SUPERIOR FITNESS IN ENTOMOPATHOGENIC NEMATODES APPLIED IN INFECTED HOSTS

Authors: Shapiro Ilan, David; GULZAR, SEHRISH - University Of Faisalabad; USMAN, MUHAMMAD - University Of Faisalabad; WAKIL, WAQAS - University Of Faisalabad; GULCU, BARIS - Duzce University; HAZIR, CANANA - Adnan Mederes University; KARAGOZ, MEHMET - Adnan Mederes University; HAZIR, SELCUK - Adnan Mederes University

Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: 6/23/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Entomopathogenic nematodes in the genera Steinernema and Heterorhabditis are biocontrol agents that are used to control a wide variety of economically important insect pests. Generally, the nematodes are applied in aqueous suspension using standard agricultural equipment (e.g., sprayers and irrigation systems). However, the nematodes can also be applied in their infected hosts. In this approach, the infected cadavers are applied to the target site and pest suppression is subsequently achieved by the emerging progeny nematodes. In prior studies, the infected host application approach was reported to be superior to aqueous application in terms of nematode dispersal, infectivity, and biocontrol efficacy. In the current study, we explored the impact of application approach on environmental tolerance. Prior to our research, differential stress tolerance among nematodes that emerged from infected host cadavers versus those applied in aqueous suspension had not been investigated. Specifically, we explored the fitness of nematodes applied by cadaver versus aqueous following exposure to temperature extremes (heat and cold) and desiccation. The nematodes, Heterorhabditis bacteriophora and Steinernema glaseri were assessed for viability, virulence, and reproductive capacity. Following exposure to 30 ºC, 35 ºC and 37.5 ºC, nematodes of both species exhibited higher survival and reproductive capacity in the cadaver treatment compared with aqueous application. No differences were observed between the cadaver and aqueous treatments in cold tolerance, i.e., after a sequence of exposures from 10 ºC to -2 ºC. For desiccation tolerance, following exposure to 85% relative humidity both nematode species exhibited higher survival and reproduction in the cadaver treatment than in the aqueous treatment, whereas no differences were observed in virulence. Our findings indicate additional advantages when using the cadaver approach for biocontrol applications, and suggest EPNs existing in natural populations may have broader environmental tolerance than those applied via aqueous suspension.