Identifier

etd-04092017-164424

Degree

Master of Science (MS)

Department

Entomology

Document Type

Thesis

Abstract

The crapemyrtle bark scale, Acanthococcus lagerstroemiae (Kuwana) (Hemiptera: Eriococcidae), is an exotic pest on crapemyrtles, Lagerstroemia spp. (Myrtales: Lythraceae). Because of its recent arrival in the US, little is known about its biology and ecology. The purpose of my thesis was to improve the knowledge about A. lagerstroemiae in four aspects involving its thermal tolerance, physiological adaptations to cold temperatures, temperature-dependent development and host range. Thermal tolerance was determined to understand how temperature extremes constrain the distribution of A. lagerstroemiae in the US. Results suggested that A. lagerstroemiae can tolerant high heat, but its potential distribution to the northern US may be limited by cold temperatures. Based on laboratory experiments and local temperatures from reported infestations, A. lagerstroemiae can establish in areas south of 43 °N, which is similar to the northern distribution limit of crapemyrtles. Therefore, the temperature extremes cannot limit its distribution on crapemyrtles in the US. To adapt to winter, cold tolerance of A. lagerstroemiae nymphs was observed to increase since November. The mechanisms of this increase were investigated by measuring seasonal changes of biochemical variables. From November to February, A. lagerstroemiae had 20% less water and higher energy reserves, which could have contributed to the increased cold tolerance. A restructuring of fatty acid composition in the body fat of overwintering nymphs was reported indicating accumulation of fatty acids in shorter chains (C6:0, C8:0 and C10:0), resulting in lower melting points that can help maintain lipid fluidity for energy conversion. The development and host range of A. lagerstroemiae were also studied. Developmental time and survival of A. lagerstroemiae eggs and nymphs were assessed under different temperatures, and results can help IPM practitioners improve field sampling strategies and timing of control measures. Callicarpa americana L. (Lamiales: Lamiaceae), Heimia salicifolia Link, Lawsonia inermis L., Lythrum alatum Pursh, and Punica granatum L. (Myrtales: Lythraceae) supported life cycle development and reproduction of A. lagerstroemiae and thus determined as suitable hosts other than Lagerstroemia spp. Scouting is recommended on these host species, following immediate responses to avoid additional spread, economic loss, and ecological disturbance of this pest.

Date

2017

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Diaz, Rodrigo

Included in

Entomology Commons

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