European fruit lecanium (Parthenolecanium corni) occurrence in hybrid hazelnut plantings in Minnesota and associated parasitoid fauna from 2022

Abstract

These data were collected in the summer of 2022 as an independent undergraduate research project at the University of Minnesota by Simone Traband (undergraduate student, class of '24) under the mentorship of Hailey Shanovich (graduate student, class of '23). The goals of the project were to collect preliminary data on 1) the abundance of a soft scale insect pest, European fruit lecanium (Parthenolecanium corni), on hybrid hazelnut plants (Corylus americana x Corylus avellana) in experimental plantings at the University of Minnesota research stations, and 2) the prevalence of biological control by Hymenopteran parasitoid wasps and an endoparasitic fungi (Ophiocordyceps clavulata). These data accompany the paper "Synopsis of biological control for European fruit lecanium (Parthenolecanium corni) by parasitoids in North America and preliminary findings in hybrid hazelnut orchards" by Traband et al. 2023 in the Great Lakes Entomologist.

The preliminary field experiment was conducted at two experimental hybrid hazel plantings in Rosemount, Minnesota. Full details of study sites and other methodology can be found in the paper by Traband et al. 2023. On 11 July 2022 seven infested hazel plants were chosen to sample for scale insects from one hybrid hazelnut planting (n=7), and then on 22 July 2022 from two hybrid hazelnuts plantings (n = 4, n = 3) for a total of 14 plants. On each date, sampling of each plant was done for 15 person-minutes (i.e., three observers searching each plant for scales for five minutes), during which branches observed to contain one or more scale insects, no matter the status (i.e., showed signs of parasitism or not), were collected via hand pruners. Collected branches were immediately brought back to the lab and thoroughly examined to determine the number and status of every scale insect broken into three categories: showing signs of parasitism by fungus (i.e., fungal stromata protruding from scale insect), showing signs of parasitism by Hymenopteran parasitoids (i.e., containing a parasitoid exit hole in shell), or showing no signs of parasitism (i.e., showing no signs of parasitism). Branches containing scales showing no signs of parasitism were preserved for a duration of three weeks for purposes of parasitoid rearing and inspected every other day and any emerged parasitoids were collected and frozen until they could be identified. On 8 August 2022, all scale insects contained in jars were inspected for parasitoid exit holes, dissected to check for parasitoid larvae, pupae, or adults, and then discarded. All collected Hymenopteran parasitoid wasps were identified to the lowest taxonomic level possible.