Submitted to: Biocontrol
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2001
Publication Date: 12/1/2001
Citation: Lacey, L.A., Rosa, J.S., Simoes, N.O., Amaral, J.J., Kaya, H.K. 2001. Comparative dispersal and larvicidal activity of Steinernema glaseri and Azorean isolates of entomopathogenic nematodes against Popillia japonica (Coleoptera: Scarabaeidae). Biocontrol. 98:439-444. Interpretive Summary: The Japanese beetle is an introduced pest on Terceira, one of nine islands in the Azorean Archipelago. Early research conducted on Terceira indicated that insect specific nematodes in the families Steinernematidae and Heterorhabditidae provide good to excellent control of Japanese beetle larvae, but the species that have been evaluated are not native to the Azores. An effective nematode that is native to Terceira and/or other islands in the archipelago might provide increased capabilities for persisting and recycling under Azorean soil and weather conditions. Surveys on the islands yielded several isolates with good insecticidal activity against Japanese beetle. The native nematodes offer alternatives to the introduction of exotic species in island habitats where increasing public concern and/or legislation may restrict or prohibit such introductions.
Technical Abstract: An efficacious nematode species that is native to Terceira or other islands in the Azorean Archipelago might provide increased capabilities for persisting and recycling under Azorean soil and weather conditions over that of introduced species. Surveys on Terceira and Santa Maria resulted in the isolation of 2 Heterorhabditis strains (Sao Mateus and Praia Formosa) with good larvicidal activity for P. japonica. Comparative bioassays of the native isolates and Steinernema glaseri against P. japonica revealed similar larvicidal activity. The LC50s of the Sao Mateus and Praia Formosa isolates were 3.64x105 and 4.44x105 IJs/m2, respectively. The LC50 of S. glaseri ranged from 3.2 to 5.5x105 IJs/m2. The elevated larvicidal activity of the Azorean Heterorhabditis isolates for P. japonica indicates that efficacious species of nematodes are available within the Archipelago that are as effective as S. glaseri. Heterorhabditid species also have demonstrated ability for persistence and apparent recycling under the conditions where sustainable control of this introduced pest is needed. Studies comparing the dispersal of the Sao Mateus H. bacteriophora Poinar isolate with that of S. glaseri and native and exotic strains of Steinernema carpocapsae (Weiser) revealed significantly greater propensity to disperse in the H. bacteriophora isolate than in the other strains in the presence or absence of P. japonica larvae. In the presence of a host, a greater proportion of H. bacteriophora and S. glaseri dispersed than either of the 2 S. carpocapsae strains.