Biology and life history of Tetrastichus planipennisi (Hymenoptera: Eulophidae), a larval endoparasitoid of the emerald ash borer (Coleoptera: Buprestidae)

Authors: Duan, Jian; Oppel, Craig; ULYSHEN, MICHAEL - Michigan State University; BAUER, LEAH - Us Forest Service (FS); LELITO, JONATHAN - Animal And Plant Health Inspection Service (APHIS)

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2011
Publication Date: 12/1/2011
Citation: Duan, J.J., Oppel, C.B., Ulyshen, M., Bauer, L., Lelito, J. 2011. Biology and life history of Tetrastichus planipennisi (Hymenoptera: Eulophidae), a larval endoparasitoid of the emerald ash borer (Coleoptera: Buprestidae). Florida Entomologist. 94(4):933-940.

Interpretive Summary: The parasitic wasp, Tetrastichus planipennisi, is one of the natural enemies that were recently introduced for biological control of the emerald ash borer (EAB), a serious invasive pest that has destroyed millions of ash trees in the U.S. This wasp attacks grubs (larval stage) of the EAB, which feed on the phloem tissues of ash trees under the bark. In this study, we investigated the biology and life history of this parasitic wasp and its potential for biological control of EAB. The female wasp lays multiple eggs inside the body of EAB larvae, and the hatched wasp larvae grow inside the hosts for approximately a week, and then consumes the entire body of beetle grub and live freely (outside the body of beetle grub) for another three weeks before turning into adults. In the laboratory, this wasp took approximately four weeks to complete its life cycle (from eggs to adults). Female wasps lived over eight weeks, and were able to attack beetle grubs immediately following emergence. Each female wasp was able to produce an average of 57 offsprings throughout her life span. Because of the long life span and egg-laying period of adults, this wasp is likely to have multiple overlapping generations in North America, and has great potential to be an effective natural enemy for controlling EAB.

Technical Abstract: Tetrastichus planipennisi (Hymenoptera:Eulophidae) is a gregarious larval endoparasitoid from China that is being released in North America in an effort to control the emerald ash borer (Agrilus planipennis Fairmaire), an exotic beetle responsible for widespread ash mortality. The developmental time of immature stages, adult longevity, reproductive age, oviposition rate, and realized fecundity were determined in the laboratory under normal rearing conditions (25±2°C, 65±10% RH, and L:D 16:8 hr photoperiod). Tetrastichus planipennisi takes approximately four weeks to complete a single generation (from egg to adult) under normal rearing conditions. While male T.planipennisi lived for a median of 5 weeks (95% CI 4 to 6 weeks), females lived significantly longer with a median survival time of 6 weeks (95% CI 6 to 8 weeks) and a maximum survival time of 9 weeks. Newly emerged females appeared to be as capable of producing progeny as older females, indicating that T. planipennisi is not synovigenic. The average number of progeny per reproductive female remained relatively constant through the first 6 weeks of the trial with each reproductively active female producing 23 - 26 progeny each week. All females stopped producing progeny eight weeks after emergence. Lifetime realized fecundity of the adults averaged 57 progeny per reproductively active female; the maximum number of progeny produced by a single female was 108. These results suggest that T. planipennisi may have several generations in the mid-Atlantic and Midwestern regions of United States, where normal growing seasons (with average temperature >25oC) are normally four to five months (May – September). Because of the gregarious nature, long life span and oviposition period of adults, T. planipennisi is likely to have multiple overlapping generations and has the potential to be an effective biocontrol agent against EAB.