DNA holds great potential for species identification and efforts to create a DNA database of all animals and plants currently contains >7.5 million sequences representing Cognato et al. Taxonomic Expertise Improves Beetle DNA-Identification species was poor. In a demonstration of iterative taxonomy, we constructed parsimonybased phylogenies using COI and CAD sequences for two genera. Although not all clades were resolved or supported, we provided better explanations for species boundaries in light of morphological and DNA sequence differences. Confident species identifications demonstrated <3% COI and <1% CAD difference and recognition of new species became more probable when there was >10-12% COI and/or >2-3% CAD. Involvement of taxonomic experts from the start of this project was essential for the creation of a stable foundation for the DNA identification of xyleborine species. In general, their role in DNA barcoding cannot be underestimated and is further discussed.

The dynamics of the fungal symbionts in the gallery system and the mycangia of the ambrosia beetle, Xylosandrus mutilatus, were studied in relation to its life history using both isolation experiments and scanning electron microscopy (SEM). In the galleries, Ambrosiella sp. was predominant during the larval stages but its relative dominance gradually decreased during the development of the larvae. In contrast, yeasts (mainly Candida sp.) and Paecilomyces sp. dominated continuously in the galleries after eclosion. Ambrosiella sp. was consistently stored in the mycangia in all adult stages, except in the teneral and overwintering adults when the other fungi were dominant. No fungal spores occurred in the mycangia of the adult beetles reared under aseptic conditions from the pupal stage, while only Ambrosiella sp. was stored in those reared from the teneral-adult stage. These results suggest that: (i) X. mutilatus is associated with at least three fungal species, among which Ambrosiella sp. is the most essential food resource for development of the broods; (ii) immediately after edosion, new female adults may take at least four associated fungal species, with no or incomplete selection, into their mycangia from the walls of the cradles; and (iii) conditions may wei1 be produced in the mycangia of both matured and dispersing beetles whereby only the spores ofAmbrosiella sp. can proliferate.

We provide an overview of both traditional and innovative control tools for management of three Xylosandrus ambrosia beetles (Coleoptera: Curculionidae: Scolytinae), invasive species with a history of damage in forests, nurseries, orchards and urban areas. Xylosandrus compactus, X. crassiusculus and X. germanus are native to Asia, and currently established in several countries around the globe. Adult females bore galleries into the plant xylem inoculating mutualistic ambrosia fungi that serve as food source for the developing progeny. Tunneling activity results in chewed wood extrusion from entry holes, sap outflow, foliage wilting followed by canopy dieback, and branch and trunk necrosis. Maintaining plant health by reducing physiological stress is the first recommendation for long-term control. Baited traps, ethanol-treated bolts, trap logs and trap trees of selected species can be used to monitor Xylosandrus species. Conventional pest control methods are mostly ineffective against Xylosandrus beetles because of the pests’ broad host range and rapid spread. Due to challenges with conventional control, more innovative control approaches are being tested, such as the optimization of the push–pull strategy based on specific attractant and repellent combinations, or the use of insecticide-treated netting. Biological control based on the release of entomopathogenic and mycoparasitic fungi, as well as the use of antagonistic bacteria, has yielded promising results. However, these technologies still require validation in real field conditions. Overall, we suggest that management efforts should primarily focus on reducing plant stress and potentially be combined with a multi-faceted approach for controlling Xylosandrus damage.

Haplodiploidy is a sex determination system in which fertilized diploid eggs develop into females and unfertilized haploid eggs develop into males. The evolutionary explanations for this phenomenon include the possibility that haplodiploidy can be reinforced by infection with endosymbiotic bacteria, such as Wolbachia. The subfamily Scolytinae contains species with haplodiploid and diploid sex determination systems. Thus, we studied the association with Wolbachia in 12 diploid and 11 haplodiploid scolytine beetles by analyzing wsp and multilocus sequence typing (MLST) of five loci in this endosymbiont. Wolbachia genotypes were compared with mitochondrial (COI) and nuclear (EF) genotypes in the scolytines. Eight of the 23 scolytine species were infected with Wolbachia, with haplodiploids at significantly higher rates than diploid species. Cloning and sequencing detected multiple infections with up to six Wolbachia strains in individual species. Phylogenetic analyses of wsp and five MLST genes revealed different Wolbachia strains in scolytines. Comparisons between the beetle and Wolbachia phylogenies revealed that closely related beetles were infected with genetically different Wolbachia strains. These results suggest the horizontal transmission of multiple Wolbachia strains between scolytines. We discuss these results in terms of the evolution of different sex determination systems in scolytine beetles.

Ceratocystis ficicola causes serious wilt disease in many fig orchards in Japan. The transmission of this pathogen is thought to occur via soil to host roots, and an ambrosia beetle, Euwallacea interjectus, has been reported as a vector of the pathogen. Anatomical investigations were made on the disease development process with a particular focus on the responses of host tissue to the activities of the vector beetle and the pathogen. Living 26- and 8-year-old Ficus carica trees that were naturally infected with C. ficicola and had holes excavated by E. interjectus were used for analysis. Dark brown discoloration was observed in the sapwood of specimens with poor shoot elongation and slight leaf wilt at harvest. Discolored sapwood coincided with the distribution of hyphae of the pathogen, which was verified by the presence of conidiophores. Most of the beetle’s gallery was distributed inside the discolored area. In the non-discolored sapwood adjacent to the border of the discolored area, some galleries were elongated and contained living new generation adults and larvae of E. interjectus. Hyphae of the pathogen and colored substances were identified also around those new galleries.The present study showed that elongation of galleries by E. interjectus in the functional sapwood induces the wide distribution of the pathogen and contributes to the expansion of the discolored area in which vessels were dysfunctional. This process causes a shortage of water supply and wilting in the infected trees. Euwallacea interjectus must be contributing to the symptom development of this wilt disease.