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Fulltext The first record of a fly of the family Milichiidae (Diptera) interacting with an ant of the genus Polyrhachis Smith, 1857 (Hymenoptera: Formicidae)

Yusah KM, Fayle TM

Biodivers Data J, 2014.
PMID: 25425942 DOI: 10.3897/BDJ.2.e4168

Flies in the family Milichiidae are often myrmecophilic. We document the first record of a fly from this family interacting with an ant of the genus Polyrhachis. In lowland riparian rainforest in Sabah, Malaysia, we observed a female of the genus Milichia following an ant of the species of P.illaudata, and repeatedly attempting to make close contact. Our observation suggests that the dipteran may have been attempting to feed kleptoparasitically from the Polyrhachis worker, since members of this ant genus often feed on liquid carbohydrate-rich food resources. This is the first time an interaction has been observed between a fly of this family and an ant of this widespread old world tropical genus.
Fulltext Ant mosaics in Bornean primary rain forest high canopy depend on spatial scale, time of day, and sampling method

Yusah KM, Foster WA, Reynolds G, Fayle TM

PeerJ, 2018;6:e4231.
PMID: 29423344 DOI: 10.7717/peerj.4231

Background: Competitive interactions in biological communities can be thought of as giving rise to "assembly rules" that dictate the species that are able to co-exist. Ant communities in tropical canopies often display a particular pattern, an "ant mosaic", in which competition between dominant ant species results in a patchwork of mutually exclusive territories. Although ant mosaics have been well-documented in plantation landscapes, their presence in pristine tropical forests remained contentious until recently. Here we assess presence of ant mosaics in a hitherto under-investigated forest stratum, the emergent trees of the high canopy in primary tropical rain forest, and explore how the strength of any ant mosaics is affected by spatial scale, time of day, and sampling method.
Methods: To test whether these factors might impact the detection of ant mosaics in pristine habitats, we sampled ant communities from emergent trees, which rise above the highest canopy layers in lowland dipterocarp rain forests in North Borneo (38.8-60.2 m), using both baiting and insecticide fogging. Critically, we restricted sampling to only the canopy of each focal tree. For baiting, we carried out sampling during both the day and the night. We used null models of species co-occurrence to assess patterns of segregation at within-tree and between-tree scales.
Results: The numerically dominant ant species on the emergent trees sampled formed a diverse community, with differences in the identity of dominant species between times of day and sampling methods. Between trees, we found patterns of ant species segregation consistent with the existence of ant mosaics using both methods. Within trees, fogged ants were segregated, while baited ants were segregated only at night.
Discussion: We conclude that ant mosaics are present within the emergent trees of the high canopy of tropical rain forest in Malaysian Borneo, and that sampling technique, spatial scale, and time of day interact to determine observed patterns of segregation. Restricting sampling to only emergent trees reveals segregatory patterns not observed in ground-based studies, confirming previous observations of stronger segregation with increasing height in the canopy.
Fulltext Experimentally testing and assessing the predictive power of species assembly rules for tropical canopy ants

Fayle TM, Eggleton P, Manica A, Yusah KM, Foster WA

Ecol Lett, 2015 Mar;18(3):254-62.
PMID: 25622647 DOI: 10.1111/ele.12403

Understanding how species assemble into communities is a key goal in ecology. However, assembly rules are rarely tested experimentally, and their ability to shape real communities is poorly known. We surveyed a diverse community of epiphyte-dwelling ants and found that similar-sized species co-occurred less often than expected. Laboratory experiments demonstrated that invasion was discouraged by the presence of similarly sized resident species. The size difference for which invasion was less likely was the same as that for which wild species exhibited reduced co-occurrence. Finally we explored whether our experimentally derived assembly rules could simulate realistic communities. Communities simulated using size-based species assembly exhibited diversities closer to wild communities than those simulated using size-independent assembly, with results being sensitive to the combination of rules employed. Hence, species segregation in the wild can be driven by competitive species assembly, and this process is sufficient to generate observed species abundance distributions for tropical epiphyte-dwelling ants.
The first record of the parasitic myrmecophilous caterpillar Liphyrabrassolis (Lepidoptera, Lycaenidae) inside Asian weaver ant (Oecophyllasmaragdina) nests in oil palm plantations

Dwi Advento A, Yusah KM, Salim H, Naim M, Caliman JP, Fayle TM

Biodivers Data J, 2022;10:e83842.
PMID: 36761604 DOI: 10.3897/BDJ.10.e83842

Asian weaver ants (Oecophyllasmaragdina) are an important biocontrol agent in agricultural habitats. We conducted surveys in oil palm plantations in Riau, Indonesia for an obligate myrmecophilous butterfly larvae, Liphyrabrassolis (Lepidoptera, Lycaenidae), that is known to consume weaver ant larvae in other habitat types. We found L.brassolis larvae in five of the twenty nests surveyed, with larval presence not being related to weaver ant nest size. We also observed L.brassolis larvae in a weaver ant mass rearing facility. This is the first report of L.brassolis from oil palm plantations and may have implications for the use of weaver ants as biological control agents.
Fulltext Limited contributions of plant pathogens to density-dependent seedling mortality of mast fruiting Bornean trees

Cannon PG, O'Brien MJ, Yusah KM, Edwards DP, Freckleton RP

Ecol Evol, 2020 Dec;10(23):13154-13164.
PMID: 33304525 DOI: 10.1002/ece3.6906

Fungal pathogens are implicated in driving tropical plant diversity by facilitating strong, negative density-dependent mortality of conspecific seedlings (C-NDD). Assessment of the role of fungal pathogens in mediating coexistence derives from relatively few tree species and predominantly the Neotropics, limiting our understanding of their role in maintaining hyper-diversity in many tropical forests. A key question is whether fungal pathogen-mediated C-NDD seedling mortality is ubiquitous across diverse plant communities. Using a manipulative shadehouse experiment, we tested the role of fungal pathogens in mediating C-NDD seedling mortality of eight mast fruiting Bornean trees, typical of the species-rich forests of South East Asia. We demonstrate species-specific responses of seedlings to fungicide and density treatments, generating weak negative density-dependent mortality. Overall seedling mortality was low and likely insufficient to promote overall community diversity. Although conducted in the same way as previous studies, we find little evidence that fungal pathogens play a substantial role in determining patterns of seedling mortality in a SE Asian mast fruiting forest, questioning our understanding of how Janzen-Connell mechanisms structure the plant communities of this globally important forest type.
Fulltext Establishing the evidence base for maintaining biodiversity and ecosystem function in the oil palm landscapes of South East Asia

Foster WA, Snaddon JL, Turner EC, Fayle TM, Cockerill TD, Ellwood MD, et al.

Philos Trans R Soc Lond B Biol Sci, 2011 Nov 27;366(1582):3277-91.
PMID: 22006968 DOI: 10.1098/rstb.2011.0041

The conversion of natural forest to oil palm plantation is a major current threat to the conservation of biodiversity in South East Asia. Most animal taxa decrease in both species richness and abundance on conversion of forest to oil palm, and there is usually a severe loss of forest species. The extent of loss varies significantly across both different taxa and different microhabitats within the oil palm habitat. The principal driver of this loss in diversity is probably the biological and physical simplification of the habitat, but there is little direct evidence for this. The conservation of forest species requires the preservation of large reserves of intact forest, but we must not lose sight of the importance of conserving biodiversity and ecosystem processes within the oil palm habitat itself. We urgently need to carry out research that will establish whether maintaining diversity supports economically and ecologically important processes. There is some evidence that both landscape and local complexity can have positive impacts on biodiversity in the oil palm habitat. By intelligent manipulation of habitat complexity, it could be possible to enhance not only the number of species that can live in oil palm plantations but also their contribution to the healthy functioning of this exceptionally important and widespread landscape.
Fulltext Logging cuts the functional importance of invertebrates in tropical rainforest

Ewers RM, Boyle MJ, Gleave RA, Plowman NS, Benedick S, Bernard H, et al.

Nat Commun, 2015 Apr 13;6:6836.
PMID: 25865801 DOI: 10.1038/ncomms7836

Invertebrates are dominant species in primary tropical rainforests, where their abundance and diversity contributes to the functioning and resilience of these globally important ecosystems. However, more than one-third of tropical forests have been logged, with dramatic impacts on rainforest biodiversity that may disrupt key ecosystem processes. We find that the contribution of invertebrates to three ecosystem processes operating at three trophic levels (litter decomposition, seed predation and removal, and invertebrate predation) is reduced by up to one-half following logging. These changes are associated with decreased abundance of key functional groups of termites, ants, beetles and earthworms, and an increase in the abundance of small mammals, amphibians and insectivorous birds in logged relative to primary forest. Our results suggest that ecosystem processes themselves have considerable resilience to logging, but the consistent decline of invertebrate functional importance is indicative of a human-induced shift in how these ecological processes operate in tropical rainforests.