Evidence of Pheromone Use in a Fulgorid, Spotted Lanternfly

Abstract

The spotted lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae) is a polyphagous, phloem-feeding invasive forest, agricultural, and nuisance pest that is rapidly spreading through the U.S. Little is known about how fulgorids locate each other to mate. To determine if conspecific semiochemicals such as pheromones occur, whole body extracts (WBE) of adult spotted lanternflies from different physiological states were tested for attraction in a dual-choice olfactometer. In olfactometer assays, prior to mating, males were oriented to WBE from males and females. During their mating period, males were attracted to WBE of females, but not to that of males. After mating and oviposition had taken place, males were not attracted to either male or female extracts. Conversely, females did not orient to any WBE from either sex during any physiological state. These behavioral responses by males but not females to WBE from conspecifics in different physiological states suggest the possible presence of an aggregation-sex pheromone in the spotted lanternfly.

Factors Guiding the Orientation of Nymphal Spotted Lanternfly, Lycorma delicatula

“…Only the first instars prioritized higher SLF density over larger trees. Whether SLF moved to trees with higher background populations of SLF on them because the SLF were producing attractive signals (i.e., pheromones, substrate vibrations, or damage kairomones) [ 28 , 29 , 30 ], or because there was something initially more attractive about those trees (i.e., kairomones, visual cues, or nutritional quality) [ 9 , 31 ], which consequently lured both the marked and wild SLF, could not be ruled out from this experiment. However, the fact that tree size is also strongly attractive and correlated to SLF density suggests that there could be a positive feedback loop in which SLF may initially be attracted to larger trees, and once groups of SLF find those trees, the combination of the larger trees and signals from SLF may result in more SLF attraction.…”

“…The insects themselves could emit chemical signals such as pheromones that also could indicate the presence of conspecifics and facilitate aggregation. Evidence that pheromones may exist in SLF honeydew and body volatiles has been reported for adults as a possible mechanism for observed aggregation behavior and for mate location [ 28 , 29 ], and aggregation in SLF nymphs could also be mediated by pheromones. The first evidence of pheromones in the suborder Auchenorrhyncha, to which fulgorids belong, was recently reported [ 48 ], and pheromones have been documented in the two other major hemipteran suborders Heteroptera (true bugs) [ 49 , 50 ] and Sternorrhynca (aphids, whiteflies, psyllids, scales) [ 51 , 52 , 53 , 54 ].…”

“…Although the possibility of nutritional differences between host plants has been proposed [ 25 ], other factors are likely involved in SLF arriving or arresting on one host over another and thus should be considered. Possible mechanisms driving this phenomenon could involve semiochemicals such as kairomones from host plants [ 9 ] or semiochemicals from SLF honeydew exudates [ 28 ], pheromones [ 29 ], vibroacoustic signals [ 30 ], visual cues [ 31 , 32 ], or some combination thereof. Despite attraction to the kairomone methyl salicylate in both laboratory and field experiments [ 33 ], numerous other kairomones that were attractive in the laboratory [ 9 ] were not attractive in the field (MFC, unpublished data) [ 34 ], and methyl salicylate also yielded inconsistent field results [ 35 ], suggesting that yet unknown factors may compete with the efficacy of those semiochemical lures in the field.…”

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]. During courtship, males and females huddle in tight clusters, unlike looser aggregations seen before Mid [15].…”

“…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.…”