|BERGH, J. CHRISTOPHER - Virginia Tech|
|DYER, JARED - Virginia Tech|
|BRANDT, SAMUEL - Virginia Tech|
|NIXON, LAURA - Orise Fellow|
|NITA, MIZUHO - Virginia Tech|
Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2022
Publication Date: 9/6/2022
Citation: Bergh, J., Dyer, J., Brandt, S., Cullum, J.P., Nixon, L., Nita, M., Leskey, T.C. 2022. Spatial distribution of 17-year periodical cicada (Hemiptera: Cicadidae) exuviae and oviposition injury in mid-Atlantic, USA apple orchards and implications for management. Crop Protection. https://doi.org/10.1016/j.cropro.2022.106095.
Interpretive Summary: Mid-Atlantic orchards are within the geographic range of 17-year periodical cicada Brood X, Magicicada septendecim (L.), M. cassini (Fisher) (Hemiptera: Cicadidae). Because tree branches can be injured by egglaying females, resulting in loss of fruit buds and reducing growth, insecticides are often applied. In 2021, we recorded the location of molted nymphal exoskeletons (a proxy for egglaying locations during 2004) and egglaying injury was measured using tree transects in commercial apple orchards in Virginia and West Virginia, USA. Overall, there was a tendency for somewhat greater numbers of molted exoskeletons and branches with egglaying injury on the border rows facing woods. These results help provide information regarding relative risk to fruit orchards in the future when Brood X emerges in 2038.
Technical Abstract: Tree fruit orchards in some Mid-Atlantic states are within the geographic range of 17-year periodical cicada Brood X, Magicicada septendecim (L.), M. cassini (Fisher) (Hemiptera: Cicadidae), and can be badly affected by injury from its oviposition in branches. Several applications of broad-spectrum insecticides, such as pyrethroids, are needed to mitigate this injury but can incite secondary pest outbreaks by impacting natural enemy populations. The spatial distribution of cicada exuviae and oviposition injury in orchards have not been examined in relation to edge effects or the effect of different adjoining habitats, from which cicadas can move into orchards. Addressing these knowledge gaps may reveal the potential for spatially precise insecticide applications targeting cicadas, thereby, mitigating the effects of spraying entire orchard blocks. In 2021, the distribution of Brood X cicada exuviae (a proxy for oviposition during its previous emergence in 2004) and oviposition injury was measured using tree transects in commercial apple orchards in Virginia and West Virginia, USA. All orchards had woods and non-woods habitats along opposite borders and depending on their age, were or were not exposed to cicadas previously. Orchard edges facing and not facing woodlands were vulnerable to the effects from cicada. Overall, there was a tendency for somewhat higher numbers of exuviae and oviposition sites in orchard border rows facing woods. Both variables were recorded in considerable numbers in the orchard interior on edges facing and not facing woods. Results are discussed in relation to their implications for cicada management in fruit orchards.