Field evaluation of potato plants transgenic for a cry1Ac gene conferring resistance to potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae)

Cry1Ac-transgenic potato plants derived from Russet Burbank and Red Rascal cultivars were evaluated in field trials at Lincoln, Canterbury, New Zealand. Foliage of transgenic plants had fewer potato tuber moth (Phthorimaea operculella (Zeller)) mines, of which the majority were <200 mm2, than the non-transgenic control plants. Of the 800 transgenic tubers examined 5 months after harvesting the first field trial (1999/2000), 0.5% had potato tuber moth mine damage compared with 9% of non-transgenic tubers. After the second field trial (2000/2001) 0.06% of 5307 transgenic tubers had mine damage compared with damage to 25% of non-transgenic tubers. Mined foliage was collected during the first field trial, resulting in a total of 45 larvae from transgenic foliage and 269 from non-transgenic foliage. Two pupae and nine parasitoids emerged from larvae collected from and reared on transgenic foliage. Between 86% and 88% (Red Rascal or Russet Burbank cultivar, respectively) of larvae collected and reared on non-transgenic foliage either pupated or were parasitised. In the second field trial, three of the four transgenic lines evaluated produced yields comparable with their non-transgenic parent cultivar. These results suggest transgenic potato plants resistant to potato tuber moth could augment integrated pest management programmes. However, the potential of the target pest to develop resistance to such plants and effects on non-target insects must be evaluated before such plants can be recommended for potato tuber moth management.