Submitted to: Arthropod-Plant Interactions
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/18/2012
Publication Date: 9/1/2012
Citation: Sisterson, M.S. 2012. Host selection by a phytophagous insect: the interplay between feeding, egg maturation, egg load, and oviposition. Arthropod-Plant Interactions. 6:351-360. Interpretive Summary: The glassy-winged sharpshooter (Homalodisca vitripennis) is a primary vector of Xylella fastidiosa in Southern California and southern portions of the San Joaquin Valley. For insect transmitted pathogens, patterns of pathogen spread reflect movement patterns of the vector. Thus, a better understanding of movement patterns of the glassy-winged sharpshooter will provide insight into spread of X. fastidiosa. Key aspects of insect movement patterns include selection of plants for feeding and egg laying. Studies on selection of plants for feeding found that plant species varied in quality for providing nutrients to mature eggs and that females preferentially fed on plant species that imparted the greatest egg maturation rate. Studies on selection of plants for egg laying found that females were more likely to deposit eggs as egg load (number of mature eggs carried by a female) increased. Further, females were more likely to accept a low-ranked egg laying host as egg load and time since last egg deposition increased. Results of this study will improve understanding of the epidemiology of diseases caused by X. fastidiosa and will aid in development of novel management strategies for the glassy-winged sharpshooter.
Technical Abstract: Understanding movement patterns of phytophagous insects among plants is a primary goal of insect ecology. Adult females may visit plants for the purpose of depositing eggs, feeding, or both. For some species, egg maturation may be dependent on adult feeding. As a result, rates of egg maturation may be dependent on both quality and quantity of available food sources. Such effects of the plant community on egg maturation could in turn affect oviposition behavior via changes in egg load (number of mature eggs carried by a female). To determine if such effects are possible, experiments were conducted using the glassy-winged sharpshooter, Homalodisca vitripennis. No-choice tests demonstrated that eggs accumulated in the female abdomen as time since last oviposition increased largely as a function of feeding plant species. In choice tests, females were observed most frequently on plant species that imparted the greatest egg maturation rate in no-choice tests. Direct tests of the effects of egg load on oviposition behavior found that females were more likely to deposit eggs as egg load increased. Similarly, acceptance of a low ranked oviposition host increased with egg load and time since last oviposition. The results indicate that adult feeding affects egg maturation, plants vary in quality for providing nutrients to mature eggs, and egg load affects oviposition behavior. Thus, quantity and quality of feeding plants within a community will affect egg maturation rates which, in turn, may affect choice of oviposition plant.