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Like many other transgenic crops, Bt maize synthesises its own pesticide: a toxic protein produced in its leaves and stems, which kills pests in a matter of days. Perfect… Except when insect populations develop resistance to the toxin! To date, management strategies implemented to delay the evolution of resistance have been successful. Notwithstanding the success of these strategies, IRD scientists and their South African partners have now revealed that a major pest of maize, the moth Busseola fusca , has developed an unusual defense mechanism against Bt toxin in South Africa. By contrast with the usual expectations, this resistance is inherited as a dominant trait, a characteristic that may have contributed to its rapid geographical expansion. This result recently published in the journal PLoS ONE , suggests that insect resistance management should be more finely tuned to local pests and should go beyond the simple implementation of refuges for Bt -susceptible moths.
The Ribeirinhos live in the heart of Brazilian Amazon between the forest and the tranquil waters of the Tapajós river. These descendants of the American Indians and Portuguese settlers are at the heart of major challenges involving the management and use of forest resources. Their presence in the Tapajós National Forest, a so-called "sustainable use" protected area has, in some villages, indirectly led to deterioration of their farming system and traditional practices. Researchers from the IRD and its partners reveal that local development projects and biodiversity conservation have promoted forest extractivism, to the detriment of subsistence activities that enable the Ribeirinhos to be self-sufficient in food.
Introduced in Central America twenty years ago, the Guatemalan potato moth is wreaking havoc in potato crops in Venezuela, Colombia and Ecuador. Its larvae can devour entire stocks of potato tubers, one of the main crops and the staple food of Andean populations. Control measures exist, but are toxic or financially out of reach for farmers. To combat this scourge, IRD researchers and their Ecuadorian partners have developed a promising alternative: a biopesticide based on a virus that infects the moths in order to preserve the ecosystem and reduce the risk of pollution as well as the resistance of these destructive insects.