|WATT, TIMOTHY - University Of Delaware|
|LARSON, KRISTI - University Of Delaware|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/17/2014
Publication Date: 6/1/2014
Citation: Duan, J.J., Watt, T., Larson, K. 2014. Biology, life history and laboratory rearing of Spathius galinae (Hymenoptera: Braconidae), a larval parasitoid of the invasive Emerald Ash Borer (Coleoptera: Buprestidae). Journal of Economic Entomology. 107:936-946.
Interpretive Summary: Understanding the biology and life history of insect natural enemies (predators and parasitoids) is critical to the development of effective biological control programs against agricultural and forest arthropod pests. The parasitic wasp (Spathius galinae) is a newly discovered natural enemy of the invasive emerald ash borer (Agrilus plannipennis) that has killed tens of millions of North American ash trees since it was discovered in 2002 in US. This natural enemy has been recently imported to the US and is being considered for introduction to the US for biological control of the invasive emerald ash borer. However, little is known about the biology, life history and possible laboratory rearing method of this newly discovered emerald ash borer natural enemy. Using emerald ash borer larvae reared with freshly cut ash (Fraxinus spp.) sticks, we characterized the developmental time and stages of this parasitic wasp in the laboratory under normal rearing conditions. Our study showed that this wasp took approximately one month to complete a single generation (from egg to adult) under laboratory rearing conditions. Results from our study showed that this wasp could be effectively reared with emerald ash borer larvae reared in both green (F. pennsylvanica) and tropical [F. uhdei] ash sticks. This information is useful to the development of effective rearing programs for mass production of this parasitic wasp for biological control of emerald ash borers in the US.
Technical Abstract: Spathius galinae Belokobylskij & Strazajac is a recently described parasitoid of the emerald ash borer, Agrilus plannipennis Fairmaire, in the Russian Far East, and is currently being considered for biocontrol introduction in the US. Using A. planipennis larvae reared with freshly cut ash (Fraxinus spp.) sticks, we characterized the developmental time and stages of immature S. galinae in the laboratory under normal rearing conditions (25 ± 1°C, 65 ±10 %RH, L:D16:8 hr photoperiod) . Our study showed that S. galinae took approximately one month (29 days) to complete a single generation (from egg to adult) under the laboratory rearing condition. After eclosion from eggs, larvae of S. galinae molted four times to reach 5th instar, which then spun cocoons for pupation and development to adults. Adult female wasps had a median survival time of 7 weeks with the fecundity peaking in three weeks after emergence when reared in groups (of five females and five males) and two weeks in single pairs. Throughout the life span, a single female S. galinae produced a mean of 31 (± 3.0) progeny when reared in groups, and a mean of 47 (± 5.3) progeny when reared in single pairs. Results from our study also showed that S. galinae could be effectively reared with A. planipennis larvae reared in both green (F. pennsylvanica Marshall) and tropical [F. uhdei (Wenzig) Lingelsh] ash sticks. However, the abortion (unemergence) rate of S. galinae progeny was much higher (20%) when reared with host larvae in green ash sticks than that (2.1%) in tropical ash sticks.