Inheritance of Cry1Ac resistance and associated biological traits in the cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)

Transgenic crops expressing Bacillus thuringiensis (Bt) toxins have been adopted worldwide, notably in developing countries. In spite of their success in controlling target pests while allowing a substantial reduction of insecticide use, the sustainable control of these pest populations is threatened by the evolution of resistance. The implementation of the “high dose/refuge” strategy for managing insect resistance in transgenic crops aims at delaying the evolution of resistance to Bt crops in pest populations by promoting survival of susceptible insects. However, a crucial condition for the “high dose/refuge” strategy to be efficient is that the inheritance of resistance should be functionally recessive. Busseola fusca developed high levels of resistance to the Bt toxin Cry 1Ab expressed in Bt corn in South Africa. To test whether the inheritance of B . fusca resistance to the Bt toxin could be considered recessive we performed controlled crosses with this pest and evaluated its survival on Bt and non-Bt corn. Results show that resistance of B . fusca to Bt corn is dominant, which refutes the hypothesis of recessive inheritance. Survival on Bt corn was not lower than on non-Bt corn for both resistant larvae and the F1 progeny from resistant × susceptible parents. Hence, resistance management strategies of B . fusca to Bt corn must address non-recessive resistance.

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“…fusca ) and probably two others (i.e., H. armigera [25] and H . zeae [4]) do not correspond to recessive resistance cases.…”

Section: Discussionmentioning

confidence: 99%

“…Field-evolved resistance alleles of H. armigera in India and Helicoverpa zeae in the United States have been reported to be semi-dominant [25] and incompletely dominant [4], respectively. Field resistance has largely been ascribed to a lack of sufficient refugia and/or failure to use high-dose Bt cultivars [12,26].…”

Section: Introductionmentioning

confidence: 99%

Dominant Inheritance of Field-Evolved Resistance to Bt Corn in Busseola fusca

et al. 2013

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“…Genetic dominance of the ED trait was calculated using a modification of the method described by Stone (1968), a method widely used to determine the genetic dominance of resistance traits in insects (Liu and Tabashnik 1997;Tabashnik et al 2002;Germano et al 2010;Nair et al 2010;Kaur and Dilawari 2011;Jagadeesan et al 2012). Based on the formula of Stone (1968), we calculated the degree of dominance (D) for both the 1-year and 2-year diapause traits using: D D = (2(Htz)ÀHmz D ÀHmz ED )/(Hmz D ÀHmz ED ) and D ED = (2(Htz)ÀHmz ED ÀHmz D )/(Hmz ED ÀHmz D ); where Hmz ED = homozygote with extended diapause (♀ED 9 ♂ED), Htz = heterozygote for diapause, Hmz D = homozygote for 1-year diapause (♀D 9 ♂D).…”

Section: Variance and Inheritance Of Extended Diapause In Ncr Pedigreesmentioning

confidence: 99%

Inheritance of an extended diapause trait in theNorthern corn rootworm,Diabrotica barberi(Coleoptera:Chrysomelidae)

French

Coates

Sappington

2012

J Applied Entomology

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Diapause is an adaptive trait that delays development or reproduction under unfavourable circumstances. The northern corn rootworm,Diabrotica barberi Smith & Lawrence, an important maize, Zea mays L., pest in the Diabroticite species complex, overwinters in diapause during the egg stage. Some NCR populations are adapted to crop rotation by expressing an extended diapause (ED) trait that delays embryonic development for 2 years. This ED trait has increased in frequency and geographic distribution since first reported in Illinois in 1932. Reciprocal single pair crosses among beetles from a laboratory colony with the ancestral 1-year diapause trait and field collected beetles with the 2-year ED trait indicated that ED females laid significantly more ED eggs than did females with the 1-year diapause trait regardless of male genotype. The ED trait was highly heritable [realized heritability (h 2 ) = 0.698 ± 0.314], with genetic dominance (D) of the trait strongly influenced by female genotype. Selection of the ED trait and maintenance of polymorphic diapause phenotypes within maize-soybean cropping systems is discussed in relation to response to a fluctuating environment and as a potentially advantageous life history adaptation. AbstractDiapause is an adaptive trait that delays development or reproduction under unfavourable circumstances. The northern corn rootworm, Diabrotica barberi Smith & Lawrence, an important maize, Zea mays L., pest in the Diabroticite species complex, overwinters in diapause during the egg stage. Some NCR populations are adapted to crop rotation by expressing an extended diapause (ED) trait that delays embryonic development for 2 years. This ED trait has increased in frequency and geographic distribution since first reported in Illinois in 1932. Reciprocal single pair crosses among beetles from a laboratory colony with the ancestral 1-year diapause trait and field collected beetles with the 2-year ED trait indicated that ED females laid significantly more ED eggs than did females with the 1-year diapause trait regardless of male genotype. The ED trait was highly heritable [realized heritability (h 2 ) = 0.698 ± 0.314], with genetic dominance (D) of the trait strongly influenced by female genotype. Selection of the ED trait and maintenance of polymorphic diapause phenotypes within maize-soybean cropping systems is discussed in relation to response to a fluctuating environment and as a potentially advantageous life history adaptation.

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“…Data indicate that genetic background of H. armigera strains and characteristics of cotton plants affect the dominance of resistance to Cry1Ac and Cry2Ab, which can vary from recessive to partially dominant (Akhurst et al 2003;Akhurst 2004, 2005;Mahon et al 2007aMahon et al , 2008Wu et al 2009;Nair et al 2010). We thus used a sensitivity analysis to determine the effect of dominance of resistance to each toxin (D LC = 0, 0.1, 0.3, and 0.5) on the evolution of resistance.…”

Section: Parameter Estimationmentioning

confidence: 99%

Assessing the role of non‐cotton refuges in delaying Helicoverpa armigera resistance to Bt cotton in West Africa

Brévault

Nibouche

Achaleke

et al. 2011

Evolutionary Applications

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Non-cotton host plants without Bacillus thuringiensis (Bt) toxins can provide refuges that delay resistance to Bt cotton in polyphagous insect pests. It has proven difficult, however, to determine the effective contribution of such refuges and their role in delaying resistance evolution. Here, we used biogeochemical markers to quantify movement of Helicoverpa armigera moths from non-cotton hosts to cotton fields in three agricultural landscapes of the West African cotton belt (Cameroon) where Bt cotton was absent. We show that the contribution of non-cotton hosts as a source of moths was spatially and temporally variable, but at least equivalent to a 7.5% sprayed refuge of non-Bt cotton. Simulation models incorporating H. armigera biological parameters, however, indicate that planting non-Bt cotton refuges may be needed to significantly delay resistance to cotton producing the toxins Cry1Ac and Cry2Ab. Specifically, when the concentration of one toxin (here Cry1Ac) declined seasonally, resistance to Bt cotton often occurred rapidly in simulations where refuges of non-Bt cotton were rare and resistance to Cry2Ab was non-recessive, because resistance was essentially driven by one toxin (here Cry2Ab). The use of biogeochemical markers to quantify insect movement can provide a valuable tool to evaluate the role of non-cotton refuges in delaying the evolution of H. armigera resistance to Bt cotton.

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Inheritance of Cry1Ac resistance and associated biological traits in the cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)

Cited by 17 publications

References 44 publications

Dominant Inheritance of Field-Evolved Resistance to Bt Corn in Busseola fusca

Dominant Inheritance of Field-Evolved Resistance to Bt Corn in Busseola fusca

Inheritance of an extended diapause trait in theNorthern corn rootworm,Diabrotica barberi(Coleoptera:Chrysomelidae)

Assessing the role of non‐cotton refuges in delaying Helicoverpa armigera resistance to Bt cotton in West Africa

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