land, Bt is very effective on species such as Plodia interpunctella (Indian meal moth) and Pieris rapae (cabbage caterpillar), but not all insect pest varieties. Therefore, insecticides are still needed to control pests that are not affected by the endotoxin expressed by the crop (Ginzburg 1991). Although Lepidoptera species are affected by Bt toxin, field and laboratory tests suggest that many resistance problems are likely to develop in Bt crops. This resistance combined with the extended use of Bt toxin could create a strong selection pressure against the Bt toxin (Ginzburg 1991). Even though different strains of Bt toxins can be developed, insects will continue to develop resistance against the insecticide, creating a never-ending struggle between insect and plant. Bt crops also impact the ecological balance of nature. By keeping pest populations at low levels, parasites and natural enemies will starve because prey is needed to survive in the agro-ecosystem (Altieri 1998). The Bt toxin may affect non-target organisms as well. A study in Scotland posed that aphids were capable of gathering the Bt toxin from crops and transferring the toxin to its predators. The transfer of Bt toxin from the aphid affected the predator beetle’s reproduction and longevity (Altieri 1998). According to Reaka-Kudla et al., it is not uncommon to find plant alleles that affect a parasite’s performance in nature (1997), but the potential of Bt toxins moving through food chains may cause serious changes to agro-ecosystems. Neighboring farms could also be at a disadvantage if Bt toxin reaches their crops. Insect pests might then acquire a resistance to Bt toxin and make it impossible for farmers to control the pests. Resistant insect populations produced from Bt toxin overuse may end up colonizing other farming fields, leaving farmers defenseless (Pollan 1998). Since insect resistance is not directly controlled by anyone, no one can be...
