AbstractScientists trying to find biological controls for insect pests are hamperedd by the absence of rapid methods for screening organisms such as bacteria for potential pathogenicity. An organism must grow in the gut of the insect to be pathogenic. By using radioisotopes as tracers a quick method of screening potential insect pathogens may be developed.Escherichia coli and Sarcina flava were used as known nonpathogens and Bacillus thuringiensis was used as a known pathogen. In this work an attempt was made to verify the presence of bacteria in specific tissues of the insects.European corn borer larvae were fed 1-C14 palmitic acid and labeled E. coli, S. flava and B. thuringiensis. Parasaggital sections were made of the corn borers and radioautograms were made of the sections. Grain counts over a 2,000 u2 area were made of various tissues and compared.There was a statistically significant difference in the distribution of label in corn borer larvae fed labeled bacteria as compared to corn borers fed 1-C14 palmitic acid. Label tended to incorporate into fatty tissue in the corn borers.If this technique can be used to positively demonstrate the establishment of selected bacteria in the gut of the insect then it may be possible to use such methods to screen for potential insect pathogens and give insight into the mechanisms which result in the death of insects.Ball State UniversityMuncie, IN 47306

Climate change is a major threat to global biodiversity, and will alter species ranges, plant and animal phenology, and species interactions within ecosystems. Climate mediates plant-insect interactions, and consequently has the potential for positive or negative effects on biological control systems. Observational evidence suggests that a recent dramatic reduction in the density of diffuse knapweed, Centaurea diffusa Lamarck, in sites in British Columbia, Canada is attributed to the biological agent Larinus minutus Gyllenhal (Coleoptera: Curculionidae). This decline took place over several years of late spring and summer drought which suggested an association between dry conditions and successful biological control. To explore this, I conducted field experiments using rain shelters and watering treatments to assess the effectiveness of plant attack by L. minutus under moist and dry conditions. I found that L. minutus reduced seed production regardless of moisture conditions, with a trend towards greater seed reduction under dry conditions. Two or more species of insects in the same genera have been introduced in some weed biocontrol programs. If the species are ecological equivalents and compete the introduction of both species may be detrimental and reduce their impacts. If however the species vary in their distributions, the introduction of congeners may be advantageous. I review the following cases of species pair releases: the beetles Chrysolina quadrigemina (Suffrian) and Chrysolina hyperici (Forster) for St. John’s wort (Hypericum perforatum L.); the gallflies Urophora affinis Frfld. and Urophora quadrifasciata (Meig.) for Centaurea species; the weevils Neochetina bruchi Hustache and Neochetina eichhorniae Warner for water hyacinth (Eichhornia crassipes (Mart.) Solms.) and the beetles Galerucella pusilla Duftschmidt and Galerucella calmariensis L. for purple loosestrife (Lythrum salicaria L.). I found that congeneric agents can offer complementary control of target weeds in slightly different habitats. Given the increasing focus on possible non-target effects of biological control introductions, I recommend that greater care be taken to avoid mixed species introductions and that judicious use be made of controlled field experimentation to determine species impacts. Molecular studies of species before introduction could help prevent the accidental introduction of multiple species.

S'avaluaren 58 soques de Pseudomonas fluorescens i Pantoea agglomerans per la seva eficàcia en el biocontrol de la malaltia causada per l'oomicet Phytophthora cactorum en maduixera i pel nematode formador de gal·les Meloidogyne javanica en el portaempelt GF-677.Es desenvolupà un mètode ex vivo d'inoculació de fulla amb l'objectiu de seleccionar soques bacterianes com a agents de control biològic de P. cactorum en maduixera. Tres soques de P. fluorescens es seleccionaren com a soques eficaces en el biocontrol del patogen en fulles i en la reducció de la malaltia en plantes de maduixera. La combinació de soques semblà millorar la consistència del biocontrol en comparació amb les soques aplicades individualment.Tres soques de P. fluorescens es seleccionaren per la seva eficàcia en la reducció de la infecció de M. javanica en portaempelts GF-677. La combinació d'aquestes soques no incrementà l'eficàcia del biocontrol, però semblà reduir la seva variabilitat. / 58 Pseudomonas fluorescens and Pantoea agglomerans strains were evaluated for their biocontrol efficacy against the oomycete Phytophthora cactorum in strawberry and the root-knot nematode Meloidogyne javanica in GF-677 rootstocks.An ex vivo detached leaf inoculation method was developed to select bacterial strains as biological control agents of P. cactorum in strawberry. Three P. fluorescens strains were selected as effective in biocontrol of the pathogens on leaves and in disease reduction in strawberry plants. Combination of strains improved biocontrol consistency compared to strains applied individually. Three P. fluorescens strains were selected for their efficacy in M. javanica infection reduction in GF-677 rootstocks. Combination of these strains did not increase biocontrol efficacy, but reduced its variability.

Solenopsis invicta, the red imported fire ant, has recently become associated with Antonina graminis, an invasive pest, and Neodusmetia sangwani, biological control agent, and maybe negatively affecting established biological control. A preliminary survey outlined the range of A. graminis and its parasitoids, and found N. sangwani was present at a reduced rate in South Texas and in the southeastern United States. A greenhouse experiment demonstrated that S. invicta decreased the rate of parasitism of A. graminis by N. sangwani, with S. invicta directly interfering with oviposition. Interactions between S. invicta and A. gaminis may be facilitating the spread and establishment of two invasive pests which has a negative impact on established classical biological control of A. graminis by N. sangwani.

Diorhabda elongata elongata leaf beetles were released at two field locations in the upper Colorado River watershed of Texas in 2003 and 2004 for the biological control of invasive Tamarix, exotic trees deteriorating riparian ecosystems of western North America. Establishment and biological success were monitored using trees on transects from the release points. D. elongata elongata released at the Lake Thomas site in August 2003 successfully overwintered and were recovered in the spring 2004; however, beetles were not present after June 2004. The April 2004 release at Beals Creek led to establishment and survival during 2005 and 2006. Mean abundance increased from less than five insects per tree per 2 minute count in August 2004 to more than 40 insects per tree per 2 minute count in August 2006. By then the population was dispersed throughout an area of approximately 12 hectares and beetles were present on 100% of the 47 trees surveyed, 57% of which were at least 90% defoliated. To measure the impact of beetle defoliation on Tamarix, nonstructural carbohydrates (NCHOs) were measured in manipulative field cage experiments in Texas and natural experiments in Nevada. There was no significant difference in NCHOs between trees with versus trees without beetle herbivory in the cage experiment, although spring foliage regrowth was reduced by 35% in trees defoliated the previous fall. In Nevada, root crown tissue was sampled in 2005 and 2006 from trees that had experienced 0-4 years of defoliation. In 2005, NCHO concentrations differed between tree stands and ranged from 9.0 ± 0.8% (Mean ± SE) in non-defoliated trees to 3.2 ± 0.4%, 2.1 ± 0.4% and 2.3 ± 0.4% in trees defoliated for 1, 2 and 3 successive years, respectively. NCHO concentrations in 2006 were similar, ranging from 13.6 ± 0.9% in non-defoliated trees to 7.6 ± 0.8%, 2.3 ± 0.4%, 1.5 ± 0.3% and 1.7 ± 0.4% in trees defoliated for 1, 2, 3 and 4 years, respectively. The establishment, biological success and host impact of D. elongata leaf beetles suggest there is potential for biological control of Tamarix in the United States.

The first objective of this study was to investigate the role of an invasive grass species, Arundo donax (L.), on the hydrologic cycle. At a site on the Rio Grande in South Texas, we measured the gas exchange of carbon dioxide and water vapor at the leaf scale and structural characteristics, such as leaf area and shoot density, at the stand scale. In order to assess the effect of water availability, this study was conducted along transects perpendicular to the edge of the river along a potential moisture gradient. The second objective was to quantify the effect of two herbivores, an armored scale, Rhizaspidiotus donacis (Leonardi), and a stem-galling wasp, Tetramesa romana (Walker),on the photosynthetic and transpiration rates of A. donax. Leaf gas exchange measurements were made to determine the direction and magnitude of the effect on physiological processes and by what mechanisms any effects arose. Stands of A. donax used approximately 9.1 � 1.1 mm of water per day. This rate of water use was at the high end of the spectrum for plants. The major controls on stand scale transpiration were evaporative demand, leaf area index, and water availability. During two summer seasons, stand scale transpiration varied greatly, following the pattern of variability in precipitation, suggesting that recent rainfall constituted a significant proportion of the water taken up by this species. Herbivory by a stem-galling wasp and a sap-feeding scale, both separately and together, reduced the rates of leaf scale physiological processes in A. donax. The efficacy of the wasp was density dependent, and this herbivore reduced the carboxylation rate of Rubisco. The effect of the scale took approximately five months to manifest, which coincided with generation time. Scale reduced photosynthesis by decreasing the maximum rate of electron transport. When the two insects were both present, the effect of their herbivory seemed to be additive. These results will assist the responsible management agencies in evaluating the propriety of using one or both of the insect herbivores as biological control agents.

This work covers stages one through seven (of nine stages) of a classical biological control program for Mediterranean fruit fly (=medfly), Ceratitis capitata (Wiedemann). Major research objectives concentrate on stage five (exploration and collection of natural enemies), and stage seven (testing and selecting natural enemies for additional work). Coffee was collected monthly from three locations in Kenya from November 1997 through July 1999. Four species of tephritid flies and ten parasitoid species were recovered. Four guilds of parasitoids were recorded, and two egg-prepupal endoparasitoids, Fopius caudatus (Szépligeti) and F. ceratitivorus (Wharton), were discovered. The oviposition behavior of these two species is contrasted. Domination of this tropical parasitoid assemblage by koinobionts is discussed relative to the dominance of temperate fruit-infesting tephritid systems by idiobionts. Fruit handling procedures were examined for impact on overall percent emergence and specifically percent emergence of flies versus parasitoids. It was determined that stirring samples had a significant positive effect on overall emergence, however daily misting of fruit did not. The only treatment without a significant bias in fly emergence over parasitoids was the stirred/dry treatment. Effects of these results on rearing procedures are discussed. Host specificity and host suitability of parasitoids reared from coffee were examined via: (1) association of parasitoids with host flies based on characteristics of the fly puparia from which parasitoids emerged, (2) rearing of cucurbit infesting tephritids and their parasitoids in Kenya, (3) rearing of flowerhead infesting tephritids and their parasitoids in Kenya and Hawaii, and (4) host range testing of Psyttalia species in Kenya and Hawaii. These results are discussed in terms of their utility for predicting nontarget effects. Psyttalia concolor (Szépligeti) was shipped to Hawaii and tested against the nontarget gall forming tephritid Procecidochares utilis Stone introduced to control the weed Ageretina adenophora (Maui pamakani). Psyttalia concolor failed to attack the gall-forming P. utilis both in choice and no-choice tests, but readily attacked tephritid larvae offered in fruit in choice tests. Recommendations for further testing and release of the parasitoids from Kenya are discussed for Hawaii and Latin America.

Multiple Pseudacteon phorid fly species, including P. tricuspis and P. curvatus, have been released in the southern United States beginning in 1997 and 2003 (respectively) to serve as biological control agents against red imported fire ants Solenopsis invicta Buren (hereafter referred to as RIFA). Field research in the United States on phorid/RIFA interactions has addressed establishment and spread of released species. Additionally, studies are needed on phorid biology and ecology with respect to spatial distribution and phenology, phorid/habitat associations and phorid-mediated affects on RIFA foraging patterns. A suite of manipulative laboratory and field experiments/observations were conducted to 1) develop a novel phorid sampling device to provide uniform and repeatable sampling of flies, 2) assess spatial distributions and phenology of Pseudacteon tricuspis and P. curvatus, 3) assess P. tricuspis and P. curvatus habitat associations and 4) assess phorid-mediated affects on RIFA foraging patterns and caste ratios. PTS Traps (developed for this research) are significantly more effective than previous sampling methods in terms of mean number of flies collected, efficiency of use and % trap success. Data collected with these traps allowed for the determination of patterns of species-specific phenology and relative densities through time and speciesspecific numerical/spatial superiority (Chapter IV). P. curvatus was significantly more abundant than P. tricuspis in only one of the habitat types sampled (df (160) = 4.57, P < 0.005). P. tricuspis densities did not differ significantly among habitat type. Llaboratory experiments revealed that phorid-exposed RIFA colonies foraged less intensively diurnally (df = 1,558; P < 0.05) and more intensively nocturnally (df = 778; P < 0.05) relative to control colonies. Field data regarding this compensatory nocturnal foraging shift did not corroborate those of the laboratory work. In the field there was no significant difference in foraging intensity during nocturnal (df (18) = -0.486, P = 0.633) and diurnal (df (18) = 1.375 P = 0.186) sampling periods. Lastly, chi-square analysis of RIFA forager size-classes revealed significant differences between phorid-infested (treatment) and phorid-free (control) sites (X 2 = 6811.85, df = 3, P < 0.05) with a significantly greater proportion of small RIFA foragers at the phorid-infested site.

A three-year field experiment was conducted to evaluate the tolerance and compensatory response of rice (Oryza sativa L.) to injury caused by the sugarcane borer, Diatraea saccharalis (F.). Two mechanisms of within-plant tolerance/compensation were observed. Stem injured plants produced ca. 0.69 more tillers than uninjured plants, while tillers with leaf and leaf sheath injury produced larger panicles, up to 39.5% and 21.0% heavier than uninjured tillers, when injury occurred at 3rd tiller stage and at panicle differentiation, respectively. A 2-year field cage experiment was conducted to determine the biological control potential of Cotesia flavipes (Cameron) against the sugarcane borer on rice. The effective search rate was 49 cm2 ground area (2.2 tillers) parasitoid-1 day-1. A cohortbased age-structured model was developed to simulate the population dynamics and economic value of the sugarcane borer and C. flavipes in rice, as affected by overwintering larval density, timing and rate of parasitoid aerial release, and year-to-year climate (temperature and rainfall). The results suggest C. flavipes was most effective when released during the 1st sugarcane borer generation. The maximum simulated economic benefit ($112.05 ha-1) was ca. 7.8% of that provided by insecticide-based control. The inability of C. flavipes to provide economic control in temperate-subtropical areas is due to its high rearing cost, a low effective search rate, a low maximum rate of parasitism per female, and both spatial and temporal asynchrony of parasitoid emergence with the larval hosts. The biocontrol capability of Trichogramma galloi Zucchi was also simulated. The maximum economic benefit provided by T. galloi was $1128.75 ha-1, ca. 79.0% of that provided by insecticide-based control. Theoretical analyses were conducted to estimate the effectiveness of augmentative releases, using data from previous studies of parasitism of lepidopteran pests by hymenopteran parasitoids with host and parasitoid density as factors. The maximum daily parasitism per female was highest for parasitoids that attack exposed larvae, followed by parasitoids that attack eggs, semi-exposed larvae, and concealed larvae. Simulation analyses were conducted to estimate the population dynamics and economic value of D. saccharalis, herein used as a model host, and each of 5 parasitoid categories (solitary parasitoids that attack eggs, exposed larvae, and semi-exposed larvae, gregarious parasitoids that attack eggs and concealed larvae) in rice, as affected by overwintering larval density, timing of parasitoid release, and year-to-year climate. Among the 13,500 simulations that were conducted, 480 (3.6%) provided a greater economic value than insecticide-based control. All 480 simulations were obtained using solitary parasitoids that attack exposed or semi-exposed larvae. Solitary egg parasitoids provided an average of 42.2% of the economic value provided by insecticide-based control when released 30 days after planting. Gregarious parasitoids that attack eggs or concealed larvae provided almost no positive economic benefit. For parasitoid species that do not overwinter successfully in areas where they are released or that exhibit temporal or spatial asynchrony with their host early in the spring, our results suggest augmentative biological control is only effective for solitary parasitoids that attack either exposed or semi-exposed larvae, with current rearing, shipping and release costs.

Sphingolipids are a complex family of molecules that participate in many aspects of cell structure and function, including an essential cellular process known as autophagy. Autophagy is a degradation and recycling pathway whereby intracellular components are sequestered into double-membrane vesicles, known as autophagosomes, for subsequent fusion with lysosomes and degradation. Autophagy takes part in cell survival, host immune defense against pathogens, and other biological processes, but is also sometimes lethal. Ceramide, sphingosine 1-phosphate, and more recently dihydroceramide have been shown to induce autophagy, which opens an interesting new field of cell regulation by sphingolipids. This dissertation describes two new cases in which sphingolipids participate in the induction of autophagy: a) RAW264.7 cells treated with Kdo2-Lipid A, a lipopolysaccharide sub-structure with endotoxin activity equal to LPS; and b) MCF7 cells treated with fenretinde, a chemotherapeutic agent which has shown success in clinical trials. It also analyzes the structural properties of fenretinide that contribute to its ability to modulate sphingolipid metabolism through inhibition of dihydroceramide desaturase, thereby elevating dihydroceramide and induction of autophagy. Autophagy was monitored by following the redistribution of GFP-LC3 into discrete punctate vesicles in response to the agents and by Western blotting; in parallel, the sphingolipid composition of the cells was monitored by liquid chromatography, electrospray ionization tandem mass spectrometry. These analyses revealed that Kdo2-Lipid A and fenretinide induce profound changes in sphingolipid metabolism in RAW264.7 and MCF7 cells, respectively, and that one of the purposes for increased de novo biosynthesis is to enable the production of autophagosomes, as the autophagic response was inhibited by myriocin. These studies have uncovered a direct link between sphingolipid metabolism and autophagy, which could pave the way for new therapeutic interventions for the treatment of pathogenic infection and be clinically useful in enhancing the efficacy of current cancer treatment strategies.