Canadian Forest Service Publications

Lethal and sublethal effects of topical tebufenozide application to Choristoneura fumiferana pupae  (Lepidoptera: Tortricidae). 2020. Roscoe, L.E.; Forbes, G.; Lamb, R.; and Silk, P.J. Insects 11 (3).

Year: 2020

Issued by: Atlantic Forestry Centre

Catalog ID: 40542

Language: English

Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.3390/insects11030184

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Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae) is a defoliating pest in Canada and the northeastern United States. Given its important ecological and economic effects in affected regions, several direct management techniques have been developed, including the application of the insect growth regulator tebufenozide (Mimic™, RH-5992) to feeding larval stages. While the effectiveness of tebufenozide, in this capacity, is understood, management programs of other lepidopteran pests have demonstrated the effectiveness of tebufenozide application when utilized against other life stages. Here, we investigated the toxicity of topically-applied tebufenozide to C. fumiferana pupae to determine if such a strategy could be feasible. We observed significant dose-dependent decreases in the likelihood of adult emergence, increases in the likelihood of pupal death or adult deformity at eclosion, and significant decreases in mean adult longevity. Estimated LD 50 (lethal dose) values for adult male and female C. fumiferana treated as pupae ≤ 4 days after pupation were approximately 1–3 and 2–3.5% ACI (active commercial ingredient) respectively. Estimated L-SD (lethal-sublethal) 50 doses for adult male and female C. fumiferana treated as pupae ≤4 days after pupation were

Plain Language Summary

Among the most useful control methods for the defoliating pest spruce budworm is tebufenozide. Tebufenozide is an insect growth regulator that, when ingested, stimulates abnormal and fatal moutling in the target insect. While it’s effectiveness as an ingested compound has been demonstrated, it’s potential as a contact bioinsecticide is yet to be known. Some similar compounds have been used in such a way, providing an important addition to the use of insect growth regulators against pest insects. Here, we analyzed the toxicity of tebufenozide when topically applied to spruce budworm pupa. While we were able to ascertain lethal and sublethal (ie. Negative effect on weight, and adult attributes) dose amounts far exceeded those associated with ingestion. While this precludes the use of tebufenozide here as a topical bioinsectide, our work provides an important example of the potential for existing technologies to be used effectively outside of their original designs.