2013 Annual Report
1a.Objectives (from AD-416):
Investigate the feasibility of using silver nanoparticles as novel microbial delivery vehicles targeting pest insects.
1b.Approach (from AD-416):
We intend to investigate the potential use of silver nanoparticles as vehicles for targeted delivery of baculoviruses in cooperation with Nanoparticle Biochem, Inc. This start-up company began in biomedicine and it has the technology to deliver silver nanoparticles to specific tissues within mammals. All silver nanoparticles are stabilized by coatings. Our goal is to create silver nanoparticles coated with baculoviruses in an attempt to stabilize them in the field. However, it is unknown whether silver nanoparticles are toxic to invertebrates over acute or long-term exposure. To address this deficiency, baseline impact of silver nanoparticle ingestion on both pest and nontarget insects will be examined over multiple generations. We will expose the pest insect, Heliothis virescens and the beneficial insect, Podisus maculiventris, to known concentrations of silver nanoparticles by incorporating the nanoparticles into the insect culture media. Based on prelimary data, the silver nanoparticles had a small impact on the pest insect, H. virescens. The same particles had very little impact on the nontarget beneficial insect, P. maculiventris. We propose to repeat these experiments to allow rigorous statistical analyses. We will also carry the experiments over several generations of each insect to determine longer term impacts of the nanoparticles. Moving beyond baseline studies, in cooperation with Nanoparticle Biochem, we intend to generate silver nanoparticles coated with baculovirus isolates. Using established feeding protocols, we will expose the pest and the beneficial insects via their culture media and will replicate all feeding experiments to allow appropriate statistical analyses. Later in this research we will use Nanoparticle Biochem, Inc., equipment to determine the fate of silver nanoparticles within infected bodies. Our approach has added value because studies of nanoparticles as environmental contaminants, termed nanotoxicology, are only beginning. A few studies have addressed nanotoxicology in aquatic environments, however, information on the impact of silver nanoparticles on terrestrial pest and beneficial insects is lacking. Aside from thorough study of silver nanoparticles as potential microbial delivery systems, this work will provide important information on the impact of these nanoparticles on terrestrial insects.
We measured the effect of ingested nanoparticles on the development of three insects; the agricultural pest moths, the budworm and cabbage looper, and a non-target generalist predator, the spined soldier bug. Four silver nanoparticles differing either in shape or charge were tested at different dosages. One nanoparticle delayed development slightly in T. ni but not in H. virescens. Pupal weights were not significantly different. Additionally, very little impact was observed in the length of development of the beneficial predator due to the nanoparticles. However, female and male predators fed two different nanoparticles had a significantly lower weight than control fed adults. One nanoparticle caused a lower than average number of eggs/laying female predator though this was not significantly lower than the control group. Overall, the nanoparticles were generally not found to be harmful at the concentrations tested in any of the insects examined. This work addresses objective 3 “In partnership with small and urban vegetable growers, develop novel beneficial insect and baculovirus delivery systems for application, using such strategies as chemical attractants, artificial diets, and release mechanisms.” The building block of information generated by this agreement will be used to test the feasibility of using nanoparticles as a completely novel vehicle to stabilize baculoviruses and deliver them to pest insects.