Twig beetles, Pityophthorus spp. (Coleoptera: Scolytidae), as vectors of the pitch canker pathogen in California

AbstractTwig beetles in the genus Pityophthorus Eichhoff are known to be associated with the pitch canker pathogen, Fusarium circinatum, in California. Phoresy of the pathogen on these species has been reported to occur when insects emerge from diseased branches and when they infest disease-free, cut branch tips. To demonstrate that twig beetles can vector the pathogen, studies of phoresy and transmission were conducted in a native Monterey pine, Pinus radiata D. Don (Pinaceae), forest. Phoresy was confirmed for both Pityophthorus setosus Blackman and Pityophthorus carmeli Swaine, and P. setosus was shown to vector the pitch canker pathogen when contaminated with fungal spores and caged onto Monterey pine branches. When attractive baits were used to increase visitation to Monterey pines by P. setosus, baited trees were more likely to develop pitch canker than unbaited trees even though the beetles did not tunnel into the host to develop egg galleries. Therefore, twig beetles are competent as vectors of the pitch canker pathogen, and their vectoring activity, though requiring a wound, does not require that they establish egg galleries in the host.

Download Full-text

Effects of pitch canker pathogen on gallery excavation and oviposition by Ips paraconfusus (Coleoptera: Scolytidae)

The Canadian Entomologist ◽

10.4039/ent134519-4 ◽

2002 ◽

Vol 134 (4) ◽

pp. 519-528 ◽

Cited By ~ 4

Author(s):

Andrew J. Storer ◽

David L. Wood ◽

Thomas R. Gordon

Keyword(s):

Pinus Radiata ◽

Ips Paraconfusus ◽

Multiple Infections ◽

Pitch Canker ◽

Fusarium Circinatum ◽

Monterey Pine ◽

Naturally Occurring ◽

Canker Pathogen ◽

Negative Effect ◽

The Mean

AbstractIps paraconfusus Lanier is a vector of the pitch canker fungus, Fusarium circinatum Nirenberg and O’Donnell, in California. Multiple infections of Monterey pine, Pinus radiata D. Don. (Pinaceae), branches and main stems appear to predispose trees to infestation by I. paraconfusus. The effect of cankers produced in response to F. circinatum on oviposition and gallery construction was investigated. Introduction of beetles into artificially induced or naturally occurring cankers was less likely to result in oviposition and resulted in shorter galleries than introductions into logs without cankers. Of all adults that produced eggs, the mean number of eggs per adult was no different in logs with cankers than in canker-free logs; however, the distance across the grain from the introduction point to the first egg was greater for adults introduced into cankers than for adults introduced away from cankers. These results indicate that the pitch canker pathogen has a negative effect on I. paraconfusus, as cankers produced in response to the pathogen are unsuitable for exploitation by the insect.

Download Full-text

Incidence of the pitch canker pathogen and associated insects in intact and chipped Monterey pine branches

The Canadian Entomologist ◽

10.4039/ent13447-1 ◽

2002 ◽

Vol 134 (1) ◽

pp. 47-58 ◽

Cited By ~ 18

Author(s):

William R. McNee ◽

David L. Wood ◽

Andrew J. Storer ◽

Thomas R. Gordon

Keyword(s):

Temporal Variation ◽

Pinus Radiata ◽

Pitch Canker ◽

Fusarium Circinatum ◽

Coastal Site ◽

Monterey Pine ◽

Canker Pathogen ◽

The Mean ◽

Emerging Insects

AbstractIn a 2-year study of Monterey pine, Pinus radiata D. Don (Pinaceae), infected with pitch canker, caused by Fusarium circinatum Nirenberg and O'Donnell, less than 2% of symptomatic branches with green foliage were colonized by twig beetles in the genus Pityophthorus Eichhoff (Coleoptera: Scolytidae), whereas approximately 50% of branches with yellow and red foliage were colonized. More Pityophthorus spp. emerged from yellow branches (mean ± SE = 12.1 ± 1.7 per 30 cm) than from red branches (6.9 ± 0.9) at an inland study site (Oakland) but, at a coastal site (Pebble Beach), the means were not significantly different (4.3 ± 0.6 and 3.8 ± 0.7). The mean phoresy rate of all emerging insects was higher at Pebble Beach (17.7 ± 0.6%) than at Oakland (5.3 ± 0.2%). At both sites, there was considerable temporal variation in the proportion of branches colonized by twig beetles, mean numbers of emerging twig beetles, and phoresy rates of emerging insects. Chipping branches reduced the emergence of Pityophthorus spp. and associates by approximately 95%, compared with emergence from intact branches. The pathogen was isolated from 1-year-old branches and chips in up to 68% of samples, but was only recovered from 3-year-old branches in 1 of 46 sampled. It is recommended that recent branch cuttings and chips originating from symptomatic trees not be transported to areas that are believed to be free of the disease.

Download Full-text

Detection and Quantification of Airborne Conidia of Fusarium circinatum, the Causal Agent of Pine Pitch Canker, from Two California Sites by Using a Real-Time PCR Approach Combined with a Simple Spore Trapping Method

Applied and Environmental Microbiology ◽

10.1128/aem.70.6.3512-3520.2004 ◽

2004 ◽

Vol 70 (6) ◽

pp. 3512-3520 ◽

Cited By ~ 122

Author(s):

Wolfgang Schweigkofler ◽

Kerry O'Donnell ◽

Matteo Garbelotto

Keyword(s):

Real Time ◽

Filter Paper ◽

Real Time Pcr ◽

Fungal Spores ◽

Seasonal Fluctuation ◽

Selective Medium ◽

Pitch Canker ◽

Fusarium Circinatum ◽

Intergenic Spacer Region ◽

Monterey Pine

ABSTRACT Pinus radiata (Monterey pine), a tree native to coastal California and Mexico, is widely planted worldwide for timber production. A major threat to Monterey pine plantations is the fungal disease pine pitch canker, caused by Fusarium circinatum (Hypocreales). We present a novel trapping approach using filter paper in combination with a rapid molecular method to detect the presence of inoculum in the air. The assay is also useful for diagnosing the presence of the pathogen on plants. The test is based on the F. circinatum specific primer pair CIRC1A-CIRC4A, which amplifies a 360-bp DNA fragment in the intergenic spacer region of the nuclear ribosomal operon. Real-time PCR was used to calculate the number of fungal spores present in each reaction mixture by comparing the threshold cycle (Ct) of unknown spore samples to the Ct values of standards with known amounts of F. circinatum spores. The filter paper method allows prolonged and more sensitive spore sampling in the field compared to traditional traps using petri dishes filled with selective medium. A field test at two sites in coastal California infested with pine pitch canker was carried out during the summer and fall of 2002. Spore counts were in the range of ca. 1 Ã¯Â¿Â½ 103 to ca. 7 Ã¯Â¿Â½ 105/m2, with the highest spore counts in the fall, suggesting a seasonal fluctuation.

Download Full-text

The role of Pityophthorus spp. as vectors of pitch canker affecting Pinus radiata

The Canadian Entomologist ◽

10.4039/n07-022 ◽

2007 ◽

Vol 139 (6) ◽

pp. 864-871 ◽

Cited By ~ 23

Author(s):

Joyce M. Sakamoto ◽

Thomas R. Gordon ◽

Andrew J. Storer ◽

David L. Wood

Keyword(s):

Relative Humidity ◽

Pinus Radiata ◽

Low Temperatures ◽

Native Species ◽

Field Experiments ◽

Infection Frequency ◽

Pitch Canker ◽

Monterey Pine ◽

Canker Pathogen

AbstractThe fungus Fusarium circinatum Nirenberg and O’Donnell (Hypocreaceae) causes pitch canker, a disease affecting pines worldwide. In California, many native insect species have been implicated in transmission of F. circinatum. This study showed that two twig beetle species, Pityophthorus setosus Blackman and Pityophthorus carmeli Swaine (Coleoptera: Curculionidae: Corthylini), can make wounds on healthy Monterey pine (Pinus radiata D. Don (Pinaceae)) branches that are suitable for infection by the pitch canker pathogen. Because these two species are not known to engage in maturation feeding and the observed wounds were not associated with tunneling, we hypothesize that the wounds reflect “exploratory tasting” to assess the suitability of the substrate for colonization. This behavior would help to explain how twig beetles can serve as wounding agents on healthy host branches, which are not amenable to colonization by these insects. We tested two specific hypotheses: (1) two native species of Pityophthorus can create wounds on F. circinatum-contaminated trees that are sufficient for development of disease; and (2) the efficiency with which F. circinatum infects beetle wounds is affected by relative humidity. Under growth-chamber conditions, both Pityophthorus species indulged in exploratory behavior that caused wounds suitable for development of pitch canker. Field experiments did not confirm a significant effect of beetle activity on infection frequency, perhaps because of an overall low infection rate due to low temperatures. Experiments conducted under controlled conditions documented a significant effect of relative humidity on the success rate of twig beetle-initiated infections.

Download Full-text

Projecting Monterey Pine (Pinus radiata) Populations over Time in the Presence of Various Representations of Pitch Canker Disease, Caused by Fusarium circinatum

Forests ◽

10.3390/f10050437 ◽

2019 ◽

Vol 10 (5) ◽

pp. 437

Author(s):

Gregory J. Reynolds ◽

Thomas R. Gordon ◽

Neil McRoberts

Keyword(s):

Pinus Radiata ◽

Transition Probabilities ◽

Transition Probability ◽

Initial Population ◽

Native Forest ◽

Pitch Canker ◽

Fusarium Circinatum ◽

Projection Model ◽

Size Classes ◽

Monterey Pine

Monterey pine (Pinus radiata D. Don) is native to California and widely planted in Mediterranean climates around the world. Pitch canker, a disease caused by Fusarium circinatum Nirenberg and O’Donnell, is a serious threat to P. radiata in native forests and in plantations. Because of its economic importance worldwide, conservation of P. radiata native populations is a high priority. We developed a demographic matrix projection model to simulate dynamics of naturally occurring P. radiata populations in California in the presence of the disease. Tree demography data for the model were collected from seven sites in a native forest on the Monterey Peninsula. Height and stem diameter were recorded for all trees, which were divided into five size classes based on these data. Transition probabilities were calculated for each size class; cone production, seed release, and seed transition probability were estimated using an iterative search process. In the model, pitch canker influences state-specific fecundity and survival probabilities. Five different approaches to include these effects were compared. Populations were projected over 50 decades from three specified initial population sizes. Elasticity analysis indicated that facilitating survival of all size classes is vital to maintaining the structure of the forest.

Download Full-text

ASSOCIATION BETWEEN A NATIVE SPITTLEBUG (HOMOPTERA: CERCOPIDAE) ON MONTEREY PINE AND AN INTRODUCED TREE PATHOGEN WHICH CAUSES PITCH CANKER DISEASE

The Canadian Entomologist ◽

10.4039/ent130783-6 ◽

1998 ◽

Vol 130 (6) ◽

pp. 783-792 ◽

Cited By ~ 22

Author(s):

Andrew J. Storer ◽

David L. Wood ◽

Karen R. Wikler ◽

Thomas R. Gordon

Keyword(s):

Pinus Radiata ◽

Spore Suspension ◽

Field Observations ◽

Pitch Canker ◽

Canker Disease ◽

Feeding Sites ◽

Monterey Pine ◽

Canker Pathogen ◽

Monterey Peninsula

AbstractJuvenile Monterey pines, Pinus radiata D. Don (Pinaceae), in a native stand on the Monterey Peninsula, California, exhibited wilted green shoots in the spring of 1996. The pitch canker fungus, Fusarium subglutinans (Wollenweb. & Reinking) P.E. Nelson, Toussoun & Marasas f.sp. pini, was subsequently isolated from 95% of these shoots. Spittle masses produced by Aphrophora canadensis Walley were observed on the symptomless shoots of many of these trees. The pitch canker fungus was isolated from the feeding sites of this insect on 55% of symptomless shoots, and from shoot sections adjacent to these feeding sites on 29% of the shoots. Shoots with spittlebugs feeding on them in May 1996 were more likely to develop pitch canker disease by September 1996 and March 1997 than shoots without spittlebugs. Shoots with spittle masses in March 1997 were as likely to develop pitch canker disease by May and August 1997 as shoots without spittle masses, but the origin of the infection was most likely where A. canadensis feeding had taken place. In a controlled test, the incidence of pitch canker on shoots of potted Monterey pines was dependent on the presence of a spittlebug and a spore suspension of the pathogen. Thus, both field observations and controlled studies show an association between native A. canadensis and the introduced pitch canker pathogen. The role of A. canadensis in the epidemiology of pitch canker disease remains to be determined.

Download Full-text

Sequence characterized amplified polymorphic markers for the pitch canker pathogen, Fusarium circinatum

Molecular Ecology Notes ◽

10.1046/j.1471-8286.2002.00324.x ◽

2002 ◽

Vol 2 (4) ◽

pp. 577-580 ◽

Cited By ~ 11

Author(s):

H. Britz ◽

B. D. Wingfield ◽

T. A. Coutinho ◽

M. J. Wingfield

Keyword(s):

Polymorphic Markers ◽

Pitch Canker ◽

Fusarium Circinatum ◽

Canker Pathogen

Download Full-text

Assessment of Pathogenic Variation against Pitch Canker Pathogen, Fusarium circinatum in Pinus thunbergii and Responses of Natural Selection Pinus × rigitaeda to Branch Inoculation in a Seed Orchard

The Plant Pathology Journal ◽

10.5423/ppj.2010.26.4.299 ◽

2010 ◽

Vol 26 (4) ◽

pp. 299-305 ◽

Cited By ~ 2

Author(s):

Kwan-Soo Woo ◽

Jun-Hyuck Yoon ◽

Sang-Urk Han ◽

Chang-Soo Kim

Keyword(s):

Natural Selection ◽

Seed Orchard ◽

Pinus Thunbergii ◽

Pitch Canker ◽

Fusarium Circinatum ◽

Canker Pathogen ◽

Pathogenic Variation

Download Full-text

Monterey pine forest made a remarkable recovery from pitch canker

California Agriculture ◽

10.3733/ca.2020a0019 ◽

2020 ◽

Vol 74 (3) ◽

pp. 169-173

Author(s):

Gordon Thomas R. ◽

Reynolds Gregory J. ◽

Kirkpatrick Sharon C. ◽

Storer Andrew J. ◽

Wood David L. ◽

...

Keyword(s):

Pinus Radiata ◽

Rapid Progression ◽

Native Forest ◽

Pitch Canker ◽

Santa Cruz ◽

Monterey Pine ◽

Native Populations ◽

Remarkable Recovery ◽

Monterey Peninsula ◽

Observation Period

Monterey pine (Pinus radiata) is a species of limited distribution, with three native populations in California. In 1986, a disease known as pitch canker, caused by the fungus Fusarium circinatum, was identified as the cause of extensive mortality in planted Monterey pines in Santa Cruz County. Monitoring studies on the Monterey Peninsula documented rapid progression of the disease in the native forest during the 1990s, with most trees sustaining some level of infection. However, between 1999 and 2013, the severity of pitch canker stabilized, with many previously diseased trees then free of symptoms, and plots monitored between 2011 and 2015 documented a steady decline in the occurrence of new infections. Consequently, whereas pitch canker was once a conspicuous visual blight in the forest, by the end of the observation period, symptomatic trees had become a rarity. The arrested development of pitch canker is suggestive of a reduction in the frequency and duration of fog near the coast, which provides conditions necessary for the pathogen to establish infections.

Download Full-text