Larvicidal activity of the symbiotic bacterium Xenorhabdus japonicus from the entomopathogenic nematode Steinernema kushidai against Anomala cuprea (Coleoptera:Scarabaeidae).
The entomopathogenicity of the symbiotic bacterium Xenorhabdus japonicus and the nematode Steinernema kushidai was determined. Phase I and II X. japonicus were cultured on an artificial medium and inoculated into the test insect or established into axenic S. kushidai populations. When 100, 1000, or 10,000 bacterial cells of phase I or II were directly injected into the hemocoels of 3rd instar cupreous chafer, Anomala cuprea, both phases in the late log period killed 100% of the larvae by the 2nd day postinoculation. However, both phases in the stationary period were less pathogenic with cupreous chafer mortality < 20 and 80% at 100 and 1000 bacterial cells/ larva, respectively. In vitro studies showed that axenic S. kushidai provided with phase I or II symbionts grew well and produced equal numbers of progeny on a dog food medium, but nematodes with no symbionts did not grow at all. Pig liver extracts added as a dietary supplement to the dog food medium completely restored growth and progeny production of the nematode with no bacterial cells. Studies were conducted with infective juveniles (IJs) harboring phase I or II or no symbionts that were applied against 3rd instar cupreous chafer larvae in compost or injected directly into their hemocoels. In the compost study, IJs harboring phase I killed 100% within 10 days. IJs with phase II or no symbionts caused low mortality of the cupreous chafer larvae at 10 days (< 20%). In the intrahemocoelic injection study, IJs harboring phase I resulted in 60% larval mortality at five nematodes/larva, and as the number of IJs injected increased, significantly higher larval mortality was obtained.
Tachibana
M
M
Biopesticide Laboratory at Advanced Technology Institute, Kubota Corporation, Ibaraki, Japan.
Hori
H
H
Suzuki
N
N
Uechi
T
T
Kobayashi
D
D
Iwahana
H
H
Kaya
H K
HK
D000818:Animals; D001517:Coleoptera; D004755:Enterobacteriaceae / Q000254:growth & development / Q000472:pathogenicity* / Q000648:ultrastructure; D007306:Insecticides; D007814:Larva; D010572:Pest Control, Biological; D017172:Rhabditoidea / Q000254:growth & development / Q000382:microbiology*; D013559:Symbiosis
D007306:Insecticides