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ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Emerging Pests and Pathogens Research » Research » Publications at this Location » Publication #352675

Research Project: Microbial and Arthropod Biological Control Agents for Management of Insect Pests of Greenhouse Crops and Trees

Location: Emerging Pests and Pathogens Research

Title: Characterization of a novel dimorphic Deladenus beddingi n. sp. and its associated woodwasp and fungus

item MORRIS, E. ERIN - Cornell University
item STOCK, S. PATRICIA - University Of Arizona
item Castrillo, Louela
item WILLIAMS, DAVID - Animal And Plant Health Inspection Service (APHIS)
item HAJEK, ANN - Cornell University

Submitted to: Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2018
Publication Date: 6/1/2018
Citation: Morris, E., Stock, S., Castrillo, L.A., Williams, D., Hajek, A. 2018. Characterization of a novel dimorphic Deladenus beddingi n. sp. and its associated woodwasp and fungus. Nematology.

Interpretive Summary: Sirex noctilio is an invasive woodwasp that attacks pines and other conifers and is considered a major pest in commercial plantations. The wasp is associated with a fungal symbiont that causes wood rot and females inject venom during egg laying that results in tree mortality. Native to Asia and Europe, this wasp was detected in New York in 2004 and since then has spread to other states in the northeastern US. Current biological control strategies use the nematode Deladenus siricidicola that attacks the wasp and also feeds on the fungal symbiont. Since it is possible that introduced Deladenus nematodes can switch hosts and attack indigenous Sirex species, studies on native Sirex-fungal symbiont-Deladenus associations are critical to document existing communities where the invasive S. noctilio has not been detected. This study is part of a survey on native Sirex species in North America, and it describes a new species of Deladenus nematode and identifies the fungal symbiont associated with Sirex californicus in northwestern US. The results obtained expand our knowledge of the diversity of native Deladenus species and provide new information on Sirex-fungal symbiont associations in North America. These data are essential when evaluating the risks of the non-target effects of mass releasing biological control nematodes.

Technical Abstract: We describe a new dimorphic species of Deladenus isolated from Sirex californicus from Washington, USA: D. beddingi n. sp. Evolutionary relationships of the new species with other Deladenus species were assessed using multilocus sequencing. Molecular results indicate that D. beddingi n. sp. is a member of the Deladenus siricidicola species complex, which also includes native Deladenus isolated from Sirex cyaneus and Sirex nitidus and D. siricidicola from Sirex noctilio. Mycophagous adults were characterized by the position of the excretory pore, which was 32 (22-52) and 48(38-69) micrometers anterior to the hemizonid in females and males, respectively. Typologically, the new species is similar to D. siricidicola, D. proximus, and D. nitobei. This novel nematode species feeds on the fungus Amylostereum chailletii during its mycophagous phase. Experimental results showed very little reproduction by D. beddingi n. sp. when feeding on A. areolatum compared to robust reproduction when feeding on A. chailletii.