Symbiont-mediated adaptation by planthoppers and leafhoppers to resistant rice varieties
Ferrater, J.B. ; Jong, P.W. de; Dicke, M. ; Chen, Y.H. ; Horgan, F.G. - \ 2013
Arthropod-Plant Interactions 7 (2013)6. - ISSN 1872-8855 - p. 591 - 605.
nilaparvata-lugens stal - yeast-like symbiote - sogatella-furcifera horvath - laodelphax-striatellus homoptera - nephotettix-cincticeps uhler - oryza-sativa l. - brown planthopper - whitebacked planthopper - histological observations - phylogenetic position
For over 50 years, host plant resistance has been the principal focus of public research to reduce planthopper and leafhopper damage to rice in Asia. Several resistance genes have been identified from native varieties and wild rice species, and some of these have been incorporated into high-yielding rice varieties through conventional breeding. However, adaptation by hoppers to resistant rice has been phenomenally rapid, and hopper populations with virulence against several resistance genes are now widespread. Directional genetic selection for virulent hoppers seems unlikely given the rapid pace of adaptation reported from field and laboratory studies. Among the alternative explanations for rapid hopper adaptation are changes (genetic, epigenetic, or community structure) in endosymbiont communities that become advantageous for planthoppers and leafhoppers that feed on resistant rice varieties. This review examines the nature of these symbiont communities and their functions in planthoppers and leafhoppers—focusing on their likely roles in mediating adaptation to plant resistance. Evidence from a small number of experimental studies suggests that bacterial and eukaryotic (including yeast-like) symbionts can determine or mediate hopper virulence on rice plants and that symbiont functions could change over successive generations of selection on both resistant and susceptible plants. The review highlights the potential complexity of rice hopper–symbiont interactions and calls for a more careful choice of research materials and methods to help reduce this complexity. Finally, the consequences of symbiont-mediated virulence adaptation for future rice breeding programs are discussed.
Insect egg deposition induces indirect defense and epicuticular wax changes in Arabidopsis thaliana
Blenn, B. ; Bandoly, M. ; Küffner, A. ; Otte, T. ; Geiselhardt, S. ; Fatouros, N.E. ; Hilker, M. - \ 2012
Journal of Chemical Ecology 38 (2012)7. - ISSN 0098-0331 - p. 882 - 892.
furcifera horvath homoptera - plant cuticular waxes - whitebacked planthopper - eceriferum mutants - trissolcus-basalis - pierid butterflies - nezara-viridula - host location - up-regulation - rice plants
Egg deposition by the Large Cabbage White butterfly Pieris brassicae on Brussels sprouts plants induces indirect defense by changing the leaf surface, which arrests the egg parasitoid Trichogramma brassicae. Previous studies revealed that this indirect defense response is elicited by benzyl cyanide (BC), which is present in the female accessory reproductive gland (ARG) secretion and is released to the leaf during egg deposition. Here, we aimed (1) to elucidate whether P. brassicae eggs induce parasitoid-arresting leaf surface changes in another Brassicacean plant, i.e., Arabidopsis thaliana, and, if so, (2) to chemically characterize the egg-induced leaf surface changes. Egg deposition by P. brassicae on A. thaliana leaves had similar effects to egg deposition on Brussels sprouts with respect to the following: (a) Egg deposition induced leaf surface changes that arrested T. brassicae egg parasitoids. (b) Application of ARG secretion of mated female butterflies or of BC to leaves had the same inductive effects as egg deposition. Based on these results, we conducted GC-MS analysis of leaf surface compounds from egg- or ARG-induced A. thaliana leaves. We found significant quantitative differences in epicuticular waxes compared to control leaves. A discriminant analysis separated surface extracts of egg-laden, ARG-treated, untreated control and Ringer solution-treated control leaves according to their quantitative chemical composition. Quantities of the fatty acid tetratriacontanoic acid (C34) were significantly higher in extracts of leaf surfaces arresting the parasitoids (egg-laden or ARG-treated) than in respective controls. In contrast, the level of tetracosanoic acid (C24) was lower in extracts of egg-laden leaves compared to controls. Our study shows that insect egg deposition on a plant can significantly affect the quantitative leaf epicuticular wax composition. The ecological relevance of this finding is discussed with respect to its impact on the behavior of egg parasitoids.
Plant Volatiles Induced by Herbivore Egg Deposition Affect Insects of Different Trophic Levels
Fatouros, N.E. ; Lucas-Barbosa, D. ; Weldegergis, B.T. ; Pashalidou, F.G. ; Loon, J.J.A. van; Dicke, M. ; Harvey, J.A. ; Gols, R. ; Huigens, M.E. - \ 2012
PLoS ONE 7 (2012)8. - ISSN 1932-6203
furcifera horvath homoptera - elm leaf beetle - whitebacked planthopper - cotesia-glomerata - herbaceous plants - pieris-brassicae - host location - rice plants - oviposition - defense
Plants release volatiles induced by herbivore feeding that may affect the diversity and composition of plant-associated arthropod communities. However, the specificity and role of plant volatiles induced during the early phase of attack, i.e. egg deposition by herbivorous insects, and their consequences on insects of different trophic levels remain poorly explored. In olfactometer and wind tunnel set-ups, we investigated behavioural responses of a specialist cabbage butterfly (Pieris brassicae) and two of its parasitic wasps (Trichogramma brassicae and Cotesia glomerata) to volatiles of a wild crucifer (Brassica nigra) induced by oviposition of the specialist butterfly and an additional generalist moth (Mamestra brassicae). Gravid butterflies were repelled by volatiles from plants induced by cabbage white butterfly eggs, probably as a means of avoiding competition, whereas both parasitic wasp species were attracted. In contrast, volatiles from plants induced by eggs of the generalist moth did neither repel nor attract any of the tested community members. Analysis of the plant’s volatile metabolomic profile by gas chromatography-mass spectrometry and the structure of the plant-egg interface by scanning electron microscopy confirmed that the plant responds differently to egg deposition by the two lepidopteran species. Our findings imply that prior to actual feeding damage, egg deposition can induce specific plant responses that significantly influence various members of higher trophic levels.