BACKGROUND The sesquiterpene (E)-ß-farnesene is the main component of the alarm pheromone system of various aphid species studied to date, including the English grain aphid, Sitobion avenae. Aphid natural enemies, such as the marmalade hoverfly Episyrphus balteatus and the multicolored Asian lady beetle Harmonia axyridis, eavesdrop on aphid chemical communication and utilize (E)-ß-farnesene as ...

Organic farming is one of the most successful agri-environmental schemes, as humans benefit from high quality food, farmers from higher prices for their products and it often successfully protects biodiversity. However there is little knowledge if organic farming also increases ecosystem services like pest control. We assessed 30 triticale fields (15 organic vs. 15 conventional) and recorded va...

1. One of the oldest questions in ecology is how species diversity in any given trophic level is related to the availability of essential resources that limit biomass (e.g. water, nutrients, light or prey). Researchers have tried to understand this relationship by focusing either on how diversity is influenced by the availability of resources, or alternatively, how resource abundance is influen...

Refuges have been shown to be important mediators of predator–prey interactions, and in particular, have been proposed as a potential mechanism allowing herbivore populations to reach outbreak levels. However, very little research on the role of refuges has been conducted in systems dominated by generalist predators. We investigated the existence of refuges from predation for the soybean aphid,...

We extend detection of arthropod predator gut contents by polymerase chain reaction (PCR), heretofore restricted to insect predators, to spiders. Single individuals of the corn lead aphid, Rhopalosiphum maidis, were detected in the guts of spiderlings of Oxyopes salticus up to 12 h after feeding; individuals of the congeneric bird cherry oat aphid, R. padi, were not detected. Unfed O. salticus ...

The predator and parasitoid fauna associated with cereal aphids is described, emphasizing the fauna associated with classical biological control efforts against the greenbug and Russian wheat aphid. We focus on literature from North America and include work from Europe and elsewhere when it is desirable to draw contrasts between approaches that affect cereal aphid biological control. Effects on...

In the north central United States, populations of the exotic soybean aphid, Aphis glycinesMatsumura (Hemiptera: Aphididae), are highly variable across space, complicating effective aphid management. In this study we examined relationships of plant nutrients, landscape structure, andnatural enemieswith soybeanaphid abundance across Iowa,Michigan,Minnesota, andWisconsin, representing the range o...

Alternative strategies to the common practice of spraying with insecticide in order to control the rosy apple aphid Dysaphis plantaginea (Pass.) (Homoptera: Aphididae) are required. Biological control by natural enemies is a possible tool. In Asturies, despite the tradition of growing local cider apple trees, there are no studies about the community of D. plantaginea predators and their impact ...

Aphids are major pests in apple orchards, debilitating the crop and spreading disease. We investigated whether early-season predation by canopy spiders may be effectively controlling aphid numbers in three organic orchards. For this purpose, we monitored the aphid population dynamics from the winter eggs to colony stages and compared this to spider abundances and rates of predation on aphids de...

To cope with pathogen and insect attacks, plants develop different mechanisms of defence, in both direct (physical and chemical) and indirect ways (attractive volatiles to entomophagous beneficials). Plants are then able to express traits that facilitate “top-down” control of pests by attracting herbivore predators. Here we investigate the indirect defence mechanism of potato plants by analyzin...