Virulence of entomopathogenic nematodes of Pupae of Frankliniella Fusca (Thysanoptera; Thripidae

Authors: GULZAR, SEHRISH - Pakistan University Of Agriculture; USMAN, MUHAMMAD - Pakistan University Of Agriculture; WAKIL, WAQAS - Pakistan University Of Agriculture; WU, SHAOHUI - University Of Georgia; Hofman, Camila; SRINIVASAN, RAJAGOPALBABU - University Of Georgia; TOEWS, MICHAEL - University Of Georgia; Shapiro Ilan, David

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2021
Publication Date: 10/13/2021
Citation: Gulzar, S., Usman, M., Wakil, W., Wu, S., Hofman, C.O., Srinivasan, R., Toews, M., Shapiro Ilan, D.I. 2021. Virulence of entomopathogenic nematodes of Pupae of Frankliniella Fusca (Thysanoptera; Thripidae. Journal of Economic Entomology. https://doi.org/10.1093/jee/toab132.
DOI: https://doi.org/10.1093/jee/toab132

Interpretive Summary: Tobacco thrips are major pests of various crops. Chemical insecticides are commonly used to control this pest. However, due to environmental and regulatory concerns, alternative methods of pest management are being sought. Entomopathogenic nematodes, also known as beneficial nematodes, are small round worms that kill insects. These nematodes occur naturally and are used as environmentally-friendly bio-pesticides. Different beneficial nematode species have different levels of virulence (killing-power) against various pests. Therefore, it is important to choose the best nematode match for the pest that one is targeting. In this study, we investigated the virulence of eight beneficial nematode species against tobacco thrips. We found that the nematode called Heterorhabditis bacteriophora (Fl-1) was the most virulent but some others also showed high virulence. Our findings indicate that beneficial nematodes have significant promise in providing a sustainable solution to controlling tobacco thrips.

Technical Abstract: Tobacco thrips, Frankliniella fusca, is an economically significant pest with wide distribution, yet relatively little work on its biological control has been undertaken. Entomopathogenic nematodes (EPNs) have shown promise as biocontrol agents against certain thrips species, but their use has not been explored for suppression of F. fusca. In the present study, we investigated the potential of EPNs to manage F. fusca by conducting three different bioassays: (a) a small cup dose-response bioassay (25, 50 and 100 IJs cm-2) with four EPN strains, (b) a broad virulence bioassay with eight EPN strains at 100 IJs cm-2, and (c) a potted soil bioassay testing with four EPN strains (100 IJs cm-2) that exhibited the highest virulence in the broad virulence screening. In the dose-response bioassay, all treatments reduced adult emergence compared with the control, but the minimum adult emergence (30%) was observed at 7 days post-treatment when Heterorhabditis bacteriophora (FL1-1) was applied at the highest rate (100 IJs cm-2). In the broad virulence study, all nematode treatments caused significant reductions in F. fusca adult emergence (18.3-75.0%) in comparison with the control. Heterorhabditis bacteriophora (Fl1-1) was more virulent than other nematode treatments except S. feltiae and S. riobrave, while S. rarum was the least virulent. In the potted soil bioassay, the lowest emergence (10.6%) was observed in H. bacteriophora (Fl1-1) treatment, followed by S. feltiae (SN), S. riobrave (355) and H. indica (HOM1) treatments. These results indicate that EPNs have the ability to suppress the soil dwelling stage of F. fusca and should be explored further under greenhouse and field conditions for biocontrol potential within an IPM context.