Insect floral herbivory can dramatically reduce plant reproductive success. Thus, plants should have evolved mechanisms that minimize the effect of insect herbivores, particularly in monocarpic species that must maximize fitness in a single flowering year. Tolerance is one such mechanism; however, few experiments to date evaluate underlying mechanisms of plant tolerance under natural conditions...

Phytochemical investigation of Tanacetum parthenium L. family Asteraceae cultivated in Egypt resulted in isolation and identification of four flavonoids. One surface flavonoid was isolated from the fresh leaves and three other flavonoids were isolated from the flower heads. Four sesquiterpene lactones were isolated from the leaves. Two sterols were isolated from the roots. A comparative study o...

this study was done to evaluate the effect of different planting arrangements (square, lozenge and rectangular) and various concentrations of potassium sulfate (k2so4) fertilizer (0, 100, 200 and 300 kg/ha) on yield and essential oils quantitative of calendula officinalis l., a medicinal and ornamental plant. the experiment was done as a factorial in randomized completely blocks design (r.c.b.d...

Dispersal is a key process in biological studies of spatial dynamics, but the initiation of dispersal has often been neglected, despite strong indications that differential timing of dispersal can significantly affect dispersal distances. To investigate which plant and environmental factors determine the release of plumed seeds by the invasive thistles Carduus acanthoides and Carduus nutans, we...

Ann. Entomol. Soc. Am. 89(2): 252-260 (1996) ABSTRACT The biologies of the sympatric, cryptic species, Trupanea nigricornis (Coquillett), a flower head-infesting fruit fly attacking a wide range of hosts in 8 tribes, 33 genera, and at least 71 species of Asteraceae, and T. bisetosa (Coquillett), an oligophage attacking only 6 hosts in 4 genera of the tribe Heliantheae, are described and compare...

Abundances and interactions among biological control insects and their effects on target invasive plants were monitored within the flower heads and roots of diffuse knapweed, Centaurea diffusa, and in spotted knapweed, Centaurea stoebe, along the Colorado Front Range. Flower weevils, (Larinus species) and root-feeders (Cyphocleonus achates and Sphenoptera jugoslavica) were released on knapweed ...

Widespread destruction of tallgrass prairies in the midwestern United States has fragmented plant communities with the result that populations of endemic animal species have become geographically isolated from one another. The goal of the research summarized here was to evaluate the potential for conserving endemic prairie species of herbivorous insects by managing their host plants. Our study...