Host utilization patterns of the walnut fly, Rhagoletis juglandis, and their implications for female and offspring fitness

Persistent Link:
http://hdl.handle.net/10150/280047
Title:
Host utilization patterns of the walnut fly, Rhagoletis juglandis, and their implications for female and offspring fitness
Author:
Nufio, Cesar R.
Issue Date:
2002
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Choosing where offspring will develop is especially important for insects whose larval stages are restricted to a particular host resource. In such insects, maternal egg laying decisions may not only involve choosing optimal hosts based on their intrinsic qualities but also avoiding hosts occupied by conspecific brood. The ability to discriminate between previously exploited and unexploited hosts is often mediated by the use of a marking pheromone. Despite engaging in what appears to be host-marking behavior, the walnut fly Rhagoletis juglandis prefers to deposit clutches into previously exploited hosts. In this dissertation, I quantified host reuse in R. juglandis and assessed its impacts on offspring fitness. I also explored the role that marking pheromone plays in level of reuse. Host reuse by the walnut fly was common in the field, where trees were synchronously infested over a 14-17 day period. It was not unusual for individual fruit to bear 40-80 eggs; given that females laid clutches of ca. 16 eggs, each oviposition puncture probably contained ca. 1.6 clutches. The overall number of eggs deposited into fruit was positively correlated with fruit volume. Field and laboratory experiments showed that increases in larval densities within fruit reduced larval survival and pupal weight, the latter being strongly correlated with the number of eggs a female produced over her lifetime. The temporal staggering of clutches strongly and negatively impacted survival of later clutches. The effect of spatial patterning of clutches on offspring fitness depended on the number of clutches in the fruit: at higher densities, clutches performed better when deposited into the same puncture than when distributed uniformly over fruit. The evidence taken together suggests that host reuse by the walnut fly, R. juglandis, reduces per capita offspring fitness. Consistent with this inference was a final set of observations on female host-marking behavior. In field-cage experiments, fruit that were marked by females for longer durations were less acceptable to other females. Moreover, the duration of time that a female marked a fruit was positively correlated with the size of her clutch. These results indicate that, while females commonly reuse fruit, they nevertheless signal the level of larval competition associated with a fruit and adjust allocation of eggs to fruit accordingly.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Ecology.; Biology, Entomology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Insect Sciences
Degree Grantor:
University of Arizona
Advisor:
Papaj, Daniel R.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleHost utilization patterns of the walnut fly, Rhagoletis juglandis, and their implications for female and offspring fitnessen_US
dc.creatorNufio, Cesar R.en_US
dc.contributor.authorNufio, Cesar R.en_US
dc.date.issued2002en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractChoosing where offspring will develop is especially important for insects whose larval stages are restricted to a particular host resource. In such insects, maternal egg laying decisions may not only involve choosing optimal hosts based on their intrinsic qualities but also avoiding hosts occupied by conspecific brood. The ability to discriminate between previously exploited and unexploited hosts is often mediated by the use of a marking pheromone. Despite engaging in what appears to be host-marking behavior, the walnut fly Rhagoletis juglandis prefers to deposit clutches into previously exploited hosts. In this dissertation, I quantified host reuse in R. juglandis and assessed its impacts on offspring fitness. I also explored the role that marking pheromone plays in level of reuse. Host reuse by the walnut fly was common in the field, where trees were synchronously infested over a 14-17 day period. It was not unusual for individual fruit to bear 40-80 eggs; given that females laid clutches of ca. 16 eggs, each oviposition puncture probably contained ca. 1.6 clutches. The overall number of eggs deposited into fruit was positively correlated with fruit volume. Field and laboratory experiments showed that increases in larval densities within fruit reduced larval survival and pupal weight, the latter being strongly correlated with the number of eggs a female produced over her lifetime. The temporal staggering of clutches strongly and negatively impacted survival of later clutches. The effect of spatial patterning of clutches on offspring fitness depended on the number of clutches in the fruit: at higher densities, clutches performed better when deposited into the same puncture than when distributed uniformly over fruit. The evidence taken together suggests that host reuse by the walnut fly, R. juglandis, reduces per capita offspring fitness. Consistent with this inference was a final set of observations on female host-marking behavior. In field-cage experiments, fruit that were marked by females for longer durations were less acceptable to other females. Moreover, the duration of time that a female marked a fruit was positively correlated with the size of her clutch. These results indicate that, while females commonly reuse fruit, they nevertheless signal the level of larval competition associated with a fruit and adjust allocation of eggs to fruit accordingly.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Ecology.en_US
dc.subjectBiology, Entomology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineInsect Sciencesen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorPapaj, Daniel R.en_US
dc.identifier.proquest3053915en_US
dc.identifier.bibrecord.b42819775en_US
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