Author ORCID Identifier:
Date of Graduation
5-2026
Document Type
Thesis
Degree Name
Master of Science in Entomology (MS)
Degree Level
Graduate
Department
Entomology
Advisor/Mentor
Kariyat, Rupesh
Committee Member
Gibson, Kristen
Second Committee Member
Dickson, Ryan
Keywords
integrated pest management (IPM); biochar; pests; insects; hydroponic lettuce production
Abstract
Insect pests remain one of the most significant biotic threats in agriculture, causing significant economic loss across different production systems. This challenge is intensified due to rise of insecticide resistance among major pest species, diminishing the effectiveness of conventional chemical control. Clearly, there is an urgent need to developing sustainable alternatives within integrated pest management (IPM). As production systems transition toward reduced reliance on chemical pesticides, new biorational strategies are getting increasingly important. Biochar, a carbon rich product of biomass pyrolysis has gained attention for its agronomic benefits, yet its potential as a pest management tool remains under explored, particularly within soilless controlled environment agriculture (CEA) systems such as hydroponics. This thesis examined whether biochar can serve as a sustainable IPM tool to manage a lepidopteran chewing and a hemipteran sap feeding pest, which are prevalent in conventional and soilless production systems respectively. In the first study, we explored post ingestion effects of walnut derived biochar through artificial lepidopteran diet, on the growth and development success of fall armyworm (FAW; Spodoptera frugiperda). The caterpillars that fed on biochar amended artificial diet were found to have significantly reduced larval mass, pupal volume, pupal mass and impaired adult morphology. These findings provide direct evidence that biochar has adverse effects on herbivore fitness through ingestion mediate mechanisms. The second part of the thesis focused on extending the application of biochar to control sap feeding pests in hydroponic lettuce production. Here, we tested the efficacy of pine-derived liquid biochar as a substrate amendment against the green peach aphid (GPA; Myzus persicae), a major sap feeding pest in CEA systems. Through optimization experiments, we found that 5% biochar sub-irrigation treatment enhanced early seedling vigor of lettuce while significantly reducing aphid population growth and host preference. Through this study we developed an optimization protocol for biochar use in hydroponic systems via substrate amendment, and we demonstrated the strong concentration dependent effects of biochar on both plant performance and pest suppression. Collectively, these results offer empirical evidence of biochar’s potential beyond conventional soil amendment properties and lays essential groundwork for future exploration of biochar-based pest management strategies within controlled environment agriculture. This is also important, because biochar is derived from recycled agricultural residues and its use not only mitigates waste but also transforms it into a value-added product with pest management benefits. This circular resource approach has the potential to enhance long term system sustainability while contributing to safer and more efficient food production.
Citation
Unnikrishnan, S. (2026). Evaluating the Potential of Biochar to Manage Chewing and Sap Feeding Insect Pests. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/6167
