The gypsy moth, Lymantria dispar L., is one of the most important forest pests in the United States. Insecticides are frequently used to suppress outbreaks, however, untreated outbreaks generally collapse due to disease epizootics caused by a nuclear polyhedrosis virus (NPV). Knowledge of NPV epizootiology could aid in the use of NPV as a biological control agent. In this study, the mechanisms by which the NPV is transmitted across host generations, factors affecting host susceptibility to the pathogen, and the effects of NPV on the behavior and distribution of infected larvae in natural populations were investigated. A series of experiments were conducted in the field to determine whether maternal or environmental mechanisms are responsible for transgenerational transmission of the pathogen. Larvae hatching from egg masses oviposited in NPV-contaminated environments became infected, whereas, progeny of NPV-fed parents did not, indicating that environmental contamination of egg masses, rather than maternal transmission, is the principle means of transmission across generations. Further tests showed that egg masses acquire inoculum from the substrate during oviposition, rather than through rain-caused leaching. The pathogenesis of the virus in gypsy moth larvae, pupae, and adults was followed using nucleic acid-hybridization techniques. Virus was not detected in adult moths suggesting that vertical transmission of NPV from infected moths to progeny may not be possible in the gypsy moth. Susceptibility to disease may also be affected by disease prevalence. In laboratory assays, larvae from populations with more heavily NPV-contaminated eggs were more resistant to NPV than were populations with little inoculum present. These results suggest that exposure to NPV may favor selection for resistance to the pathogen. It was also demonstrated that NPV infection alters the behavior of larvae, resulting in the tendency of infected larvae to die in the upper crowns of trees. Thus, samples of larvae collected from the upper canopy contain a higher proportion of infected larvae compared with those collected from under burlap bands wrapped around tree trunks. Therefore, NPV prevalence is more precisely estimated by rearing larvae collecting by a stratified-random sampling design.

Brachymeria intermedia is an introduced endoparasitoid of the gypsy moth, Lymantria dispar. To gain understanding of the basic mechanisms by which B. intermedia influence population densities of the gypsy moth, the oviposition behavior of this parasitoid was studied. Both the physiological state and the informational state of the animal at a certain point in time may influence the development of the behavior. Factors of the physiological state here investigated are egg load and age of the female parasitoid. Factors of the informational state here investigated are the number of hosts previously encountered, the host species encountered and characteristics of the sites where pupae previously were encountered. Chapter 1 contains the introduction and outline of the study. Chapter 2 shows that experience is an important factor influencing the rate of acceptance of hosts by the parasitoid. The sequence of behaviors before ovipositor insertion does not change with experience. Chapter 3 shows that parasitoids, deprived of hosts from emergence, accumulate eggs up to a certain level, but have a low rate of acceptance. Early exposure to pupae increases the rate of acceptance. B. intermedia adjust their egg production to host availability. Chapter 4 shows that the rate of acceptance for an alternate host increased with age in parasitoids, deprived of hosts from emergence. Rearing the parasitoids on an alternate host and/or oviposition experience on an alternate host did not influence the rate of acceptance of the alternate host. After oviposition experience on the alternate host contaminated with kairomone, uncontaminated hosts were accepted at the same rate as gypsy moth. Chapter 4 shows that B. intermedia is able to use learned visual cues, thereby restricting their searching area to a microhabitat previously found to be profitable. Under laboratory conditions and under semi-natural conditions, parasitoids could be trained to search for pupae either on the ground or on a tree model. Subsequent training to the other microhabitat reversed this effect. The studies show that both the physiological state and the informational state of the parasitoid influence oviposition behavior. Questions are raised and discussed as to the extent of polyphagy of B. intermedia in North America.

A Ca$\sp{2+}$-binding protein has been purified and characterized from Blattella germanica eggs. This protein has biochemical features in common with calmodulin. These common features include a relatively low molecular weight of $\sim$19 KDa, thermal stability, an acidic pI of 4.0, a low specific absorbance (E$\sb{\rm 277nm}\sp{1\%}$ = 2.8), an altered electrophoretic mobility in SDS-polyacrylamide gels in the presence of 1 mM Ca$\sp{2+},$ and calcium-dependent binding to the calmodulin antagonist W-7. These features, considered together with activation of calmodulin-dependent phosphodiesterase in a Ca$\sp{2+}$-dependent manner and cross-reactivity with anti-bovine brain calmodulin antibody, are sufficient to define this protein as bone fide calmodulin. A rabbit antibody specific for the B. germanica calmodulin cross-reacts with bovine brain calmodulin. The calmodulin levels during oogenesis and embryogenesis were estimated by densitometric analysis of immunoblots using anti-Blattella germanica egg calmodulin antibody as a probe. A high concentration of calmodulin is present in vitellogenic follicles and early embryonic eggs (about 15 ng calmodulin/$\mu$g protein). During oogenesis calmodulin accumulates in the oocyte throughout the yolk deposition phase. During embryogenesis calmodulin is present at uniformly high levels until vitellin utilization starts, then it is undetectable until the pharate larval stage at the end of embryogenesis. $\sp{14}$C-labeled egg calmodulin in a gel-overlay technique binds to vitellin, the major yolk protein of B. germanica eggs. The calmodulin-binding site of vitellin is located on the 95 KDa subunit before degradation, and on the 53 KDa fragment after 95 KDa subunit breakdown. There is sufficient calmodulin to bind stoichiometrically (1:1) with the vitellin trimer. Circumstantial evidence suggests that this CaM is derived from outside the oocyte. In vitro experiments with ($\sp{35}$S) -methionine showed that the highly abundant calmodulin accumulating in vitellogenic follicles was not synthesized by the oocyte. On the other hand, isolated follicle cells rapidly synthesize large amounts of calmodulin. No calmodulin is detectable in serum. These facts suggest that calmodulin produced by follicle cells is most likely the source of calmodulin in the vitellogenic oocyte. Indirect immunofluorescent staining with anti-egg calmodulin demonstrated that in early- and mid-vitellogenic follicles calmodulin is localized in the cytoplasm of follicle cells and the cytoplasmic compartment surrounding yolk granules but not inside yolk granules. Immunofluorescence was most intense in the cortex of the oocyte and outside the membranes of yolk granules. Transport of calmodulin into the cytoplasmic compartment of the oocyte is not via binding to vitellogenenin.

The influence of the completeness of the blend and quantity of female produced pheromone on the response of male Cadra cautella (Lepidoptera: Phycitidae) was investigated. The threshold concentrations for initiation of pheromone-mediated behaviors are set solely by (Z,E)-9,12-Tetradecadienyl Acetate (the major component), but the presence of (Z)-9-Tetradecenyl Acetate (the minor component) at concentration levels above threshold increased the proportion of males engaging in intermediate and late in-the-sequence behaviors. The organization of male response to pheromone in C. cautella is in accordance with the component hypothesis. Investigation of the effects of blend and concentration of pheromone upwind flight orientation of C. cautella males demonstrated that males fly directly upwind not only to the blend that mimics the female gland extract, but also to an array of "wrong" or "sub-optimal" pheromone blends. The structure of the pheromone plume influences the flight pattern of C. cautella males flying to the complete blend at optimal dosages. Increase in plume size resulted in faster ground velocities, lower turning frequency, narrower turns, and reduced track angles. In short, increasing plume size results in faster and more direct upwind flight. Although changes in pheromone concentration had discernible effects on male upwind flight, concentration effects were smaller than the effects related to changes in plume shape. The internal structure among the plumes was manipulated to produce pulses of pheromone in turbulent plumes and no pulses in the homogeneous filament plume. When filamentous pheromone plumes were marked with smoke, in wind tunnel situations, we were able to monitor C. cautella males changing their inflight maneuvers in response to encounters with pheromone plumes. We explored two features determining the internal structure of the plume, the volume of "continuous" plumes, and the interval between several pulse durations. Males fly faster and straighter to intermittent pheromone plumes consisting of large puffs pulsed at high frequency. When pheromone puffs were delivered at low frequencies, moths responded to individual pulses by "locking on" and flying upwind after contact. The basis of the in flight pheromone-mediated behavior might be the individual responses to single pulses. (Abstract shortened by UMI.)

The effects of a single aerial application of diflubenzuron (Dimilin$\sp\circler$ over Warwick State Forest, MA, on nontarget aquatic macroinvertebrates of vernal pools and a stream was studied. Vernal pool populations which significantly decreased after the treatment were mosquito (Culicidae) pupae and Cyclops. No impact was demonstrated for the other abundant taxa in these vernal pools (mosquito larvae, water mites (Hydrarchanidae), tardigrades and springtails (Collembola)). The stream nontarget populations which significantly decreased after the treatment include 3 taxa of black flies (Prosimulium mixtum/fuscum, Simulium vernum & S. vittatum; Diptera: Simuliidae). No impact was demonstrated for the other abundant taxa (Amphinemora, Leuctra, Ostrocerca (Plecoptera); Siphlonurus (Ephemeroptera); Rhyacophila, Ironoquia, Lepidostoma, Neophylax (Trichoptera): Chironomidae (Diptera)) nor for a particular size class of these taxa. The timing of population growth and development, and pesticide exposure by filter-feeding are the reasons used to explain these results. A laboratory acute toxicity study of diflubenzuron with mosquito larvae (Aedes aegypti; Culicidae) under different water acidities was conducted. Low pH treatments (pH = 4.5) resulted in 100 fold higher mortality of 4-day-old larvae (LC$\sb{50} = 5\ {\rm n}M$) compared with less acid water (pH = 6.6; LC$\sb{50} = 500\ {\rm n}M$). The synergist action of diflubenzuron with lowered pH has implications for prediction of nontarget impact in habitats exposed to acid rain. A diflubenzuron biochemical mode-of-action study was conducted to determine if: (1) dolichol is present in the chitin-synthesizing plasma membrane of Chironomus tentans cell line, (2) dithiocarbanilates (i.e. nucleoside-transport inhibitors that affect membrane characteristics) inhibit chitin synthesis as does diflubenzuron in C. tentans, and, (3) diflubenzuron has a binding affinity for dolichol pyrophosphate N-acetylglucosamine (Dol-PP-GlcNAc). Plasma membrane was isolated from C. tentans by the method of Chaney & Jacobson (1983). No dolichol was found in this preparation, however, the preparation was never characterized as plasma membrane. Low cell culture growth prevented further study. Dol-PP-GlcNAc was produced from rat liver enzymes, however, diflubenzuron quantification limits (HPLC, ELISA) were too low to conduct a binding affinity study.

The apple maggot fly, Rhagoletis pomonella (Walsh), is a key pest attacking apple fruit in eastern and midwestern North America. Sticky-coated 8-cm spheres baited with fruit odor (butyl hexanoate) have been the mainstay of a behavioral approach to direct maggot fly control. Improvements upon the red sphere trapping system are needed, however, if it is to be feasible and cost-effective for widespread commercial use. Several aspects of visual and odor stimuli influencing apple maggot fly captures on sticky red spheres were investigated. Results indicated that the efficacy of spheres in capturing adults was not improved by increasing sphere size to a diameter greater than that of 8-cm or by using more synthetic fruit odor (butyl hexanoate). Significant improvement was attained by using synthetic food odor (ammonium carbonate) together with butyl hexanoate. Distance (15-60 cm) of a butyl hexanoate source from a red sphere had no significant effect on fly captures. Semi-natural (field cage) conditions were used to examine response patterns of females to red spheres in relation to fly age and prior ovipositional experience. As fly age increased from a reproductively immature stage to a mature stage, the probability of a fly finding a sphere hung in a host tree increased. Simultaneously, the likelihood that a fly would deposit eggs in host fruit before encountering a sphere increased. Prior experience with different species or cultivars of host fruit did not have significant effect on the ability of flies to find red spheres but reduced the likelihood of oviposition in unfamiliar fruit. Prior experience with the same species or cultivar of host fruit had no apparent effect on fly ability to find a red sphere trap or to oviposit in familiar fruit. Various feeding stimulants, pesticides, and residue-extending agents were evaluated in laboratory and field cage experiments for suitability in developing a nonsticky lethal sphere. Spheres treated with a mixture containing 1.05% (a.i.) dimethoate (insecticide), 58.95% corn syrup (feeding stimulant) and 40% latex paint (residue extending agent) and not exposed to weather killed a great majority of alighting flies. However, these spheres became ineffective after exposure to weather (rainfall). Retreating weather-exposed spheres with feeding stimulant restored effectiveness. Studies conducted in commercial orchards showed that pesticide-treated spheres, like the sticky spheres, had much potential for eliminating insecticide sprays against the flies. Current necessity of retreating pesticide-treated spheres with feeding stimulant after each rainfall compromises present utility for commercial use. Development of a polymer to protect residual effectiveness of feeding stimulant is key to further widespread commercial use of this simpler behavioral approach to controlling apple maggot flies.

Flying insects can use volatile attractants to find food, mates, and oviposition sites. To gain understanding of the behavioral mechanisms involved, three questions were studied: how do insects find attractants, how do they maintain contact with attractants once found, and how are attractants used to locate resources that emitted the attractants. The study focused on the role of two senses, vision and olfaction. Chapter 1 presents the current knowledge of odor-mediated flight, the methods of study, and a general outline of the studies presented in later chapters. In Chapter 2 the precision of an existing measurement system for flight behavior is compared with a system developed as part of this dissertation. This new system can reconstruct flight in three dimensions. Chapter 3 proposes a novel approach to the description of flight behavior using a set of mutually exclusive and collectively exhaustive maneuvers obtained with cluster analysis of measurements derived from flight tracks. Responses to changes of the floor pattern by the parasitoid Microplitis croceipes and the gypsy moth Lymantria dispar are compared in Chapter 4 to further the understanding of the role of vision during odor-mediated upwind flight. Chapter 5 described how flight of M. croceipes is affected by increases in wind velocity. Studies presented in Chapter 6 with tagged L. dispar show in greater detail than was possible before, how this moth species controls direction of flight in increasing winds. In Chapter 7 a test of a model for responses to shifting winds to optimize plume location is presented, using flight responses of two species of food-deprived fruitflies, Drosophila funebris and D. immigrans. The effect of changes in contrast of the floor and removal of the host-odor plume on flights of M. croceipes measured in 3-D are presented in Chapter 8. Chapter 9 demonstrates that M. croceipes uses transverse chemotaxis to maintain contact with a host-odor plume.

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