Occurrence, Seasonal Abundance, and Superparasitism of Ooencyrtus kuvanae (Hymenoptera: Encyrtidae) as an Egg Parasitoid of the Spotted Lanternfly (Lycorma delicatula) in North America

Houping Liu

doi:10.3390/f10020079

Abstract

The occurrence of egg parasitoid Ooencyrtus kuvanae (Howard) (Hymenoptera: Encyrtidae) on its new host, the spotted lanternfly (Lycorma delicatula (White) (Hemiptera: Fulgoridae)), was surveyed at 4 study plots in 2016 and 10 additional plots in 2017 in Pennsylvania through field collection and laboratory incubation. O. kuvanae adults were found on L. delicatula egg mass surfaces at two plots (ODSouth and Lutz) in 2016, but at none in 2017. The results of laboratory incubation showed that O. kuvanae adults were only recovered from host eggs collected at plot ODSouth in 2016, with adults emerging between 22 April and 2 May 2016 at 22 ± 1 °C, 40% ± 5% relative humidity (RH), and a 16:8 h photoperiod (light/dark). The overall parasitism at this study plot was 6.0% by egg mass and 1.2% by egg. Two oviposition sites contained parasitized L. delicatula eggs, with 12.3% (9.5–15.0%) host egg masses and 3.1% (1.3–5.0%) host eggs utilized by the parasitoid. O. kuvanae parasitism by egg was significantly higher on oviposition site ODSouth #7 than on ODSouth #8. No O. kuvanae adults were reared out of field-collected host eggs from the 10 plots in 2017. Seasonal abundance and superparasitism of O. kuvanae was examined at plot ODSouth in 2017. O. kuvanae-parasitized L. delicatula eggs were found on all four oviposition sites based on field monitoring of parasitoid adult emergence, resulting in a parasitism of 35.4% (18.8–55.6%) by egg mass and 2.2% (0.5–3.9%) by egg. No significant difference in parasitism by egg was observed among oviposition sites. O. kuvanae adults emerged in the field between 2 May and 1 June 2017. Superparasitism was confirmed for O. kuvanae on L. delicatula eggs based on parasitoid production (1.0–3.3 adults/parasitized egg) and adult exit holes (1–3 exit holes/parasitized egg). As the first parasitoid recorded from L. delicatula in North America, O. kuvanae has the potential to become an important biological control agent for L. delicatula in North America, with its well-synchronized life history in the spring, century-long field establishment, superparasitism, and female-biased progeny population. L. delicatula complements the gypsy moth well as an alternative host for O. kuvanae in the field.

Highlights

The spotted lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoridae), a sporadic pest of tree-of-heaven, Ailanthus altissima (Mill.) Swingle (Simaroubaceae), in its native range of China, Taiwan, and Vietnam [1,2,3,4], was first discovered in North America near Boyertown (40.33366 N, 75.63744 W) inBerks county, Pennsylvania, in 2014 [5,6]
L. delicatula egg masses were found on all sorts of oviposition sites, including various live and dead trees, shrubs, building structures, fence posts, rocks, etc
Dominant tree species at each study plot were not necessarily the most used oviposition sites by L. delicatula females, tree-of-heaven would have been preferred if the majority of them were not preemptively excluded at most plots due to chemical or mechanical control (Table 1)

Summary

Introduction

The spotted lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoridae), a sporadic pest of tree-of-heaven, Ailanthus altissima (Mill.) Swingle (Simaroubaceae), in its native range of China, Taiwan, and Vietnam [1,2,3,4], was first discovered in North America near Boyertown (40.33366 N, 75.63744 W) inBerks county, Pennsylvania, in 2014 [5,6].

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