LeBow College of Business
College of Arts & Sciences
DO FREQUENCIES OF BACTERIAL SYMBIONTS IN PEA APHIDS VARY WITH PARASITISM RATES?
Steven G. Doll Biological Sciences
Dr. Jacob Russell Faculty Mentor Biology
Andrew Smith Graduate Student Mentor
20
The pea aphid, Acyrthosiphon pisum, harbors several facultative bacterial endosymbionts. One of these endosymbionts, Hamiltonella defensa, is of particular interest due to its capacity to defend pea aphids against the parasitoid wasp Aphidius ervi. This study seeks to determine the relationship amongst symbiont frequency and the prevalence of parasites. We sampled several alfalfa and clover ields in southeastern Pennsylvania and central New York for A. pisum and its natural enemies once every three weeks beginning in May, 2011. Aphids collected in the ield were either immediately stored in ethanol and screened for the presence of endosymbionts in the laboratory or brought back to the laboratory to determine rates of successful A. ervarasitism. We predict that H. defensa frequencies should vary according to wasp  densities. There is an apparent cost of infection in the absence of parasitism, and so we predict that H. defensa frequencies should vary in relation to wasp density. Our current indings indicate a low frequency of H. defensa within pea aphids collected from alfalfa in New York on the irst sampling date in early May. Pea aphids collected from alfalfa in Pennsylvania on the same sampling date had a higher frequency of H. defensa and a substantial parasitism rate. Temperature may be an important factor in determining aphid resistance to parasitism. As such, future analyses will examine the relationship between temperatures recorded in the sample ields and any seasonal changes in symbiont frequency, helping to further elucidate the relationships amongst A. pisum, its natural enemies, and H. defensa.
STAR Scholars Summer Showcase 2011
R&D POLICIES FOR SMES: A CROSS-COUNTRY ANALYSIS
Given its overarching reach, and provided with the right stimulus, small and medium�sized enterprises (SMEs) could provide a very valuable social bene it. In the European Union, SMEs are seen as the drivers for economic recovery and growth. The systemic de iciencies with small irms such as unavailability of easy credit, paucity of infrastructure and susceptibility to losses have prompted governments to devote special policies to SMEs. I compared the approaches of the United States and the EU in aiding small enterprises and the impetus given to the development of R&D. I studied the most ef icient methods of effusing the subsidies to small irms and the indirect effects that the aforementioned subsidies have on the market. Since the target audience for such policies number is in the tens of millions, there is an element of populism involved with the governments. In this positive analysis, using my indings, I have evaluated the merits and demerits of subsidizing SMEs.
STAR Scholars Summer Showcase 2011
Ananth Bevinahally Economics
Dr. Christopher Laincz Faculty Mentor Economics
101