Location: Fruit and Tree Nut ResearchTitle: The impact of chemical nematicides on entomopathogenic nematode survival and infectivity
|TOURAY, MUSTAPHA - Adnan Mederes University|
|CIMEN, HARUN - Adnan Mederes University|
|SEBNEM, GULSEN - Adnan Mederes University|
|ULUG, DERYA - Adnan Mederes University|
|ERDOGUS, DOLUNAY - Central Research Institute - Turkey|
|Shapiro Ilan, David|
|HAZIR, SELCUK - Adnan Mederes University|
Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2021
Publication Date: 6/8/2021
Citation: Touray, M., Cimen, H., Sebnem, G., Ulug, D., Erdogus, D., Shapiro Ilan, D.I., Hazir, S. 2021. The impact of chemical nematicides on entomopathogenic nematode survival and infectivity. Journal of Nematology. 53/49. https://doi.org/10.21307/jofnem-2021-049.
Interpretive Summary: Entomopathogenic nematodes, also known as beneficial nematodes, are small round worms that are used as environmentally-friendly biopesticides. Plant parasitic nematodes are small round worms that attack plants and many of them are major plant pests in various crops including peach, pecan, soybean, etc. Nematicides are pesticides that are used to control plant parasitic nematodes. It is important to know if these nematicides harm the “good” nematodes (beneficial nematodes) as well as the plant parasitic nematodes. We tested four different nematicides and found that they can be harmful to both beneficial as well as plant parasitic nematodes. We also observed that the beneficial nematodes can sense the nematicides in the soil and move away from them. Our study indicates that nematicides and beneficial nematodes should not be applied at the same time. Future research should explore optimization of timing when applying nematicides and beneficial nematodes.
Technical Abstract: Entomopathogenic nematodes belonging to the genera, Steinernema and Heterorhabditis, occur naturally in the soil along with plant-parasitic nematodes which are important root pests of many different crops. Here, we report the effects of four registered nematicidal compounds (fluopyram, fosthiazate, metam potassium and fenamiphos) on the survival, virulence, penetration efficiency and reproduction of the infective juveniles of S. carpocapsae and H. bacteriophora. Despite previous studies warning of the impact of nematicidal compounds on nematode survival and infectivity, none have assessed their impact on chemotaxis, penetration into and reproduction in host or conducted longer term soil assays. Survival of EPNs, based on observing nematode movement under a stereomicroscope after 24- and 48-hour incubation in different concentrations of nematicides in 24-well plates, showed that =80% of both nematode species were killed by fosthiazate, fenamiphos and metam potassium within 24-hour. Nematodes exposed to the nematicides were less virulent against Galleria mellonella larvae in a sand bioassay As a first, the chemotaxis experiments using Pluronic F-127 gel indicated that H. bacteriophora were repelled from nematicide-treated environments. We also assessed the effects of nematicides on nematodes added to natural loamy-clay soil at 5-day-intervals for 30 days post application of nematicides. Nematicidal compounds adversely affected EPN survival with increasing concentrations of all four tested nematicidal compounds. Except for S. carpocapsae IJs added to fosthiazate-treated soil, IJs of both species added at various times after nematicide application to soil were generally unable to induced larval mortality of G. mellonella. Overall, our study indicates that there were detrimental effects of the nematicides on EPN IJs in treated soil. Therefore, overlap in timing for control of PPNs and the use of EPNs for biological insect control must be avoided. Future studies should assess the optimization of timing for nematicides use and survival and infectivity of IJs in the soil.