Efficacy of the newly discovered entomopathogenic nematode Steinernema adamsi against Helicoverpa zea: life stage susceptibility, UV tolerance, and field performance

Journal of Nematology

Volume 57 (2025): Issue 1 (February 2025)

By:

James Paul Glover, Nathan Spaulding, Justin George, Maribel Portilla, Gadi V.P. Reddy and Adler Dillman

Open Access

|Apr 2025

Figures & Tables

Stages of S. adamsi Infection in H. zea Larvae. (A) Second instar Helicoverpa zea larva showing a positive infection of Steinernema adamsi through the anus. (B) Fourth instar H. zea larva with a large EPN mat covering most of its body, indicating advanced nematode infection. The upper right inset image shows a H. zea larva with a severe infection of the head capsule by S. adamsi.

Application of Alginate/Congo Red Encapsulated S. adamsi Nematodes on H. zea larvae in Cotton Blooms. (A) Three-day-old Helicoverpa zea larva inside a cotton bloom, demonstrating infestation conditions. (B) Detailed view of an alginate/Congo red treatment droplet applied to the dorsal surface of the larva. (C) Magnified image showing encapsulated Steinernema adamsi nematodes within the alginate/Congo red droplet.

Mortality (% ± SEM) of 2nd instars of Helicoverpa. zea caused by Steinernema adamsi exposed to ultraviolet radiation in the laboratory (27°C, 75% RH).
Means with different letters are significantly different via Tukey’s HSD test after a significant ANOVA, p = 0.05). — Mortality (% ± SEM) of 2nd instars of Helicoverpa. zea caused by Steinernema adamsi exposed to ultraviolet radiation in the laboratory (27°C, 75% RH). Means with different letters are significantly different via Tukey’s HSD test after a significant ANOVA, p = 0.05).

Effect of Steinernema adamsi formulations from field experiments A and B on 1st instars of Helicoverpa zea in cotton (2024, Leland, Mississippi). Field experiment A (Initial efficacy test) was conducted on August 29, 2024, with an average 33°C, 62%RH and under full sun (9495/29) (U.V. AB/C) using water as the carrier agent at 10 IJs/cm2. Field experiment B (Encapsulation and UV degradation test) was conducted on September 4, 2024, with an average 34°C, 55%RH, and full sun (9289/33) (U.V. AB/C) using alginate (0.05%, w/v) and Congo red (0.02%, w/v) formulations at 50 IJs/cm2.
Means with different letters are significantly different via Tukey’s HSD test after a significant ANOVA, p = 0.05). — Effect of Steinernema adamsi formulations from field experiments A and B on 1st instars of Helicoverpa zea in cotton (2024, Leland, Mississippi). Field experiment A (Initial efficacy test) was conducted on August 29, 2024, with an average 33°C, 62%RH and under full sun (9495/29) (U.V. AB/C) using water as the carrier agent at 10 IJs/cm2. Field experiment B (Encapsulation and UV degradation test) was conducted on September 4, 2024, with an average 34°C, 55%RH, and full sun (9289/33) (U.V. AB/C) using alginate (0.05%, w/v) and Congo red (0.02%, w/v) formulations at 50 IJs/cm2. Means with different letters are significantly different via Tukey’s HSD test after a significant ANOVA, p = 0.05).

Mortality (% ± SEM) of 2nd instars of Helicoverpa_ zea caused by Steinernema adamsi mutualistic bacteria Xenorhabdus hemocoel injections and oral toxicity in the laboratory (27°C, 75% RH)_

Exposure method	% Mortality ± SEM
Hemocoel injections Water	5^th instar
	100^a
	0^b
	F_{(1, 4)} = 69.45
	P < 0.0001
Oral toxicity Water	2^nd instar
	35.93 ± 1.5^a
	2.83 ± 0.87^b
	F_{(1, 4)} = 35.04
	P < 0.0274

Mortality (% ± SEM) of 1st-5th instars, and pupae of Helicoverpa_ zea caused by Steinernema adamsi entomopathogenic nematode strain in the laboratory (27°C, 75% RH)_ Mean values within a column followed by the same letter are not significantly different at P < 0_05 (Tukey’s HSD test)_

EP^N strain	H. zea

	1^st instar	2^nd instar	3^rd instar	4^th instar	5^th instars	Pupae
S. adamsi	75.83 ± 4.7^a	74.21 ± 1.6^a	79.16 ± 2.3^a	100^b10 ± 1.2^d	36.66 ± 3.6^c	0^d
Water	0^d	0^d	0^d		0^d	0^d
F-Value_{(1, 7)}	353.76	62.57	166.20	1019.97	87.96	-
P-Value	<.0001	<.0002	0.0001	<.0001	<.0001	-

DOI: https://doi.org/10.2478/jofnem-2025-0012 | Journal eISSN: 2640-396X | Journal ISSN: 0022-300X

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Language: English

Submitted on: Nov 12, 2024

Published on: Apr 24, 2025

Published by: Society of Nematologists, Inc.

In partnership with: Paradigm Publishing Services

Publication frequency: 1 times per year

Keywords:

IPM,

entomopathogenic nematode,

Related subjects:

© 2025 James Paul Glover, Nathan Spaulding, Justin George, Maribel Portilla, Gadi V.P. Reddy, Adler Dillman, published by Society of Nematologists, Inc.
This work is licensed under the Creative Commons Attribution 4.0 License.

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Efficacy of the newly discovered entomopathogenic nematode Steinernema adamsi against Helicoverpa zea: life stage susceptibility, UV tolerance, and field performance

Figures & Tables

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Mortality (% ± SEM) of 2nd instars of Helicoverpa_ zea caused by Steinernema adamsi mutualistic bacteria Xenorhabdus hemocoel injections and oral toxicity in the laboratory (27°C, 75% RH)_

Mortality (% ± SEM) of 1st-5th instars, and pupae of Helicoverpa_ zea caused by Steinernema adamsi entomopathogenic nematode strain in the laboratory (27°C, 75% RH)_ Mean values within a column followed by the same letter are not significantly different at P < 0_05 (Tukey’s HSD test)_

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