Host plant volatiles play a key role in mediating plant–herbivore interactions. How an array of host plant volatiles guides host preference and attraction in the invasive polyphagous Lycorma delicatula (White), the spotted lanternfly (SLF), is largely unknown. A pernicious phloem feeder, SLF feeds on over 70 species of plants, some with high economic impact. To aid the development of detection and monitoring tools for SLF, we used a two-choice olfactometer to compare 14 host plant species for attraction, first to a blank control, and then to their preferred host Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae), tree-of-heaven. SLF were significantly attracted to seven host plants compared to a blank control, but no host plant was more attractive than tree-of-heaven. We then used electroantennographic detection (EAD) to screen select host plants for EAD active compounds, hypothesizing that EAD-active plant volatiles act as kairomones and mediate SLF attraction to host plants. Out of 43 unique antennal responses, 18 compounds were identified and tested individually for attraction in a two-choice olfactometer against a blank control and then against methyl salicylate, the current best attractant. Eleven compounds were significantly attractive, and one, sulcatone, was more attractive than methyl salicylate. Blends of kairomones were then tested for attraction, revealing five blends that were significantly more attractive than methyl salicylate, and could be developed into lures for field testing. The presence of these kairomones in volatile profiles of 17 plant species is described. These findings support the hypothesis that the identified volatiles act as kairomones and function in attraction to host plants.

Recent research has shown that volatile sex and aggregation-sex pheromones of many species of cerambycid beetles are highly conserved, with sympatric and synchronic species that are closely related (i.e., congeners), and even more distantly related (different subfamilies), using the same or similar pheromones. Here, we investigated mechanisms by which cross attraction is averted among seven cerambycid species that are native to eastern North America and active as adults in spring: Anelaphus pumilus (Newman), Cyrtophorus verrucosus (Olivier), Euderces pini (Olivier), Neoclytus caprea (Say), and the congeners Phymatodes aereus (Newman), P. amoenus (Say), and P. varius (F.). Males of these species produce (R)-3-hydroxyhexan-2-one as their dominant or sole pheromone component. Our field bioassays support the hypothesis that cross attraction between species is averted or at least minimized by differences among species in seasonal phenology and circadian flight periods of adults, and/or by minor pheromone components that act as synergists for conspecifics and antagonists for heterospecifics.

The spotted lanternfly (SLF), Lycorma delicatula (Hemiptera: Fulgoridae), is a generalist phloem feeder that produces copious amounts of honeydew, which in turn coats the understory. These insects form large aggregations covering the trunks of some trees, while similar trees nearby mysteriously seem unattractive. We investigated whether volatiles from SLF honeydew are attractive to conspecifics by collecting honeydew from the field and testing it for SLF attraction in a two-choice olfactometer. We found that honeydew excreted by adult male SLF was significantly attractive to male SLF, but not female SLF. Although the honeydew excreted by adult female SLF did not significantly attract male or female SLF, both sexes showed a positive trend towards attraction in response to female honeydew in the olfactometer. Analysis of the headspace volatiles of honeydew was conducted, and numerous semiochemicals were identified. Five of which, 2-heptanone, 2-octanone, 2-nonanone, benzyl acetate, and 1-nonanol, were tested in two-choice behavioral assays against a blank control. Benzyl acetate and 2-octanone were attractive to both sexes, whereas 2-heptanone was only attractive to males, and 2-nonanone only to females. The remaining compound, 1-nonanol, repelled females, but not males. Although honeydew has been reported as a source of kairomones for some natural enemies, this may be the first report of sex-specific attractants for conspecific insects found in the honeydew volatiles of a planthopper.

We summarize field data on the species composition and seasonal phenology of the community of cerambycid beetles of east-central Illinois. Data were drawn from field bioassays conducted during 2009 – 2012 that tested attraction of adult beetles of diverse species to a variety of synthetic pheromones and host plant volatiles. A total of 34,086 beetles of 114 species were captured, including 48 species in the subfamily Cerambycinae, 41 species in the Lamiinae, 19 species in the Lepturinae, two species in the Spondylidinae, and one species each in the Necydalinae, Parandrinae, Prioninae, and the Disteniidae. Most of the best-represented species were attracted to pheromones that were included in field experiments, particularly species that use (R)-3-hydroxyhexan-2-one as a pheromone component. The species captured, and their patterns of abundance and seasonal phenology were similar to those in an earlier study conducted in Pennsylvania. The most abundant species identified in both studies included the cerambycines Elaphidion mucronatum (Say), Neoclytus a. acuminatus (F.), Neoclytus m. mucronatus (F.), and Xylotrechus colonus (F.). Cerambycine species became active in an orderly progression from early spring through late fall, whereas most lamiine species were active in summer and fall, and lepturine species were limited to summer. Potential cross attraction between some cerambycine species that shared pheromone components may have been averted by differences in seasonal activity period, and by minor pheromone components that acted as synergists for conspecifics and/or antagonists for heterospecifics. These results provide quantitative data on the abundance and seasonal phenology of a large number of species.

Research over the last decade has revealed extensive parsimony among pheromones within the large insect family Cerambycidae, with males of many species producing the same, or very similar aggregation pheromones. Among some species in the subfamily Cerambycinae, interspecific attraction is minimized by temporal segregation, and/or by minor pheromone components that synergize attraction of conspecifics or inhibit attraction of heterospecifics. Less is known about pheromone-based mechanisms of reproductive isolation among species in the largest subfamily, the Lamiinae. Here, we present evidence that the pheromone systems of two sympatric lamiine species consist of synergistic blends of enantiomers of (E)-6,10-dimethyl-5,9-undecadien-2-ol (fuscumol) and the structurally related (E)-6,10-dimethyl-5,9-undecadien-2-yl acetate (fuscumol acetate), as a mechanism by which species-specific blends of pheromone components can minimize interspecific attraction. Male Astylidius parvus (LeConte) were found to produce (R)- and (S)-fuscumol + (R)-fuscumol acetate + geranylacetone, whereas males of Lepturges angulatus (LeConte) produced (R)- and (S)-fuscumol acetate + geranylacetone. Field experiments confirmed that adult beetles were attracted only by their species-specific blend of the enantiomers of fuscumol and fuscumol acetate, respectively, and not to the individual enantiomers. Because other lamiine species are known to produce single enantiomers or blends of enantiomers of fuscumol and/or fuscumol acetate, synergism between enantiomers, or inhibition by enantiomers, may be a widespread mechanism for forming species-specific pheromone blends in this subfamily.