Preliminary Study of Pear Ester Toxicity When Consumed by Polistes dominula (Hymenoptera: Vespidae)

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, 3 wasp castes were fed 17% sugar water, or sugar water mixed with 0.5%, 1.0%, 5.0%, or 10.0% (w/v) solutions of pear ester. Mortality after 24 h ranged from 0% among wasps fed sugar water only, to >10% among wasps that were fed pear ester. Mortality increased logarithmically with pear ester concentration. Pear ester toxicity differed among wasp castes, with 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 demonstrate lethal effects of pear ester compound and may indicate its potential as an insecticide for paper wasps. La avispa cartonera europea, Polistes dominula (Christ) (Hymenoptera: Vespidae), compite directamente con las Polistes nativas y, además, es una preocupación de seguridad para trabajadores y familias en sus casas. Una investigación previa sobre el comportamiento de Polistes, encontró que algunas de las avispas morían después de consumir una solución de éster de pera, un compuesto comúnmente encontrado en frutas y que no es considerado tóxica para humanos. El objetivo de nuestro estudio fue corroborar esas observaciones preliminares e investigar la toxicidad del éster de pera para P. dominula. Se realizaron 2 experimentos. Primero, 3 castas de avispas fueron alimentadas con soluciones de 17% agua azucarada, o agua mezclada con 0.5%, 1.0%, 5.0% y 10.0% (p/v) con éster de pera. La mortalidad después de 24 horas varió desde 0% entre avispas alimentadas solamente con agua azucarada, a >10% entre avispas a las cuáles se les dio éster de pera