Chestnut species and jasmonic acid treatment influence development and community interactions of galls produced by the Asian chestnut gall wasp, Dryocosmus kuriphilus

William R. Cooper1,2a and Lynne K. Rieske1b*

1University of Kentucky, Department of Entomology, S-225 Ag North, Lexington KY 40546-0091
2Current address: USDA–ARS, 17053 North Shafter Ave, Shafter, CA 93263

Abstract

Jasmonic acid (JA) is a plant–signaling hormone involved in defenses against insects and pathogens as well as the regulation of nutrient partitioning. Gall wasps (Hymenoptera: Cynipidae) induce the formation of galls on their host plants, which house immature wasps and provide them with nutrition and protection. The goal of this study was to investigate the effects of JA application on gall development and defenses. Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae) galls on American chestnut, Castanea dentata (Marsh.) Borkhausen (Fagales: Fagaceae), and Chinese chestnut, C. mollissima Blume, were treated with JA or a JAinhibitor, diethyldithiocarbamic acid (DIECA), to determine the effects of these treatments on gall characteristics and defenses. Chinese chestnut galls treated with JA had greater volume and dry weight, thicker sclerenchyma layers, and fewer external fungal lesions compared with controls. Galls from both chestnut species treated with JA contained a lower proportion of empty chambers, and elevated tannin levels compared with controls. The effects of DIECA on galls were generally opposite from those of JA. American chestnut galls treated with DIECA had lower dry weight and fewer feeding punctures caused by the lesser chestnut weevil compared with controls. Galls from both chestnut species that were treated with DIECA were smaller and had more external fungal lesions compared with controls. Compared to American chestnut galls, Chinese chestnut galls had increased parasitism rates and fewer gall wasps. This study is the first to investigate the effects of JA on an insect gall, and indicates that JA treatments benefit gall wasps by increasing gall size and defenses.

Keywords: chestnut blight, Cynipidae, endophyte, lesser chestnut weevil, plant signaling compounds, Torymus

Abbreviations: JA, jasmonic acid; DIECA, diethyldithiocarbamic acid

Correspondence: a rodney.cooper@ars.usda.gov, b lrieske@uky.edu, *Corresponding author

Editor: Nadir Erbilgin was Editor of this paper.

Received: 17 December 2010 | Accepted: 22 February 2011 | Published: 20 October 2011

ISSN: 1536-2442 | Volume 11, Number 140

Cooper WR, Rieske LK. 2011. Chestnut species and jasmonic acid treatment influence development and community interactions of galls produced by the Asian chestnut gall wasp, Dryocosmus kuriphilus. Journal of Insect Science 11:140 available online: insectscience.org/11.140