Arboriculture & Urban Forestry 41(2): March 2015 lenge by beetles (at least 50% of subsamples with activity) and the threshold for treatment effective- ness (no more than 20% of subsamples positive for Ips activity to indicate an effective treatment). Small-Bolt Laboratory Evaluation of Tree Protection Treatments Laboratory evaluations of treatments were con- ducted with SPB and employed methods previously developed for testing tree protection treat- ments with this species (Strom and Roton 2009). Southern pine beetles emerged into refrigerated containers from infested pitch pine bolts taken from the Harding site. Within 48 hours of emer- gence, SPB were separated into groups of 75 and released into plastic and screen containers (~6,900 cm3 ; Pioneer Plastics, Inc., Dixon, Kentucky, U.S.) with small bolts. Beetles were allowed to attack ad libitum for 48 hours, at which time the con- tainers with beetles were placed into refrigerators to suspend their activity until bolt dissections. Three experimental trials were conducted in the laboratory (Table 1). The first two utilized NJ beetles and bolts from the same trees as the field trial in MS. The third laboratory trial used SPB from MS, collected and handled in the same way as the NJ beetles. New Jersey SPB were confined with bolts on May 25, 2012 (72 days posttreat- ment) and May 31, 2012 (78 days posttreatment). For both trials with NJ beetles, the trees were the same and were cut on May 25, 2012, one tree per treatment. The combination of treatments (five) and replicates (two bolts) provided 10 bolts in each trial, four replicate bolts per treatment over the two trials. Beetles from Mississippi were used in the third trial, which began on July 16, 2012 (124 days post treatment), with study trees being cut on July 15, 2012. In this trial, two trees per treatment were used, each donating two bolts to the test. This resulted in 20 bolts (five treatments, two trees per treatment, two bolts per tree, pro- viding four replicate small-bolts per treatment). Evaluation of Bolts Small bolts were evaluated similarly whether expo- sure to SPB took place in the field or in the lab; however, increased replication in the lab allowed more extensive evaluation of treatments. Both field- and lab-exposed bolts were dissected in the 93 laboratory by first removing SPB from the outer bark, where they are oſten found in crevices, and counting them along with those found elsewhere in the container. Bolts were then dissected by par- ing away the outer bark, counting the number of attacks (nuptial chambers and galleries), and mea- suring the total length of adult gallery constructed in the bolt during the exposure period. Parameters for discerning successful versus unsuccessful treat- ments outlined elsewhere (Strom and Roton 2009; Strom and Roton 2011) were adopted with slight revision for this study. Briefly, the interest was to determine treatment efficacy (i.e., the ability of a treatment to achieve a management objective defined a priori). In this case, the desire was to de- termine a probability that a treatment will protect trees from beetle-caused mortality under verifiable pressure (Shea et al. 1984). This cannot be done directly using the methods in this study because tree mortality was not an observation available to researchers. However, treatments were evaluated against a predetermined level of protection, and where sample sizes were sufficient, treatments were also compared. Strom and Roton (2009; 2011) sug- gest that successful protective treatments be iden- tified by one or more of the following criteria: a 95% confidence interval (CI) that includes zero for the average number of attacks for each treatment; fewer than two attacks per bolt; or, for I. avulsus, ≤20% of subsamples positive for beetle activity. For this study researchers revised the CI approach to employ a one-way interval [lower boundary (LB) only] to increase the statistical power for elimi- nating ineffective treatments. This change did not affect the results of this study, but it is believed to be a better approach. For all of these methods it is suggested that a minimum of four to five repli- cate bolts be used to establish each mean and that a predetermined level of beetle activity be observed in control bolts to accept a test as valid (Table 1). For SPB, ≥5 attacks per control bolt was proposed as a minimum threshold for experimental validity, and for I. avulsus, ≥50% of subsamples being posi- tive for activity (Strom and Roton 2009; Strom and Roton 2011). When beetle pressure does not result in these criteria being met on control bolts, the test is not considered valid for treatment inferences. Exposure of beetles to systemic treatments occurs at a different stage in the host selection ©2015 International Society of Arboriculture
March 2015
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
