Performance and host association of spotted lanternfly (Lycorma delicatula) among common woody ornamentals

Abstract

Lycorma delicatula (spotted lanternfly) has a broad host range with a strong preference for the invasive host plant from its native range, tree of heaven (Ailanthus altissima); it had long been speculated that L. delicatula could not develop or reproduce without access to tree of heaven. In 2019, we found that this assumption was incorrect, but fitness was reduced in the absence of A. altissima in that the number of egg masses laid was dramatically fewer for insects reared on suitable non-A. altissima host plants that had recently been established. We hypothesized that longer established, larger trees (of the same species) would improve the fitness of L. delicatula in the absence of tree of heaven. In spring 2020, we examined insect performance with and without access to A. altissima by tracking development, survival, host tree association and oviposition in large enclosures with trees planted two years prior to the study. Each enclosure included one each of Juglans nigra, Salix babylonica and Acer saccharinum along with either one A. altissima or one Betula nigra; these trees had twice the diameter of the same trees the previous year. We reared nymphs with and without access to A. altissima, released them into the corresponding large enclosures as third instars, and monitored them from early July 2020 through November 2020. We also determined whether lack of access to A. altissima by parents of L. delicatula have any fitness effects on offspring performance. To ensure adequate adult populations for comparing fecundity between treatments, third instars were released into the multi-tree enclosures due to high mortality in earlier instars that occurred in a similar study in 2019. Insect survival was higher and development faster with access to A. altissima. Third and fourth instar nymphs were most frequently observed on A. altissima when it was present, while adults were equally associated with A. saccharinum and A. altissima. In the absence of A. altissima, nymphs were most frequently found on S. babylonica, while adults were most often on A. saccharinum. Females with access to A. altissima deposited nearly 7-fold more egg masses than those without access to A. altissima, which is consistent with the difference in egg mass numbers between the two treatments the previous year; thus, our hypothesis was rejected. The offspring of parents that had been reared without access to A. altissima showed similar survival and development time from egg to adult as offspring from parents that never had access to A. altissima. These findings suggest that managers need to be aware that even in the absence of A. altissima in the landscape, several hardwood host trees can be utilized by L. delicatula to develop and reproduce, but fitness without A. altissima is likely to still be reduced.

Sizing up spotted lanternfly nymphs for instar determination and growth allometry

“…None of these previous studies provided statistical data to guide the classification of new datasets for instar determination. Furthermore, studies of other insect species have shown that the size ranges for each instar can depend on factors such as date of emergence, diet (18), host plants, temperatures, and environment (e.g., laboratory vs fieldraised) (19) Indeed, prior research has indicated that SLF nymphs develop and survive differently when reared with different diets in the field (19,20), at different temperatures (21), and artificial conditions (i.e., enclosures or laboratory conditions) (1,16), but these studies did not consider how these factors affected instar morphometrics. In other insect and arthropod species, instar determination has often relied on Dyar's rule: the finding that nymphal body sizes tend to be distributed among distinct clusters because each instar stage attains a maximum body size before molting (22).…”

Development of rearing methodology for the invasive Spotted Lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae)

“…Tree of heaven, Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae), is often referred to as the primary or preferred host of L. delicatula, although it is not obligatory for completion of their development (7)(8)(9). Damage caused by L. delicatula phloem feeding has been reported on grapevine and peach trees in its invaded range in South Korea (4).…”

“…As L. delicatula is univoltine, establishing and maintaining a productive colony can be challenging. Information on such variables as diapause during the egg stage and nutritional needs for L. delicatula is still emerging (7)(8)(9)17). Here, we evaluated several sources of A. altissima plant material and abiotic conditions promoting L. delicatula development and survivorship and different substrates for the promotion of mating and oviposition under laboratory conditions to generate standardized methods for maintaining a colony of L. delicatula.…”

Ecology and genetic structure of the invasive spotted lanternfly Lycorma delicatula in Japan where its distribution is slowly expanding

“…The spotted lanternfly, Lycorma delicatula (White), is a sap-feeding insect native to China. The main host plant of this species is the tree of heaven, Ailanthus altissima 1 , 2 , but it can utilise more than 70 plant species such as apples and grapes 3 – 5 . L. delicatula damages or even kills trees, including crops, by feeding on large amounts of plant sap and excreting honeydew on the leaf surfaces which promotes the growth of sooty mould fungus on them 3 , 4 .…”