Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


osu1306856939.pdf (2.06 MB)

ETD Abstract Container

Abstract Header

Poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch: Euphorbiacea) Resistance Mechanisms against the Silverleaf Whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Biotype B

Medina-Ortega, Karla Jacqueline
http://rave.ohiolink.edu/etdc/view?acc_num=osu1306856939

Abstract Details

2011, Doctor of Philosophy, Ohio State University, Entomology.
The silverleaf whitefly (Bemisia tabaci biotype B) is the main insect pest of poinsettias (Euphorbia pulcherrima). Among potted plants, poinsettias rank first in sales across the nation. Control of whiteflies in greenhouses is primarily with insecticides; therefore, mechanisms of resistance in poinsettias are not well understood and have not been thoroughly studied. The goal of this research was to determine if poinsettia cultivars possess physical and chemical factors/traits affecting the behavior and physiology of the silverleaf whitefly and to some extent evaluate tritrophic interactions. The objectives were to (1) determine silverleaf whitefly behavioral preference for, and performance on different cultivars through choice and no-choice assays; (2) evaluate physical traits possibly mediating resistance, including visual cues by excluding light, leaf thickness, and leaf color indirectly via chlorophyll content using a SPAD meter, and with the use of a color reader; (3) determine free amino acids and phenolic compounds potentially involved in mediating resistance to B. tabaci; (4) evaluate tritrophic interactions by comparing Eretmocerus mundus parasitism preference between B. tabaci nymphs from a more and a less susceptible poinsettia cultivars. Behavioral preference of B. tabaci varied among cultivars, but cultivars with light green leaves were preferred than cultivars with dark green leaves. Leaf color appeared to be influenced by chlorophyll content and leaf thickness. Cultivars with light green leaves had less chlorophyll and had thinner leaves. Trichome density was not significantly different among the cultivars. Visual cues were important in recognition of a more susceptible host in the presence indicating leaf color of poinsettia plants plays a key role in recognition by B. tabaci. Cultivars were similar in the composition and concentration of amino acids, and cultivars with light green leaves averaged a higher concentration of amino acids. Concentration of individual phenolic compounds, in both leaf and petioles, were higher in a less susceptible cultivar (cv [‘Freedom Red’]) with dark green leaves, and where fertility of B. tabaci was lower, than on a more susceptible cultivar (‘Monet Twilight’) with light green leaves where fertility of B. tabaci was higher. Concentrations of over 45 % of individual phenolics shared between the two cultivars were higher in ‘Freedom Red’. While ‘Freedom Red’ had four unique compounds, only one compound was unique to ‘Monet Twilight’. Compounds unique to, and in higher amount in ‘Freedom Red’ included galloyl quinic acids, digalloyl glucose, apigenin diglucoside, apigenin glucoside, kaempferol hexoside, and quercetin pentose rutinoside, and rutin. These compounds have been associated with resistance to herbivores, prolonging developmental times, acting as antifeedants and toxins. Higher parasitism of B. tabaci nymphs on cv ‘Monet Twilight’ was observed than on cv ‘Freedom Red’. More studies are needed to determine if preferences of parasitism are due to the host plant or the nymphs to understand the dynamic interactions of bottom-up and top-down factors; also more in-depth analysis comparing the ratio of amino acids and phenolic compounds in less and more susceptible poinsettia cultivars in relation to whiteflies and its parasitoids needs to be conducted to better understand their ecological role.
Luis Cañas (Advisor)
Larry Phelan (Committee Member)
Daniel Herms (Committee Member)
Claudio Pasian (Committee Member)
149 p.
Entomology
Plant defenses resistance plant-insect interactions phenolics amino acids

Recommended Citations

Citations

  • Medina-Ortega, K. J. (2011). Poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch: Euphorbiacea) Resistance Mechanisms against the Silverleaf Whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Biotype B [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306856939

    APA Style (7th edition)

  • Medina-Ortega, Karla. Poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch: Euphorbiacea) Resistance Mechanisms against the Silverleaf Whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Biotype B. 2011. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1306856939.

    MLA Style (8th edition)

  • Medina-Ortega, Karla. "Poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch: Euphorbiacea) Resistance Mechanisms against the Silverleaf Whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Biotype B." Doctoral dissertation, Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306856939

    Chicago Manual of Style (17th edition)

osu1306856939
2,610
© 2011, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.