Arbuscular mycorrhizal (AM) fungi are root symbionts that can facilitate plant growth and influence communities by altering interactions with herbivores. Therefore, AM could be critical for the conservation of certain rare plants For example, North American milkweed species crucial hosts monarch butterflies (Danaus plexippus). Understanding how composition affects milkweeds will have direct imp...

Photo 1. Freshly hatched swamp milkweed beetle (Labidomera clivicollis; pictured here) or monarch caterpillar (Danaus plexippus; not shown) larva were placed on common plants (Asclepias syriaca) in the field to assess effect of defense traits herbivore performance. credit: Collin B. Edwards. 2. For each A. syriaca plant used, we measured a variety traits, including quantity latex exuded from se...

Systemic insecticides used for ornamental horticulture crops can protect all portions of a plant with long-lasting effects. However, they may be hazardous to pollinators foraging on contaminated nectar or pollen. Two model plant cultivars were chosen based upon their ability to produce large quantities of pollen or nectar, enabling examination of the level of nectar or pollen contamination (e.g...

Ambient concentrations of tropospheric ozone and ozone-induced injury to black cherry (Prunus serotina) and common milkweed (Asclepias syriaca) were determined in north central Pennsylvania from 29 May to 5 September 2000 and from 28 May to 18 September 2001. Ogawa passive ozone samplers were utilized within openings at 15 forested sites of which six were co-located with TECO model 49 continuou...

Effects on monarch butterfly, Danaus plexippus L., after continuous exposure of larvae to natural deposits of Bacillus thuringiensis (Bt) and non-Bt pollen on milkweed, were measured in five studies. First instars were exposed at 3–4 and 6–7 d after initial anthesis, either directly on milkweed plants in commercial cornfields or in the laboratory on leaves collected from milkweeds in corn plots...

Coexistence of host-specific herbivores on plants is believed to be governed by interspecific interactions, but few empirical studies have systematically unraveled these dynamics. We investigated the role of several factors in promoting coexistence among the aphids Aphis nerii, Aphis asclepiadis, and Myzocallis asclepiadis that all specialize on common milkweed (Asclepias syriaca). Competitive ...

Broad-scale geographical gradients in the abiotic environment and interspecific interactions should select for clinal adaptation. How trait clines evolve has recently received increased attention because of anticipated climate change and the importance of rapid evolution in invasive species. This issue is particularly relevant for clines in growth and defense of plants, because both sets of tra...