No description available.

Armored scale insects have long been known to harbor endosymbionts, but until recently the endosymbionts have remained unidentified. Using DNA data I have identified the primary endosymbiont as a bacterium from the phylum Bacteriodetes. To accomplish this, I amplified DNA sequences from two genes of the endosymbiont and use these sequences (16S and 23S, 2105 total base pairs), along with previously published sequences from the armored scale hosts (elongation factor 1α and 28S rDNA) to investigate phylogenetic congruence between the two clades. The Bayesian tree for the bacteria is roughly congruent with that of the hosts, with 67% of nodes identical. The high level of congruence between the topologies indicates that these Bacteroidetes are the primary endosymbionts of armored scale insects. To investigate the phylogenetic affinities of these endosymbionts, I aligned some of their 16S rDNA sequences with other known Bacteroidetes endosymbionts and with other similar sequences identified by BLAST searches. I found these endosymbionts to be closely related to bacteria associated with eriococcid and margarodid scale insects, and enodosymbionts of cockroaches and auchenorrynchan insects, and proposed the name " Candidatus Uzinura diaspidicola" for the primary endosymbionts of armored scale insects. I have also investigated secondary endosymbionts found in the armored scale insect species Aspidiotus nerii. A host manipulating endosymbiont similar to Wolbachia, Cardinium was found in Aspidiotus nerii and there is circumstantial evidence that Cardinium is responsible for inducing parthenogenesis in Aspidiotus nerii. Using PCR and sequencing of 16S rDNA, we have tested 593 individuals and obtained positive PCR results in 67 individuals of 34 populations representing 20. A phylogenetic analysis including all known insect-associated Cardinium 16S sequences shows patterns of horizontal transmission of this endosymbiont among insects. Lastly, I tested molecular evolution rates of Uninura from sexual and parthenogenetic populations of Aspidiotus nerii using five loci: two host nuclear loci, one mtDNA loci, and two symbiont loci. I hypothesized that the symbionts and mitochondria would evolve at similar rates, however, though the endosymbionts are vertically transmitted and experience similar bottlenecks to the mitochondria, the data suggest that they evolve at similar or slower rates to the nuclear DNA.

The ambermarked birch leafminer (AMBLM) (Profenusa thomsoni) is an invasive leafminer native to the Palearctic from the United Kingdom to Turkey to Japan. It was introduced to the eastern United States in 1921 and has since spread to the mid-western U.S. states and Canadian provinces. This leafminer was introduced to Alaska in 1996, where it has since spread over 140,000 acres, from Haines to Fairbanks. The most severe damage is found throughout the Anchorage bowl, which extends south to Girdwood and North to Wasilla. The damage caused by P. thomsoni can be severe, defoliating entire trees. In 2006, it was noted that urban areas in Alaska experienced higher densities of AMBLM leafminer than adjacent forested areas. To examine the effects of habitat on leafminer densities, twenty permanent plots were established in Anchorage, Alaska in 2006 and were classified as urban and forest (ten each). Temperature records for the twenty permanent sites showed that average daily temperatures and average accumulated degree-days differed significantly between urban and forest sites. In 2007 and 2008, leafminer abundance in each habitat was examined weekly at six plots (three urban and three forest) within the city of Anchorage. Asynchronous emergence, flight, and oviposition times were observed between leafminers in forests versus urban areas, with peaks of these parameters in forests being about three weeks later than in urban areas. To control the spread and effects of P. thomsoni, a cooperative biological control project was launched in 2003 and the parasitoid wasp Lathrolestes thomsoni (Hymenoptera: Tenthredinidae) was selected for release. Parasitized leafminer larvae were collected from the provinces of Northwest Territories and Alberta, in Canada and transferred in soil tubs as pre-pupae to Alaska. From 2004-2008, 3636 adult L. thomsoni adults were released in birch tree stands in Anchorage, Soldotna, and Fairbanks, Alaska. Parasitoids have been recovered at all release sites in Alaska and have established populations at most release sites. Currently, AMBLM densities have declined by over 40% in the Anchorage area and the spread of the leafminer throughout the state appears to have slowed. Throughout the course of the biological control program two additional parasitoids were discovered attacking P. thomsoni in Alaska. The first, Lathrolestes soperi, an endoparasitoid with similar biology to the released parasitoid L. thomsoni, was found to attack early instar larvae within the leaf. The second species, Aptesis segnis, is an ecotoparasitoid that attacks pupae and prepupae in their earthen cells in soil. Lathrolestes soperi was found to contribute a significant proportion of mortality against the leafminer. The presence of A. segnis in the parasitoid guild raised mortality of P. thomsoni to 40.3%, showing that the percent parasitism by A. segnis was 26%, double that provided by L. soperi. This suggests that A. segnis is the dominant parasitoid in the guild. It is unknown what effect that the introduced wasp L. thomsoni will have on the presumably native L. soperi and if one species will outcompete the other over time, or both will coexist. Future work on this system is recommended in five to ten years to see if L. thomsoni and L. soperi populations remain stable or to see if one parasitoid outcompetes the other and if A. segnis maintains its dominant place in the system.

No description available.

To estimate the impact of parasitoids, one must be able to accurately measure the mortality they cause. I therefore investigated biases associated with several methods of calculating stage-specific and time-specific parasitism by Cotesia melanoscela, Parasetigena silvestris, and Brachymeria intermedia. I released laboratory-reared gypsy moths into the field to measure the timing of oviposition by parasitoids. I determined the timing of emergence of parasitoids by collecting naturally occurring gypsy moths. I also monitored the timing of host recruitment to and advancement out of the stage(s) that was susceptible to parasitism. I found that many of the methods used in previous studies of gypsy moth dynamics were affected by overlap of these processes and that several methods severely over- or underestimated parasitism. I estimated temperature-dependent development of C. melanoscela for use with the Southwood & Jepson method of calculating the number of parasitoids attacking hosts. I also studied some effects of superparasitism by P. silvestris. The dispersion of eggs of P. silvestris on gypsy moth larvae collected in the field was more aggregated when larvae were collected from under burlap bands. This resulted in lowered percentage parasitism of hosts collected in this manner. In laboratory studies, deposition of more than one egg on a single host significantly increased host mortality, but had a negative effect on survival of the immature parasitoid and the size of the puparium produced. Experimental manipulations of densities of gypsy moths revealed a strong, positive spatially density-dependent reduction in gypsy moth populations. Positive density-dependent mortality occurred during the early and mid larval stages and was primarily due to Compsilura concinnata, a polyphagous parasitoid. Oviposition by P. silvestris, an oligophagous parasitoid, was initially inversely density-dependent, but became positively density-dependent during the late larval period. I conclude that if populations of gypsy moths increase and decrease in density asynchronously on a spatial scale of a few ha, the density-dependent responses of parasitoids could suppress the populations to a point where small mammal predation would be able to prevent population increase. This phenomenon may explain the apparent stability of gypsy moth populations on a region-wide basis for the years between outbreaks.

Mature female apple maggot flies, Rhagoletis pomonella (Walsh) were released individually onto a single fruitless hawthorne tree in the center of an open field. This tree was surrounded by four 1 m$\sp2$ plywood host tree models painted green or white, with or without synthetic host fruit odor (butyl hexanoate), placed at one of several distances from the release tree. Each fly was permitted to forage freely on the release tree for up to 1 hour, or until it left the tree. Flies left the tree significantly sooner when green models with host fruit odor were present at 0.5 m, 1.5, or 2.5 m distance from the release tree than when these models were placed at a greater distance (4.5 m) from the release tree or when no models were present. These results suggest that female apple maggot flies did not detect green 1 m$\sp2$ models with odor 4.5 m away or models without odor 2.5 m or more away. Increasing model size to 2 m$\sp2$ increased the distance at which flies responded to green models without odor. Decreasing model size to 0.5 m$\sp2$ reduced fly responsiveness. The presence of host-fruit odor alone did not influence residence time on the release tree. Rate of movement and upwind orientation ($\pm$22.5$\sp\circ$) of individually-caged R. pomonella flies increased significantly over no-odor conditions in the presence of a stationary point source of butyl hexanoate at a distance of 12 m (P $\le$ 0.03) in an open grassy field, but not at 24 m. Increasing the rate of butyl hexanoate release from ca. 500 ug per hour to ca. 6000 ug per hour did not significantly increase distance of response. Take-off direction of R. pomonella from a platform in the center of a large open field was random with respect to wind direction when no host odor stimulus was present. Take-off direction was significantly biased upwind ($\pm$67.5$\sp\circ$) when 8 evenly spaced butyl hexanoate-filled vials surrounded the release platform in a circle with a radius 6 m (P $\le$.03), and downwind ($\pm$67.5$\sp\circ$) when the same number of vials encircled the platform at 12 m (P $\le$ 0.01). Similarly, take-off direction tended towards upwind when 16 evenly spaced butyl hexanoate-filled vials surrounded R. pomonella at 12 m (P $\le$ 0.10), and was significantly biased downwind at 24 m (P $\le$ 0.01).

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No description available.

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No description available.