Evidence of Pheromone Use in a Fulgorid, Spotted Lanternfly

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

Investigating Photo-Degradation as a Potential Pheromone Production Pathway in Spotted Lanternfly, <i>Lycorma delicatula</i>

Since its discovery in North America in 2014, the spotted lanternfly (SLF), Lycorma delicatula, has become an economic, ecological, and nuisance pest there. Developing early detection and monitoring tools is critical to their mitigation and control. Previous research found evidence that SLF may use pheromones to help locate each other for aggregation or mating. Pheromone production necessitates specific conditions by the insects, and these must be investigated and described. A chemical process called photo-degradation has been described as a final step in the production of pheromones in several diurnal insect species, in which cuticular hydrocarbons were broken down by sunlight into volatile pheromone components. In this study, photo-degradation was investigated as a possible pheromone production pathway for SLF. Extracts from SLF mixed-sex third and fourth nymphs and male or female adults were either exposed to simulated sunlight to produce a photo-degradative reaction (photo-degraded), or not exposed to light (crude), while volatiles were collected. Behavioral bioassays tested for attraction to volatiles from photo-degraded and crude samples and their residues. In third instars, only the volatile samples from photo-degraded mixed-sex extracts were attractive. Fourth instar males were attracted to both crude and photo-degraded residues, and volatiles of photo-degraded mixed-sex extracts. Fourth instar females were attracted to volatiles of crude and photo-degraded mixed-sex extracts, but not to residues. In adults, only males were attracted to body volatiles from crude and photo-degraded extracts of either sex. Examination of all volatile samples using gas chromatography coupled with mass spectrometry (GC-MS) revealed that most of the identified compounds in photo-degraded extracts were also present in crude extracts. However, the abundance of these compounds in photo-degraded samples were 10 to 250 times more than their abundance in the crude counterparts. Results from behavioral bioassays indicate that photo-degradation probably does not generate a long-range pheromone, but it may be involved in the production of a short-range sex-recognition pheromone in SLF. This study provides additional evidence of pheromonal activity in SLF

Pheromones of three ambrosia beetles in the Euwallacea fornicatus species complex: ratios and preferences

Three cryptic species in the Euwallacea fornicatus species complex were reared in laboratory colonies and investigated for the presence of pheromones. Collections of volatiles from combinations of diet, fungus, beetles, and galleries from polyphagous shot hole borer (Euwallacea sp. #1) revealed the presence of 2-heneicosanone and 2-tricosanone only in the presence of beetles, regardless of sex. Subsequent examination of volatiles from the other two species, tea shot hole borer (Euwallacea sp. #2) and Kuroshio shot hole borer (Euwallacea sp. #5), revealed these two ketones were present in all three species but in different ratios. In dual choice olfactometer behavioral bioassays, mature mated females were strongly attracted to a synthetic binary blend of ketones matching their own natural ratios. However, females in each species were repelled by ketone blends in ratios corresponding to the other two species. Males of each species responded similarly to females when presented with ratios matching their own or the other two species. The presence of these compounds in the three beetle species, in ratios unique to each species, and their strong species-specific attraction and repellency, suggests they are pheromones. The ecological function of these pheromones is discussed. In addition to the pheromones, the previously known attractant (1S,4R)-p-menth-2-en-1-ol (also known as quercivorol) was discovered in the presence of the fungal symbionts, but not in association with the beetles. Quercivorol was tested in a dual-choice olfactometer and was strongly attractive to all three species. This evidence suggests quercivorol functions as a kairomone for members of the E. fornicatus species complex, likely produced by the symbiotic fungi