Scolytine Beetles Research Articles

Cosmopolitan Scolytinae: strong common drivers, but too many singularities for accurate prediction

Many scolytine beetle species have been expanding in new territories, travelling with wood and plants for planting, sometimes with a high impact on plant health. Here, we attempt to quantify the mobility of these species and to identify the biological drivers of mobility and impact. Mobility was estimated by counting the numbers of landmasses (contiguous pieces of land, surrounded by ocean or sea) colonised by each species. A series of potential drivers (taxonomic tribes; feeding regimes; polyphagy; reproductive strategy; host taxa; aggregation pheromones and long-range primary attractants), as well as impact on host health were recorded. A total of 163 species were identified, out of 5546 counted in the whole subfamily. The cosmopolitan taxa amongst the subfamily showed significant disharmony with regards to invasion frequency. Four tribes (Xyleborini; Ipini; Crypturgini; Hylastini) were significantly over-represented and two others (Corthylini; Hexacolini) were under-represented. Some 53% of the 163 species are inbreeding, a very significant excess as compared to the whole subfamily (29%). The inbreeders colonised more landmasses than the outbreeders. There is a significant relationship between the number of host families attacked by a species and the number of colonised landmasses. Most of the invasive species are recorded to respond to long-range host primary attractants, only one quarter respond to pheromones. All very mobile species respond to long-range primary attractants and none is known to respond to pheromones. Very mobile species are all associated with a substantial or moderate impact. The most mobile species belong to a limited number of subtribes. They are often inbreeding, polyphagous and respond to long-range primary attractants, but do not produce pheromones. However, there are many counter-examples. The outbreeding Scolytus multistriatus attacks only three host families, producing aggregation pheromones and has established in thirteen landmasses, with a high impact. Due to these many exceptions, species-based risk prediction relying on the few traits routinely analysed in literature suffers from important uncertainties.

Xylosandrus crassiusculus (Motschulsky) on Cocoa Pods (Theobroma cacao L.): Matter of Bugs and Fungi.

Simple SummaryDuring standard monitoring activities aimed at preventing the insurgence of a pest infestation in a cocoa plantation in Karnataka (India), a sudden and unprecedented infestation of cocoa pods was recorded in 2021. The symptoms were the exudation of a brownish gummy substance from mature pods and the presence of pinhead-sized holes on the pod husk. Morphological and molecular characterization identified the cause of the symptoms to be the activity of the native ambrosia beetle Xylosandrus crassiusculus. Given the uniqueness of the attack, research was undertaken to investigate the causes of the infestation, describe the type of damage caused, and characterize possible fungal symbionts that allow the beetle to reproduce. Results showed that the infestation of X. crassiusculus was most likely triggered by previous attacks of Helopeltis theivora (Hemiptera: Miridae), a common pest that causes necrotic injuries to cocoa pods. Furthermore, the success of X. crassiusculus using cocoa as a reproductive substrate appeared to be dependent on its symbiotic fungi and yeasts, possibly involved in the detoxification or enrichment of the substrate, besides being the food source of the beetle.Exudation of mucilage from pinhead-sized boreholes in cocoa pods was recorded in Karnataka, India, during 2021. Further investigations showed the association of scolytine beetles with infested pods. The identity of the pest, Xylosandrus crassiusculus, was confirmed through morphological characterization and sequencing of the mitochondrial COI gene. We studied the predisposing factors for its infestation, visible and concealed damaging symptoms, and fungal symbionts. In addition to its well-known symbiotic fungus, Ambrosiella roeperi, a new association of yeast, Ambrosiozyma monospora, was discovered. We also traced the possible role of the mirid bug, Helopeltis theivora, in host selection by X. crassiusculus. Overall results indicated that a ‘mirid bug-ambrosia beetle–pathogen complex’ is responsible for the severe damage to cocoa pods in South India.

Preinvasion Assessment of Exotic Bark Beetle-Vectored Fungi to Detect Tree-Killing Pathogens.

Exotic diseases and pests of trees have caused continental-scale disturbances in forest ecosystems and industries, and their invasions are considered largely unpredictable. We tested the concept of preinvasion assessment of not yet invasive organisms, which enables empirical risk assessment of potential invasion and impact. Our example assesses fungi associated with Old World bark and ambrosia beetles and their potential to impact North American trees. We selected 55 Asian and European scolytine beetle species using host use, economic, and regulatory criteria. We isolated 111 of their most consistent fungal associates and tested their effect on four important southeastern American pine and oak species. Our test dataset found no highly virulent pathogens that should be classified as an imminent threat. Twenty-two fungal species were minor pathogens, which may require context-dependent response for their vectors at North American borders, while most of the tested fungi displayed no significant impact. Our results are significant in three ways; they ease the concerns over multiple overseas fungus vectors suspected of heightened potential risk, they provide a basis for the focus on the prevention of introduction and establishment of species that may be of consequence, and they demonstrate that preinvasion assessment, if scaled up, can support practical risk assessment of exotic pathogens.

Diversity and Evolution of Entomocorticium (Russulales, Peniophoraceae), a Genus of Bark Beetle Mutualists Derived from Free-Living, Wood Rotting Peniophora.

Symbiosis between insects and fungi arose multiple times during the evolution of both groups, and some of the most biologically diverse and economically important are mutualisms in which the insects cultivate and feed on fungi. Among these are bark beetles, whose ascomycetous cultivars are better known and studied than their frequently-overlooked and poorly understood basidiomycetous partners. In this study, we propose five new species of Entomocorticium, fungal mutualists in the Russulales (Basidiomycota) that are mutualistic symbionts of scolytine beetles. We have isolated these fungi from the beetle mycangia, which are structures adapted for the selective storage and transportation of fungal mutualists. Herein, we present the most complete phylogeny of the closely related genera Entomocorticium and Peniophora and provide insights into how an insect-associated taxon (Entomocorticium) evolved from within a wood-decaying, wind-dispersed lineage (Peniophora). Our results indicate that following a transition from angiosperms to gymnosperms, fungal domestication by beetles facilitated the evolution and diversification of Entomocorticium. We additionally propose four new species: Entomocorticium fibulatum Araújo, Li & Hulcr, sp. nov.; E. belizense Araújo, Li & Hulcr, sp. nov.; E. perryae Araújo, Li & Hulcr, sp. nov.; and E. macrovesiculatum Araújo, Li, Six & Hulcr, sp. nov. Our findings highlight the fact that insect-fungi associations remain an understudied field and that these associations harbor a large reservoir of novel fungal species.

Bark beetles breeding in petioles in Fiji (Coleoptera: Curculionidae: Scolytinae)

The scolytine beetles found breeding in the petioles of the fallen leaves of Fijian trees are listed together with their host trees, and information is provided on the biology of the species. The majority of species are known to breed in other habitats. Brood sizes are generally low, and the leafstalks may provide a 'refuge' when more suitable habitat is not available. The community found in Fiji is compared with the communities found in petioles in West Malaysia and Costa Rica.

New Records of Bark and Ambrosia Beetles (Coleoptera: Scolytinae) from Cuba with Description of a New Species

We present a reassessment of the diversity of bark and ambrosia beetles in Cuba. For the first time in decades, an official Cuban-American binational collaboration allowed us to re-visit all known entomology collections in Cuba, and collect in the field. There are at least 94 species of scolytine beetles in Cuba. We report a new species, Xylosandrus aurinegro Gomez & Hulcr (Coleoptera: Curculionidae), and 7 new species records, including the first genus record for Dryocoetoides Hopkins and Tricolus Blandford (both Coleoptera: Curculionidae) for the island. In terms of species with potential concern to the USA, we corroborate a subspecies of Ips calligraphus Wood & Bright (Coleoptera: Curculionidae) that acts as a pine pest in Cuba and is not yet present in North America.

A test of metabarcoding for Early Detection and Rapid Response monitoring for non-native forest pest beetles (Coleoptera)

In response to the threat of introductions of non-native forest insects, the Early Detection and Rapid Response (EDRR) program in Alaska monitors for arrivals of non-native insects, an effort that is limited by the time required to process samples using morphological methods. We compared conventional methods of processing EDRR traps with metabarcoding methods for processing the same samples. We deployed Lindgren funnel traps at three points of entry in Alaska using standard EDRR methods and trap samples were later processed using routine sorting and identification based on morphology. Samples were then processed using High Throughput Sequencing (HTS) metabarcoding methods. In three samples bycatch was included and in three samples non-native species were added. Morophological and HTS methods yielded generally similar results for scolytine and cerambycid beetle assemblages, but HTS provided more species-resolution identifications (46 species) than morphological methods (4 species plus the 3 non-native species known a priori). None of the non-native species were detected by HTS. Including bycatch did not appear to hinder identifications of scolytine and cerambycid beetles by HTS. From among the bycatch, two Palearctic species adventive to North America, Placusa incompleta Sjöberg, 1934 and Hydrophoria lancifer (Harris, 1780), are newly reported from Alaska. We do not recommend replacing our current morphological monitoring methods with HTS methods because we believe that we would be more likely to detect known non-native pest species using morphology. However, we would use HTS to increase our sample size without greatly increasing time required to process samples. We would also recommend HTS methods for surveillance monitoring where the set of target taxa is not limited to known pest species.

A duplex ddPCR assay for simultaneously detectingIps sexdentatusandIps typographus(Coleoptera: Curculionidae) in bulk trap samples

Bark beetles in the family Curculionidae present a growing hazard to forests worldwide. Like native bark beetles, introduced exotic species can pose a serious threat to North American forests. Ips typographus (Boerner) and Ips sexdentatus (Linnaeus), both native to Europe, are two such pests that have caused widespread forest loss in their native ranges. International trade has led to increased interceptions of Scolytine beetles at ports of entry to the United States. Most intercepted individuals are not identified to species due to lack of expert identifiers, poor specimen quality, or incomplete taxonomy. These same problems affect identification for domestic surveys. Therefore, development of molecular methods for identification of potentially invasive Ips species is essential. Because of the need to scrutinize large numbers of beetles in an efficient manner, we describe a duplex droplet digital PCR (ddPCR) assay to identify I. typographus and I. sexdentatus simultaneously in bulk trap samples containing 500 Scolytinae specimens using a scalable, two-step DNA extraction. This ddPCR method is highly effective for processing the entire contents of beetle traps and identifying these potentially invasive species in a timely and definitive manner. We also describe a nondestructive DNA extraction technique that preserves specimens for morphological identification.

Pleistocene climate cycling and host plant association shaped the demographic history of the bark beetle Pityogenes chalcographus

Historical climatic oscillations and co-evolutionary dependencies were key evolutionary drivers shaping the current population structure of numerous organisms. Here, we present a genome-wide study on the biogeography of the bark beetle Pityogenes chalcographus, a common and widespread insect in Eurasia. Using Restriction Associated DNA Sequencing, we studied the population structure of this beetle across a wide part of its western Palaearctic range with the goal of elucidating the role of Pleistocene glacial-interglacial cycling and its close relationship to its main host plant Norway spruce. Genetic distance among geographic sites was generally low, but clustering analysis revealed three genetically distinct groups, that is, southern, central/south-eastern, and north-eastern locations. Thus, three key P. chalcographus glacial refugia were identified: in the Italian-Dinaric region, the Carpathians, and the Russian plain, shared with its main host. The current phylogeographic signal was affected by genetic divergence among geographically isolated refugia during glacial periods and postglacial re-establishment of genetic exchange through secondary contact, reflected by admixture among genetic groups. Additionally, certain life history traits, like the beetle’s dispersal and reproductive behaviour, considerably influenced its demographic history. Our results will help to understand the biogeography of other scolytine beetles, especially species with similar life history traits.

The Structure and Phenology of Non-Native Scolytine Beetle Communities in Coffee Plantations on Kaua'i.

Populations and communities are known to respond to abiotic conditions, but the forces determining the distribution of particular insect pests are sometimes overlooked in the process of developing control methods. Bark and ambrosia beetles (Curculionidae: Scolytinae) are important pests of crops, forestry, and ecosystems worldwide, yet the factors that influence their success are unknown for many species. The Hawaiian archipelago is host to over three dozen invasive scolytines, many of which occur on Kauaʻi and are pests of agriculture. We analyzed scolytine community dynamics at two coffee estates: a hand-harvested site in a tropical wet forest and a mechanically harvested site in a tropical dry savanna. Our regression analyses show overall scolytine abundance was negatively correlated with rainfall, as were four species: the tropical nut borer (Hypothenemus obscurus), H. brunneus, Cryphalus longipilus, and Xyleborinus andrewesi. These relationships contributed to the compositions of the communities being markedly dissimilar despite having the same species richness. Multivariate analysis found no influence from temperature or harvest method on community dynamics. This information can be valuable for the timing of pest control methods, for predicting the success of possible new scolytine arrivals on Kauaʻi, and for forecasting how these species may spread with climate change.

Molecular identification and enzymatic profiling of Trypodendron (Curculionidae: Xyloterini) ambrosia beetle-associated fungi of the genus Phialophoropsis (Microascales: Ceratocystidaceae)

Abstract Ambrosia fungi are a polyphyletic group from currently seven ascomycete and basidiomycete lineages that independently evolved an obligate farming mutualism with wood-boring weevils. One long known, but understudied, association is the mutualism between the scolytine beetle genus Trypodendron (Curculionidae: Xyloterini) and the Microascales fungal genus Phialophoropsis (Ascomycota: Ceratocystidaceae) for which a species-specific association has not been safely established yet. Moreover, the fungal wood degrading capabilities are completely unknown. Here, the ambrosia fungi of three Xyloterini species, Trypodendron domesticum, Trypodendron lineatum and Trypodendron signatum, were isolated and identified using culture-dependent methods. T. lineatum was confirmed to be exclusively associated with Phialophoropsis ferruginea, whereas T. domesticum and T. signatum are associated with a closely related but putatively novel Phialophoropsis species. Investigations of their wood decomposing potential revealed that both fungi mainly depolymerize xylan but are weak mannan decomposers. In addition, robust cellulolytic activity was observed, indicating cellulose as another main carbon source.

A review of acarid mites (Acariformes: Acaridae) associated with bark beetles (Coleoptera: Curculionidae: Scolytinae), with description of Ipsoglyphus bochkovi gen. and sp. nov.

Acarid mites associated with bark beetles feed on fungi, transfer fungal spores, and promote fungal strain recombination inside beetles’ galleries. Many of these mites are omnivorous generalists, with a clear preference to mycetophagy, living in different subcortical habitats, including galleries of bark beetles. We reviewed associations of acarid mites and scolytine beetles numbering 26 mite species in 11 genera associated with 45 bark beetle species in 17 countries (134 unique records total). A new genus and species of acarid mite, Ipsoglyphus bochkovi, gen. and sp. nov. (Acariformes: Acaridae) collected from Ips typographus pheromone traps in Western Siberia, Russia, is described and illustrated from deutonymphs. The new genus differs from all other acarid genera of by a combination of the following characters: two solenidia on genu I, an unpaired eye-spot present on the anterior prodorsum, and palpal supracoxal setae (elc p) lanceolate. As part of this work, we established the following new synonymies and combinations: Halictacarus zakhvatkini (Delfinado and Baker, 1976) comb. nov. from Schulzea (=Schulzea orientalis Putatunda & Kapil, 1995 syn. nov.; Schulzea halicti Putatunda and Kapil, 1995 syn. nov.); Halictacarus indicus (Putatunda & Kapil, 1995) comb. nov. from Schulzea; Forecellinia insolita (Woodring & Moser, 1970) comb. nov. from Anoetus; Histiogaster wichmanni (Türk & Türk, 1957) comb. nov. from Caloglyphus; Reckiacarus sudeticus (Kiełczewski & Wiśniewski, 1975), comb. n. from Histiogaster; Reckiacarus stammeri (F. Türk & E. Türk, 1957) comb. n. from Histiogaster. The following names were emended to agree in gender with the generic name Histiogaster Berlese, 1883 (feminine): Histiogaster iberica Kadzhaya, 1959, Histiogaster robusta Woodring, 1966, Histiogaster rotunda Woodring, 1966, Histiogaster striatissima Mahunka, 1973. Between the variant spellings Histiogaster arborsignum Woodring, 1963 and Histiogaster arborsignis Woodring, 1966, the latter is an incorrect subsequent spelling, however, because it is in prevailing usage, we treat it as correct: Histiogaster arborsignis Woodring, 1963.

Vertical stratification of scolytine beetles in temperate forests

AbstractAlthough most studies exploring the vertical distribution of arthropods in forests have been limited to discrete comparisons between understorey and canopy, few have sampled across multiple heights.We studied vertical distribution of scolytine beetle flight activity in temperate lowland broadleaf and montane beech‐fir forests using flight interception traps arranged in vertical transects with traps placed 0.4, 1.2, 7, 14, and 21 m above ground. In each forest type 15 vertical transects (75 traps) were used.The assemblages sampled at 0.4 and 1.2 m above ground (undergrowth) clearly differed from those at 7, 14, and 21 m (midstorey and canopy).Ambrosia‐fungi feeder abundance peaked at 1.2 m in the mountains, whereas in the lowland they were almost evenly distributed from 1.2 to 21 m. Phloem feeders were significantly more abundant in the midstorey and canopy than in the undergrowth.Height preferences of eleven species were identified. Four species were associated with traps exposed at 7, 14, or 21 m, whereas seven species were associated with the height of 1.2 m. No species was associated with the 0.4 m height.To cover entire scolytine assemblages of forest stands, sampling should thus not be restricted to the usually sampled understorey level, but also cover the canopy.

Landscape-scale genetic differentiation of a mycangial fungus associated with the ambrosia beetle, Xylosandrus germanus (Blandford) (Curculionidae:Scolytinae) in Japan.

In this study, we examined the genetic structures of the ambrosia fungus isolated from mycangia of the scolytine beetle, Xylosandrus germanus to understand their co‐evolutionary relationships. We analyzed datasets of three ambrosia fungus loci (18S rDNA, 28S rDNA, and the β‐tubulin gene) and a X. germanus locus dataset (cytochrome c oxidase subunit 1 (COI) mitochondrial DNA). The ambrosia fungi were separated into three cultural morphptypes, and their haplotypes were distinguished by phylogenetic analysis on the basis of the three loci. The COI phylogenetic analysis revealed three distinct genetic lineages (clades A, B, and C) within X. germanus, each of which corresponded to specific ambrosia fungus cultural morphptypes. The fungal symbiont phylogeny was not concordant with that of the beetle. Our results suggest that X. germanus may be unable to exchange its mycangial fungi, but extraordinary horizontal transmission of symbiotic fungi between the beetle's lineages occurred at least once during the evolutionary history of this symbiosis.

Evaluation of Lure Combinations Containing Essential Oils and Volatile Spiroketals for Detection of Host-Seeking Xyleborus glabratus (Coleoptera: Curculionidae: Scolytinae).

The invasive redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), vectors the fungal pathogen (Raffaelea lauricola) that causes laurel wilt, a disease responsible for widespread mortality of trees in the Lauraceae in the southeastern United States. Early detection of incipient vector populations may allow for management practices that could successfully mitigate damage. Developing new, highly effective attractants is a priority for improving sensitivity of early detection efforts. In this study, two field tests were conducted to evaluate combinations of commercially available bark and ambrosia beetle lures for enhanced attraction of host-seeking female X. glabratus. In addition, lures were compared for capture of nontarget scolytine beetles. In the first experiment, traps baited with a combination of cubeb oil, conophthorin, chalcogran, and ethanol captured greater numbers of X. glabratus than cubeb oil alone, the current standard attractant. However, this combination lure resulted in higher nontarget scolytine captures than with the cubeb lure. In the second field test, an oil enriched in the sesquiterpene α-copaene caught significantly more X. glabratus than other lures currently available for monitoring this pest. There were no differences in efficacy between cubeb oil lures produced by two different manufacturers, and a combination lure containing copaiba and cubeb oils did not increase captures over the cubeb lure alone. Results of these two tests suggest that increased sensitivity for detection of X. glabratus may be achieved with a multicomponent lure that incorporates α-copaene, spiroketals, and low release of ethanol.

Artificial diet sandwich reveals subsocial behaviour in the coffee berry borer Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae)

AbstractAn artificial diet sandwich, consisting of coffee berry borer artificial diet within two glass plates, has been developed to elucidate the behaviour of the coffee berry borer, an insect that in nature spends most of its life cycle inside the coffee berry. Various types of behaviour have been observed for the first time, including gallery construction, oviposition, gallery blocking, mating and most remarkably, subsocial tasks such as maternal sanitation and tending of eggs and larvae. This observational technique is a breakthrough for studies and manipulations of the coffee berry borer's social behaviour and could be applicable to other bark beetles, consequently yielding important insights into the origin of parental care in scolytine beetles.

Invasive Asian Fusarium – Euwallacea ambrosia beetle mutualists pose a serious threat to forests, urban landscapes and the avocado industry

Several species of the ambrosia beetle Euwallacea (Coleoptera: Curculionidae: Scolytinae) cultivate Ambrosia Fusarium Clade (AFC) species in their galleries as a source of food. Like all other scolytine beetles in the tribe Xyleborini, Euwallacea are thought to be obligate mutualists with their fungal symbionts. Published diversification-time estimates suggest that the Euwallacea – Fusarium symbiosis evolved once approximately 21 million years ago. Female Euwallacea possess paired oral mycangia within which foundresses transport their Fusarium symbiont vertically from their natal gallery to new woody hosts. During the past two decades, exotic Asian Euwallacea – Fusarium mutualists have been introduced into the United States, Israel and Australia. Because these invasive pests attack and can reproduce on living woody hosts, they pose a serious threat to native forests, urban landscapes and the avocado industry.

Wolbachia endosymbionts in haplodiploid and diploid scolytine beetles (Coleoptera: Curculionidae: Scolytinae).

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.

Bark and ambrosia beetles (Curculionidae: Scolytinae), their phoretic mites (Acari) and associated Geosmithia species (Ascomycota: Hypocreales) from Virgilia trees in South Africa

Bark and ambrosia beetles are ecologically and economically important phloeophagous insects that often have complex symbiotic relationships with fungi and mites. These systems are greatly understudied in Africa. In the present study we identified bark and ambrosia beetles, their phoretic mites and their main fungal associates from native Virgilia trees in the Cape Floristic Region (CFR) of South Africa. In addition, we tested the ability of mites to feed on the associated fungi. Four species of scolytine beetles were collected from various Virgilia hosts and from across the CFR. All were consistently associated with various Geosmithia species, fungi known from phloeophagous beetles in many parts of the world, but not yet reported as Scolytinae associates in South Africa. Four beetle species, a single mite species and five Geosmithia species were recovered. The beetles, Hapalogenius fuscipennis, Cryphalini sp. 1, and Scolytoplatypus fasciatus were associated with a single species of Elattoma phoretic mite that commonly carried spores of Geosmithia species. Liparthrum sp. 1 did not carry phoretic mites. Similar to European studies, Geosmithia associates of beetles from Virgilia were constant over extended geographic ranges, and species that share the same host plant individual had similar Geosmithia communities. Phoretic mites were unable to feed on their Geosmithia associates, but were observed to feed on bark beetle larvae within tunnels. This study forms the first African-centred base for ongoing global studies on the associations between arthropods and Geosmithia species. It strengthens hypotheses that the association between Scolytinae beetles and dry-spored Geosmithia species may be more ubiquitous than commonly recognised.

Ambrosia Beetles (Coleoptera: Curculionidae: Scolytinae) that Breed in Avocado Wood in Florida

Laurel wilt is a destructive disease caused by the fungus Raffaelea lauricola, which is transmitted by the invasive redbay ambrosia beetle, Xyleborus glabratus. Here we document ambrosia beetles that emerged from wilted avocado trees throughout Florida. In addition, the ambrosia beetle fauna associated with wilted swampbay trees in Miami-Dade was studied. Fourteen species of scolytine beetles were found associated with avocado wood from different parts of Florida. Multiple species of ambrosia beetles were found breeding in avocado and swampbay wood infected by R. lauricola with or without the presence of its primary vector, X. glabratus. Work is under way to determine whether other ambrosia beetle species can carry R. lauricola and transmit this pathogen to healthy avocado and swampbay trees. Resumen: La marchitez del laurel es una enfermedad destructiva causada por el hongo Raffaelea lauricola, el cual es transmitido por el escarabajo de ambrosia, Xyleborus glabratus. Se presenta un registro de las especies de escarabajos de ambrosia que emergieron de arboles de aguacate marchitos, colectados en diferentes partes de Florida. Tambien se estudio la fauna de escarabajos de ambrosia asociados a Persea palustris en el condado de Miami-Dade. Catorce especies de escarabajos de ambrosia fueron encontradas reproduciendose en madera de aguacate en diferentes partes de Florida. Varias especies de escarabajos de ambrosia se encontraron en arboles infectados con R. lauricola. Sin embargo, su principal vector, X. glabratus, no se encontro en todos los arboles infectados. Se esta trabajando para determinar si otras especies de escarabajos de ambrosia pueden transmitir este patogeno a plantas sanas de aguacate y P. palustris.View this article in BioOne