Biological-insecticidal integration for managing Pangaeus bilineatus (Hemiptera: Cydnidae) and aflatoxin risk in peanuts

Pangaeus bilineatus (Hemiptera: Cydnidae), a subterranean pest of economic importance, contributes to preharvest yield losses and facilitates aflatoxin contamination in peanuts, particularly in Georgia. With the increasing restrictions on the use of chlorpyrifos in crop pest management, there is a critical need for sustainable alternatives. This study evaluated the efficacy of field applications of two entomopathogenic nematodes (EPNs)—Steinernema carpocapsae (All strain; Sc) and Heterorhabditis bacteriophora (Oswego strain; Hb), or in combination with imidacloprid (Im) and chlorpyrifos (Ch) for managing P. bilineatus. Field trials were conducted from June to November 2024 using the Georgia-06G peanut cultivar. Integrated EPN-chemical treatments significantly increased P. bilineatus mortality (95.3–100% at 14 days after treatment) compared to individual treatments (p < 0.05). The Hb+Im ½ field rate (FR) treatment yielded the highest number of sound mature pods (125.8 ± 7.6 per plant) and the lowest aflatoxin levels (0.1 ± 0.0 ppb) compared to the untreated control (104.0 ± 6.4 pods; 1.0 ± 0.8 ppb). Combinations such as Sc+Ch ⅛FR and Hb+Im ½FR also significantly reduced insect-damaged kernels (0.9–1.2%) relative to individual treatments (1.1–3.0%) and the untreated control (3.2%). Discolored or moldy kernels were minimized in integrated treatments (< 7.8%) compared to the control (≥12.2%). These results demonstrate that EPN-insecticide combinations offer synergistic pest suppression, improved crop quality, and reduced aflatoxin risk, even at sublethal insecticide rates. This integrated approach represents a promising and environmentally sound alternative to conventional chemical control. Future research should optimize application strategies and evaluate economic feasibility for broader adoption.