An Herbivore-Induced Plant Volatile From Saltcedar (Tamarix spp.) Is Repellent to Diorhabda carinulata (Coleoptera: Chrysomelidae)

Alexander M Gaffke; Sharlene E Sing; Jocelyn G Millar; Tom L Dudley; Daniel W Bean; Robert K D Peterson; David K Weaver

doi:10.1093/ee/nvaa079

An Herbivore-Induced Plant Volatile From Saltcedar (Tamarix spp.) Is Repellent to Diorhabda carinulata (Coleoptera: Chrysomelidae)

Environ Entomol. 2020 Oct 17;49(5):1063-1070. doi: 10.1093/ee/nvaa079.

Authors

Alexander M Gaffke^{1

2}, Sharlene E Sing³, Jocelyn G Millar⁴, Tom L Dudley⁵, Daniel W Bean⁶, Robert K D Peterson¹, David K Weaver¹

Affiliations

¹ Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT.
² Agricultural Research Service, Department of Agriculture, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL.
³ USDA Forest Service, Rocky Mountain Research Station, Bozeman, MT.
⁴ Department of Entomology, University of California, Riverside, CA.
⁵ Marine Science Institute, University of California, Santa Barbara, CA.
⁶ Colorado Department of Agriculture, Palisade Insectary, Palisade, CO.

PMID: 32725136
DOI: 10.1093/ee/nvaa079

Abstract

The leaf beetle Diorhabda carinulata Desbrochers (Coleoptera: Chrysomelidae) was introduced into the United States in 1999 for classical biological control of the exotic woody invader saltcedar (Tamarix spp. L. [Caryophyllales: Tamaricaceae]). The recent southern expansion of the range of D. carinulata in the United States has precipitated conflict between proponents of biological control of Tamarix and those with concerns over habitat conservation for avian species. Several semiochemicals that mediate aggregations by this species have been reported, but no repellent compounds have been recorded thus far. We now report a repellent compound, 4-oxo-(E)-2-hexenal, induced by adult D. carinulata feeding on saltcedar foliage. Collection of headspace volatiles, gas chromatography mass spectrometry, and electroantennographic analyses identified 4-oxo-(E)-2-hexenal as an insect-induced compound that is antennally active. Behavioral and exposure assays were conducted to test for repellency and toxicity in adults and larvae. Headspace volatiles were also collected from adult males exposed to 4-oxo-(E)-2-hexenal to determine the impact exposure might have on the emission of the aggregation pheromone. 4-Oxo-(E)-2-hexenal elicited electrophysiological responses in adults of both sexes. Behavioral responses indicated repellency across multiple doses for reproductive D. carinulata adults but not in nonreproductive adults. Exposure assays indicated altered behaviors in first instar larvae and adults, but not in third instar larvae. Collection of headspace volatiles indicated that exposure to 4-oxo-(E)-2-hexenal did not alter emission of the D. carinulata aggregation pheromone by adult males. The continued development and field deployment of this repellent compound may provide a new tool for the management of D. carinulata.

Keywords: Tamarix; olfactometer; biological control; chrysomelidae; coleoptera.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Animals
Coleoptera*
Female
Herbivory
Larva
Male
Pheromones / pharmacology
Tamaricaceae*

Substances

Pheromones