Field Response of Black Turpentine Beetle to Pine Resin Oxidation and Pheromone Displacement.

The black turpentine beetle, Dendroctonus terebrans, is an economically important pest of pines in the Southeastern U.S., with a high potential for invasion to other pine-rich regions. Dendroctonus terebrans attraction to an injured host tree lessens over time as the host material degrades. Likewise, kairomonal volatiles emitted from the host change as constituents of the defensive resin oxidize. Therefore we hypothesized that volatiles associated with a fresh host would be more attractive to D. terebrans than those associated with a dead or dying host. We replicated the natural oxidation process of turpentine, fractionated the distilled products to isolate the oxidized products, and deployed the complex mixtures to measure field attraction based on the amount of oxidation performed. Contrasting with previous studies, our results suggest that D. terebrans attraction is not primarily based on host tree degradation. In a second experiment incorporating Dendroctonus pheromones, we demonstrate D. terebrans has a displacement-dependent response to endo-brevicomin, a pheromone associated with the sympatric southern pine beetle, D. frontalis. This has implications not only for possible interspecific signaling, but also for the role of endo-brevicomin in D. terebrans colonization behavior. The results from this study broaden the understanding of D. terebrans chemical ecology and directly contribute to the development of an effective lure-based monitoring system that will benefit future research and management efforts. This may become important if the species is established outside its native range, as in the closely related red turpentine beetle, Dendroctonus valens, which caused mass pine tree mortality following its introduction to Asia.

New species of smiley-faced spider Spintharus (Araneae, Theridiidae) from Brazil, and comments on unobserved diversity in South America.

Spintharus is a genus of spiders that contained only two species until 2018 when it was demonstrated that a 'widespread' species was instead composed of multiple short-range endemics. This note redescribes Spintharus gracilis Keyserling and describes a new species of Spintharus (Araneae, Theridiidae), S. leverger sp. nov., both based on specimens from Brazil. We also examine specimens from several additional localities in Brazil displaying variation consistent with patterns previously found within the Caribbean: geographically isolated and unique localities may contain independent species lineages. Given the limited number of specimens, profuse variation, and lack of DNA data from museum specimens, it is challenging to gauge the number of species in the observed material. Instead of describing these as new species here, we highlight this variation and hypothesize that in South America, a greater diversity of the genus across the geographical landscape will be found than predicted based on Levi's "widespread Spintharus flavidus" hypothesis. Our results suggest that continental efforts to sample the genus would be profitable, as this charismatic group likely harbors unappreciated diversity throughout the continent.