Qualitative Examination of the Hypersensitive Response of Loblolly Pine, Pinus taeda L., Inoculated with Two Fungal Associates of the Southern Pine Beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Scolytidae)

by Dr. Molly Darr | Jun 17, 2022 | 1981-1990 Publications

Abstract

Loblolly pine, Pinus taeda L., responded to wounding and wounding plus inoculation with two fungal associates of the southern pine beetle (SPB), Dendroctonus frontalis Zimmermann by forming a hypersensitive reaction zone around the wound sites. There was a significant difference in the length of the reaction produced depending upon treatments. A simple mechanical wound produced a shorter lesion than a wound accompanied by inoculation with Ceratocystis minor (Hedgecock) Hunt var. barrussi Taylor which produced a shorter lesion than a wound accompanied by a C. minor inoculation. There was a significant change in monoterpene composition and a significant decrease in soluble sugars present in the hypersensitivereaction zones compared with unwounded phloem, but there were no differences in these parameters between the reaction zones resulting from the two fungal inocula. The overall response of the trees to invasion by SPB fungal associates was a compositional change in potential toxins (monoterpenes) accompanied by a decrease in potential nutrients (soluble sugars) in the area directly surrounding the wound site. Also, the more virulent invader appeared to evoke a stronger response (lesion length) by the trees.

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Comparison of Loblolly and Shortleaf Pine Bolts as Hosts of the Southern Pine Beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Scolytidae)

by Dr. Molly Darr | Jun 17, 2022 | 1981-1990 Publications

Abstract

Southern pine beetle, Dendroctonus frontalis Zimmermann, adults were introduced to 2-m bolts of loblolly, Pinus taeda L., and shortleaf pine, P. echinata Mill., to determine the effect of host species on the beetle’s reproductive potential. A multivariate analysis of variance test revealed significant differences in parent gallery characteristics between host species. Although the average distance between egg niches was similar in both species, the average parent gallery was almost 90 mm longer in the shortleaf bolts. No statistically significant differences were found in average brood survival or average brood length. However, loblolly pine bolts consistently produced more brood adults. The sex ratio of emerged brood was not significantly different from 1:1 for either host species..

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Ceratocystiopsis ranaculosus sp. nov. Associated with the Southern Pine Beetle

by Dr. Molly Darr | Jun 17, 2022 | 1981-1990 Publications

Abstract

Most bark beetles carry bluestaining fungi of the genera Ceratocystis, Ceratocystiopsis, or Ophiostoma, which are thought to be important to the success of beetles (Whitney, 1984). Among aggressive bark beetles of the genus Dendroctonus, fungi are thought to be pathogens, enabling beetles to overcome otherwise healthy trees (Berryman, 1972). The southern pine beetle, Dendroctonus frontalis Zimmermann, usually carries Ceratocystis minor (Hedgcock) Hunt. This fungus is pathogenic to pines and is thought to create conditions within the trees conducive to beetle development (Blanche et al., 1983). However, southern pine beetle infestations without C. minor have recently been documented (Bridges et al. 1985). These findings suggest that C. minor is not necessary for southern pine beetle development as previously thought. Because fungi other than C. minor may be responsible for tree death, studies were conducted to identify fungi associated with the southern pine beetle. During these studies, a new species of Ceratocystiopsis was discovered and is described herein.

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BRIDGES, JR, and TJ PERRY. 1987. “CERATOCYSTIOPSIS-RANACULOSUS SP-NOV ASSOCIATED WITH THE SOUTHERN PINE-BEETLE.” Mycologia79 (4): 630–33. https://doi.org/10.2307/3807605.

Relationship of Phoretic Mites (Acari: Tarsonemidae) to the Bluestaining Fungus~ Ceratocystis minor, in Trees Infested by Southern Pine Beetle (Coleoptera: Scolytidae)

by Dr. Molly Darr | Jun 17, 2022 | 1981-1990 Publications

Abstract

Amount of bluestain caused by Ceratocystis minor (Hedgcock) Hunt in trees infested with the southern pine beetle (SPB), Dendroctonus frontalis Zimmermann, was measured in three Texas and Louisiana forests. It was significantly correlated with number of Tarsonemus krantzi Smiley & Moser, a mite phoretic on SPB. Significantly less bluestain and significantly fewer mites were found in certain Texas infestations where SPB outbreak was most severe.

Keywords

Dendroctonus frontalis, Tarsonemus krantzi, Tarsonemus ips, Ceratocystis
minor

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BRIDGES, JR, and JC MOSER. 1986. “RELATIONSHIP OF PHORETIC MITES (ACARI, TARSONEMIDAE) TO THE BLUESTAINING FUNGUS, CERATOCYSTIS-MINOR, IN TREES INFESTED BY SOUTHERN PINE-BEETLE (COLEOPTERA, SCOLYTIDAE).” Environmental Entomology15 (4): 951–53. https://doi.org/10.1093/ee/15.4.951.

Prevalence of Unikaryon minutum (Microsporida: Nosematidae) Infection in Outbreak Populations of the Southern Pine Beetle (Coleoptera: Scolytidae)

by Dr. Molly Darr | Jun 16, 2022 | 1981-1990 Publications

Abstract

Unikaryon minutum is a microsporidian parasite of the southern pine beetle, Dendroctonus frontalis. It infects muscle tissue, the alimentary tract, Malphighian tubules, and fat body of larvae and adult beetles (J. D. Knell and G. E. Allen, Acta Protozool. 17, 271-278, 1978). The effects
of U. minutum on southern pine beetle population dynamics are not known, although most beetle populations examined have been infected.

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