| One study found that larvae feeding on Bt maize emerge as adults on average 12 days later than larvae fed on non-Bt maize. This is not uncommon for rootworms in general, however it does pose potential problems. If the rootworms feeding on non-Bt maize emerge 12 days earlier there is the potential for non-random or assortative mating (Petzold–Maxwell et al. 2013). This is where the resistant rootworms that are able to survive on Bt maize would emerge later and mate with other Bt-resistant corn rootworms. The susceptible corn rootworms that fed on refuge or non-Bt maize would then mate with other susceptible corn rootworms rather than with the Bt-resistant rootworms. Susceptible corn rootworms mate with other susceptible rootworms and the resistant corn rootworms would mate with other resistant rootworms. This can lead to rapid resistance development. Rapid developement of resitance creates a challenge for managing resistance in corn rootworm populations and further illustrates the importance of using multiple control tactics for effective management. |
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