Comparative dispersal and larvicidal activity of exotic and Azorean isolates of entomopathogenic nematodes against Popillia japonica (Coleoptera: Scarabaeidae)

Abstract

Abstract. The Japanese beetle, Popillia japonica Newman, is an introduced pest on Terceira, one of nine islands in the Azorean Archipelago. Research conducted on Terceira indicates that entomopathogenic nematodes in the families Steinemematidae and Het erorhabditidae provide good to excellent control of Japanese beetle larvae, but the species that have been evaluated are not native to the Azores. An efficacious species that is native to the archipelago might provide increased capabilities for persisting and recycling in Azorean soil and weather conditions. Surveys on the islands of Terceira and Santa Maria resulted in the isolation of two Hetero rhabditis strains (Sao Mateus and Praia Formosa) with good larvicidal activity for P. japonica. Initial bioassays conducted with Steinernema glaseri (Steiner) originally from North Carolina against P. japonica third instar larvae and pupae produced LC50 values of 3.2 x 105 infectivejuveniles (IJs)/m2 and 0.9 x 105 IJs/m2, respectively. Comparative bioassays of the native isolates and S. glaseri against P. japonica revealed similar larvicidal activity. The LC5os of the Sao Mateus and Praia Formosa isolates against third instar larvae were 3.64 x 105 and 4.44 x 105 IJs/m2, respectively. The LC50 of S. glaseri ranged from 3.2 to 5.5 x 105 IJs/m2. The higher larvicidal activity of the Azorean Heterorhabditis isolates for P. japonica indicates that native nematodes are as effective as S. gla seri. Heterorhabditid species also have demonstrated ability for persistence and apparent recycling under conditions where sustain able control of this introduced pest is needed. Studies comparing the dispersal behavior of the Heterorhabditis bacteriophora Poinar Sao Mateus isolate with that of S. glaseri and native and exotic strains of Steinernema carpocapsae (Weiser) revealed that the H. bacteriophora isolate demonstrated a greater propensity to disperse than other strains in the presence or absence of P. japonica lar vae. In the presence of a host, a greater proportion of H. bacteriophora and S. glaseri dispersed than either of the two S. carpocapsae strains.

Attraction of four entomopathogenic nematodes to four white grub species

“…While the response of S. glaseri in Koppenhöfer et al (2000) was very similar to the one observed in our study, the response of H. bacteriophora was different in as much as it showed lower dispersal but a stronger relative response. Using a horizontal experimental setup, Lacey et al (2001) found a similar relative response as in our study with a 10-fold increase in the presence of third-instar P. japonica for S. glaseri (NC1 strain) and only a 2-fold increase for H. bacteriophora (AZ162 isolate). However, H. bacteriophora was more active resulting in twice as many H. bacteriophora than S. glaseri dispersing toward the host.…”

“…The nematodes used in this study are cruisers based on their attraction to host volatiles or hosts and their mobility and distribution throughout the soil profile (e.g., Grewal et al, 1993a;Lewis et al, 1993;Westermann, 1995;Lacey et al, 2001;Koppenhöfer and Fuzy, 2003b). Results from our study should help explain differences in nematode efficacy against different white grub species and thereby help to optimize nematode species-target host matching for improved biological control.…”

Potential of Nepalese entomopathogenic nematodes as biocontrol agents against Holotrichia longipennis Blanch. (Coleoptera: Scarabaeidae)

“…In general, pupae of white grubs are more susceptible to EPN than active feeding larvae (Lacey et al 2001;Lee et al 2002;Koppenhöfer and Fuzy 2004). Our bioassays yielded similar results for all isolates.…”

“…The positive influence of host insect cues on the migration of EPN is well documented (e.g. Lacey et al 2001;Koppenhöfer and Fuzy 2008). Nematode attraction in response to insects is reported to be due to host cues like CO 2 (Gaugler et al 1980; Lewis et al 1993) and/or gut fluids (Grewal et al 1993a, b).…”

PM 9/21(1) Popillia japonica: procedures for official control

“…and Heterorhabditis bacteriophora have been evaluated for effectiveness against P. japonica in the Azores (Simões et al, 1993) and in Piedmont (B. Cavagna, Regione Lombardia, pers. In the Azores efforts have been made to find endemic entomopathogenic nematodes for the control of P. japonica (Lacey et al, 2001). Steinernema glaseri and Steinernema carpocapsae both reduced larval populations when applied in September but proved ineffective during the colder months (November to February) (Simões et al, 1993).…”