The pine bark adelgid, Pineus strobi (Hemiptera: Adelgidae) is a native herbivore of eastern white pine, Pinus strobus (Pinales: Pinaceae), in eastern North America. It is a sessile insect that settles on P. strobus and inserts its stylet bundle to feed on the tree’s phloem. Although P. strobi is not considered a serious pest, it shares its range with the invasive hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae). Predators introduced as biological control agents of A. tsugae interact with P. strobi and its native predators, including Laricobius rubidus LeConte (Coleoptera: Derodontidae). Prior to this study, little work had been done to document the phenology or predators of P. strobi, particularly in its southern range. In the present study, the phenology of P. strobi is reported in southwestern Virginia. Patterns in overwintering population dynamics varied notably from those described from this species’ northern range. The number of annual generations could not be measured due to overlap following two distinct spring generations. Adult body size varied seasonally and was greatest in the spring. Variation between observations from the northern and southern ranges of P. strobi indicate phenological plasticity that informs biological control efforts and offers insight into implication of climatic effects on population dynamics of this and related species. Arthropod predators associated with P. strobi in forests of southwest Virginia were collected during a two-year survey. Morphology and DNA barcoding were used for identification. Species of predators found included: Laricobius rubidus (Coleoptera: Derodontidae), a native adelgid specialist, and two species from the dipteran family Chamaemyiidae, Leucopis piniperda Malloch and L. argenticollis Zetterstedt, which are adelgid specialists. Members of the families Cecidomyiidae, Coccinellidae, Chrysopidae, Hemerobiidae, and Syrphidae were also recovered. Most diverse were the Cecidomyiidae, with 15 different species inferred from their DNA barcodes. Additional work was performed to quantify supercooling points of L. rubidus collected from November – December 2016. These will be compared to those of other Laricobius species in a parallel study. Knowledge of this predator complex is beneficial to describing P. strobi ecology, and also with regard to potential biological control of invasive adelgids in the same region. / Ph. D. / The pine bark adelgid, Pineus strobi (Hemiptera: Adelgidae) is a native herbivore of eastern white pine, Pinus strobus (Pinales: Pinaceae), in eastern North America. It is a sedentary insect that settles on P. strobus bark, branches, and needle bases where it inserts its mouthparts to feed on the tree’s fluid nutrients. Even when P. strobi populations are dense, it does not harm the tree and is not considered a serious pest. It does, however, share its range with the invasive hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae). Predators introduced as biological control agents of A. tsugae also interact with P. strobi and its native predators, including Laricobius rubidus LeConte (Coleoptera: Derodontidae). Prior to the current study, little work had been done to document the natural history or predators of P. strobi, particularly in its southern range, both of which are relevant to the management of other invasive adelgid species found there. In the present study, the natural history of P. strobi is reported in southwestern Virginia. Patterns in the frequencies of various life stages present during the winter varied notably from those described from this species’ northern range. The number of annual generations could not be accurately measured due to the degree of overlap following two distinct spring generations. Adult body size varied seasonally and was greatest in the spring. Variation between observations from the northern and southern ranges of P. strobi indicates that its natural history can vary with the climate, which not only informs biological control efforts, but also offers insight into implication of climatic effects on the population dynamics of this and related species. This study also describes arthropod predators associated with the pine bark adelgid in forests of southwest Virginia found during a two-year survey. Physical characteristics and molecular techniques were used in identification. Species of predators found include: Laricobius rubidus (Coleoptera: Derodontidae), a native adelgid specialist, and two species from the family Chamaemyiidae, Leucopis piniperda Malloch (Diptera: Chamaemyiidae) and L. argenticollis Zetterstedt (Diptera: Chamaemyiidae), which are known adelgid specialists. Members of the families Cecidomyiidae, Coccinellidae, Chrysopidae, Hemerobiidae, and Syrphidae were also recovered. Most diverse were the Cecidomyiidae, with 15 different species genetically identified. Additional work was performed to quantify the bodily freezing points of L. rubidus collected from November – December 2016. These will be compared to those of related biological control agents in a parallel study. Knowledge of this predator complex is beneficial to describing P. strobi ecology, and also with regard to potential biological control of other invasive adelgids in the same region.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/93205 |
| Date | 27 February 2018 |
| Creators | Wantuch, Holly Anne |
| Contributors | Entomology, Kuhar, Thomas P., Salom, Scott M., Marek, Paul E., Havill, Nathan P., Pfeiffer, Douglas G. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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