Kulkarni, I. | bioRxiv Science

bioRxiv2026

Two Pellioditis biocontrol nematode species infect Ariolimax columbianus, the Pacific banana slug, and increase mortality in laboratory infectivity trials

Gastropods are a highly diverse and often overlooked taxonomic group of significant ecological and economic importance. Some terrestrial gastropods are critical pests of commercial agriculture and home gardens worldwide. Malacopathogenic nematodes offer an effective biological control method of managing pest slugs and snails as a natural enemy. Pellioditis (syn. Phasmarhabditis) hermaphrodita and Pellioditis (syn. Phasmarhabditis) californica are two species of biocontrol nematodes that have been commercialized, sold as Nemaslug(R) and Nemaslug(R) 2.0 respectively on three continents. Although there is interest in bringing Nemaslug(R) products to the US, they are currently not permitted due to limited knowledge on their North American distribution and effects on non-target and native species. In this study, we investigated the impact of P. hermaphrodita and P. californica on Ariolimax columbianus across two slug-host life stages, in laboratory infectivity assays. The objectives were to 1. determine whether P. hermaphrodita and P. californica nematodes impact survival of A. columbianus, and 2. evaluate whether there are differential effects on survival in juvenile and adult life stages of A. columbianus, in laboratory infectivity trials. We found that P. hermaphrodita caused significant mortality in A. columbianus with 100% mortality observed in both juvenile and adult slug hosts. The P. californica treatment had significant effects on the juvenile A. columbianus group only, with 80% mortality. By contrast, only 16% of unexposed control juveniles and 4% of control adult slugs died during the experiment. These results indicate that P. hermaphrodita and P. californica are lethal to the native, non-target Pacific banana slug (A. columbianus) under laboratory conditions, with mortality differing between juvenile and adult host life stages. Given the ecological importance of A. columbianus, these findings raise concerns for potential non-target effects of P. californica and P. hermaphrodita on terrestrial gastropod communities and emphasize the need for testing biocontrol agents against multiple life stages.

zoology↗

bioRxiv2024

Multiple roles for TFG ring complexes in neuronal cargo trafficking

Pathological variants in Trk-fused gene (TFG) have been implicated in a variety of neurodegenerative conditions. In particular, mutations within its amino-terminal PB1 domain have been suggested to cause hereditary spastic paraplegia (HSP), resulting in progressive lower limb spasticity and weakness. The structural basis for this effect is unknown. Here, we combine X-ray crystallography and cryo-electron microscopy to determine a structural model of TFG, demonstrating the mechanism by which it forms octameric ring complexes. A network of electrostatic and hydrophobic interactions defines the interface between protomers. Moreover, we show that mutations identified previously in HSP patients disrupt this interface, destabilizing octamers, which ultimately leads to axonopathy. Surprisingly, the impacts of these variants are not equivalent in vivo, highlighting the existence of multiple, distinct mechanisms by which TFG mutations contribute to neurodegenerative disease.

biochemistry↗