elisa values (o.d.s) of extracts of separately roots and individual leaves of barley and wheat plants infected by a french bydv-pav isolate (pav-4), were assessed for five dif-ferent virus incubation periods in controlled conditions (5, 10, 15, 20 and 25 days after in-oculation). in most cases, virus contents of individual roots or leaves were not statistically different for barley and wheat. f...

the bird cherry-oat aphid, rhopalosiphum padi (l.) is a serious threat to several cereal crops. host-plant resistance to this aphid could be especially valuable in cereal crops pest management. therefore, we evaluated the development, survivorship, reproduction and population growth parameters of r. padi as resistance indices among six wheat cultivars, including gaskojen, tajan, falat, saysonz,...

Among 170 insects infected by fungal pathogens, obtained during 2003-08 from three Northern provinces of Iran (Mazandaran, Gilan and Golestan), eight taxa of entomophthoralean fungi were identified including four pathogens of dipteran insects: Entomophaga tipulae was found on a crane fly, Entomophthora muscae was seen on five flies attached to broadbean leaves, Pandora bulata was observed only ...

In most aphid species, facultative parthenogenetic reproduction allows rapid growth and formation of large single-genotype colonies. Upon predator attack, individual aphids emit an alarm pheromone to warn the colony of this danger. (E)-beta-farnesene (EBF) is the predominant constituent of the alarm pheromone in Myzus persicae (green peach aphid) and many other aphid species. Continuous exposur...

Regiella insecticola has been found to enhance the performance of host aphids on certain plants, but its functional role in adaptation of host aphids to plants is still controversial. Here we evaluate the impacts of R. insecticola infections on vital life-history traits of Sitobion avenae (Fabricius), and their underlying genetic variation and phenotypic plasticity on three plants. It was shown...

Sieve tubes are transport conduits not only for photoassimilates but also for macromolecules and other compounds that are involved in sieve tube maintenance and systemic signalling. In order to gain sufficient amounts of pure phloem exudates from barley plants for analyses of the protein and mRNA composition, a previously described stylectomy set-up was optimized. Aphids were placed in sealed c...