Testing of selected South African Pinus hybrids and families for tolerance to the pitch canker pathogen, Fusarium circinatum

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.

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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.

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

The Canadian Entomologist ◽

10.4039/n03-118 ◽

2004 ◽

Vol 136 (5) ◽

pp. 685-693 ◽

Cited By ~ 34

Author(s):

Andrew J. Storer ◽

David L. Wood ◽

Thomas R. Gordon

Keyword(s):

Pinus Radiata ◽

Fungal Spores ◽

Pitch Canker ◽

Fusarium Circinatum ◽

Monterey Pine ◽

Canker Pathogen ◽

Disease Free

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.

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