Parasitic wasps protect offspring by avoiding the smelly feet of ladybirds
21 September 2006
Scientists at Rothamsted Research have identified how aphid parasitic wasps prevent their offspring being eaten by ladybirds. The tiny wasps implant their offspring parasitically into aphid pests, but should the aphid get eaten by a ladybird, the growing wasp would be consumed as well. The researchers, supported by the Biotechnology and Biological Sciences Research Council (BBSRC), have found that to protect their offspring, adult wasps have evolved to avoid the smell of a short-lived blend of chemicals that ladybirds deposit with each footprint they make. The scientists have identified the particular cocktail of chemicals.
Both wasps and ladybirds are predators of aphids but they have evolved techniques to enable them avoid each other and maximise their own success. As aphids are significant pests for gardeners and farmers the natural mechanisms that have developed help these two predators to interact efficiently to help control aphid numbers.
The scientists at Rothamsted Research, Professor Wilf Powell and Dr Mike Birkett, together with visiting Japanese scientist Dr Yoshitaka Nakashima, have identified the chemicals involved and have also shown that the smell of different ladybird species repels different parasitic wasp species to various degrees. Dr Wilf Powell explained: ”We found that parasitic wasps attacking aphids living in a wooded area responded most strongly to the chemical footprints of woodland-dwelling ladybirds and similarly for those found more often in fields of crops. This suggests that these two aphid predators have evolved mutually beneficial avoidance techniques to maximise their own chances of success.
“A better understanding of the natural interactions between parasitic wasps, insect predators and their prey has the potential to help us to use them more effectively to control garden and agricultural pests and reduce the amount of pesticides we spray.”The research is being displayed to the public for the first time at an open weekend at Rothamsted Research next weekend (30 September-1 October). The Rothamsted scientists worked in collaboration with a visiting researcher from the University of Agriculture and Veterinary Medicine, Obihoro, Japan who was supported by the Japanese Society for the Promotion of Science. Some aspects of the work were also supported by the Department for Food, Environment and Rural Affairs (Defra).
Notes to editors
Rothamsted Research is in Harpenden, Hertfordshire, UK
The Rothamsted Open Weekend is on 30th September - 1st October. The largest research station in the country for agriculture and the environment, throws its doors open to the public.
The open day is supported in part by BBSRC.
This work is published in; Nakashima, Y., Birkett, M.A., Pye, B.J., Pickett, J.A. & Powell, W. (2004) The role of semiochemicals in the avoidance of the seven-spot ladybird, Coccinella septempunctata by the aphid parasitoid, Aphidius ervi. Journal of Chemical Ecology, 30, 1103-1116.
The Biotechnology and Biological Sciences Research Council (BBSRC) is the UK funding agency for research in the life sciences. Sponsored by Government, BBSRC annually invests around £380 million in a wide range of research that makes a significant contribution to the quality of life for UK citizens and supports a number of important industrial stakeholders including the agriculture, food, chemical, healthcare and pharmaceutical sectors. http://www.bbsrc.ac.uk
Click on the thumbnails to view and download full-size images.
Seven-spot ladybird eating an aphid (1.20 MB)
Female parasitic wasp searching a plant for an aphid into which it can lay eggs (2.33 MB)
Parasitic wasp alongside one of its aphid hosts (1.21 MB)
Note that these images are protected by copyright law and may be used with acknowledgement of Rothamsted Research.
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