Date of Graduation

5-2015

Document Type

Thesis

Degree Name

Master of Science in Entomology (MS)

Degree Level

Graduate

Department

Entomology

Advisor/Mentor

Stephen, Frederick M.

Committee Member

Kring, Timothy J.

Second Committee Member

Guldin, James M.

Keywords

Arkansas; Bark beetles; Ips; Pine; Pissodes nemorensis

Abstract

The abundance of the southern pine engraver beetles, Ips avulsus (Eichhoff), I. grandicollis (Eichhoff), and I. calligraphus (Germar), was monitored with pheromone-baited traps in 2012 and 2013 in Arkansas and eastern Texas. Additionally, vehicle-based and comprehensive ground-based surveys were used to estimate and confirm the amount of dead and fading trees in each trapping site. Pine engraver beetles have historically been recognized as secondary invaders of healthy trees, but observations of pine mortality in Texas and Arkansas appeared to correspond with high population densities of Ips spp. Forest sites exhibiting subjectively high or low incidence of Ips-associated mortality in Arkansas and Texas were monitored using short trapping periods in the spring, summer, and fall of 2012 and the spring of 2013. Results of trapping indicated that Ips abundance steadily declined from the start of the study, and I. calligraphus abundance was considerably less than the other two species. Over the course of this study, a total of 127,823 I. avulsus, 217,636 I. grandicollis, and 26,290 I. calligraphus were trapped. The most abundant predators trapped were: 7555 Cleridae (Thanasimus dubius F. and Enoclerus spp.), 9036 Temnochila virescens (F.), 7162 Histeridae (Platysoma spp. and Plegaderus spp.), and 42,313 Lasconotus spp. For the sites used in this study, vehicle-based surveys did provide a good predictive model of actual stand mortality. The existence of a correlation between Ips abundance and surveys of tree mortality was investigated. A strong relationship was found between the abundance of Ips and the total number of standing dead and fading trees during the spring and summer of 2012; however, this relationship dissolved as Ips abundance declined over the course of the study. The number of fading trees alone did not provide a good indication of high Ips abundance.

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