First laboratory evaluation of Gryon gonikopalense (Hymenoptera: Scelionidae) as potential biological control agent of Bagrada hilaris (Hemiptera: Pentatomidae)

Authors: MARTEL, GUILLAUME - EUROPEAN BIOLOGICAL CONTROL LABORATORY (EBCL); AUGE, MATTHEW - BBCA-ONLUS, ITALY; TALAMAS, ELIJAH - FLORIDA DEPARTMENT OF AGRICULTURE; ROCHE, MARIE - EUROPEAN BIOLOGICAL CONTROL LABORATORY (EBCL); SMITH, LINCOLN; SFORZA, RENE - EUROPEAN BIOLOGICAL CONTROL LABORATORY (EBCL)

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2019
Publication Date: 4/25/2019
Citation: Martel, G., Auge, M., Talamas, E., Roche, M., Smith, L., Sforza, R. 2019. First laboratory evaluation of Gryon gonikopalense (Hymenoptera: Scelionidae) as potential biological control agent of Bagrada hilaris (Hemiptera: Pentatomidae). Biological Control. 135:48-56. https://doi.org/10.1016/j.biocontrol.2019.04.014.
DOI: https://doi.org/10.1016/j.biocontrol.2019.04.014

Interpretive Summary: Bagrada bug or painted bug is reported as a major pest of cole crops in its native range of eastern and southern Africa and the Indian subcontinent. In 2008, it was first reported in California, where it now attacks a wide range of Brassicaceae crops, including cabbage, broccoli, and radish. The bug has spread to New Mexico, Mexico, Hawaii, and Chile. Yield losses reached 25% in Arizona on crucifer crops and up to 70% on Indian mustard crops.To date, no efficient monitoring tools exist to long-term manage Bagrada bug populations in North America. The massive economic loss and the lack of alternative control practices, led U.S. growers to use broad-spectrum insecticides to reduce local pest populations. As new insecticides have been shown to be less effective on crucifer crops, a program on classical biological control based on foreign exploration in the native range has been initiated in 2015. Several parasitoid wasps of Bagrada were collected in Pakistan are now under investigation at USDA-ARS-EBCL. The aim of the present study was first to clarify the species status of the egg parasitoid, which is now Gryon gonilopalense and to understand its reproductive and developmental biology in the frame of a Classical biocontrol program for California and beyond in southern U.S. states. We studied life history traits of this egg parasitoid that develop in 25 days inside Bagrada eggs in the EBCL quarantine. They can also live up to 2 months and females may produce nearly 60 progenies during their entire life. The final purpose of the present study will be to gather sufficient datasets for working on a petition to release this parasitoid against Bagrada in western USA.

Technical Abstract: The pentatomid bug Bagrada hilaris is a severe invasive pest of Brassicaceae crops which first appeared in California in 2008 and has spread into several southern U.S. states and Mexico. To answer the demand of organic growers for sustainable management methods, a biological control program started in 2015. The egg parasitoid Gryon gonikopalense Sharma was collected in Pakistan and is being evaluated as a candidate for classical biological control against B. hilaris. Basic life history studies were performed in climatic chambers (22 ± 0.5°C, RH 50 ± 5 %, L/D 12:12). On average, Gryon gonikopalense developed in 25.07 ± 1.44 days and adult females lived up to 120 days. Allowing females to oviposit reduced their lifespan by 52%, and food deprivation reduced it by 87%. During their life, females produced 59.23 offspring on average with maximum fecundity during the first week of their life. Mean progeny sex ratio was 46.26% female. Live host eggs from 1 to 4 days old were suitable for parasitoid oviposition, but eggs stored at -80°C were not. Hence, the parasitoid could attack a wide range of hosts in the field but cold storage of bagrada eggs for later use in rearing or as sentinel eggs in the field is not recommended. These data provide a foundation for designing host specificity tests to help determine whether G. gonikopalense is suitable to use as a biocontrol agent of Bagrada hilaris