METHODS FOR AND COMPARISON OF SAMPLING SCHEMES FOR ESTIMATING WITHIN TREE SOUTHERN PINE BEETLE POPULATIONS (COLEOPTERA: SCOLYTIDAE)

1978 ◽  
Vol 110 (10) ◽  
pp. 1015-1022 ◽  
Author(s):  
T. E. Nebeker ◽  
O. P. Hackney ◽  
R. R. Hocking ◽  
M. Paz ◽  
J. H. Lashomb
Keyword(s):  
Surface Area ◽  
Relative Efficiency ◽  
Southern Pine Beetle ◽  
Optimal Sampling ◽  
Unit Size ◽  
Southern Pine ◽  
Beetle Population ◽  
Sampling Schemes ◽  
Pine Beetle ◽  
Measure Of Performance

AbstractNine sampling units for estimating southern pine beetle population within a tree are compared according to unit size, strata size, and number and type of sampling allocation. As a measure of performance of different sampling schemes or different unit sizes the ratio of the variances of the estimate is used, i.e. relative efficiency.Relative efficiency decreases as unit size increases, where equal surface area is sampled. Unequal stratification, which allocates smaller area to the upper and lower strata, results in higher relative efficiencies than equal stratification. Thus, unequal stratification is recommended. Samples should be allocated to these strata according to the optimal sampling ratios.

Southern Pine Beetle: Factors Influencing the Growth and Decline of Summer Infestations in East Texas

1979 ◽  
Vol 25 (4) ◽  
pp. 547-556
Author(s):  
Roy L. Hedden ◽  
Ronald F. Billings
Keyword(s):  
Basal Area ◽  
Population Level ◽  
Dendroctonus Frontalis ◽  
Southern Pine Beetle ◽  
Forest Site ◽  
East Texas ◽  
Southern Pine ◽  
Beetle Population ◽  
Pine Beetle ◽  
Stand Basal Area

Abstract The influence of selected forest site and stand factors on the rate of expansion of individual infestations (spots) of southern pine beetle (Dendroctonus frontalis) was studied during the summer months of 1975-77 in east Texas. In small spots (≤20 active trees), further expansion seldom occurred, presumably due to an insufficient quantity and distribution of brood to perpetuate necessary pheromone production. Similarly, the proportion of spots that had declined to less than 20 active trees after 1 month (day 30) was inversely related to number of active trees at first visit (day 0). In expanding spots, the number of additional trees killed per day was significantly and positively correlated with number of active trees per spot and stand basal area. In addition, mean rates of summer spot growth varied among years in direct relation to areawide beetle population levels in east Texas which increased to outbreak levels and then collapsed over the 3-year study period. This emphasizes the need to include some measure of beetle population level and/or aggressiveness in future spot growth models. No correlation was found between number of brood trees per spot at the first visit and stand basal area at the spot origin. These findings support the following hierarchy of priorities for direct control: Priority 1--spots with >100 active trees, even in sparse stands; Priority 2--spots with 20-100 active trees in high basal area stands; Priority 3--spots with 20-100 active trees in low basal area stands; Priority 4--spots with ≤20 active trees. During the summer, small spots, particularly those lacking freshly attacked trees (pheromone source), have a high probability of soon going inactive without control. Forest Sci. 25:547-556.

scholarly journals Contrasting Competitor and Predator Responses to a Short-Lived Southern Pine Beetle Outbreak: A Case Study

2020 ◽  
Author(s):  
Stephen R Clarke ◽  
Jessica Hartshorn
Keyword(s):  
Natural Enemy ◽  
Bark Beetles ◽  
Southern Pine Beetle ◽  
National Forest ◽  
Population Fluctuations ◽  
Thanasimus Dubius ◽  
Southern Pine ◽  
Widespread Application ◽  
Pine Beetle

Abstract The southern pine beetle (SPB) Dendroctonus frontalis Zimmermann, is the most important insect pest of pines in the southeastern United States, with outbreaks often resulting in thousands of hectares of pine mortality. Natural enemies and competitors have been cited as significant regulators of SPB populations and, therefore, outbreaks. A recent outbreak on the Homochitto National Forest (NF) in Mississippi provided an opportunity to undertake a case study comparing population fluctuations of SPB, its major predator Thanasimus dubius, and its competitors, Ips bark beetles. Trap catches of all three were tracked through the course of the outbreak on the Homochitto NF as well as in two other forests with low or no SPB activity. The number of predators collected initially increased on the Homochitto NF in response to the SPB outbreak, but their impact on reducing infestation numbers was unclear. Numbers of Ips trapped were similar across all three forests, indicating that other factors were regulating SPB populations. The outbreak only lasted a single year, and its brevity likely limited the availability of host resources for natural enemy and competitor populations. Additional studies are warranted to explore the mechanisms affecting the extent and duration of SPB outbreaks, such as active forest management. Study Implications: The widespread application of cut-and-leave treatments during a short duration southern pine beetle (SPB) outbreak on the Homochitto National Forest did not result in immediate increased collections of Ips bark beetles, competitors of SPB. Similar population trends of Ips bark beetles in areas with and without SPB infestations suggest that other factors, such as climate, regulate population numbers. Low numbers of the main SPB predator, Thanasimus dubius, immediately preceded an outbreak, and trap collections increased after outbreak onset, reaffirming the importance of this natural enemy in SPB population fluctuations.

Southern pine beetle: Enhancement or inhibition of aggregation response mediated by enantiomers of endo-brevicomin

1985 ◽  
Vol 72 (2) ◽  
pp. 99-100 ◽  
Author(s):  
J. P. Vit� ◽  
R. F. Billings ◽  
C. W. Ware ◽  
K. Mori
Keyword(s):  
Southern Pine Beetle ◽  
Southern Pine ◽  
Aggregation Response ◽  
Pine Beetle
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