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Abstract

The solitary parasitic wasp Lysiphlebus testaceipes, is a species native to North America. The species has a broad aphid host range and has been accidentally spread or introduced as a biocontrol agent to many regions of the world. In Benin, L. testaceipes is a newly found species, and it is the dominating primary parasitoid of aphids on vegetables.

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Abstract

Apple fruit moth Argyresthia conjugella is a specialist seed predator of rowan Sorbus aucuparia. Large-scale synchronous fluctuation of seed production in rowan (i.e. named masting) drives the apple fruit moth to seek alternative host plants such as apple, during years when rowan berries are not available for oviposition. The role of plant volatile compounds in the attraction of gravid apple fruit moth females is studied in a laboratory wind tunnel. Volatiles from rowan branches with green berries stimulate female moths to fly upwind and to land at the odour source. By contrast, females are not attracted to rowan branches without green berries, and they are not attracted to apple, demonstrating that the chemical stimulus from rowan berries is required for attraction. Attraction to synthetic compounds identified from rowan, anethole and 2-phenyl ethanol confirms the role of plant volatiles in host finding. These two compounds, however, show a discrepant behavioural effect in wind tunnel and field tests. Field traps baited with 2-phenyl ethanol capture female moths but anethole does not produce significant captures. Wind tunnel tests produce the opposite results: moths fly upwind towards the anethole lure, whereas 2-phenyl ethanol is not attractive at all. Wind tunnel attraction to 2-phenyl ethanol is achieved by adding odour from a rowan branch without berries, which is not attractive on its own. This finding demonstrates that interaction with the background odour contributes to the behavioural effect of plant volatile stimuli in the field.

Abstract

The egg parasitoid O. epuhts and the pupal parasitism caused by the P. foveolatus and Mesopolobus spp. were the key mortality factors in the population dynamics of the C. similis. The egg and pupal parasitism were density dependant at two and one locality, respectively. (c) 2007 Elsevier Ltd. All rights reserved.