Population dynamics and integrated control of the damson-hop aphid Phorodon humuli (Schrank) on hops in Spain

Abstract

[EN] The hop aphid Phorodon humuli(Schrank) (Hemiptera: Aphididae) is a serious pest in most areas where hops aregrown. A field trial was performed on a hop yard throughout 2002, 2003 and 2004 in León (Spain) in order to analysethe population development of Phorodon humuliand its natural enemies, as well as to determine the most effectiveintegrated program of insecticide treatments. The basic population development pattern of P. humuliwas similar inthe three years: the population peaked between mid to late June, and then decreased in late June/early July, rising againand reaching another peak in mid-July, after which it began to decline, rising once more in late August; this last riseis characteristic of Spain and has not been recorded in the rest of Europe. The hop aphid’s main natural enemy foundon the leaves was Coccinella septempunctata (Coleoptera: Coccinellidae). The multiple regression analysis showedthat aphids are positively related with the presence of beetle eggs and mean daily temperatures and negatively relatedwith maximum daily temperature integral above 27°C in plots without insecticide treatment. The most effective programof insecticide (imidacloprid) treatments consisted of an initial treatment in June and a second treatment in the secondhalf of July or at the beginning of August. However, a single treatment in June would be sufficient when in this lastperiod the maximum daily temperatures were higher than 27°C for at least 15 days, avoiding in this way the harmfuleffects of imidacloprid on predators