Factors Guiding the Orientation of Nymphal Spotted Lanternfly, Lycorma delicatula

Abstract

A mark–release–recapture experiment was conducted to evaluate the orientation of spotted lanternfly (SLF) Lycorma delicatula White (Hemiptera: Fulgoridae) nymphs when released equidistant between two trees. The experiment was repeated weekly for eight weeks in a heavily infested area with mature tree-of-heaven Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae) planted in rows as ornamental street trees in Beijing, China. One tree in each pair received a methyl salicylate lure, and the lure was rotated between trees every week as it aged. Two additional independent variables for each tree were also analyzed: size and SLF population density. Marked–released SLF significantly chose trees with higher SLF population density over trees with lower density populations, and they also chose larger trees significantly more than smaller trees. Population density and tree size were better predictors of attraction than lures, but when those factors were controlled, SLF significantly chose trees with methyl salicylate lures over control trees for the first 4 weeks of lure life. Wild SLF distribution was assessed weekly, revealing strong aggregation in first and second instars that diminished with development to the third and fourth instars. Thus, nymphal SLF aggregate, and orientation is strongly guided by the presence of other SLF and tree size.

Radio Telemetry and Harmonic Radar Tracking of the Spotted Lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoridae)

“…Aggregation behavior was previously demonstrated in the field for all SLF nymphal stages [61], and adult females at all stages [15], whereas males in the latter study oriented to higher-density trees baited with caged females or males only after mating commenced. Thus, adult males orient to, and form, tight aggregations with females for courtship and mating, and are guided at least in part by semiochemicals [62,63].…”

“…Locusts famously migrate en masse, triggered by a combination of abiotic factors, such as decreasing light intensity, and biotic factors such as crowding [72][73][74], which, along with high population density, was found to be mediated by an aggregation pheromone [75]. SLF appear to share some of these features, including aggregation behavior, which may be guided by semiochemicals such as an aggregation pheromone or feedinginduced plant volatiles [15,[61][62][63]76,77], and mass migration events at times when large SLF populations have depleted food resources [64,66]. Under this lens, it makes sense that in the low-density site used in 2020, only a small fraction of SLF traveled long distances, whereas in the high-density site used in 2019, several long-distance flights were recorded.…”

The subapical labial sensory organ of spotted lanternfly Lycorma delicatula

“…Of particular interest, methyl salicylate, identified as the most potent activator of the B neuron in our study, is a major volatile associated with the preferred host plant for SLF, Ailanthus altissima (also known as the tree-of-heaven) [ 6 ]. Moreover, methyl salicylate is attractive to adults and nymphs of SLF under laboratory conditions and, to some extent, under field conditions as well [ 6 , 50 ].…”

Antennal Sensitivity of Spotted Lanternflies, Lycorma delicatula: Differential Electrophysiological Responses of Males and Females to Compounds Derived from Host Plants and Conspecifics

“…The development of effective semiochemical-based monitoring tools for SLF is an objective of our research [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. However, due to the large number of volatile compounds identified from SLF host plants, their honeydew, and body volatiles [ 16 , 18 , 19 , 20 ], there are too many individual compounds and potential blends to practically test, especially given the constraints of SLF being univoltine and lacking artificial rearing capabilities.…”