Within-field distribution of the damson-hop aphid Phorodon humuli (Schrank) (Hemiptera: Aphididae) and natural enemies on hops in Spain

Abstract

A field trial was performed in a hop yard throughout 2002, 2003 and 2004 in order to determine the within-field distribution of Phorodon humuli (Schrank) (Hemiptera: Aphididae) and its natural enemies. The distribution of P. humuli was directly affected by the position of the hop plants in the garden, with significantly higher concentrations of aphids (p=0.0122 in 2002 and p=0.0006 in 2003) observed along the edge. However, in 2004 the plants located on the marginal plots had similar populations to those on the more inner plots. This can be explained by a higher wind speed which made it more difficult to land on edge plants first. The hop aphid's main natural enemy was Coccinella septempunctata (Coleoptera: Coccinellidae), whose population was greatest where the aphids were most abundant with a significantly greater number of eggs (p=0.0230) and adults (p=0.0245) in 2003. Lacewing eggs were also frequently observed, with a significantly higher population (p=0.0221 in 2003 and p=0.0046 in 2004) where the aphid numbers were high. The number of winged aphids was greatest towards the margins of the garden in 2003. It is argued that the spatial distribution of the hop aphid and its natural enemies could be used to plan a sampling program and to estimate the population densities of these insects for use in integrated pest management programs.Additional keywords: Humulus lupulus; spatial distribution; Coleoptera; Coccinelidae; winged aphids; integrated pest management.

Green Strategies of Powdery Mildew Control in Hop: From Organic Products to Nanoscale Carriers

“…Infection of leaves infrequently produces economic losses but contributes to a source of inoculum for inflorescences and cones prompting their abortion, malformation, and discoloring, thus reducing yield and quality [ 3 , 4 ] and affecting the economic balance with the usage of phytosanitary products [ 5 ]. However, the potential effects of powdery mildew on both yield quantity and quality are still poorly understood [ 2 , 6 ].…”

“…On the other hand, some studies have focused on controlling the powdery mildew by removing the basal leaves [ 4 , 14 ] or increasing plant resistance [ 2 ]. However, the knowledge about the direct effect of powdery mildew on both quantity (yield index) and quality (α-acid content) of cones is scarce [ 2 , 6 , 7 ].…”