"...More bad news for plant biotechnologists comes from Nick Birch of the Scottish Crop Research Institute in Dundee and Mike Majerus of the University of Cambridge. They fed two-spot ladybirds, Adalia bipunctata, for two weeks on peach-potato aphids, Myzus persicae, that had fed on sap from potatoes engineered to carry a lectin from snowdrops--a protein that interferes with insect digestion.
The engineered potatoes were made by John and Angharad Gatehouse of the University of Durham, and in greenhouse tests they killed off significant numbers of the aphid pests. But in experiments to be reported in a future issue of Molecular Breeding, Birch and Majerus found that female ladybirds fed with aphids from the engineered potatoes lived half as long as those fed on aphids from normal potatoes. Males given lectin-containing aphids lived for an average of 46 days, 5 days less than those in the control group.
In mating studies, up to 30 per cent fewer viable eggs were laid when one of the parent ladybirds was fed aphids from lectin-transformed potatoes. "But these effects on ladybird reproduction wear off after three to four weeks," says Birch.
This is the first time that such a knock-on effect on a beneficial predator species has been seen. While it adds to the concerns about the safety of transgenic crops, Birch notes that the engineered potatoes should require less insecticides. "It may become a question of balancing the risks of transgenic plants with the risks of chemical applications," he says."