Authors

R M Morris¹; L W Wilson¹; N W Warnock¹; A M Maule¹; J D Dalzell¹; D C Cox¹; M S Sturrock¹;  ¹ Queen's University Belfast

Discussion

Entomopathogenic nematodes (EPNs) are a guild of obligate insect parasites which share many physiological and behavioural traits with mammalian strongylid and strongyloidid parasites; including host-finding nictation behaviour. EPNs are also interesting from the perspective of insect biocontrol. Like other parasitic nematodes, EPNs employ a sophisticated chemosensory apparatus to detect potential hosts and communicate with conspecifics. Understanding the underlying molecular basis of relevant host-finding behaviours could facilitate improved EPN biocontrol approaches, and could lend insight to similar behaviours in economically important animal parasites. FMRFamide-like neuropeptides are enriched and conserved across the Phylum Nematoda, and have been linked with motor and sensory function, including dispersal and aggregating behaviours in the free living nematode Caenorhabditis elegans. RNA interference (RNAi) was used to knockdown the expression of the flp-21 gene in Steinernema carpocapsae. Our results show that knockdown of flp-21 has a significant impact on dispersal behaviour, nictation and jumping of S. carpocapsae, relative to controls. Immunocytochemical localisation of FLP-21 to paired anterior neurons corroborates the RNAi data suggesting a role in sensory modulation. This study represents the first demonstration of a functional neuronally-sensitive RNAi pathway in S. carpocapsae; linking the neuropeptide FLP-21 to dispersal, nictation and jumping phenotypes in a parasitic nematode for the first time.