Biologists have long been interested in using population parameters not only to assess species’ growth trajectories, but also to make inferences about the processes underlying animal behavior. One parameter of considerable contemporary interest, fluctuating asymmetry, is characteristic of all bilaterally symmetrical animals. In the first chapter of this thesis, fluctuating asymmetry is defined in empirical terms and by how it relates to organism stress. Its importance to biologists is briefly reviewed, and some potential limitations to its utility are outlined. The second chapter is a report of a laboratory experiment designed to detect fluctuating asymmetry in wing traits of the model butterfly Vanessa cardui, and to test whether fluctuating asymmetry varied with the degree of environmental stress to which larvae and pupae were exposed. Finally, the third chapter critiques the author’s experiment and evaluates the likely usefulness of fluctuating asymmetry as an indicator of changing environments in nature. Recommendations are made for those interested in studying fluctuating asymmetry further.

This dissertation research examined whether generalist feeding Vanessa cardui larvae display dietary self-selection, what rules of compromise are followed when larvae are constrained to suboptimal diet, how larval and adult nutrition affect butterfly fitness, and whether adults are able to compensate for variations in larval nutrition with differential adult foraging. First, I examined dietary self-selection and rules of compromise for protein and digestible carbohydrate intake by 5th instar V. cardui larvae. Larvae regulated nutrient intake to a near equal-ratio protein:carbohydrate in choice trials, consistent with results found for other Lepidoptera. Larvae on no-choice diets had reduced fitness on protein-biased or carbohydrate-biased larval diets relative to equal-ratio, and the rule of compromise exhibited by V. cardui is consistent with that expected for a generalist herbivore.

Second, I determined whether larval nutrition affects adult foraging behaviors. Females reared on carbohydrate-biased diet were more likely to probe towards nectar mimic containing sugars and amino acids than towards mimic containing sugars alone. Butterflies reared on protein-biased diet consumed more nectar than butterflies reared on carbohydrate-biased diet. Butterflies, however, did not exhibit preference between sugar and sugar plus amino acids solutions, regardless of larval nutrition.

Third, I examined the relative importance of larval and adult dietary nutrient intake on V. cardui fitness. Adult nutrition played a greater role in realized fitness than larval nutrition, but was mediated by larval dietary history. The most important factor influencing female fitness was adult carbohydrate consumption. Nectar-derived amino acids did not appear to increase fitness, but appeared to negatively affect total egg production when butterflies were reared on equal-ratio larval diet.

Lastly, I studied whether V. cardui exhibit mate choice based on the levels of proteins/amino acids and carbohydrates on which potential mates fed. Mate choice was not affected by larval diet, but was affected by the adult diet of potential mates. Overall, selecting butterflies were more likely to pair with animals provided sugar and amino acids than those given sugar alone. Those fed protein-biased diet as juveniles and sugars plus amino acids as adults were most preferred, while animals provided carbohydrate-biased diet and sugars were least preferred.

Whether interactions among biocontrol agents limits their ability to control shared prey has been one of the most important and controversial questions surrounding biological control. In California multiple parasitoid wasp species have been introduced to control the invasive giant whitefly Aleurodicus dugesii Cockerell (Hemiptera: Aleyrodidae). The overall goal of this dissertation was to determine aspects of these species’ basic biologies and investigate factors contributing to the efficacy of these parasitoids. Findings of these studies will provide a better understanding of how parasitoid community complexity affects biological control and may enhance biological control of A. dugesii in California and elsewhere.

First the effects of temperature on survival and development of A. dugesii were assessed. Starting at 10°C development rate of A. dugesii increased until an optimum of 29°C was reached, then development ceased at 30°C. Using these data developmental degree days were calculated for A. dugesii.

Second, host stage preferences of the three parasitoids were determined. All host nymphal stages were accepted by I. affinis for oviposition, while only the 2nd–4th and 3rd–4th instars were accepted by E. noyesi and E. krauteri respectively. Host stage preferences overlapped considerably between species.

Third, the effects of A. dugesii nymphal wax production on I. affinis and E. noyesi efficacy was determined. Wax production decreased parasitoid effectiveness, with I. affinis being more negatively impacted by wax than E. noyesi. Wax was found to serve as an effective defense against parasitism.

Finally, the effects of climate and season on population dynamics of species in this system were assessed. Population densities of A. dugesii were found to not differ across climate types in southern California. Total and E. noyesi parasitism rates also did not differ across climate types. Parasitism rates of I. affinis were highest in inland climate sites. Parasitism by E. noyesi and I. affinis was high throughout the year, except during the early spring. The contribution of E. krauteri to A. dugesii biological control appears to be negligible.

Exchanges among ants, honeydew-producing hemipteran pests (HPHs), and natural enemies are highly economically relevant interactions. Though ant-HPH pest partnerships are well-documented for many systems, little is known about the long-term consequences of these interactions in California citrus, particularly for newly emerging, economically devastating pests such as Diaphorina citri. We aim to bridge this knowledge gap by first, elucidating the impact of Argentine ant, Linepithema humile, management on infestation by several economically important HPH pests and the efficacy of their natural enemies and second, developing and commercializing critically needed L. humile chemical control and monitoring technologies.

The Western Riverside County Multiple Species Habitat Conservation Plan has been presented to the public as a complete draft having been reviewed and modified as a result of comments from resource agencies, the Scientific Review Panel (SRP), local stakeholder groups, cities, and numerous other individuals at key intervals in the planning process. The goal is to develop a land-use plan that preserves open space for individual species of concern, protects existing natural communities that sustain the biodiversity of the planning region, and creates constraints for planned growth and development of the region that respect the rights of property owners. It seeks to use the “Best Available Science” as an approach to the planning process. This document is a review of the "science" in the final draft of the Western Riverside County Multiple Species Habitat Conservation Plan, by the Science Review Panel assembled by the Center for Conservation Biology at the University of California, Riverside.

Background

Results

Conclusions