RESISTANCE OF TRANSGENIC POTATOES TO ATTACK BY EPITRIX CUCUMERIS (COLEOPTERA: CHRYSOMELIDAE)

Abstract

AbstractPotato plants (Solanum tuberosum, cv. Russet Burbank) genetically altered to produce the CryIIIA protein from Bacillus thuringiensis var tenebrionis were tested for susceptibility to attack by the potato flea beetle, Epitrix cucumeris (Harris), on Prince Edward Island, Canada, from 1993 to 1996. Average weekly damage to the fourth terminal leaf of transgenic potato plants was 31% lower in 1993 and 20% lower in 1994 compared with nontransgenic plants. Transgenic plants had 29% fewer potato flea beetle adults when compared with nontransgenic plants in 1994, although no difference was detected between the two plant types in 1993. Recovery of potato flea beetle pupae in the soil was noticeably lower from transgenic plants expressing the CryIIIA protein in all parts of the plant (Construct No. RBBT02-10Y1) than from either the transgenic plants that expressed the CryIIIA protein primarily in the green foliage (Construct No. RBBT04-01) or the nontransgenic plants. Adult potato flea beetles, when given a choice between transgenic and nontransgenic leaf material, fed preferentially on nontransgenic material. In contrast, when adults were not given a choice, feeding damage was similar between treatments. These results suggest that the reason for reduced feeding on transgenic potato plants by the potato flea beetle is, at least in part, due to some toxicity of the plants to immature growth stages and a preference for adults to feed on nontransgenic material when it is available.