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Article

Comparative Screening of Mexican, Rwandan and Commercial Entomopathogenic Nematodes to Be Used against Invasive Fall Armyworm, Spodoptera frugiperda

1
Laboratory of Fundamental and Applied Research in Chemical Ecology, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland
2
CABI, Rue des Grillons 1, CH-2800 Delémont, Switzerland
3
Experimental Biology Research Group, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland
4
Department of Entomology, Texas A&M University, College Station, TX 77840, USA
5
Rwanda Agriculture and Animal Resources Development Board (RAB), KG 569 Street, Kigali 5016, Rwanda
6
MARA-CABI Joint Laboratory for Biosafety, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Academic Editors: Adler R. Dillman and Raquel Campos-Herrera
Insects 2022, 13(2), 205; https://doi.org/10.3390/insects13020205
Received: 1 December 2021 / Revised: 7 February 2022 / Accepted: 11 February 2022 / Published: 16 February 2022
(This article belongs to the Special Issue Entomopathogenic Nematodes: Lethal Parasites of Insects)
The fall armyworm is a devastating insect pest of maize that has recently spread from the Americas to Africa and Asia. Synthetic insecticides are currently being used excessively to fight this pest. Safe, effective and more sustainable alternatives are urgently needed. We explore the use of beneficial entomopathogenic nematodes to control the fall armyworm. These tiny soil-born roundworms are lethal parasites of insects, including caterpillars such as the fall armyworm. We tested forty nematode strains from either the native range of the fall armyworm (Mexico), or the area of invasion (Rwanda), and commercial strains. We found that certain strains of local nematodes from the area of invasion can be as effective in infecting and killing fall armyworm as commercial strains or those from the armyworm’s native range. These findings will aid the development of locally acceptable and effective biological control products.
The fall armyworm (FAW), Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) is an important pest of maize originating from the Americas. It recently invaded Africa and Asia, where it causes severe yield losses to maize. To fight this pest, tremendous quantities of synthetic insecticides are being used. As a safe and sustainable alternative, we explore the possibility to control FAW with entomopathogenic nematodes (EPN). We tested in the laboratory whether local EPNs, isolated in the invasive range of FAW, are as effective as EPNs from FAW native range or as commercially available EPNs. This work compared the virulence, killing speed and propagation capability of low doses of forty EPN strains, representing twelve species, after placing them with second-, third- and sixth-instar caterpillars as well as pupae. EPN isolated in the invasive range of FAW (Rwanda) were found to be as effective as commercial and EPNs from the native range of FAW (Mexico) at killing FAW caterpillars. In particular, the Rwandan Steinernema carpocapsae strain RW14-G-R3a-2 caused rapid 100% mortality of second- and third-instar and close to 75% of sixth-instar FAW caterpillars. EPN strains and concentrations used in this study were not effective in killing FAW pupae. Virulence varied greatly among EPN strains, underlining the importance of thorough EPN screenings. These findings will facilitate the development of local EPN-based biological control products for sustainable and environmentally friendly control of FAW in East Africa and beyond. View Full-Text
Keywords: biological control; integrated pest management; East Africa; maize; invasive species; food security biological control; integrated pest management; East Africa; maize; invasive species; food security
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MDPI and ACS Style

Fallet, P.; De Gianni, L.; Machado, R.A.R.; Bruno, P.; Bernal, J.S.; Karangwa, P.; Kajuga, J.; Waweru, B.; Bazagwira, D.; Degen, T.; Toepfer, S.; Turlings, T.C.J. Comparative Screening of Mexican, Rwandan and Commercial Entomopathogenic Nematodes to Be Used against Invasive Fall Armyworm, Spodoptera frugiperda. Insects 2022, 13, 205. https://doi.org/10.3390/insects13020205

AMA Style

Fallet P, De Gianni L, Machado RAR, Bruno P, Bernal JS, Karangwa P, Kajuga J, Waweru B, Bazagwira D, Degen T, Toepfer S, Turlings TCJ. Comparative Screening of Mexican, Rwandan and Commercial Entomopathogenic Nematodes to Be Used against Invasive Fall Armyworm, Spodoptera frugiperda. Insects. 2022; 13(2):205. https://doi.org/10.3390/insects13020205

Chicago/Turabian Style

Fallet, Patrick, Lara De Gianni, Ricardo A. R. Machado, Pamela Bruno, Julio S. Bernal, Patrick Karangwa, Joelle Kajuga, Bancy Waweru, Didace Bazagwira, Thomas Degen, Stefan Toepfer, and Ted C. J. Turlings. 2022. "Comparative Screening of Mexican, Rwandan and Commercial Entomopathogenic Nematodes to Be Used against Invasive Fall Armyworm, Spodoptera frugiperda" Insects 13, no. 2: 205. https://doi.org/10.3390/insects13020205

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