Preliminary study of pear ester toxicity when consumed by Polistes dominula (Hymenoptera: Vespidae)

Authors: ASCHE, MEGAN - Animal And Plant Health Inspection Service (APHIS); LANDOLT, PETER - Former ARS Employee; Cooper, William - Rodney; SHEPPARD, WALTER - Washington State University; ZACK, RICHARD - Washington State University

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/9/2023
Publication Date: 12/30/2023
Citation: Asche, M., Landolt, P., Cooper, W.R., Sheppard, W.S., Zack, R.S. 2023. Preliminary study of pear ester toxicity when consumed by Polistes dominula (Hymenoptera: Vespidae). Florida Entomologist. 106(4);205-210. https://doi.org/10.1653/024.106.0401.
DOI: https://doi.org/10.1653/024.106.0401

Interpretive Summary: European paper wasp is an invasive species now found throughout the United States. This wasp species displaces native species of paper wasps and is a danger to workers and homeowners, yet very few products have been developed for its control. Researchers at Washington State University and USDA-ARS in Wapato, WA found that the plant-based chemical, pear ester, kills paper wasp adults when they drink solutions with this chemical. This is the first report that pear ester causes insect mortality, and could lead to new management tools for this invasive insect.

Technical Abstract: The European paper wasp, Polistes dominula (Christ) (Hymenoptera: Vespidae), directly competes with native Polistes and is a safety concern for workers and homeowners. A previous investigation of Polistes behavior found that a portion of wasps died after consuming a solution of pear ester, a compound commonly found in fruits that is considered non-toxic to humans. The goal of our study was to corroborate those preliminary observations and investigate the toxicity of pear ester to P. dominula. Two experiments were performed. First, three wasp castes were fed 17% sugar water, or sugar water mixed with 0.5%, 1%, 5%, or 10% (w/v) solutions of pear ester. Mortality rates after 24 hours ranged from 0% among wasps fed sugar water only, to >10% among wasps that were fed pear ester. Mortality rates increased logarithmically with pear ester concentration. Pear ester toxicity differed among wasp castes, with <5% mortality recorded among fall gynes to >10% mortality among workers. The second experiment attempted to define the relationship between morbidity and volume of pear ester consumed by P. dominula workers. Although results confirmed that ingestion of pear ester causes death or paralysis of P. dominula workers, there was no clear relationship between volume of ingested pear ester and wasp morbidity. About 80% of P. dominula were unaffected by pear ester despite consuming large quantities of the solution. This is the first study to show that ingestion of pear ester by an insect causes paralysis or death.