Antixenosis and larval and adult dispersal in the Mediterranean corn borer, Sesamia nonagrioides, in relation to Bt maize

Abstract

Sesamia nonagrioides Lef ebvre (Lepidoptera: Noctuidae) is a key pest of maize [Zea mays L. (Poaceae)] and a main target of Bt maize in the Mediterranean area. To choose the most suitable non-Bt refuge strategy for preventing or delaying resistance development in this maize borer, we examined its biology and behaviour. No antixenotic effects were found on numbers of eggs and egg batches per plant in choice (Bt vs. non-Bt plants) and no-choice assays. However, a greater ratio of young larvae dispersed from Bt than from non-Bt plants. In addition, larvae that hatched on Bt plants tended to disperse more than those that hatched on non-Bt plants, particularly during young growth stages. Many adults, especially females, could fly at least up to 400 m, as was found in a dispersal study with rubidium-marked adults. The stimulation of larval dispersal by the Bt trait and the dispersal capacity of adults might compromise the efficacy of seed mixtures as an insecticide resistance management strategy.

Feeding and Dispersal Behavior of the Cotton Leafworm, Alabama argillacea (Hübner) (Lepidoptera: Noctuidae), on Bt and Non-Bt Cotton: Implications for Evolution and Resistance Management

“…According to Razze et al [22] and Davis and Onstad [29] , newly hatched O. nubilalis larvae dispersed more quickly on Bt corn plants than on non-Bt corn plants. Similar behavior was reported by López et al [26] for Sesamia nonagrioides Lefebvre (Lepidoptera: Noctuidae) larvae on Bt corn. According to Goldstein et al [17] , the neonate O. nubilalis larvae were able to quickly detect Bt toxins in the leaves of Bt corn plants.…”

“…Hence, dispersion behavior may reduce the effectiveness of strategies, such as mixing transgenic and nontransgenic seeds, to manage and delay lepidopteran pests from developing resistance to the Bt cotton cultivars. Moreover, the early migration of neonate A. argillacea larvae stimulated by the Bt cotton cultivars compared with non-Bt plants does not prevent larvae in more developed instars, which are more tolerant to Bt proteins, from migrating later from non-Bt cotton plants to Bt cotton plants; thus, favoring the development of resistance in lepidopteran pests to Bt cotton cultivars [26] .…”

Larval dispersal of the invasive fall armyworm, Spodoptera frugiperda, the exotic stemborer Chilo partellus, and indigenous maize stemborers in Africa

“…In gregarious species the risk of reduced larval fitness as a result of rapidly declining host quality due to overcrowding is high. Thus, population density and host quality may mediate their dispersal from natal hosts (van Huis, 1981; Chapman et al, 1983; Berger, 1992; Price, 1997; Cohen et al, 2000; Dirie et al, 2000; Zalucki et al, 2002; Moore & Hanks, 2004; Lopez et al, 2013; Ramalho et al, 2014; Bernal et al, 2015).…”

Blended Refuge and Insect Resistance Management for Insecticidal Corn

“…The probabilities of leaving both a refuge plant and an insecticidal plant must be measured. Greater movement away from insecticidal plants compared with departure rates from refuge plants can reduce selection pressure ( Onstad et al 2011 , Lopez et al 2013 ). In general, it is important to know whether movement consists of discrete steps with each interval of feeding followed by movement or whether movement is mostly one long, continuous step from the natal plant to the final destination with no feeding between points.…”