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

Abstract

The pentatomid bug Bagrada hilaris is a severe invasive alien pest of Brassicaceae crops, which first appeared in California in 2008 and is expanding to several southern U.S. states and South America. To answer the demand of growers for sustainable management methods, a biological control program started in 2015. The egg parasitoid Gryon gonikopalense Sharma was collected in Pakistan, and after morphological identification here described, 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 25.1 ± 1.4 (mean ± sd) days and live 66.4 ± 30.7 days. Allowing females to oviposit reduced their lifespan by 52%, and food deprivation reduced it by 87%. During their life, females produced 59.2 ± 22.3 offspring on average with a maximum fecundity during the first week of their life. Mean progeny sex ratio was 46.3% 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 bagrada eggs for most of their development in the field but storage of bagrada eggs at very low temperature for later use in rearing or as sentinel eggs in the field is not recommended. These data provide a baseline for designing host specificity tests to help determine whether G. gonikopalense is suitable to use as a biocontrol agent of Bagrada hilaris.