D3432: Conspecific and heterospecific dispersal effect of exometabolomes on some entomopathogenic nematode species

Entomopathogenic nematodes (EPNs) are biological control agents for insect pests; the infective juveniles (IJs), specialized third-stage juveniles, are the life stage responsible for infecting insect larvae. IJ dispersal is driven by their response to cues and signals present in the media, such as exometabolomes released by con- and heterospecific species. A wide range of nematode species secrete exometabolomes that contain ascarosides, which play an essential role in regulating nematode development and behavior. Our study aimed to investigate the conspecific and heterospecific effects of the exometabolome of the following EPNs species Heterorhabditis bacteriophora (Hb), Steinernema carpocapsae (Sc), S. feltiae (Sf) and S. diaprepesi (Sd). We collected exometabolomes water (EW) from four EPN species at 1, 7, 10, and 14 days of incubation and tested whether exometabolomes can increase the dispersal of conspecific and heterospecific EPNs. The results show that the EW treatment significantly increased the dispersal of EPNs compared to the control (DI water). However, the dispersal effect of EW treatment on heterospecific conditions was noticeably higher. The increase of the EPNs dispersal is notable in 7 days and older EW. Our results suggest exometabolomes may be used to enhance the dispersal of EPNs in the field, which would significantly impact the biological control of insect pests by EPNs. However, further studies are needed to confirm this observed pattern in natural conditions.