Resistance of Cry1Ab maize to spotted stemborer Chilo partellus (Lepidoptera: Crambidae) in India

Abstract

Three transgenic maize hybrids, viz. Prabal YG, Hishell YG and Double YG, producing Bacillus thuringiensis (Bt) Cry1Ab protein (event Mon 810), were evaluated under field and laboratory conditions for their resistance to spotted stemborer Chilo partellus (Swinhoe). The Bt maize hybrids suffered less damage than their non-Bt iso-hybrids with respect to per cent plant infestation (0.0 -0.6), leaf injury rating (1.0 -1.1) and per cent stem tunnelling. These hybrids also resulted in significantly higher larval mortality (79.4 -100.0%) in laboratory bioassays. The toxin protein produced in leaves was equally effective against neonates and 15-day-old larvae. Neonate larvae consumed less leaf area (5.0 -13.8%) in case of Bt hybrids than their non-Bt iso-hybrids.

Oviposition and feeding behavior of the maize borer, Chilo partellus, in response to eight essential oil allelochemicals

“…This insect is a key pest on and one of the limiting factors in the successful cultivation of maize, Zea mays (L.) (Poaceae). Yield losses from 27 to 80% have been reported in various agro climatic regions in India (Panwar, 2005; Hari et al., 2008).…”

Baseline sensitivity of maize borers in India to theBacillus thuringiensisinsecticidal proteins Cry1A.105 and Cry2Ab2

“…What are available are baseline sensitivity data for Cry2Ab2 with multiple populations of H.armigera collected from cotton fields during the 2004 and 2007 seasons . Similarly, data are available on baseline sensitivity with Cry1Ab for the three lepidopteran pests of this study and the efficacy of three hybrids of Bt maize of event MON810 (expressing Cry1Ab) to C. partellus , as studied in the laboratory, greenhouse and field …”

Binding of Bacillus thuringiensis Cry1A toxins with brush border membrane vesicles of maize stem borer (Chilo partellus Swinhoe)

“…Earlier sharing of receptor binding sites by Cry1Aa, Cry1Ac and Cry1Ba have been reported in closely related species C. suppralis (Fiuza et al, 1996). However, that study did not include Cry1Ab toxin, that have been deployed in transgenic maize and sorghum (Hari et al, 2007;Ramkumar et al, 2005;Tende et al, 2010). The sharing of binding sites between Cry1Aa, Cry1Ab and Cry1Ac observed in C. partellus is a general feature of these toxins that has been found in many lepidopterans (Estela et al, 2004;González-Cabrera et al, 2006;Herrero et al, 2001;Jurat-Fuentes and Adang, 2001;Tabashnik et al, 1997).…”

“…This high margin of safety recommends its use in food crops or in other sensitive sites where chemical pesticides can cause adverse effects (Shelton et al, 2002). Development of C. partellus resistant Bt transgenic maize and sorghum makes it imperative to design resistance management strategies such as gene stacking (Hari et al, 2007;Girijashankar et al, 2005;Ramkumar et al, 2005;Tende et al, 2010), and knowledge of receptor sharing among different Bt toxins is crucial to design a suitable gene stack (Bravo and Soberon, 2008;Frutos et al, 1999;Pigott and Ellar, 2007).…”