results showed that crab density was higher and the sex ratio was more male biased in NDA than in DA. Human disturbance and sex affected time allocations but their interaction had no effect. Crabs in DA spent more time running, standing, and inside burrows but less time walking, burrowing, fighting, and waving than crabs in NDA. Between sexes, males spent more time standing, burrowing, grooming, and fighting but less time feeding, and walking than females. This indicates that human disturbances force the crabs to spend more time on anti-predator and escape behavior (standing/vigilance, running, inside burrows) rather than courting (waving) and constructing burrows (mating/breeding sites), which are important for breeding.(AU)

Spatial and temporal variations on the coexistence of Aedes and Culex larvae in Southern Thailand

This study investigated spatial and temporal variations on the coexistence of Aedes aegypti, Aedes albopictus, and Culex larvae in five subdistricts in Nakhon Si Thammarat, Thailand. We tested two main hypotheses on the spatial and temporal coexistence of mosquito larvae: (1) condition-specific competition and (2) spatial variation among the five subdistricts. We compared the number of positive houses, positive containers, mosquito coexistence during both the wet and dry seasons. The results showed that from a total of 1,072 positive containers collected in both seasons, Ae. albopictus larvae were found in the highest number of containers (745 containers), followed by containers with Ae. aegypti larvae (283 containers) and containers with Culex larvae (254 containers). During the wet season, there were higher numbers of positive houses, positive containers, and containers with only Ae. albopictus larvae than during the dry season. On the other hand, during the dry season when the water containers were very scarce, there were higher numbers of containers with Culex larvae, and containers held more than one type of mosquito larvae. This indicates that both temporal and spatial variations may contribute to the local coexistence of Aedes and Culex mosquito larvae species in Lansaka District areas in Thailand.(AU)

Spatial and temporal variations on the coexistence of Aedes and Culex larvae in Southern Thailand

This study investigated spatial and temporal variations on the coexistence of Aedes aegypti, Aedes albopictus, and Culex larvae in five subdistricts in Nakhon Si Thammarat, Thailand. We tested two main hypotheses on the spatial and temporal coexistence of mosquito larvae: (1) condition-specific competition and (2) spatial variation among the five subdistricts. We compared the number of positive houses, positive containers, mosquito coexistence during both the wet and dry seasons. The results showed that from a total of 1,072 positive containers collected in both seasons, Ae. albopictus larvae were found in the highest number of containers (745 containers), followed by containers with Ae. aegypti larvae (283 containers) and containers with Culex larvae (254 containers). During the wet season, there were higher numbers of positive houses, positive containers, and containers with only Ae. albopictus larvae than during the dry season. On the other hand, during the dry season when the water containers were very scarce, there were higher numbers of containers with Culex larvae, and containers held more than one type of mosquito larvae. This indicates that both temporal and spatial variations may contribute to the local coexistence of Aedes and Culex mosquito larvae species in Lansaka District areas in Thailand.

Seasons and water container types affecting Culex spp. in Southern Thailand

Usually, Culex mosquitoes are responsible for spreading several human diseases such as malaria, Japanese encephalitis, yellow fever, filariasis, and Zika. Lymphatic filariasis and Zika cases are increasing in Thailand with more prevalent in southern Thailand. In this study, our aim is to examine how seasons and water container types affect Culex spp. larvae numbers in Lansaka district, Nakhon Si Thammarat province, southern Thailand. This study was conducted in five sub-districts (Lansaka, Khaokaew, Thadi, Kamlon, and Khunthale) in Lansaka district. In each subdistrict, 120 houses were randomly selected to study the breeding sites of Culex mosquito in dry (March-May, 2018) and wet (October-December, 2018) seasons. Mosquito larvae were collected from indoor, outdoor, natural, artificial, darkcoloured, light-coloured, with lid, and without lid containers. It was observed that in all sub-districts, Culex larvae numbers were higher in dry season compared to wet season. In both seasons, outdoor, without lid, dark-coloured, and artificial containers contained more Culex larvae than inside, with lid, light-coloured, and natural containers, respectively. This study shows that seasons and water container types affect Culex mosquito larvae. Since the larvae numbers are higher in dry season, as well as in outdoor, without lid, dark-coloured, and artificial containers, people should reduce the usage of these containers, especially in the dry season, to prevent Culex borne diseases.(AU)

Seasons and water container types affecting Culex spp. in Southern Thailand

Usually, Culex mosquitoes are responsible for spreading several human diseases such as malaria, Japanese encephalitis, yellow fever, filariasis, and Zika. Lymphatic filariasis and Zika cases are increasing in Thailand with more prevalent in southern Thailand. In this study, our aim is to examine how seasons and water container types affect Culex spp. larvae numbers in Lansaka district, Nakhon Si Thammarat province, southern Thailand. This study was conducted in five sub-districts (Lansaka, Khaokaew, Thadi, Kamlon, and Khunthale) in Lansaka district. In each subdistrict, 120 houses were randomly selected to study the breeding sites of Culex mosquito in dry (March-May, 2018) and wet (October-December, 2018) seasons. Mosquito larvae were collected from indoor, outdoor, natural, artificial, darkcoloured, light-coloured, with lid, and without lid containers. It was observed that in all sub-districts, Culex larvae numbers were higher in dry season compared to wet season. In both seasons, outdoor, without lid, dark-coloured, and artificial containers contained more Culex larvae than inside, with lid, light-coloured, and natural containers, respectively. This study shows that seasons and water container types affect Culex mosquito larvae. Since the larvae numbers are higher in dry season, as well as in outdoor, without lid, dark-coloured, and artificial containers, people should reduce the usage of these containers, especially in the dry season, to prevent Culex borne diseases.