The impact of chemical nematicides on entomopathogenic nematode survival and infectivity

Abstract Entomopathogenic nematodes (EPNs) belonging to the genera, Steinernema and Heterorhabditis , occur naturally in soil along with plant-parasitic which are important root pests of many different crops. Here, we report effects four registered nematicidal compounds (fluopyram, fosthiazate, metam potassium, fenamiphos) that used for control PPNs on survival, virulence, penetration efficiency, reproduction S. carpocapsae H. bacteriophora . Despite previous studies warning impact IJ survival infectivity, none have assessed their EPN chemotaxis, into insect host or conducted longer term assays. Survival EPNs, based observing movement under a stereomicroscope after incubation concentrations nematicides, showed ≥ 80% both nematode species were killed by fenamiphos potassium within 24 h. The recommended concentration fluopyram 33% 28% 48 h exposure. IJs exposed nematicides less virulent against Galleria mellonella larvae sand bioassay non-treated as significantly more penetrated (~47% added) than fosthiazate; number progeny emerging from these controls was higher treated compounds. In highly novel discovery, chemotaxis experiments using Pluronic F-127 gel indicated repelled nematicide-treated environments. Moreover, added natural loamy-clay at 5-day-intervals 30 days post application generally unable induce G. mortality, except fosthiazate-treated soil. Overall, our study indicates there detrimental Therefore, overlap timing use EPNs biological must be avoided. Future should assess optimization infectivity