Synthesis of two-chromosome double interchanges in N. crassa

Synthesis of two-chromosome double interchange

Spatial and Temporal Dynamics of Predator-Prey Interactions in Winter Wheat

Aphids (Hemiptera: Aphididae) are pests of multiple cropping systems, primarily due to the viruses they vector and direct crop damage that is exacerbated by their rapid population growth. In Kentucky, grain aphids (Rhopalosiphum padi and Sitobion avenae) cause significant yield loss to winter wheat as vectors of Barley Yellow Dwarf virus (BYDV), prompting the routine application of insecticides. Coupled with increasing human populations and decreasing arable land, it is increasingly evident that biological control services provided by natural enemies represent a viable long-term management option. Aphids are preyed upon by a diverse array of predators that can be exploited in conservation biological control. I designed a field experiment to monitor dispersal into and out of wheat fields, and how these movements were affected by the surrounding habitat. Analysis revealed there are significant movements of R. padi into the wheat in the fall, and S. avenae in spring, and that these movements are slowed down by forested edges. Natural, field-bordering weed strips were used as a conservation biological technique to enhance predator populations. Results showed that while weed strips did not affect the yield of the crop, aphid abundance, or BYDV incidence, it did significantly increase the abundance of natural enemies. Dominant predators included Coccinellidae, Anthocoridae, Chrysopidae larvae, and Braconidae. Using molecular gut-content analysis, I screened multiple species of predators and found strong trophic linkages between aphids and Orius insidiosus and multiple species of coccinellids, namely Coccinella septempunctata and Coleomegilla maculata. In aphidophagous systems, intraguild predation (IGP) can interfere with the biological control potential so I also screened coccinellids for IGP using newly designed primers. To identify intraguild prey DNA in coccinellids, I designed species-specific primers for C. maculata and C. septempunctata to use in PCR-based molecular gut-content analysis. Results revealed high frequencies of IGP between coccinellids that are significantly higher in weed strip plots. However, I observed no detectable impact on aphid predation during these increased times of IGP, suggesting it does not interfere with biological control of aphids in this system. I discuss the role of weed strips in winter wheat as part of an integrative pest management strategy

Preliminary characterization of six I-IV translocations and their intercrosses

Preliminary characterization of six I-IV translocations and their intercrosse

Physiological status of male and female Popillia japonica (Coleoptera: Scarabaeidae) affects mating and grouping behavior

Because mating may be costly, sexually active males or females are predicted to be in relatively good physiological condition and may preferentially direct their mating behavior toward relatively high-quality mates. We tested this hypothesis in Japanese beetles (Popillia japonica Newman), a pest species in which males and females may be either isolated or in aggregations while feeding on host plants. We examined male size and lipid content and female size and egg load with respect to both their pairing status and whether they were isolated or in aggregations. Males that were paired had the highest lipid levels, and single, isolated males had the lowest. Paired females had the highest egg loads and single, isolated females had the lowest. Neither male nor female size was related to pairing status. Females captured during the times of relatively high pairing frequency (i.e., morning and evening) had higher egg loads than females captured at times of lower pairing frequency (i.e., afternoon). These results suggest that mating and aggregative behaviors in Japanese beetles are dependent on the physiological status of males and the reproductive condition of females

Partial Sterility in Drosophila melanogaster: Schemes for Complex Chromosome Rearrangements

These investigations are pilot studies of possible chromosome rearrangements to effect sterility in insects . Techniques of oviposition and partial sterility in Drosophila melanogaster are described. Partial sterility is measured for a number of different crossing combinations using wildtype stocks, heterozygous translocation stocks, and homozygous translocation stocks : the highest percent partial sterility occurring when F-1 intercross translocation stocks are used as one of the parents. Three different crossing schemes to gain more complex chromosome rearrangements and their outcomes are reported, though tests indicated negative results in these . Methods devised to distinguish between simple and complex translocation stocks in Drosophila are deemed important for future work in this area

Increase in fruit size of a spontaneous mutant of ‘Gala’ apple (Malus×domestica Borkh.) is facilitated by altered cell production and enhanced cell size

Fruit size regulation was studied in the apple cultivar ‘Gala’ and a large fruit size spontaneous mutant of ‘Gala’, ‘Grand Gala’ (GG). GG fruits were 15% larger in diameter and 38% heavier than ‘Gala’ fruits, largely due to an increase in size of the fruit cortex. The mutation in GG altered growth prior to fruit set and during fruit development. Prior to fruit set, the carpel/floral-tube size was enhanced in GG and was associated with higher cell number, larger cell size, and increased ploidy through endoreduplication, an altered form of the cell cycle normally absent in apple. The data suggest that the mutation in GG promotes either cell production or endoreduplication in the carpel/floral-tube cells depending on their competence for division. Ploidy was not altered in GG leaves. During fruit growth, GG fruit cells exited cell production earlier, and with a DNA content of 4C suggesting G2 arrest. Cell size was higher in GG fruits during exit from cell production and at later stages of fruit growth. Final cell diameter in GG fruit cortex cells was 15% higher than that in ‘Gala’ indicating that enhanced fruit size in GG was facilitated by increased cell size. The normal progression of cell expansion in cells arrested in G2 may account for the increase in cell size. Quantitative RT-PCR analysis indicated higher MdCDKA1 expression and reduced MdCYCA2 expression during early fruit development in GG fruits. Together, the data indicate an important role for cell expansion in regulating apple fruit size