Scale-Dependent Spatial Ecology of Paleotropical Leaf Litter Ants (Hymenoptera: Formicidae)

The grain for which an observer conducts a study is an important determinant of its outcome. Studies of ants have considered spatial grains spanning from single meters to entire forest ecosystems and found patterns related to nutrient availability, leaf litter depth, disturbance, and forest composition. Here, we examine a Bornean leaf litter ant community at small (1–4 m) and large (50–250 m) spatial scales and consider the differences in community structure using structured 1 m2 quadrats sampled via leaf litter sifting and Berlese extraction. We found that small-scale patterns in ant abundance and richness did not spatially autocorrelate within a plot until >1.5 m. Leaf litter characteristics, forest stand characteristics and sampling season were homogenous among our sites, suggesting that macro-scale stand variables are not largely regulating the small spatial scale ant communities: These may be driven by microclimate, competition, niche space, nutrient available, microclimatic conditions, or other localized effects. Further experimental work is needed to elicit causal mechanisms.

Stretching the Habitat Envelope: Insectivorous Bat Guilds Can Use Rubber Plantations, but Need Understorey Vegetation and Forest Buffers

Effects of land-cover change on insectivorous bat activity can be negative, neutral or positive, depending on foraging strategies of bats. In tropical agroforestry systems with high bat diversity, these effects can be complex to assess. We investigated foraging habitat use by three insectivorous bat guilds in forests and rubber plantations in the southern Western Ghats of India. Specifically, we monitored acoustic activity of bats in relation to (1) land-cover types and vegetation structure, and (2) plantation management practices. We hypothesized that activity of open-space aerial (OSA) and edge-space aerial (ESA) bat guilds would not differ; but narrow-space, flutter-detecting (NSFD) bat guild activity would be higher, in structurally heterogeneous forest habitats than monoculture rubber plantations. We found that bat activity of all guilds was highest in areas with high forest cover and lowest in rubber plantations. Higher bat activity was associated with understorey vegetation in forests and plantations, which was expected for NSFD bats, but was a surprise finding for OSA and ESA bats. Within land-cover types, open areas and edge-habitats had higher OSA and ESA activity respectively, while NSFD bats completely avoided open habitats. In terms of management practices, intensively managed rubber plantations with regular removal of understorey vegetation had the lowest bat activity for all guilds. Intensive management can undermine potential ecosystem services of insectivorous bats (e.g., insect pest-control in rubber plantations and surrounding agro-ecosystems), and magnify threats to bats from human disturbances. Low-intensity management and maintenance of forest buffers around plantations can enable persistence of insectivorous bats in tropical forest-plantation landscapes.

Bat species diversity trend along an elevation gradient: A study in Crocker Range Park, Sabah, Borneo

Bats (Order: Chiroptera) is a recognised group of bioindicators due to their sensitivity towards alterations in their immediate surroundings. With the threats of climate change becoming more severe on a daily basis, it is reasonable to collect data on how bat diversity is influenced by elevation. This will be useful to predict and monitor possible upslope shifting of bat species due to increase in surrounding temperature or anthropogenic pressure. Hence, this study aims to uncover the bat diversity trend at different elevations in Crocker Range Park (CRP), Sabah, Malaysia. Bat trappings were conducted in four substations within this park, covering an elevation spectrum from 450 to 1900 m a.s.l. The overall sampling managed to capture 133 individuals of bats, predominantly Pteropodidae, with the addition of two new species locality records for CRP, Murinapeninsularis and Hypsugovondermanni. Simple linear regression analyses revealed that both bat diversity and richness have an inverse linear relationship with elevation. Likewise, the Pearson’s correlation value, associating bat diversity with elevation, also shows that they have a negative relationship at r = -0.852. Heterogeneity of habitats explain this trend, as in the lower counterpart of CRP, lowland forests, which are richer in fruit and insect resources persist. Besides, lower land forests have better niche assortment, due to the distinctive layers stratification, allowing bats utilising different guilds to thrive in the same vegetation profile. This study further emphasises the role of CRP to protect most of the bat species found in Borneo, as well as serving as the baseline data for the future studies that look into the impact of temperature increment towards the upslope shifting of the bat population in CRP.

The detection of Japanese encephalitis virus in Megachiropteran bats in West Kalimantan, Indonesia: A potential enzootic transmission pattern in the absence of pig holdings

The West Kalimantan province in Borneo island, Indonesia belongs to endemic area of Japanese encephalitis (JE) that accounts for approximately 30% of total cases yearly. As the presence of pig holdings is uncommon in West Kalimantan, another reservoir host might have played a role in the local transmission of JE virus in this area. Current study aimed to identify the potential role of bats in the local transmission of JE by performing molecular detection of JE virus in bats and mosquitoes using RT-PCR. Sample collection was performed in 3 districts in West Kalimantan, covering 3 different ecosystems: forest, coastal, and residential areas. Bat collection was performed using mist net and harp net, while mosquito collection was carried out using animal-baited trap and human landing collection. A total of 373 blood samples from bats were tested for JE virus, among which 21 samples (5.6%) showed positive results, mainly from Cynopterus brachyotis (lesser short-nosed fruit bat) found in residential areas. Out of 53 mosquito pools, 3 JE-positive pools of Culex tritaeniorhynchus and Cx. vishnui were collected at the same location as JE-positive bats. Current study showed the first evidence of JE virus detection in several species of Megachiropteran bats in Indonesia, demonstrated the potential role of frugivorous bats in local transmission of JE in West Kalimantan. More aggressive measures are required in JE risk mitigation, particularly in initiating JE vaccination campaign and in avoiding disruption of bats’ natural habitats through changes in land-use.

•

First evidence of JE virus detection in Megachiropteran bats in Indonesia.

•

Molecular detection of JE virus using RT-PCR instead of using antibodies.

•

Collection of JE-positive bats and mosquitoes at the same site.

•

Involvement of bats in JE transmission cycle in the absence of pig holdings.