Biology and behavior of Spathius agrili, a parasitoid of the emerald ash borer, Agrilus planipennis, in China
1The Key Laboratory of Forest Protection, State Forestry Administration of China, Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China
2Animal and Plant Health Inspection Service, United States Department of Agriculture, 1398 West Truck Road, Buzzards Bay, MA 02542, USA
3Forest Health Technology Enterprise Team, USDA Forest Service, 180 Canfield St., Morgantown, WV 26505, USA
4Guangang Forest Park, Dagang District, Tianjin 300270, China
Abstract
Spathius agrili Yang (Hymenoptera: Braconidae) is a gregarious larval ectoparasitoid of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) and is a recently described species. Both pest and parasitoid are native to China. In Tianjin City, China, S. agrili typically exhibited 3-4 generations per year, overwintering as a prepupa in a cocoon inside the host gallery. The multiple generations of S. agrili overlapped with its host, as did the emergence dates of the overwintering generation. From a single host, 1-18 S. agrili successfully developed to the adult stage (average 8.4), but in all cases the host was killed. The sex ratio (female: male) of the parasitoid adults emerging from field-collected cocoons was 2:1, whereas the sex ratio of parasitoids reared from field collected eggs and larvae was greater than 3:1. On average, adult females lived 29.1 d, and males lived 23.6 d when fed with 20% honey solution, significantly longer than without a nutritional supplement. Sexual reproduction is the normal mode of reproduction, but in the laboratory females did reproduce parthenogenetically, producing only males. The average fecundity was 23.3 eggs per female in the laboratory. S. agrili developed through five larval instars, and the larvae fed gregariously on the host hemolymph. The generation time from egg to adult wasp was 27-28 d at 22-26°C. Natural parasitism rates were as high as 60%, and in October they reached over 90% in some stands. This study showed that S. agrili is a promising agent for biocontrol of A. planipennis.
Keywords: Braconidae, Fraxinus, life cycle
Correspondence: ayzhqi@caf.ac.cn
Received: 7 December 2008 | Accepted: 3 February 2009 | Published: 6 April 2010
Copyright: This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.
ISSN: 1536-2442 | Volume 10, Number 30
Yang ZQ, Wang XY, Gould JR, Reardon RC, Zhang YN, Liu GJ, Liu ES. 2010. Biology and behavior of Spathius agrili, a parasitoid of the emerald ash borer, Agrilus planipennis, in China. 13pp. Journal of Insect Science 10:30, available online: insectscience.org/10.30
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