Intercontinental comparisons of invasive spotted lanternfly egg mass densities and mortality patterns

Abstract

Spotted lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoridae), is an invasive species of planthopper native to China. Populations of this invasive insect have been detected in South Korea (2006), Japan (2009), and the United States (2014). Widespread economic damage to fruit crops has been reported from South Korea and the United States, primarily in grape vineyards. In Japan, no accounts of agricultural injury have been reported despite this species maintaining established populations in the country for over 15 years. To quantify intercontinental differences in egg mass demographics, egg mass densities and nymph hatching rates were compared in China, where Ly. delicatula is native and coexists with the associated egg parasitoid, Anastatus orientalis (Yang and Choi) (Hymenoptera: Eupelmidae), and South Korea, where Ly. delicatula is invasive and An. orientalis has been released for classical biological of Ly. delicatula. These data were compared to similarly collected data from Japan and the United States, countries where Ly. delicatula is invasive and An. orientalis is absent. The results indicated egg masses from field sites in Japan generally had the highest mean proportion of Ly. delicatula nymph hatch from individual eggs (0.82–0.95). Sites in South Korea generally had the highest mean proportion of parasitism on individual eggs (0.28–0.61) followed by sites in China (0.05–0.30). Field sites in the United States overall had the highest egg mass densities (326 ± 70 egg masses found per site in a 30-min time period in Year 1 and 739 ± 47 in Year 2 of surveys) (mean ± SE). In contrast, the overall lowest recorded egg mass densities were found from the sites in South Korea (31 ± 2 Year 1 and 33 ± 1 Year 2). Additionally, we assessed the roles that biotic (i.e., egg parasitism and host plant availability) and abiotic factors (i.e., climatic differences) play in observed Ly. delicatula egg densities and mortality rates. Overall, this study provides strong evidence that biotic and abiotic factors influence Ly. delicatula egg mass densities and hatch rates across regions where this species is native or invasive.