Developing semiochemical repellents for protecting Picea from Dendroctonus rufipennis (Coleoptera: Curculionidae) in Alaska and Utah, USA

Jackson P Audley ¹, Christopher J Fettig ¹, Jason E Moan ²

⁰Pacific Southwest Research Station, USDA Forest Service, 1731 Research Park Drive, Davis, CA 95618, USA.

Journal of Economic Entomology +

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April 22, 2024

View abstract on PubMed

Summary

Spruce beetles are a major threat to western North American spruce trees. Researchers found that combining anti-aggregation pheromones with repellents effectively protected trees from beetle attacks and mortality.

Area Of Science

Forest Entomology
Chemical Ecology
Pest Management

Background

The spruce beetle (Dendroctonus rufipennis) is a significant pest of mature spruce (Picea) in western North America.
Recent outbreaks underscore the urgent need for effective protection strategies against D. rufipennis.
Semiochemicals, including pheromones and repellents, offer a promising avenue for managing spruce beetle populations.

Purpose Of The Study

To evaluate the efficacy of the primary anti-aggregation pheromone (3-methylcyclohex-2-en-1-one, MCH) and various repellent combinations in disrupting D. rufipennis attraction.
To assess the effectiveness of these semiochemical treatments in protecting Lutz spruce (Picea × lutzii) in Alaska and Engelmann spruce (Picea engelmannii) in Utah from spruce beetle colonization and mortality.

Main Methods

Two field assays were conducted in Alaska using attractant-baited multiple-funnel traps treated with MCH and other potential repellents.
Tree protection studies involved baiting experimental trees with frontalin and applying repellent treatments, including SPLAT MCH combined with other semiochemicals.
Colonization (strip and mass attacks) and mortality rates were measured for treated and control trees in both Alaska and Utah.

Main Results

All tested repellent treatments significantly reduced the number of D. rufipennis caught in traps compared to controls.
In Alaska, all treatments significantly reduced spruce beetle colonization and mortality in treated trees and surrounding Picea.
In Utah, most treatments reduced colonization, with SPLAT MCH + Acer kairomone blend (AKB) and SPLAT MCH + acetophenone and green leaf volatiles (PLUS) showing the highest effectiveness in reducing both colonization and mortality across studies.

Conclusions

Semiochemical-based repellents, particularly combinations involving MCH, are effective in disrupting spruce beetle attraction and protecting spruce trees.
SPLAT MCH combined with AKB or PLUS demonstrated significant efficacy in reducing spruce beetle colonization and mortality in both study locations.
These findings support the development of integrated pest management strategies utilizing semiochemical repellents for large-scale spruce beetle control.

Keywords:

Picea engelmannii Picea × lutzii 3-methylcyclohex-2-en-1-one spruce beetle tree protection