Solar treatments for reducing survival of mountain pine beetle in infested ponderosa and lodgepole pine logs

Abstract

Three experiments were conducted to evaluate the use of solar radiation for reducing survival of mountain pine beetle populations in infested logs. Ponderosa pine logs were used in experiments 1 and 2 and lodgepole pine logs were used in experiment 3. Experiment 1 comprised three treatments: (1) one-layer solar treatment without plastic sheeting and logs rotated one-third of a turn once a week; (2) two-layer solar treatment with plastic sheeting; and (3) two-layer solar treatment without plastic sheeting. For experiment 2, two additional one-layer treatments were added: one-layer treatment with plastic sheeting and no rotation and a one-layer with no plastic sheeting and no rotation. Experiment 3 included all the above-mentioned onelayer treatments only. For all experiments, brood density per 0.05 m 2 (0.5 ft 2 ) was estimated before and after treatment and analyzed using repeated measures analysis of variance. Subcortical temperatures were monitored in one replicate of all treatments in all experiments. In experiment 2, phloem moisture was monitored before and after treatment in uninfested logs. All treatments in all experiments caused drastic reductions in brood survival. In experiment 1, the one-layer treatment with the logs rotated once a week significantly reduced brood survival compared to the two-layer without plastic sheeting treatment but was not different from the two-layer with plastic sheeting treatment. There were no differences in brood survival after treatment associated with any treatments in experiments 2 and 3. In all experiments brood survival was consistently reduced in the aspects of the logs exposed to the sun. Maximum temperatures were consistently higher in the treatments with plastic sheeting, the exposed surfaces of the logs to the sun, and the upper layer of logs in the two-layer treatments. No differences were detected in phloem moisture content in uninfested logs before and after treatment in experiment 2, suggesting that heat is directly responsible for the observed reductions in survival. We conclude that solar treatments are an effective alternative for reducing mountain pine beetle survival in infested ponderosa and lodgepole pine logs.

The South Dakota Pine Bark Beetle Caper

“…They can fell the infested trees and either debark them or remove them to a location at least 2 miles away. They can bag every log in plastic and attempt to kill the larvae by solarization [8] (very impractical). They can use large quantities of poor insecticides on their entire stands, or Verbenone patches in an attempt to repel beetles.…”

Diesel fuel oil for increasing mountain pine beetle mortality in felled logs

“…Thus, the two-layer treatment was just as effective as the one-layer treatment with respect to mortality on the bottom surfaces. Because Negron et al (2001) have shown that survival can be substantial on the upper surfaces of bolts in the lower layer in the two-layer solar treatment, the one-layer fuel oil treatment is probably preferable in order to gain the benefit of solar radiation on the upper surface and thus maximize mortality from the fuel oil and solar radiation on the entire circumference.…”

“…The physical arrangement of the bolts was similar to the design used in the solar treatment study by Negron et al (2001) so that comparisons could be made between the results of the 2 studies.…”

“…After application of the fuel oil, the north sides of the bolts were placed so that they faced the ground. This orientation was performed because: 1) previous observations indicated that densities of MPB brood are usually greater on the north sides (Schmid 1972a), and 2) work in 1999 by Negron et al (2001) MPB densities in bolt surfaces directly exposed to the sun would suffer substantial mortality. While increasing mortality through solar radiation is desirable, the effectiveness of the fuel oil treatment might have been confounded by solar-caused mortality.…”

“…Sanitation logging of infested trees (McMillin and Allen 1999), felling and burning infested trees (Evenden et al 1943, McMillin andAllen 1999), felling infested trees and exposing them to solar radiation (Leatherman 2001, Negron et al 2001, felling and peeling off the bark (Evenden et al 1943), and felling and applying lethal chemicals (McCambridge 1972, McCambridge et al 1975) are methods for increasing MPB mortality. Sanitation logging may be useful only where the number of infested trees is large enough to make logging profitable.…”