Host manipulation by the orange leafhopper Cicadulina bipunctata: gall induction on distant leaves by dose-dependent stimulation.
The evolution of the gall-inducing ability in insects and the adaptive significance of the galling habit have been addressed by many studies. Cicadulina bipunctata, the maize orange leafhopper, is an ideal study organism for evaluating these topics because it can be mass-reared and it feeds on model plants such as rice (Oryza sativa) and maize (Zea mays). To reveal differences between gall inductions by C. bipunctata and other gall inducers, we conducted four experiments concerning (a) the relationship between the feeding site and gall-induction sites of C. bipunctata on maize, (b) the effects of leafhopper sex and density, (c) the effects of length of infestation on gall induction, and (d) the effects of continuous infestation. C. bipunctata did not induce galls on the leaves where it fed but induced galls on other leaves situated at more distal positions. The degree of gall induction was significantly correlated with infestation density and length. These results indicate that C. bipunctata induces galls in a dose-dependent manner on leaves distant from feeding sites, probably by injecting chemical(s) to the plant during feeding. We suggest that insect galls are induced by a chemical stimulus injected by gall inducers during feeding into the hosts.
Matsukura
Keiichiro
K
Research Team for Insect Pest and Nematode Management, National Agricultural Research Center for Kyushu Okinawa Region, 2421 Suya, Koshi, Kumamoto 861-1192, Japan. mtkr@affrc.go.jp
Matsumura
Masaya
M
Tokuda
Makoto
M
D000821:Animal Feed; D000818:Animals; D017753:Ecosystem; D005260:Female; D006430:Hemiptera / Q000502:physiology*; D006790:Host-Parasite Interactions; D008297:Male; D012275:Oryza / Q000469:parasitology; D010935:Plant Diseases / Q000469:parasitology; D018515:Plant Leaves / Q000469:parasitology; D010941:Plant Tumors / Q000469:parasitology*; D003313:Zea mays / Q000254:growth & development / Q000469:parasitology