Suppression of leaf feeding and oviposition of phytophagous ladybird beetles (Coleoptera: Coccinellidae) by chitinase gene-transformed phylloplane bacteria and their specific bacteriophages entrapped in alginate gel beads.
The chitinase gene-transformed strain KPM-007E/chi of Enterobacter cloacae was vitally entrapped in sodium alginate gel beads with its specific virulent bacteriophage EcP-01 to provide a new method for microbially digesting chitinous peritrophic membranes of phytophagous ladybird beetles Epilachna vigintioctopunctata. First, chitinase SH1 from a gram-positive bacterium Kurthia zopfii was overproduced by Escherichia coli cells and purified by affinity column chromatography. The purified enzyme effectively digested peritrophic membranes dissected from the ladybird beetles to expose epithelial tissues beneath the peritrophic membrane, and the beetles that had ingested chitinase after submergence in chitinase solution had considerably reduced their feeding on tomato leaves. KPM-007E/chi, entrapped in the alginate beads, released the chitinase. More chitinase was released when KPM-007E/chi was present with their specific virulent bacteriophage EcP-01 in the beads because of lysis of bacterial cells infected with the bacteriophages. This chitinase release from the microbial beads (containing KPM-007E/chi and EcP-01) was sufficient to digest the peritrophic membrane as well as to suppress feeding of bead-sprayed tomato leaves by the ladybird beetles. A daily supply of tomato leaves treated with the microbial beads considerably suppressed leaf feeding and oviposition by the ladybird beetles, suggesting a possible application of chitinase-secreting bacteria for suppressing herbivorous insect pests.
Otsu
Yasunari
Y
Laboratory of Plant Pathology and Biotechnology, Faculty of Agriculture, Kinki University, Nara, 631-8505 Japan.
Mori
Hirofumi
H
Komuta
Kenji
K
Shimizu
Hiroyuki
H
Nogawa
Souta
S
Matsuda
Yoshinori
Y
Nonomura
Teruo
T
Sakuratani
Yasuyuki
Y
Tosa
Yukio
Y
Mayama
Shigeyuki
S
Toyoda
Hideyoshi
H
D000464:Alginates; D000818:Animals; D001435:Bacteriophages / Q000502:physiology; D002688:Chitinases / Q000235:genetics / Q000378:metabolism*; D001517:Coleoptera / Q000502:physiology*; D016972:Enterobacter cloacae / Q000201:enzymology* / Q000235:genetics / Q000821:virology*; D005247:Feeding Behavior; D005782:Gels; D007300:Insect Control / Q000379:methods*; D018551:Solanum lycopersicum / Q000469:parasitology*; D008863:Microspheres; D010058:Oviposition; D018515:Plant Leaves; D014169:Transformation, Bacterial
D000464:Alginates; D005782:Gels; D002688:Chitinases