Vertical Stratification of Insect Species Developing in Water-Filled Tree Holes

Forest ecosystems have a distinct vertical dimension, but the structuring of communities in this three-dimensional space is not well understood. Water-filled tree holes are natural microcosms structured in metacommunities. Here, we used these microcosms as model systems to analyze how insect communities and the occurrence and abundance of individual species are influenced by biotic and abiotic microhabitat characteristics, the vertical position of the tree hole, and stand-scale habitat availability. We found that both the characteristics of water-filled tree holes and their insect communities differ significantly between canopy and ground level. Individual insect species showed contrasting responses to the vertical position of the tree holes when important environmental factors at the stand and the tree-hole scale were considered. While some species, such as the mosquito Aedes geniculatus and the beetle Prionocyphon serricornis, decreased in abundance with increasing tree-hole height, the biting midge Dasyhelea sp., the non-biting midge Metriocnemus cavicola and the hoverfly Myiatropa florea increased in abundance. Our results suggest that vertical stratification in forests is most likely driven not only by variation in tree-hole microhabitat properties, i.e., niche separation, but also by individual species traits, such as adult dispersal propensity, food preferences and mating behavior of adult stages, and interspecific competition of larval stages. Therefore, communities of insect species developing in tree holes are likely structured by competition–colonization trade-offs predicted by metacommunity theory.

First extraction of eDNA from tree hole water to detect tree frogs: a simple field method piloted in Madagascar

Environmental DNA (eDNA) is becoming an increasingly used tool for monitoring cryptic species within terrestrial and aquatic systems. We present the first method for extracting water from tree holes for eDNA studies of tree-dwelling frogs, and the first use of eDNA for amphibian monitoring in Madagascar. This pilot study expands on a previously developed method and aims to provide a simple field protocol for DNA extraction from very small water samples, using a relatively inexpensive kit compared to other collection methods. We collected 20 ml of water from tree holes in Ambohitantely Special Reserve in Madagascar, with the aim to survey for the Critically Endangered tree frog Anodonthyla vallani, and we developed species specific cytochrome c oxidase 1 primers for this species. While our two samples did not detect A. vallani, we successfully extracted up to 16.6 ng/µl of eDNA from the samples and using 16S rRNA primers barcoded the tree frog Plethodontohyla mihanika in one of the samples. Despite just two samples being collected, we highlight the future potential of eDNA from tree holes for investigating cryptic habitat specialist amphibians given we extracted frog eDNA from just 20 ml of water. The method provides a rapid, simple, and cost-effective method which can assist cryptic species monitoring in challenging and time-consuming field conditions and should be developed further for frog surveying in Madagascar and beyond. The newly developed primers can be used for further work using this eDNA method to survey threatened Anodonthyla frog species.

Redescription of Chiropturopoda nidiphila Wiśniewski & Hirschmann (Acari: Uropodina) from a woodpecker’s tree holes, including all development stages and first notes on its ecology

All development stages of Chiropturopoda nidiphila Wiśniewski & Hirschmann, 1983 are described, which has previously been known only from the deutonymph stage. The species is closely associated with tree holes excavated by woodpeckers. Chiropturopoda nidiphila was redescribed and the genus diagnosis was completed. The description of the species morphology is based largely on scanning (SEM) electronograms. Diagnoses differentiating all of the known species of the genus Chiropturopoda are provided, including their developmental stages.

Tracking Microbial Communities Across Aedes Albopictus Life Stages and Larval Habitat Types

Aedes albopictus, the Tiger Mosquito, has been hailed as one of the most invasive arbovirus-transmitting mosquitoes globally. With the growing potential of microbial methods for mosquito control, it has become increasingly imperative to understand the factors that contribute to naturally-occurring microbiome communities. Here, we analyzed the impact of larval water type and life stage on the microbial community of Aedes albopictus. The field-collected water samples from tree holes and tires that were used to rear larval mosquitoes in the laboratory were significantly different from each other in terms of sOTU (bacterial species) richness, with tree holes having a far greater number of sOTUs. For beta diversity measures (Bray-Curtis dissimilarity) Aedes albopictus were not significantly different from adult Aedes aegypti, but mosquito sex, life stage, and overall treatment group were significantly different when analyzed by ANOSIM. Based on our findings, the environment surrounding larval mosquitoes (and subsequent adult mosquitoes from those habitats) and the life stage of mosquitoes (regardless of species) shapes mosquito microbiome assemblages. This work further supports the idea that mosquito adults maintain a microbiome specific to larval habitat, despite major reductions to their microbiome prior to eclosion, which could shape the success of implemented microbial engineering or control methods.

Mosquito Guttersnipe: A New Sampling Tool for Roof Gutters, Tree Holes, and Other Elevated Mosquito Habitats

ABSTRACT Mosquitoes pose health risks to human populations by serving as vectors of diseases. Mosquito control organizations are responsible for inspecting and controlling vector populations to reduce the risk of infection of these diseases. Current sampling methods are effective for numerous types of mosquito habitat, but not conducive for sampling small overhead habitat such as roof gutters or tree holes. We have developed and tested a tool called the Mosquito GutterSnipe to sample these overhead habitats. Volumetric and larval capacity testing of the tool prototype demonstrated comparable sampling integrity to standard mosquito dipping methods. The GutterSnipe can be employed as a reliable way to sample previously overlooked mosquito habitat. Its current model is cost effective and easy to produce for mosquito control organizations and easy to use for inspectors.

The larval environment strongly influences the bacterial communities of Aedes triseriatus and Aedes japonicus (Diptera: Culicidae)

Mosquito bacterial communities are essential in mosquito biology, and knowing the factors shaping these bacterial communities is critical to their application in mosquito-borne disease control. This study investigated how the larval environment influences the bacterial communities of larval stages of two container-dwelling mosquito species, Aedes triseriatus, and Aedes japonicus. Larval and water samples were collected from tree holes and used tires at two study sites, and their bacteria characterized through MiSeq sequencing of the 16S rRNA gene. Bacterial richness was highest in Ae. japonicus, intermediate in Ae. triseriatus, and lowest in water samples. Dysgonomonas was the dominant bacterial taxa in Ae. triseriatus larvae; the unclassified Comamonadaceae was dominant in water samples from waste tires, while Mycobacterium and Carnobacterium, dominated Ae. japonicus. The two mosquito species harbored distinct bacterial communities that were different from those of the water samples. The bacterial communities also clustered by habitat type (used tires vs. tree holes) and study site. These findings demonstrate that host species, and the larval sampling environment are important determinants of a significant component of bacterial community composition and diversity in mosquito larvae and that the mosquito body may select for microbes that are generally rare in the larval environment.

Comparative nesting patterns and success of Mynas and Starlings (Aves: Sturnidae) inhabiting Jahangirnagar University campus, Bangladesh

Nesting patterns of four species of mynas and starlings, Common Myna (Acridotheres tristis), Jungle Myna (Acridotheres fuscus), the Asian-pied Starling (Gracupica contra) and Chestnut-tailed Mtarling (Sturnia malabarica) were studied in Jahangirnagar University campus from March to September in 2016. Nests were searched systematically throughout the study area and nesting parameters like nest dimensions, nest-site selection, tree species preference, nesting materials, clutch size and nesting success were examined. A total of 101 nests were recorded where 31 nests were of Common Myna, 10 of Jungle Myna, 49 of the Asian-pied Starling and 11 nests were of Chestnut-tailed Starling. Overall, the sturnids preferred nesting on trees (n=84) to anthropogenic structures (n=17). Common myna showed maximum variation in nest-site selection using tree holes (n=12), tree branches (n=10) and building cornices, holes or crevices (n=9) whereas Chestnut-tailed Starling nested only in tree cavities (n=11). Jungle Myna built nests both in tree holes (n=4) and in building holes and crevices (n=6). The Asian-pied Starlings built their domed nests mostly on tree branches (n=47) where 69% nests were peripheral and 31% were central in position. Out of 20 species of trees utilized for nesting purpose, the majority of nests were built on Whites iris Albizia procera (n=18) followed by Neem Azadirachta indica (n=10) and Mahogany Swietenia mahagoni (n=10). The nests were constructed between 2 and 18m (8±3.8m) from the ground level. Among 19 types of nesting materials recorded, twigs, leaves, straws, grasses, feathers, plastics and polythene were frequently used by all four species while the Asian-pied starling used more rubbish materials than other species. Highest nesting success (80%) was recorded in Common Myna whereas the Asian-pied Starling, Chestnut-tailed Starling and Jungle Myna had 77.8%, 75% and 66.7% of nesting success respectively. Adaptions to using different nesting sites in Common Myna and comparatively higher nesting height in the Asian-pied Starling may have facilitated the greater nesting success. Bangladesh J. Zool. 48(2): 321-334, 2020

NEST BOX USE AND POLYGYNY IN AN ENDANGERED PRIMATE SPECIES: THE BLACK LION TAMARIN (LEONTOPITHECUS CHRYSOPYGUS)

The black lion tamarin, Leontopithecus chrysopygus, is an endemic and endangered primate species from the Atlantic Forest of the interior of São Paulo State, Brazil. Its mating system is characterized as monogamous and females give birth to two twin infants during each breeding season. They are known to mainly sleep in tree holes, which is considered as a pertinent strategy for increasing their protection from predators during the night. Artificial cavities, like nest boxes, have been installed for other species in areas where tree cavities are depleted, in order to replace them. In this study, we report (i) the use of nest boxes in the wild by a group of black lion tamarins and (ii) the first record of polygyny for this species.