Bacterial transfer from Pristionchus entomophagus nematodes to the invasive ant Myrmica rubra and the potential for colony mortality in coastal Maine

Pristionchus - Beetle associations: Towards a new natural history

The free-living nematode Pristionchus pacificus has been established as a model system in integrative evolutionary biology by combining laboratory studies with field work and evolutionary biology. Multiple genetic, molecular and experimental tools and a collection of more than 2,500 P. pacificus strains and more than 50 Pristionchus species, which are available as living cultures or frozen stock collections, support research on various life history traits. Species of Pristionchus exhibit a number of complex traits unknown from Caenorhabditis elegans and most other free-living nematodes. First, P. pacificus can form two alternative mouth forms, an example of developmental plasticity that is increasingly studied to investigate the role of plasticity as a facilitator of evolutionary novelty. More than a decade of work has identified associated genetic and epigenetic mechanisms and revealed the evolutionary and ecological significance of feeding structure plasticity. Second, one of the two mouth morphs results in predatory behavior against other nematodes and is currently used to investigate the neurobiology of predation. Third, potential predation results in the risk of cannibalism among conspecifics. Strikingly, Pristionchus nematodes have developed a self-recognition system that allows the distinction of self (kin) and non-self. Given all these organismal features, this nematode has recently been considered a key example for research towards a new natural history (West-Eberhard, 2024). Here, I summarize recent work on Pristionchus with a focus on a 'new natural history'. In addition, I review some recent studies that indicate an interaction of Pristionchus with EPNs that was suggested based on various surveys in different ecological habitats.

Impact of Species and Developmental Stage on the Bacterial Communities of Aphaenogaster Ants

Ants are distributed across the globe and there are currently over 14,000 described species. Due to the high diversity between species, ants are considered vital keystone species to many ecosystems. They provide basic ecosystem services such as: seed dispersal, soil bioturbation, decomposition, and pest control. Within these ecosystems ants form complex symbiotic relationships with plants, fungi, and bacteria. Studying the interaction between ants and their bacteria is important because of the crucial role that microbes play in the overall health of ants. Aphaenogaster Mayr, 1853, which is a globally distributed ant genus, remains understudied in terms of their bacterial community. This study aims to determine the taxonomic composition and abundance of the Aphaenogaster bacterial community and to determine if development stage and species impact the bacterial community composition. For this study, ants from several colonies were collected from the Gordon Natural Area in West Chester, Pennsylvania, USA. DNA was then extracted from the ants in all stages of development and the 16S rRNA gene was amplified and sequencing following the NGS amplicon approach. The findings from this study reveal that species and development stage have a significant impact upon the bacterial community composition and abundance of Aphaenogaster ants, and Wolbachia is highly associated with these ants.

The evolution of entomopathogeny in nematodes

Understanding how parasites evolved is crucial to understand the host and parasite interaction. The evolution of entomopathogenesis in rhabditid nematodes has traditionally been thought to have occurred twice within the phylum Nematoda: in Steinernematidae and Heterorhabditidae families, which are associated with the entomopathogenic bacteria Xenorhabdus and Photorhabdus, respectively. However, nematodes from other families that are associated with entomopathogenic bacteria have not been considered to meet the criteria for "entomopathogenic nematodes." The evolution of parasitism in nematodes suggests that ecological and evolutionary properties shared by families in the order Rhabditida favor the convergent evolution of the entomopathogenic trait in lineages with diverse lifestyles, such as saprotrophs, phoretic, and necromenic nematodes. For this reason, this paper proposes expanding the term "entomopathogenic nematode" considering the diverse modes of this attribute within Rhabditida. Despite studies are required to test the authenticity of the entomopathogenic trait in the reported species, they are valuable links that represent the early stages of specialized lineages to entomopathogenic lifestyle. An ecological and evolutionary exploration of these nematodes has the potential to deepen our comprehension of the evolution of entomopathogenesis as a convergent trait spanning across the Nematoda.

First record of functional underground traps in a pitcher plant: Nepenthespudica (Nepenthaceae), a new species from North Kalimantan, Borneo

Nepenthespudica, a new species from North Kalimantan, Indonesia, is described and illustrated. The species belongs to the N.hirsuta group (sensu Cheek and Jebb 1999) but exhibits some characters that are unique within the group or even within the genus. Above all, it produces underground, achlorophyllous shoots with well-developed, ventricose lower pitchers that form in soil cavities or directly in the soil. No lower pitchers are formed above ground. The main part of its prey are ants, besides other litter- and soil-inhabiting species of invertebrates. A number of infaunal species were found in both aerial and underground pitchers, mainly Diptera and nematodes. Nepenthespudica is known only from a few neighbouring localities in the Mentarang Hulu district of North Kalimantan, where it grows on ridgetops at an elevation of 1100-1300 m. Its discovery underlines the natural richness of Borneo's rainforest and the necessity to preserve this important ecosystem with its enormous and still undiscovered biodiversity.