Insect-Human Connection

Pierce’s disease (PD) costs an estimated $104.4 million annually to growers and consumers 1. As the most significant vector of PD, control of the glassy-winged sharpshooter (Homalodisca vitripennis) is the top priority of control programs 1. PD posses a significant threat to the wine grape industry, uncontrolled the disease leads to complete
vineyard decline 1. As such PD is an existential threat to the industry on the level of grape phylloxera, a pest so devastating that it required the replanting of most of the world’s vineyards 2.

A number of methods to control the GWSS are being actively studied; among these include biological control (parasitoids, predators, pathogens), the use of PD resistant rootstocks, insecticides, and cultural control (scouting and removing infected vines) 1. Programs within grapevine nurseries have been established to ensure that genetic material is free of PD, this helps in preventing spread to new areas 1. The introduction of the several wasp parasitoid species following the discovery of the GWSS in California has provided up to 90% mortality of GWSS eggs, providing a benefit that precludes the use of insecticides 1. The parasitic wasp Gonatocerus triguttatus is the most common enemy of the GWSS, introduction of this species has proven successful in controlling the GWSS 4.

Biological and cultural controls are the most successful control of the GWSS at the moment. Promising research conducted at UC Berkeley has focused on inoculating vines with the endophytic bacteria Paraburkholderia phytofirmans as a means to provide protection against PD5 . The presence of this bacteria within mature grape vines inhibits the growth of Xyllela fastidiosa 5. Additionally, the development of PD resistant rootstocks derived from Vitis arizonica promise to provide long term security from the looming threat of PD 3.


  1. Glassy-winged Sharpshooter management guidelines–UC IPM. [accessed
    2023 Jul 31].
  2. Danoff-Burg JA. Invasion biology introduced species summary project – Columbia
    university. [accessed 2023 Jul 31].
  3. There’s finally hope that California grapevines can be saved from Pierce’s disease. Global Plant Protection News. 2021 Aug 13 [accessed 2023 Aug 28].
  4. California Department of Food, Agriculture. GWSS biological control agents. [accessed 2023 Aug 28].
  5. Baccari C, Antonova E, Lindow S. Biological control of Pierce’s disease of grape by an endophytic bacterium. Phytopathology. 2019;109(2):248–256. doi:10.1094/phyto-07-18-0245-fi
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