Effects of forest and cave proximity on fruit set of tree crops in tropical orchards in Southern Thailand

Pollination services to crops of watermelon (Citrullus lanatus) and green tomato (Physalis ixocarpa) in the coastal region of Jalisco, Mexico

Bees play a pivotal role as pollinators in crops essential for human consumption. However, the global decline in bee populations poses a significant threat to pollination services and food security worldwide. The loss and degradation of habitats due to land use change are primary factors contributing to bee declines, particularly in tropical forests facing high deforestation rates. Here, we evaluate the pollination services provided to crops of watermelon (Citrullus lanatus) and green tomato (Physalis ixocarpa) in three municipalities in the state of Jalisco, Mexico, a place with Tropical Dry Forest, during years 2008, and 2014 to 2017. Both crops are cultivated in the dry season, approximately during the months of November to March. We describe the composition of the pollinator community and their visitation frequency (measured through the number of visits per flower per hour), and we assess the impact of pollinators on plant reproductive success and the level of pollinator dependence for each crop species (measured through the number of flowers that developed into fruits). We also evaluate how the landscape configuration (through the percentage of forest cover and distance to the forest) influences richness and abundance of pollinators (measured as number of species and individuals of pollinators per line of 50 m), and we use the model Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) to map and value the pollination service in both crops. InVEST Crop pollination model is a simulation focuses on wild pollinators providing the pollinator ecosystem service. Our findings indicate that Apis mellifera was the primary pollinator of both crops, one of the few abundant pollinators in the study region during the dry season. In experiments where pollinators were excluded from flowers, watermelon yielded no fruits, while green tomato experienced a 65% reduction in production. In the case of green tomato, fruit set showed a positive correlation with pollinator abundance. A positive association between forest cover and total pollinator abundance was observed in green tomato in 2008, but not in watermelon. Additionally, a positive relationship was observed between the abundance of bees predicted by the InVEST model and the abundance of bees observed in green tomato flowers in 2008. In the study region, green tomato and watermelon rely on pollinators for fruit production, with honeybees (from feral and managed colonies) acting as the primary provider of pollination services for these crops. Consequently, the conservation of natural areas is crucial to provide food and nesting resources for pollinators. By doing so, we can ensure the diversity and abundance of pollinators, which in turn will help secure food security. The findings of this study underscore the critical need for the conservation of natural areas to support pollinator populations. Policymakers should prioritize the protection and restoration of habitats, particularly tropical forests, which are essential for maintaining the diversity and abundance of pollinators.

Towards evidence-based conservation of subterranean ecosystems

Subterranean ecosystems are among the most widespread environments on Earth, yet we still have poor knowledge of their biodiversity. To raise awareness of subterranean ecosystems, the essential services they provide, and their unique conservation challenges, 2021 and 2022 were designated International Years of Caves and Karst. As these ecosystems have traditionally been overlooked in global conservation agendas and multilateral agreements, a quantitative assessment of solution-based approaches to safeguard subterranean biota and associated habitats is timely. This assessment allows researchers and practitioners to understand the progress made and research needs in subterranean ecology and management. We conducted a systematic review of peer-reviewed and grey literature focused on subterranean ecosystems globally (terrestrial, freshwater, and saltwater systems), to quantify the available evidence-base for the effectiveness of conservation interventions. We selected 708 publications from the years 1964 to 2021 that discussed, recommended, or implemented 1,954 conservation interventions in subterranean ecosystems. We noted a steep increase in the number of studies from the 2000s while, surprisingly, the proportion of studies quantifying the impact of conservation interventions has steadily and significantly decreased in recent years. The effectiveness of 31% of conservation interventions has been tested statistically. We further highlight that 64% of the reported research occurred in the Palearctic and Nearctic biogeographic regions. Assessments of the effectiveness of conservation interventions were heavily biased towards indirect measures (monitoring and risk assessment), a limited sample of organisms (mostly arthropods and bats), and more accessible systems (terrestrial caves). Our results indicate that most conservation science in the field of subterranean biology does not apply a rigorous quantitative approach, resulting in sparse evidence for the effectiveness of interventions. This raises the important question of how to make conservation efforts more feasible to implement, cost-effective, and long-lasting. Although there is no single remedy, we propose a suite of potential solutions to focus our efforts better towards increasing statistical testing and stress the importance of standardising study reporting to facilitate meta-analytical exercises. We also provide a database summarising the available literature, which will help to build quantitative knowledge about interventions likely to yield the greatest impacts depending upon the subterranean species and habitats of interest. We view this as a starting point to shift away from the widespread tendency of recommending conservation interventions based on anecdotal and expert-based information rather than scientific evidence, without quantitatively testing their effectiveness.

A novel bat pollination system involving obligate flower corolla removal has implications for global Dillenia conservation

The Dilleniaceae is known to produce nectarless flowers pollinated by bees, but the fact that bats ingest Dillenia biflora pollen led us to question pollination assumptions for these trees. We aimed to identify the pollinators of D. biflora, check for nectar presence, and investigate potential for cleistogamy and global prevalence of this pollination system. We examined aspects of the pollination of D. biflora on two Fijian islands using video recordings, direct observations, hand pollination, measurements (flowers, bite marks, nectar), and monitoring. The flowers, receptive for one night, contained copious nectar and had permanently closed globose corollas that required removal by bats for pollination. All the 101 flowers that retained their corolla died and did not produce seeds by cleistogamy. The bat Notopteris macdonaldi was well adapted to corolla removal. Keeping corollas closed until bats manipulate the nectar-rich flowers is a beneficial strategy in high-rainfall environments with many flower parasites. We propose to name a pollination system reliant exclusively on bats "chiropteropisteusis." From clues in the literature, other species in the geographical range of Dillenia are probably chiropteropisunous. Chiropteropisteusis should be investigated in the Old-World range of Dillenia, many species of which are threatened. The remarkable "fall" of the entire corolla observed by an earlier botanist for several species in the genus is most likely attributable to bats. This discovery has important implications for the conservation of bat-dependent trees and their associated fauna, particularly considering the high level of threat faced by flying-foxes globally.

Tropical fruit production depends on wild insect communities: bees and lychees in Thailand

The importance of wild insects as pollinators of tropical tree crops has rarely been tested. Across 18 small-scale lychee orchards in northern Thailand, we evaluated the roles of different wild insects as pollinators and predators of pests in fruit production. Quantitative assessments showed that bees (Family Apidae) were strongly dominant (83%) among insect flower visitors, comprising four species in tribes Apini and four in Meliponini. Experimental manipulations of inflorescences showed that fruit production in these orchards was: (1) dependent on flower visits by wild insects because enclosure of inflorescences in mesh bags decreased fruit set (to one-fifth) and (2) not greatly limited by pollinator deficiencies, because hand pollination of unbagged flowers did not enhance fruit set. Pollination success, as indicated by the proportion of unmanipulated flowers setting fruit, correlated positively across orchards with the abundance of large-bodied Apidae (>7 mm; most were Apis species) and of Apini, and negatively with abundance of small-bodied Apidae and of all Meliponini, despite the latter being the commonest flower visitors. We conclude that larger-bodied bees are most likely to travel sufficiently far to import genetically diverse pollen, in this landscape-scale mosaic where non-orchard habitats (both agriculture and treed patches) were sufficient to sustain wild pollinators.

The Critical Importance of Old World Fruit Bats for Healthy Ecosystems and Economies

Despite extensive documentation of the ecological and economic importance of Old World fruit bats (Chiroptera: Pteropodidae) and the many threats they face from humans, negative attitudes towards pteropodids have persisted, fuelled by perceptions of bats as being pests and undesirable neighbours. Such long-term negativity towards bats is now further exacerbated by more recent disease-related concerns, particularly associated with the current COVID-19 pandemic. There remains an urgent need to investigate and highlight the positive and beneficial aspects of bats across the Old World. While previous reviews have summarised these extensively, numerous new studies conducted over the last 36 years have provided further valuable data and insights which warrant an updated review. Here we synthesise research on pteropodid-plant interactions, comprising diet, ecological roles, and ecosystem services, conducted during 1985-2020. We uncovered a total of 311 studies covering 75 out of the known 201 pteropodid species (37%), conducted in 47 countries. The majority of studies documented diet (52% of all studies; 67 pteropodid species), followed by foraging movement (49%; 50 pteropodid species), with fewer studies directly investigating the roles played by pteropodids in seed dispersal (24%; 41 pteropodid species), pollination (14%; 19 pteropodid species), and conflict with fruit growers (12%; 11 pteropodid species). Pteropodids were recorded feeding on 1072 plant species from 493 genera and 148 families, with fruits comprising the majority of plant parts consumed, followed by flowers/nectar/pollen, leaves, and other miscellaneous parts. Sixteen pteropodid species have been confirmed to act as pollinators for a total of 21 plant species, and 29 pteropodid species have been confirmed to act as seed dispersers for a total of 311 plant species. Anthropogenic threats disrupting bat-plant interactions in the Old World include hunting, direct persecution, habitat loss/disturbance, invasive species, and climate change, leading to ecosystem-level repercussions. We identify notable research gaps and important research priorities to support conservation action for pteropodids.

Local and Landscape Compositions Influence Stingless Bee Communities and Pollination Networks in Tropical Mixed Fruit Orchards, Thailand

Stingless bees are vital pollinators for both wild and crop plants, yet their communities have been affected and altered by anthropogenic land-use change. Additionally, few studies have directly addressed the consequences of land-use change for meliponines, and knowledge on how their communities change across gradients in surrounding landscape cover remains scarce. Here, we examine both how local and landscape-level compositions as well as forest proximity affect both meliponine species richness and abundance together with pollination networks across 30 mixed fruit orchards in Southern Thailand. The results reveal that most landscape-level factors significantly influenced both stingless bee richness and abundance. Surrounding forest cover has a strong positive direct effect on both factors, while agricultural and urbanized cover generally reduced both bee abundance and diversity. In the local habitat, there is a significant interaction between orchard size and floral richness with stingless bee richness. We also found that pollinator specialization in pollination networks decreased when the distance to the forest patch increased. Both local and landscape factors thus influenced meliponine assemblages, particularly the forest patches surrounding an orchard, which potentially act as a key reservoir for stingless bees and other pollinator taxa. Preservation of forest patches can protect the permanent nesting and foraging habitat of various pollinator taxa, resulting in high visitation for crop and wild plants.

Bats in a cave tourism and pilgrimage site in eastern India: conservation challenges

Caves and other subterranean habitats are crucial for the survival of many bat species, but often deteriorate as a result of visits by tourists. The aim of the study was to understand the conservation challenges associated with the cave dwelling bats at Gupteswar cave tourism and pilgrimage site in eastern India and to develop conservation recommendations. I counted bat populations and monitored tourist visits once per month for 12 months during September 2016–August 2017. Roosting and breeding activities of eight species of bats, including two nationally threatened species, were recorded from five caves. The number of bats counted during the 12 survey days was 785–940 individuals. Tourism activity occurred throughout the year but was higher during local festive seasons; the maximum number of tourist entries recorded in a single day was 2,769. Installation of gated entrances, scheduling of visits to control overcrowding, restriction of access to caves with maternity colonies during breeding seasons, and minimal use of electric bulbs for illumination would minimize disturbance to the bats. Installation of educational display boards would help to create awareness of the conservation importance of bats amongst the cave visitors.

Notas sobre el uso de ecosistemas subterráneos por murciélagos en el Parque Nacional Tingo María, Huánuco, Perú

En el Perú existe poca información sobre la biodiversidad de los ecosistemas subterráneos, particularmente de las cuevas. En este trabajo registré qué especies de murciélagos habitan las cuevas del Parque Nacional Tingo María (PNTM) y cómo se distribuyen dentro de las mismas categorizándolas en tipos de percha. Evalué seis formaciones rocosas en el PNTM en los años 2015 y 2017. Se usaron redes de niebla y de mano para capturar a los murciélagos. En total registre 16 especies de murciélagos pertenecientes a las familias Phyllostomidae, Emballonuridae y Mormoopidae. En la cueva de “Las lechuzas” encontré el mayor número de especies (10). Categoricé tres tipos de percha usados por los murciélagos dentro de las cuevas: (I) pequeñas bóvedas formadas como depresiones en el techo, (II) espacios angostos en medio de las estalactitas, (III) cavidades amplias entre las estalactitas y la pared en forma de campana. Las cuevas del PNTM contribuyen a la persistencia local de los murciélagos proveyéndoles de refugios, y existe la necesidad de conocer sobre los aspectos ecológicos y la importancia funcional de los murciélagos dentro de estas cuevas.

Habitat and landscape factors influence pollinators in a tropical megacity, Bangkok, Thailand

Background

Pollinators are well known for the ecosystem services they provide, and while urban areas are generally perceived as low-quality habitat for most wildlife, these cities often support a surprising degree of pollinator diversity. The current rapid growth of urban areas and concern over global pollinator declines have spurred numerous studies examining pollinator communities in temperate cities, but knowledge about tropical urban pollinators remains scarce.

Methods

This study investigated the effects of habitat and landscape factors on pollinator richness and abundance in a highly-populated, tropical city: Bangkok, Thailand. We conducted pollinator observations in 52 green areas throughout the city and collected data on patch size, floral abundance, plant richness, location type, and percent vegetation at five spatial scales.

Results

Of the 18,793 pollinators observed, over 98% were bees. Both patch size and floral abundance generally had positive effects on pollinators, although there was a significant interaction between the two factors; these findings were generally consistent across all focal taxa (Tetragonula stingless bees, Apis honey bees, Xylocopa carpenter bees, and butterflies).

Discussion

Our results demonstrate the importance of maintaining large green areas in cities, since small green areas supported few pollinators, even when floral resources were abundant. Moreover, most pollinator taxa utilized a variety of location types (e.g., public parks, school campuses, temple grounds), with the exception of butterflies, which preferred parks. Our findings are generally consistent with those of temperate urban studies, but additional studies in the tropics are needed before global patterns can be assessed.

Bees are supplementary pollinators of self-compatible chiropterophilous durian

Nocturnally foraging insects may be supplementary pollinators to chiropterophilous plant species when bats are scarce. Given that insects are much smaller than bats, they may be more effective at transferring pollen for plant species with similar stamen and pistil lengths, such as the ‘Monthong’ durian cultivar. The present study clarifies the role of insects in pollinating the ‘Monthong’ cultivar by examining the floral biology, conducting pollination treatments on 19 trees and observing floral visitors in southern Thailand. Stigmas were receptive by 17h00, and over 50% of ‘Monthong’ anthers had dehisced by 17h30. Several bee species began foraging on flowers during the late afternoon, and the giant honey bee (Apis dorsata) continued to visit throughout the night. Our results show that at 4 wk after pollination, the highest fruit set occurred from hand-crossed pollination (13.5%), followed by open pollination (5.5%), insect pollination (3.3%) and automatic autogamy (2.0%), indicating that this cultivar is highly self-incompatible. Moreover, insects appear to be important pollinators of ‘Monthong’ durian in areas where nectar bats visit infrequently. One bee species in particular,Apis dorsata, commonly foraged on flowers at dusk and appears to be the most effective insect pollinator of durian. Our findings highlight that nocturnally foraging bees are capable of securing pollination for night-blooming plant taxa, even those typically considered to be bat-pollinated.

Field evidence of strong differential pollen placement by Old World bat-pollinated plants

BACKGROUND AND AIMS

Sympatric plant species that share pollinators potentially compete for pollination and risk interspecific pollen transfer, but this competition can be minimized when plant species place pollen on different areas of the pollinator's body. Multiple studies have demonstrated strong differential pollen placement by sympatric plant species under laboratory conditions; however, field evidence collected in natural settings is less common. Furthermore, it is unknown whether precise pollen placement on the pollinator's body remains constant throughout the foraging period, or if such patterns become diffused over time (e.g. due to grooming). To test the prevalence of differential pollen placement in the wild, we examined a community of five night-blooming plant species in southern Thailand that share common bat pollinators.

METHODS

We mist-netted wild foraging nectar bats and collected pollen samples from four body parts: the crown of the head, face, chest and ventral side of one wing. We also noted the time of pollen collection to assess how pollinator pollen loads change throughout the foraging period.

KEY RESULTS

Our findings revealed that most of our plant study species placed pollen on precise areas of the bat, consistent with experimental work, and that patterns of differential pollen placement remained constant throughout the night.

CONCLUSIONS

This study demonstrates how diverse floral morphologies effectively limit interspecific pollen transfer among Old World bat-pollinated plants under natural conditions. Additionally, interspecific pollen transfer is probably minimal throughout the entire foraging period, since patterns of pollen on the bats' bodies were consistent over time.