The implementation of systemic insecticides and increased irrigation against gall wasp and scale insect pests attacking Ficus trees in Hawaii

Authors

  • Mason Russo University of Hawaiʻi at Ma –noa, Department of Plant and Environmental Protection Sciences, College of Tropical Agriculture and Human Resources, Ma –noa, Hawaiʻi, USA
  • Matthew Kellar University of Hawaiʻi at Ma –noa, Department of Plant and Environmental Protection Sciences, College of Tropical Agriculture and Human Resources, Ma –noa, Hawaiʻi, USA
  • Zhiqiang Cheng University of Hawaiʻi at Ma –noa, Department of Plant and Environmental Protection Sciences, College of Tropical Agriculture and Human Resources, Ma –noa, Hawaiʻi, USA

Abstract

Chinese banyan, Ficus microcarpa (Rosales: Moraceae), and weeping banyan, F. benjamina (Rosales: Moraceae), are commonly planted landscape trees throughout the Hawaiian Islands. They are popular landscape trees due to their large canopy, incremental leaf drop, and minimal need for management. The unintentional introduction of invasive species including a stem gall wasp, Josephiella sp. (Hymenoptera: Agaonidae), a leaf gall wasp, Josephiella microcarpae Beardsley and Rasplus (Hymenoptera: Agaonidae), and the lobate lac scale Paratachardina pseudolobata Kondo and Gullan (Hemiptera: Kerriidae); are causing negative impacts on rural and urban landscape banyan trees throughout Oahu. The deleterious impact of feeding between these 3 pests can cause moderate to severe branch dieback, canopy reduction, early leaf drop, with severe infestations causing the death or removal of landscape trees. In 2 separate studies, the use of systemic insecticides applied via soil drench or trunk injection with or without amended irrigation was examined to determine if there was a reduction of these pests over 24 mos. In the first study, emamectin benzoate was applied to F. microcarpa targeting Josephiella spp. gall wasps and a second concurrent study assessed the impact of imidacloprid on P. pseudolobata infestations of F. benjamina. The results of these trials indicated that effective treatments can be utilized as a management tactic for reducing infestations of these invasive pests in the urban landscape ecosystems of Oahu.

 

Resumen

El banyan chino, Ficus microcarpa, y el banyan llorón, F. benjamina, son árboles de paisaje comúnmente plantados en las islas hawaianas. Son árboles de paisaje populares debido a su gran dosel, caída de hojas incremental y necesidad mínima de manejo. La introducción no intencional de especies invasoras, incluida una avispa de las agallas, Josephiella sp. (Hymenoptera: Agaonidae), una avispa de las agallas de la hoja, Josephiella microcarpae Beardsley y Rasplus (Hymenoptera: Agaonidae), y la escama lobada laca Paratachardina pseudolobata Kondo y Gullan (Hemiptera: Kerriidae); están causando impactos negativos en los árboles de higuera de Bengala del paisaje rural y urbano en todo Oahu. El impacto nocivo de la alimentación entre estas tres plagas puede causar muerte regresiva de ramas de moderada a severa, reducción del dosel, caída temprana de hojas, con infestaciones severas que causan la muerte o la eliminación de árboles de paisaje. En dos estudios separados, se examinó el uso de insecticidas sistémicos aplicados mediante empapado del suelo o inyección en el tronco con o sin riego modificado para determinar si hubo una reducción de estas plagas durante 24 meses. En el primero estudio, se aplicó benzoato de emamectina a F. microcarpa contra Josephiella spp. avispas de las agallas y un segundo estudio simultáneo evaluó el impacto de imidacloprid en las infestaciones de P. pseudolobata de F. benjamina. Los resultados de estos ensayos indicaron que se pueden utilizar tratamientos efectivos como una táctica de manejo para reducir las infestaciones de estas plagas invasoras en los ecosistemas del paisaje urbano de Oahu.

Key Words: lobate lac scale; gall wasps; integrated pest management; ornamental horticulture; ornamental entomology; landscape pests

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Author Biography

Zhiqiang Cheng, University of Hawaiʻi at Ma –noa, Department of Plant and Environmental Protection Sciences, College of Tropical Agriculture and Human Resources, Ma –noa, Hawaiʻi, USA

Assistant Extension Specialist/Professor (Turfgrass and Landscape Pest Management) Dept. of Plant and Environmental Protection Sciences, CTAHR University of Hawaii at Manoa

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Published

2023-12-27

Issue

Vol. 106, No. 4 (December 2023)

Section

Research Papers

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