University of Kentucky

Poster Title

Effects of Intraguild Cues of Ground-dwelling and Foliage-dwelling Spiders on Lady Beetle Oviposition and Aphid Suppression

Institution

University of Kentucky

Abstract

The presence of multiple predators in a system causes competition for resources which can impact the life-history traits of competitors. Little is known about the interactions of spider cues and lady beetles, which are both known biological control agents of pests. In this project, the influence of chemical cues of the ground-dwelling spiders (Pardosa milvina) and foliagedwelling spiders (Frontinella communis) on oviposition of lady beetles (Hippodamia convergens) and aphid abundance was examined. Trials were performed in a greenhouse setting designed to simulate a winter wheat microhabitat with mild infestation of aphids (Rhopalosiphum padi). Spiders were placed in the microcosms two days prior to lady beetle introduction to lay silk and cues. Some treatments had the spiders removed to test the effect of only indirect cues on beetles and in other treatments, predators were left in the microcosm along with the lady beetles to assess the effect of predator presence along with the cues. In the presence of predator cues, lady beetles exhibited higher oviposition frequency. There is an indication that direct and indirect cues are important in influencing oviposition behavior. When spiders or spider cues are present, lady beetles oviposit at a greater rate. When only cues and predators are present, lady beetles forage less. These data suggest that predator cues elevate lady beetle oviposition and lower foraging, which provides evidence that beetles detect and respond to multiple predators in the system.

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Effects of Intraguild Cues of Ground-dwelling and Foliage-dwelling Spiders on Lady Beetle Oviposition and Aphid Suppression

The presence of multiple predators in a system causes competition for resources which can impact the life-history traits of competitors. Little is known about the interactions of spider cues and lady beetles, which are both known biological control agents of pests. In this project, the influence of chemical cues of the ground-dwelling spiders (Pardosa milvina) and foliagedwelling spiders (Frontinella communis) on oviposition of lady beetles (Hippodamia convergens) and aphid abundance was examined. Trials were performed in a greenhouse setting designed to simulate a winter wheat microhabitat with mild infestation of aphids (Rhopalosiphum padi). Spiders were placed in the microcosms two days prior to lady beetle introduction to lay silk and cues. Some treatments had the spiders removed to test the effect of only indirect cues on beetles and in other treatments, predators were left in the microcosm along with the lady beetles to assess the effect of predator presence along with the cues. In the presence of predator cues, lady beetles exhibited higher oviposition frequency. There is an indication that direct and indirect cues are important in influencing oviposition behavior. When spiders or spider cues are present, lady beetles oviposit at a greater rate. When only cues and predators are present, lady beetles forage less. These data suggest that predator cues elevate lady beetle oviposition and lower foraging, which provides evidence that beetles detect and respond to multiple predators in the system.