Species‐specific differences in oak foliage affect preference and performance of gypsy moth caterpillars

Abstract

The gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), is an introduced defoliator that preferentially feeds on oaks, Quercus spp. (Fagaceae) in the northeastern USA. As the gypsy moth expands its geographic range, the extensive oak component in forests and urban environments of the USA assure its successful establishment. Given their economic and ecological importance, and the gypsy moth's potential to cause mortality, we evaluated caterpillar preference and performance on various oaks prevalent in the central hardwoods region. Most of the physical and chemical characteristics we measured, from budbreak phenology to foliar chemistry, varied significantly among the oak species tested. Similarly, insect preference and performance varied significantly, though not always in predictable ways. Caterpillar preference was compared for black, Q. velutina Lamarck, burr, Q. macrocarpa Michaux, cherrybark, Q. pagoda Rafinesque, northern red, Q. rubra L., pin, Q. palustris Muenchhausen, swamp white, Q. bicolor Willdenow, white, Q. alba L., and willow, Q. phellos L., oaks. Gypsy moth preference was greatest for black and burr, and least for northern red, pin, and willow oaks. We assessed foliar characteristics and caterpillar performance on foliage from burr, cherrybark, northern red, pin, and willow oaks. Caterpillar preference did not always correlate with performance. Gypsy moth consumption and growth were highest, and development most rapid, on pin oak, which had high nitrogen and tannin levels, and was among the least preferred. Northern red and willow oaks were also among the least preferred and were the least suitable tested, producing caterpillars with moderate to low consumption and growth rates, as well as the longest development. Northern red oak contained the lowest foliar tannins; willow oak foliage was lowest in carbohydrates and nitrogen. Our results suggest that a combination of foliar characteristics may be responsible for gypsy moth preference and performance, and that an optimal combination of foliar components serves to maximize host suitability. These data will provide information useful for planning and managing urban forests in the presence of expanding gypsy moth populations.

Effect of host-plant genetic diversity on oak canopy arthropod community structure in central Mexico

“…It has been suggested that phenotypic traits that affect arthropod communities as phenology, physical defenses, and foliar chemistry are features that have a genetic basis (Johnson and Agrawal 2005;Bangert et al 2006) but have only rarely been linked to both plant genetics and arthropod community structure (Wimp et al 2007). Also, these attributes can vary between host-plant species (Foss and Rieske 2003;Forkner et al 2004;Marquis and Lill 2010), affecting both the quantity and quality of resources available to arthropods (Murakami et al 2007). Understanding the strength of these associations is important as they provide a mechanistic approach to comprehend the relationship between plant genetic diversity, environment, and arthropod community structure.…”

Qualitative Variation in Proanthocyanidin Composition of Populus Species and Hybrids: Genetics is the Key

“…Some oaks accumulate high levels of hydrolyzable tannin (bur, pin, or willow) while other species (cherrybark, Northern red) accumulate far smaller amounts (Foss and Rieske, 2003), suggesting an overall genetic constraint on the total quantity of hydrolyzable tannin that can be produced. Within that limit, both simple phenolics and complex ellagitannins are accumulated in patterns that are genetically controlled (Yarnes et al, 2006), with distinct tannin chemotypes identified in a population of Quercus gambelii x Q. grisea (Yarnes et al, 2008).…”

Response of two oak species to extensive defoliation: Tree growth and vigor, phytochemistry, and herbivore suitability

“…Oak foliar tannins vary spatially (Crawley and Akhteruzzaman, 1988), temporally (Feeny and Bostock, 1968;Makkar et al, 1991), and in response to changing light and disturbance regimes (Kruger and Reich, 1997;Rieske, 2001, 2003;Rieske, 2002). Herbivore suitability, including abundance (Hunter, 1993), preference (Foss and Rieske, 2003), and performance (Valentine et al, 1983;Bourchier and Nealis, 1993), have been linked to oak foliar tannin concentrations.…”