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ARS Home » Southeast Area » Stoneville, Mississippi » Southern Insect Management Research » Research » Publications at this Location » Publication #424263
Research Project: Insect Control and Resistance Management in Corn, Cotton, Sorghum, Soybean, and Sweet Potato, and Alternative Approaches to Tarnished Plant Bug Control in the Southern United States

Location: Southern Insect Management Research

Title: Laboratory and Greenhouse Assessments of Steinernema carpocapsae With Three Adjuvants on Chrysodeixis Includens

Author
item Zhang, Minling
item Spaulding, Nathan
item Reddy, Gadi
item Shapiro Ilan, David

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/4/2025
Publication Date: 9/16/2025
Citation: Zhang, M., Spaulding, N.R., Reddy, G.V., Shapiro Ilan, D.I. 2025. Laboratory and Greenhouse Assessments of Steinernema carpocapsae With Three Adjuvants on Chrysodeixis Includens. Journal of Nematology. 57(1):1-11. https://doi.org/10.2478/jofnem-2025-0034.
DOI: https://doi.org/10.2478/jofnem-2025-0034

Interpretive Summary: The soybean looper is a significant pest of row crops, usually controlled with chemical insecticides. Due to environmental and regulatory concerns, alternative solutions are necessary. Entomopathogenic nematodes (EPNs), or beneficial nematodes, offer a safe, environmentally friendly alternative. This experiment compared the efficacy of EPNs with three adjuvant treatments (0.125% dish soap, 0.125% dish soap with 0.25% vegetable oil, and 0.066% Southern Ag Surfactant) against soybean looper larvae under laboratory and greenhouse conditions. Laboratory data collected 24 hours post-exposure indicated that adjuvant treatments could potentially shorten the lethal time of EPNs. Greenhouse results showed that adjuvants could enhance EPN efficacy on soybean looper larvae, varying with temperature and relative humidity. Dish soap combined with vegetable oil treatments resulted in the highest number of viable EPNs most of the time.

Technical Abstract: Chrysodeixis includens (Lepidoptera: Noctuidae) is a significant crop pest in the southern United States. Resistance to many insecticides necessitates alternative control measures. Entomopathogenic nematodes (EPNs) offer a potential solution, but their aboveground efficacy may be limited by desiccation and UV radiation. This study tested the efficacy of S. carpocapsae with three adjuvant treatments (0.125% dish soap, 0.125% dish soap with 0.25% vegetable oil, and 0.066% Southern Ag Surfactant) on C. includens larvae under laboratory and greenhouse conditions. In the lab, insect mortality 72 hours post-application was significantly higher in EPN treatments with soap and oil at 1 and 4 hours and with soap alone at 4 hours, compared to EPNs alone. No significant differences were observed at 8 and 24 hours. However, 24-hour post-application data showed higher mortality for EPNs with adjuvants at 8 hours and for soap and oil at 4 and 24 hours, suggesting that adjuvants shorten the time needed for EPNs to kill larvae. In the greenhouse, adjuvants did not increase mortality in the first trial (10-32°C, 74-90% RH), but did in the second trial (22-39°C, 44-95% RH). In the third trial (22-38°C, 32-83% RH), only the soap and oil treatment increased mortality. Additionally, soap and oil treatments resulted in the highest number of viable EPNs across the trials, though this difference lacked statistical support. Overall, adjuvants enhanced the efficacy of S. carpocapsae on C. includens larvae.