Potential of an alternative prey to disrupt predation of the generalist predator,Orius insidiosus, on the pest aphid,Aphis glycines, via short-term indirect interactions

Abstract

AbstractGeneralist insect predators can significantly impact the dynamics of pest populations; and, using alternative prey, they can rapidly establish in disturbed agroecosystems. However, indirect interactions between prey can occur, leading to either increased or decreased predation on focal prey. The present paper demonstrates how alternative prey can disrupt predation by the hemipteranOrius insidiosuson the soybean aphidAphis glycinesvia short-term indirect interactions. We used laboratory microcosms to measure the impact of the predator on the population growth of the aphid in the presence of alternative prey, soybean thripsNeohydatothrips variabilis, and we characterized the foraging behaviour of the predator to assess prey preference. We showed thatO. insidiosuspredation on aphids was reduced in the presence of thrips and that this positive impact on aphids increased as thrips density increased. Results from the behavioural experiment support the hypothesis of a prey preference toward thrips. When prey-pest ratio is aphid-biased, short-term apparent commensalism between prey occurs in favour of the most abundant prey (aphids) with no switching behaviour appearing inO. insidiosus. These results demonstrate that potential indirect interactions should be taken into account when consideringO. insidiosusas a biocontrol agent against the soybean aphid.