David G. Nielsen

Interspecific Variation in Resistance of Asian, European, and North American Birches (Betula spp.) to Bronze Birch Borer (Coleoptera: Buprestidae)

ABSTRACT Bronze birch borer (Agrilus anxius Gory) is the key pest of birches (Betula spp.) in North America, several of which have been recommended for ornamental landscapes based on anecdotal reports of borer resistance that had not been confirmed experimentally. In a 20-yr common garden experiment initiated in 1979 in Ohio, North American birch species, including paper birch (Betula papyrifera Marshall), ‘Whitespire’ gray birch (Betula populifolia Marshall), and river birch (Betula nigra L.), were much more resistant to bronze birch borer than species indigenous to Europe and Asia, including European white birch (Betula pendula Roth), downy birch (Betula pubescens Ehrh.), monarch birch (Betula maximowicziana Regel), and Szechuan white birch (Betula szechuanica Jansson). Within 8 yr of planting, every European white, downy, and Szechuan birch had been colonized and killed, although 100% of monarch birch had been colonized and 88% of these plants were killed after nine years. Conversely, 97% of river birch, 76% of paper birch, and 73% Whitespire gray birch were alive 20 yr after planting, and river birch showed no evidence of colonization. This pattern is consistent with biogeographic theory of plant defense: North American birch species that share a coevolutionary history with bronze birch borer were much more resistant than naïve hosts endemic to Europe and Asia, possibly by virtue of evolution of targeted defenses. This information suggests that if bronze birch borer were introduced to Europe or Asia, it could threaten its hosts there on a continental scale. This study also exposed limitations of anecdotal observation as evidence of host plant resistance.

Spatial emergence pattern of bronze birch borer (Coleoptera: Buprestidae) from European white birch

Spatial emergence patterns of the bronze birch borer, Agrilus anxius Gory, and associated parasite and woodpecker predation in European white birch, Betula pendula Roth, were examined. Beetle and total hole density (beetle + parasite + woodpecker) were significantly lower from stem bolts 6 m above ground, 0.1 to 5.0 cm in circumference, and with 0.1 to 1.5 mm bark thickness than bolts 1 to 3 m above ground, 5.1 to 60.0 cm circumference, and with 1.51 to 3.0 mm bark thickness. Significantly more emergence occurred from the southwestern quadrant of trees than from other quadrants. Beetle emergence and total hole densities were also significantly less from branches than from tree trunks.

Reproductive biology of the bronze birch borer (Coleoptera: Buprestidae) on selected trees

Reproductive biology of the bronze birch borer, Agrilus anxius Gory, was examined by measuring the influence of host on maturation feeding period, fecundity, incubation period, egg viability, and longevity. Initially, females fed Betula pendula Roth leaves had the highest fecundity and egg hatchability. However, when large numbers of beetles were caged on an individual B. pendula in 1982, females did not oviposit. Fecundity and egg hatch varied on Populus deltoides Bartr. ex March between years but was consistently high, and the percentage of females ovipositing when fed this host was usually highest. Some beetles fed Quercus palustris Muenchh. or Salix elaeagnos Scop, produced eggs; no reproduction occurred on Acer saccharinum L. Host species and environmental variables influenced the beetles reproductive biology, but some of the observed differences may be explained by reduced foliage quality resulting from inducible plant defense or spacing pheromones produced by beetles at high densities.

Mating Behavior of the Bronze Birch Borer, (Coleoptera: Buprestidae)

Mating behavior of the bronze birch borer, Agrilus anxius, was investigated under laboratory and outdoor conditions. Propensity to mate was greater for beetles more than 1-d-old. Duration of copula...

Lesser peachtree borer: Influence of pheromone concentration, isomeric blend, and experimental design on trap capture

Trap capture data from Ohio and Wisconsin show that (E,Z)-3-13-octadecadien-1-ol acetate alone is an effective trap bait for maleSynanthedon pictipes (Grote and Robinson). Attractiveness increased by increasing attractant concentration but not by adding theZ,E geometrical isomer.S. pictipes males partitioned themselves in a linear fashion among traps baited with 10–100 μg of attractant in 10-μg increments. Furthermore, they discriminated between 50- and 100-μg baits placed in the same tree. These and other results indicate that, in clearwing experiments involving noninhibitory compounds and blend tuning, high trap density can be used successfully.

PHENOLOGY OF THE HOMOPTERAN COMPLEX ON ORNAMENTAL HONEYLOCUST IN OHIO, WITH NOTES ON HOST IMPACT

Phenology and relative abundance of the homopteran complex, including Macropsis fumipennis (Gillete and Baker), Stragania alabamensis (Baker), Empoasca fabae (Harris), Erythroneura clavata DeLong (...