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Modelling the effects of polyphagous predators on the population dynamics of the grain aphid Sitobion avenae (F.)

Modelling the effects of polyphagous predators on the population dynamics of the grain aphid Sitobion avenae (F.)
Modelling the effects of polyphagous predators on the population dynamics of the grain aphid Sitobion avenae (F.)

A systems approach was used to identify important features within the Sitobion avenae (F.)-polyphagous predator system. Field and laboratory experiments were carried out to provide data which would allow the quantification of predation by polyphagous predators. A technique was developed to determine whether predation of aphids occurred on the ground by measuring the rate at which S. avenae fell and subsequently returned to the crop canopy. A field experiment was carried out using this technique which indicated that predators present on the soil surface affected the rate at which aphids returned to the crop canopy. Simulation modelling was used to assess the importance of the searching behaviour of the carabid beetle Agonum dorsale (Pont.) in relation to the level of aphid aggregation and density. The model demonstrated that at the spatial scale studied, aphid predation was proportional to aphid availability but that aphid aggregation was unimportant. The implications of this for ground searching polyphagous predators were discussed. A second simulation model was constructed to quantify predation by the three principal groups of polyphagous predator: carabid and staphylinid beetles and linyphiid spiders. The role of these predators was assessed by comparing estimates of field predation to the mortality required to reduce an aphid population increasing at a maximum rate to that observed in the field. S. avenae population development was simulated using a model constructed by Carter el al. (1982). The model demonstrated that polyphagous predators were most important during the early stage of aphid population development and that staphylinid beetles of the genus Tachyporus were the most important predators studied. It was concluded that polyphagous predators are of importance early in the season, but that other mortality, possibly imposed by other natural enemies such as parasitoids, aphid specific predators and fungal pathogens was necessary to prevent aphid outbreaks from occurring.

University of Southampton
Winder, Linton Hugh
Winder, Linton Hugh

Winder, Linton Hugh (1990) Modelling the effects of polyphagous predators on the population dynamics of the grain aphid Sitobion avenae (F.). University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

A systems approach was used to identify important features within the Sitobion avenae (F.)-polyphagous predator system. Field and laboratory experiments were carried out to provide data which would allow the quantification of predation by polyphagous predators. A technique was developed to determine whether predation of aphids occurred on the ground by measuring the rate at which S. avenae fell and subsequently returned to the crop canopy. A field experiment was carried out using this technique which indicated that predators present on the soil surface affected the rate at which aphids returned to the crop canopy. Simulation modelling was used to assess the importance of the searching behaviour of the carabid beetle Agonum dorsale (Pont.) in relation to the level of aphid aggregation and density. The model demonstrated that at the spatial scale studied, aphid predation was proportional to aphid availability but that aphid aggregation was unimportant. The implications of this for ground searching polyphagous predators were discussed. A second simulation model was constructed to quantify predation by the three principal groups of polyphagous predator: carabid and staphylinid beetles and linyphiid spiders. The role of these predators was assessed by comparing estimates of field predation to the mortality required to reduce an aphid population increasing at a maximum rate to that observed in the field. S. avenae population development was simulated using a model constructed by Carter el al. (1982). The model demonstrated that polyphagous predators were most important during the early stage of aphid population development and that staphylinid beetles of the genus Tachyporus were the most important predators studied. It was concluded that polyphagous predators are of importance early in the season, but that other mortality, possibly imposed by other natural enemies such as parasitoids, aphid specific predators and fungal pathogens was necessary to prevent aphid outbreaks from occurring.

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Published date: 1990

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Local EPrints ID: 458258
URI: http://eprints.soton.ac.uk/id/eprint/458258
PURE UUID: 1649d89c-76fe-4bf5-a241-c1a518aa2105

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Date deposited: 04 Jul 2022 16:45
Last modified: 04 Jul 2022 16:45

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Author: Linton Hugh Winder

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