Host utilization, reproductive biology and development of the larval parasitoid Tetrastichus planipennisi as influenced by temperature: implications for biological control of the emerald ash borer in North America

Authors: Duan, Jian; Schmude, Jonathan; WATT, TIMOTHY - Dow Agro Sciences; WANG, XIAO-YI - Chinese Academy Of Forestry; BAUER, LEAH - Us Forest Service (FS)

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2018
Publication Date: 6/26/2018
Citation: Duan, J.J., Schmude, J.M., Watt, T., Wang, X., Bauer, L.S. 2018. Host utilization, reproductive biology and development of the larval parasitoid Tetrastichus planipennisi as influenced by temperature: implications for biological control of the emerald ash borer in North America. Biological Control. 125:50–56. https://doi.org/10.1016/j.biocontrol.2018.06.009.
DOI: https://doi.org/10.1016/j.biocontrol.2018.06.009

Interpretive Summary: A parasitic wasp (Tetrastichus planipennisi) is an important natural enemy of the invasive emerald ash borer (EAB) that has killed tens of millions of North American ash trees since it was discovered in the United States in 2002. This natural enemy was introduced to the United States for biological control of EAB beginning in 2007. To optimize the field-release strategy and methods for mass-rearing of this natural enemy, ARS researchers and cooperators from Chinese Academy of Forestry and U.S. Forest Service determined the effects of ambient temperatures ranging from 15°C to 35°C on the natural enemy's attack rate, development, adult longevity, and reproduction on EAB. Results showed the wasp’s development time was reduced when reared at warmer rather than cooler temperatures, but their longevity declined until all wasps died at 35°C. Attack rates of EAB by the wasp increased at the warmer temperatures. Combining these results with temperature data from USDA climate zones 2 – 7 in the United States, we predicted that T. planipennisi can complete multiple generations in all the locations in these climatic zones, with more generations in warmer climates.

Technical Abstract: Classical biological control programs depend in part on understanding climate effects on introduced agents. Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae), a larval parasitoid of emerald ash borer (EAB), Agrilus planipennis Fairmare (Coleoptera: Buprestidae) in the pest’s native Asian range, was recently introduced to EAB-invaded regions in the United States and Canada for biological control. To optimize regional release strategies and increase efficiency of the parasitoid-rearing program, we determined the effects of five constant temperatures from 15°C to 35°C on T. planipennisi parasitism rate, development, adult longevity, and fecundity on EAB. Results showed a decrease in parasitoid development time from 133 days at 15°C to 26 days at 30°C, while parasitoid eggs died at 35°C. Parasitism rates by females provisioned with host larvae throughout their life increased from 1.4% at 15°C to 28% at 30°C then declined to <0.4% at 35°C. Adult parasitoid longevity declined from 24 weeks at 15°C to 2 weeks at 35°C. Fertility table analyses revealed T. planipennisi’s net reproductive rate was the highest at 25°C, and intrinsic and finite rates of increase were highest at 30°C, suggesting 25 – 30°C as optimal rearing temperatures for this parasitoid. Combining these results with temperature data from USDA climate zones 2 – 7 in the United States, we predicted T. planipennisi can complete multiple generations in all the locations in these climatic zones, with more generations in warmer climates.