ABSTRACT
Feeding behavior of the Russian wheat aphid, Diuraphis noxia (Mordvilko)and the bird cherry-oat aphid, Rhopalosiphum padi L. (Homoptera:Aphididae) and the effect of gramine content in barley

María Luz Salas G.1, Victor Argandoña C.1y Luis Corcuera P.1
 
Chlorophyll content and water potential decreased 25 and 49%, respectively, in barley cv. Aramir(without gramine) infestad with D. noxia. When infestad with R. padi the reductions in chlorophyllcontent and water potential were 12 and 43%, respectively. In cv. Atlas 57 (4 mmol/Kg fr.wt. ofgramine), chlorophyll content and water potential decreased 10 and 59% respectively, when infestadwith D. noxia and 2 y 24% when infestad with R. padi.Survival of aphids feeding on artificial diets with gramine decreased. LD50 values were 5.5 mM and 1.5mM, for D. noxia and R. padi, respectively. Electronic monitoring the feeding behavior of aphids on barley leaves, D. noxia and R. padi showed a shorter salivation time in cv. Atlas 57 than on cv. Aramir. D. noxia ingestion time from phloem was similar in both cultivars. R. padi ingestion time from phloem was higher in cv. Atlas 57 than on cv. Aramir. D. noxia ingestion time from non phloem was similar in both cultivars. R. padi ingestion from non phloem decreased in cv. Atlas 57. Thus, the feeding behavior of aphids was different in cultivars with and without gramine, being R. padi more affected than D. noxia, because gramine is found in parenchyma cells, a preferential feeding site for R. padi.
Key words: gramine, feeding behavior, aphid, Diuraphis noxia , Rhopalosiphum padi , damage
1Depto. Biología, Fac. de Ciencias Universidad de Chile, Casilla653, Santiago, Chile.