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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #420102
Research Project: Novel Approaches for Managing Key Pests of Peach and Pecan

Location: Fruit and Tree Nut Research

Title: Persistence of the entomopathogenic nematode Steinernema feltiae in a novel capsule formulation

Author
item PERIER, JERMAINE - University Of Georgia
item WU, SHAOHUI - The Ohio State University
item ARTHURS, STEVEN - Biobee Usa
item TOEWS, MICHEAL - University Of Georgia
item Shapiro Ilan, David

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2024
Publication Date: 12/26/2024
Citation: Perier, J.D., Wu, S., Arthurs, S.P., Toews, M.D., Shapiro Ilan, D.I. 2024. Persistence of the entomopathogenic nematode Steinernema feltiae in a novel capsule formulation. Biological Control. https://doi.org/10.1016/j.biocontrol.2024.105684.
DOI: https://doi.org/10.1016/j.biocontrol.2024.105684

Interpretive Summary: Entomopathogenic nematodes are small roundworms usually found in the soil and can control insect pests naturally. Some of the insect pests that these nematodes are used against include the pecan weevil and peachtree borer. However, their persistence is dependent on several environmental conditions that may influence how long they can stay alive outside of a host. A nematode called Steinernema feltiae was used in this study because it is easily obtained and good at killing insect pests. This study tested a new capsule formulation that keeps the nematodes enclosed in oil and water and improves their chances of survival before finding a host. We compared application of nematodes in the capsule formulation to a common commercial formulation and a control (no nematodes). We also looked at the differences between burying these treatments vs. applying them on the soil surface. Experiments were carried out in the laboratory and in a pecan orchard. The capsules performed well when used as recommended by the label. Burying the capsules also improved the nematodes' persistence. This capsule formulation is a new method that may improve the use of entomopathogenic nematodes in the field.

Technical Abstract: Post-application persistence of entomopathogenic nematodes (EPNs) can vary vastly depending on environmental conditions, which affects their efficacy as biocontrol agents in the field. We evaluated the persistence of the EPN Steinernema feltiae in a novel hydrogel/emulsion capsule formulation under laboratory and field conditions. The new formulation was compared to traditional aqueous application, using the baiting method with Tenebrio molitor larvae. In the laboratory, the capsule formulation of S. feltiae ENO2 strain was compared with the aqueous application of ENO2 and SN strain at 23°C for 0, 7, 14, 21, and 28 days after treatment (DAT) in soil cups. The ENO2 capsule formulation persisted longer than ENO2 aqueous, while SN aqueous also persisted better than the ENO2 aqueous application but was not different from the ENO2 treatment. In the field, the capsule formulation (applied sub-surface) persisted longer than the aqueous application (applied on the surface) of ENO2 when applied in recommended methods; however, the formulations showed no differences when both were applied in-furrow (sub-surface) or on the soil surface. Comparing the application methods, the sub-surface application improved the persistence of capsules over the surface application while it did not affect the performance of the aqueous application. Overall, these findings suggest the novel capsule formulation could achieve improved EPN persistence but only when buried in the soil.