Some causes and consequences of the petal-feeding behavior of the serpentine leafminer, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) in cut flower production of Gerbera jamesonii Hooker

Defensive structures and chemistries, sugars, proteins, sterols, and vitamins are found in varying degrees within the different organs and tissues of plants. Plants, therefore, represent a heterogeneous environment to insect herbivores. The fact that most theories of herbivory are founded on the consumption of leaves represents an important limitation to the study of plant-insect interactions. In this thesis I explore the act of florivory, or the consumption of flowers, from the insect's perspective. Looking at the serpentine leafminer, Liriomyza trifolii (Burgess), on Gerbera jamesonii Hooker I ask the following questions about feeding and oviposition behavior in these flies: (Chapter 1) Do the residues of currently used insecticides impart any anti-feeding or oviposition deterring effects on L. trifolii, which could potentially influence petal-feeding behavior? (Chapter 2) Does the induction of natal habitat preference in leaves vs flowers influence oviposition and feeding behavior of L. trifolii, and what are the fitness consequences of florivory? Choice tests with pesticide treated and untreated plants revealed that spinosad treated plants reduced feeding and oviposition compared to controls, while abamectin and spinosad treated plants reduced oviposition, indicating that pesticide application has the potential to influence patterns of oviposition and herbivory and could contribute to florivory. A causal link, however, was not tested. The results of preference induction experiments showed that flies previously exposed to leaves preferred to feed and oviposit on leaves, while flies exposed to flowers showed no significant preferences. Flies exposed to flowers thus fed twice as often and oviposited three times as often on petals than leaf-exposed flies. Lifetime fecundity and longevity studies demonstrated that flower-fed flies were shorter-lived than leaf-fed flies or those flies that received a mixed diet Surprisingly, however, lifetime fecundity was more than 50% higher among flies in the mixed-diet treatment than the other treatments. This thesis begins with two brief literature reviews: the behavioral effects of sublethal pesticide exposure and the consequences of florivory from the insect's perspective.