Plant chemistry can strongly influence interactions between herbivores and their natural enemies, either by providing volatile compounds that serve as foraging cues for parasitoids or predators, or by affecting the quality of herbivores as hosts or prey. Through these effects plants may influence parasitoid population genetic structure. We tested for a possible specialization on specific crop p...

Background: Black henbane with the scientific name of Hyoscyamus niger which has a wide geographic distribution, is considered as one the most important species for tropane alkaloids extraction. Objective: In this research, morphological and tropane alkaloids variations were assessed within different population of H. niger in their natural habitats. Methods: Totally, 56 individuals were colle...

It is one thing to show that herbivorous insects affect plant performance. It is an entirely different matter to demonstrate that insect herbivory affects plant population dynamics. There is a vast literature on insect pests of crop plants that shows how attack by defoliating, sucking, stem-mining, and gall-forming species can delay seed ripening, reduce seed production and individual seed weig...

Patchiness has been increasingly recognized by ecologists as a ubiquitous phenomenon in nature. Therefore, substantial research has been directed at modeling the dynamics of metapopulations in patchy habitat settings (e.g., den Boer, 1968; Levins, 1969, 1970; Levins and Culver, 1971; Roff, 1974a,b; Levin, 1976b, 1978; Hastings, 1982, 1991; Hanski, 1983, 1985, 1991; Fahrig and Merriam, 1985; DeA...

There has been an enormous increase in the amount of data on DNA sequence polymorphism available for many organisms in the last decade. New sequencing technologies provide great potential for investigating natural selection in plants using population genomic approaches. However, plant populations frequently show significant departures from the assumptions of standard models used to detect selec...

Herbivory can negatively and selectively affect plant fitness by reducing growth, survival and reproductive output, thereby influencing plant population dynamics and evolution. Latitudinal variation in intensity of herbivory is common, but the extent to which it translates into corresponding variation in effects on plant performance is still poorly known. We tested the hypothesis that variation...

Modern technologies incorporating Geographic Information Systems (GIS), Global Positioning Systems (GPS), remote sensing, and geostatistics provide unique opportunities to advance ecological understanding of pests across a landscape. Increased knowledge of the population dynamics of plant pathogens will promote management strategies, such as site-specific management, and cultural practices mini...

In many animal populations age distribution ha.~ been studied as a basic component of population structure. In plants, developmental plasticity and vegetative reproduction may mean that age distribution is less significant than size distribution, particularly in production processes occurring within populaJtions. Changes in size distribution with time and at different densities are discussed, w...

urtica dioica l. is an iranian native pharmacological plant for which little attention has been paid to the anatomical structure. medical applications of this plant include diabetes therapy, digestive improvement, anemia and kidney disease therapy. because climatic conditions can affect the anatomical structure which in turn affects pharmacological compositions, research on the anatomy of this ...