Colopterus Truncatus Research Articles

Imitation of fermenting fruits in beetle-pollinated Calycanthus occidentalis (Calycanthaceae)

Calycanthus (Calycanthaceae), a genus for which three species are described, belongs to an early diverging lineage of angiosperms. As far as known, all species have highly specialized sap beetle (Nitidulidae) pollination systems. While the floral scent is likely to play a key role in attracting the beetles to the flowers, its chemistry is not known for any of the species of this genus. Herein, we analyzed the floral scent of the species Calycanthus occidentalis by dynamic headspace and gas chromatography / mass spectrometry (GC/MS), and determined its floral visitors in plants cultivated in the Botanical Garden of the University of Ulm. The protogynous flowers had one-to-two days lasting anthesis, similar to what was previously reported for native stands in California. More than ten pollinating beetle species, mainly Nitidulidae and Staphylinidae, were collected from the floral chambers of pistillate-stage flowers and identified to species level by DNA barcoding. The high number of beetle species inside the flowers was surprising, especially considering that only the nitidulid species Colopterus truncatus was known so far as pollinator in native habitats. In addition, we observed some drosophilid flies on, but not inside the flowers, which suggests that they are not pollinators. The scent of flowers had a strong alcoholic note, especially in the pistillate phase. The GC/MS data revealed that the most prominent scent compounds were ethanol, ethyl acetate, acetoin, 2,3-butanediol isomers, acetoin acetate, 2,3-butandiol monoacetate, and 2,3-butandiol diacetate. Interestingly, besides scent compounds that were previously found in plants pollinated by nitidulid and staphylinid beetles, some other compounds, including acetoin acetate and 2,3-butandiol monoacetate, were observed for the first time as floral scent of plants attracting such beetles. However, further studies will be required to investigate whether the stereoisomeric pattern of these compounds differs among plant species and whether the stereoisomers attract different pollinator species. Overall, the scent of C. occidentalis is similar to that of other plant species that release scents reminiscent of fermenting fruits and are pollinated by beetles and/or drosophilid flies, such as Asimina triloba, Ceropegia crassifolia and Arum palaestinum.

Assessing the climate suitability and potential economic impacts of Oak wilt in Canada

We assess risks posed by oak wilt—a disease caused by the fungal pathogen Bretziella fagacearum. Though not currently found in Canada, our distribution models indicate that suitable climate conditions currently occur in southern Ontario for B. fagacearum and two of its main insect dispersal vectors, Colopterus truncatus and Carpophilus sayi. Climate habitat for these species is projected to expand northward under climate change, with much of the oak range in eastern Canada becoming climatically suitable within the next two decades. Potential costs for the removal and replacement of oak street trees ranged from CDN$266 to $420 million, with variation related to uncertainty in costs, rate of tree replacement, and city-level estimates of oak street tree density. The value of standing oak timber in eastern Canada was estimated at CDN$126 million using provincial stumpage fees and as a CDN$24 million annual contribution to national Gross Domestic Product (GDP) when calculated using a combination of economic and forestry product statistics. These values can help inform the scale of eradication and/or management efforts in the event of future oak wilt introductions.

Sap Beetles (Coleoptera: Nitidulidae) in Oak Forests of Two Northeastern States: A Comparison of Trapping Methods and Monitoring for Phoretic Fungi.

Oak wilt is slowly expanding in the northeastern United States. Several nitidulid beetle species are known vectors of the fungus [Bretziella fagacearum (Bretz) Z. W. De Beer, Marinc., T. A. Duong, and M. J. Wingf (Microascales: Ceratocystidaceae)] that causes this disease, acquiring spores from fungal mats on infected trees and transmitting them to uninfected trees. Survey and fungal isolation from captured nitidulid beetles could be an important tool for detecting the presence of this disease in a geographic area not previously known to have oak wilt. In preparation for monitoring activities in such areas, two trapping studies were conducted in the northeastern United States: 1) trap test comparing the efficacy of wind-oriented pipe, multiple-funnel, and modified pitfall traps for nitidulids and 2) wet and dry collection cup comparison. Lures were a combination of nitidulid pheromones and fermenting liquid. Results support the use of multiple-funnel traps over the other two trap types, for both targeted species-specific surveys and community sampling. More total nitidulids, Colopterus truncatus (Randall), and Glischrochilus fasciatus (Olivier) were captured in wet collection cups compared with dry cups. Twenty-seven fungal species were isolated, none of which were B. fagacearum. Many fungi isolated from beetles were plant pathogens, indicating that in addition to the oak wilt fungus, sap beetles may contribute to the spread of other plant diseases.

Seasonal and Regional Distributions, Degree-Day Models, and Phoresy Rates of the Major Sap Beetle (Coleoptera: Nitidulidae) Vectors of the Oak Wilt Fungus, Bretziella fagacearum, in Wisconsin

Oak wilt is a lethal disease caused by the invasive fungus Bretziella fagacearum, which is transmitted belowground via root grafts and aboveground by sap beetles (Nitidulidae). Attempts to limit spread and impact of B. fagacearum emphasize limiting harvesting and pruning to periods of vector inactivity. However, there is limited information on sap beetle activity periods, responses to temperature, and phoresy frequencies of fungi. We sampled two major vectors in Wisconsin, Colopterus truncatus and Carpophilus sayi, for 2 yr to quantify their seasonal and geographic abundances. Trapping was performed in 12 oak stands, and beetles were assayed for B. fagacearum. C. truncatus was captured from March until November, peaking during April and May. C. sayi was captured from April until November, peaking in May and July. Relative abundances (N = 15,980) were 59.3% C. truncatus and 40.7% C. sayi. C. sayi was more abundant in southern Wisconsin, whereas C. truncatus was more evenly distributed. Both species were present at asymptomatic sites. All sites with oak wilt centers yielded beetles with viable fungal propagules, with the frequency of association ranging from 1 to 50%. Sites asymptomatic for oak wilt contained both beetle species, but no vector-borne viable pathogen. Degree-day models were constructed to improve the generality of these results and estimate cumulative emergences across a latitudinal range over the previous 10-yr means and extremes. Because activity by C. truncatus and C. sayi spans the seasonal activities of oak wilt vectors, these results can help guide oak management practices.

A Survey of Sap Beetles (Coleoptera: Nitidulidae) in Strawberry Fields in West Central Florida

Nine species of sap beetles (Nitidulidae) were collected in pitfall traps and during whole plant examinations in strawberry fields during the 1994–95, 1999 and 2000 seasons in the strawberry production area of eastern Hillsborough County, Florida. Haptoncus luteolus (Erichson), Lobiopa insularis (Castelnau) and Carpophilus fumatus Boheman accounted for about 95% of the specimens collected while C. humeralis (F), C. freemani Dobson, C. mutilatus (Erichson), Stelidota geminata (Say), S. ferruginea Reitter and Colopterus truncatus (Randall) each accounted only for ≤ 2% of the specimens.

Nitidulidae (Coleoptera) Found in Flowers of Calycanthus floridus Linnaeus (Laurales: Calycanthaceae) in Northeastern Ohio, U.S.A.

ABSTRACT Attractiveness of sweet shrub flowers, Calycanthus floridus Linnaeus, to species of Nitidulidae was determined from collections made May to mid-July (1991–2004) at the Ohio Agricultural Research and Development Center (OARDC) of the Ohio State University and surrounding areas. A total of 2064 nitidulids were collected, representing 17 species and 9 genera. The most abundant nitidulids collected at OARDC were Carpophilus lugubris Murray (56%), Colopterus truncatus (Randall) (20%) and Carpophilus brachypterus (Say) (15%). The most common nitidulids collected in the surrounding areas were C. truncatus (56%) followed by C. lugubris (28%). The remaining nitidulid species in both areas represented less than 7% of the specimens collected. Our data show a diversity of nitidulid species attracted to C. floridus flowers, with two species accounting for nearly 80% of the nitidulids associated with Calycanthus.

Three Colopterus Beetle Species Carry the Oak Wilt Fungus to Fresh Wounds on Red Oak in Missouri.

Beetles in the family Nitidulidae can transmit the oak wilt fungus, Ceratocystis fagacearum, to fresh wounds on healthy oak trees, leading to infection and disease development. Historically, nitidulid beetles have not been considered important vectors of the pathogen in Missouri. Studies were conducted in the spring of 2005 and 2006 to determine frequencies of nitidulid beetle species contaminated with C. fagacearum visiting fresh wounds on red oak trees in central Missouri. Colopterus truncatus, C. niger, and C. semitectus were the most abundant species collected from fresh wounds and the only species found to be contaminated with Ceratocystis fagacearum. Of 230 beetles assayed for C. fagacearum, 23 yielded the fungus. Contamination frequencies were higher for beetles collected in April than May; no beetles collected in June were contaminated. We hypothesize that Colopterus truncatus, C. niger, and C. semitectus are principal nitidulid beetle vector species in Missouri during spring. The risk for pathogen transmission by these beetles appears to be greatest in April and least in June.

Seasonal Dispersal of the Oak Wilt Fungus by Colopterus truncatus and Carpophilus sayi in Minnesota.

Sap beetles (Nitidulidae) are considered important overland vectors of the oak wilt pathogen, Ceratocystis fagacearum, in the north central United States. Colopterus truncatus and Carpophilus sayi are thought to be the principal sap beetle vectors in Minnesota. Field studies using windoriented funnel traps baited with aggregation pheromones of the insects were conducted during 2 years in east central Minnesota. The studies compared temporal flight dynamics of Colopterus truncatus and Carpophilus sayi from April through October, measured the proportion of dispersing adults of each species carrying viable pathogen propagules, and estimated the populations of contaminated dispersing beetles in oak (Quercus spp.) stands with and without oak wilt. Abundance of Colopterus truncatus peaked in either April or May, but the pathogen was most frequently isolated (20 to 45%) from beetles obtained from oak wilt sites from July through September. However, the highest contaminated insect population (CIP) generally occurred during April and May. Abundance of Carpophilus sayi peaked in October of both years, but the pathogen was most commonly isolated from beetles collected during May and June. The CIP was highest in June. The infective insect potential, as indexed by CIP, was greatest for both species in the spring and was greater for Colopterus truncatus than for Carpophilus sayi.

Sap Beetle Species (Coleoptera: Nitidulidae) Visiting Fresh Wounds on Healthy Oaks During Spring in Minnesota

Abstract Many species of sap beetles have been implicated as vectors of the oak wilt pathogen, (Ceratocystis fagacearum), but the species responsible for most aboveground transmission of the fungus is unknown. The abundance of adult sap beetle species inhabiting <7-day-old, artificially made wounds on healthy oaks during Apr.–June of 2 years in Minnesota, and the frequencies with which viable propagules of the fungi were present on each, were determined. Sap beetles were most abundant on wounds created in May, and 1–3-day-old wounds yielded higher numbers of insects than 4–6-day-old wounds. Of the beetles collected, >95% were Colopterus truncatus and Carpophilus sayi. C. fagacearum was isolated from 75% of 594 adults assayed for the fungus. The average number of viable propagules for pooled data of individuals of each species ranged from <100 to 18,000. Frequencies of fungus isolation differed by days after wounding, study location, and sap beetle species. These results, when coupled with previous findings on predominant species associated with oak wilt fungi mats, support the hypothesis that Co. truncatus and Ca. sayi are the principal sap beetle species transmitting C. fagacearum from diseased to healthy oaks in Minnesota. FOR. SCI. 50(6):757–764.

Semiochemical-mediated flight responses of sap beetle vectors of oak wilt, Ceratocystis fagacearum.

The sap beetle, Colopterus truncatus (Coleoptera: Nitidulidae), is one of the primary vectors of the oak wilt pathogen, Ceratocystis fagacearum, in the north-central United States. Field behavioral assays utilizing various release rates and blends of three methyl-branched hydrocarbon aggregation pheromone components showed that flight responses of this beetle were similar in Illinois and Minnesota populations. In both locations, both sexes of the beetle responded synergistically to a combination of the three-component pheromone and fermenting whole-wheat bread dough. Further, Colopterus truncatus preferred a high release rate over a low release rate of the three-component blend. In both locations, the response of C. truncatus to a simplified version of the pheromone consisting of (2E,4E,6E)-3,5-dimethyl-2,4,6-octatriene (1) and (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6,8-decatetraene (3) was not significantly different from the response to the three-component blend. An experiment in Illinois with all possible combinations of the components demonstrated that the decatetraene (3) was the crucial component in the blend; of all treatments, the maximal response was elicited by 3 + dough. Chipped bark, phloem, and xylem from northern pin oak, Quercus ellipsoidalis, was not attractive to C. truncatus in Minnesota. During a weekly survey over two seasons in Minnesota, C. truncatus flew in response to the three-component pheromone between early April and early July, with the maximum responses coming on May 4, 2000 and April 20, 2001. During both years, more than 98% of the beetles were trapped between April 14 and June 1. During the same survey, Glischrochilus spp. (Nitiduildae) flew during longer periods of the summer, particularly in 2001. The sex ratio of C. truncatus responding during all experiments was female-biased (1.8:1, female-male), which is characteristic of other male-produced coleopteran aggregation pheromones. Other sap beetles that play a minor role in the pathobiology of C. fagacearum also responded in experiments conducted in Minnesota. Carpophilus brachypterus Say was cross-attracted to the two- and three-component blends of the C. truncatus pheromone and dough, whereas two Glischrochilus spp. were attracted to all treatments that contained dough.

Predominant nitidulid species (Coleoptera: Nitidulidae) associated with spring oak wilt mats in Minnesota

Nitidulids are primary vectors of the oak wilt pathogen, Ceratocystis fagacearum (Bretz) Hunt, in the north-central United States. Species of adult nitidulids associated with different ages of oak wilt fungus mats on red oaks (Quercus rubra L. and Quercus ellipsoidalis E.J. Hill) during spring in east-central Minnesota were determined. The exoskeletal surfaces of representative specimens were assayed for the presence and abundance of the pathogen. Six species comprised 94% of 2542 adults, representing at least 12 species, collected between 1994 and 1996. Of these six species, Colopterus truncatus Randall and Epuraea corticina Erichson were the most abundant ones on immature mats (94% of 154 nitidulids). They were also more abundant than the other species on mature mats (77% of 868 nitidulids). Carpophilus sayi Parsons was the most common species (28% of 1134 nitidulids) on aging mats, while Carpophilus sayi and three Glischrochilus species (Glischrochilus sanguinolentus (Oliv.), Glischrochilus fasciatus (Oliv.), and Glischrochilus quadrisignatus Say) were predominant on declining mats (80% of 214 nitidulids). Multiple numbers of individuals of each species were commonly found on the mats. The smaller bodied species, C. truncatus and E. corticina, had the lowest numbers of fungal propagules on their bodies, while the highest incidence and numbers of viable propagules were found for the three largest bodied species (Glischrochilus spp.). These results are important to elucidating the principal nitidulid species involved in successful transmission of the pathogen in Minnesota.

Male-produced aggregation pheromone of Colopterus truncatus: structure, electrophysiological, and behavioral activity

A male-produced aggregation pheromone was demonstrated in Colopterus truncatus Randall (Coleoptera: Nitidulidae) by gas chromatographic comparisons of male and female volatile emissions. Male-specific compounds were identified with coupled gas chromatographic–mass spectrometric (GC-MS) analysis and GC and MS comparison of authentic standards. Physiological activity was evaluated by coupled gas chromatographic–electroantennographic (GC-EAG) recordings, and electroantennographic (EAG) assays of standards. The male-produced volatiles eliciting responses from male and female antennae (and relative abundance) were (2E,4E,6E)-3,5-dimethyl2,4,6-octatriene (1) (1.8), (2E,4E,6E)-4,6-dimethyl-2,4,6-nonatriene (2) (100), and (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6,8-decatetraene (3) (3.3). A fourth male-specific compound, (2E,4E,6E,8E)-4,6,8-trimethyl-2,4,6,8-undecatetraene (4) (0.6) was not EAG-active. EAG dose–response studies showed that the antennae were most sensitive to 2 followed by 3 and 1. Synthetic 2, binary blends of 1 and 3, and tertiary blends of 1, 2, and 3 were highly attractive in the field when synergized with fermenting whole-wheat bread dough. In the field, cross-attraction to the C. truncatus pheromone components was observed for Carpophilus lugubris Murray, C. antiquus Melsheimer, and C. brachypterus Say.

Seasonal Variation of Sap Beetle (Coleoptera: Nitidulidae) Populations in Central Illinois Cornfield—Oak Woodland Habitat and Potential Influence of Weather Patterns

Species of sap beetles present at a central Illinois cornfield—oak woodland habitat were determined by spring to fall collections from can traps baited with fermenting wheat dough and banana. Carpophilus lugubris Murray was the dominant species. Glischrochilus quadrisignatus (Say) and Stelidota geminata (Say) were also collected frequently. Other species collected commonly were C. antiquus Melsheimer, C. freemani Dobson, and Colopterus truncatus Randall, which were generally encountered only in the early spring and late fall. Peak collections of C. lugubris were in late April, early June, and throughout the fall. A similar trend was noted for G. quadrisignatus , but S. geminata only had late spring and fall peaks. The peaks occurred at fairly consistent intervals over all 3yr for G. quadrisignatus and S. geminata , but the spring first generation peak for C. lugubris was retarded by 3–4 wk during 1988. This change in population distribution might have resulted from the long dry period that occurred during this time.

Microenvironmental Measurements for the Dioryctria amatella-zimmermani Complex in Shortleaf Pine. 2. Cone Moisture Content, Cone Utilization, and Food Consumption123

The microenvironmental conditions for existence of Dioryctria spp. in shortleaf pine 2nd-year cones were investigated. The influence of moisture content of cones on diapausing and nondiapausing Dioryctria larvae was considered. Larvae occurred in 2nd-year cones which varied in water content from 15.6% to 78.9%. Diapausing larvae occurred in brown cones where the water content was low. Nondiapausing larvae were found in cones with a wide range of moisture conditions. Cones with high moisture content appeared to be preferred. Diapause in Dioryclria larvae was thought to result from exposure to higher temperatures and greater water stress in the habitat where diapause was noted to occur. Dioryctria spp. utilized approximately 40% by weight and 35% by volume of each 2nd-year cone. Each cone attacked was rendered useless for seed production purposes. Colopterus truncatus Rand occurred in cones which varied greatly in water content.