Yield Losses in Transgenic Cry1Ab and Non-Bt Corn as Assessed Using a Crop-Life-Table Approach

Abstract

In this study, we constructed crop life tables for Bacillus thuringiensis Berliner (Bt) Cry1Ab and non-Bt corn hybrids, in which yield-loss factors and abundance of predaceous arthropods were recorded during 2 yr at two locations. Corn kernel/grain was the yield component that had the heaviest losses and that determined the overall yield loss in the corn hybrids across years and locations. Yield losses in both corn hybrids were primarily caused by kernel-destroying insects. Helicoverpa zea (Boddie) and Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) were the key loss factors at one location, while at the other, the key loss factor was the silk fly larvae, Euxesta spp. (Diptera: Ulidiidae). Although the realized yield of corn grains was not different (P > 0.05) between Cry1Ab and non-Bt corn hybrids, the Bt corn hybrid reduced (P < 0.05) the damage by H. zea and S. frugiperda in three of the four field trials, particularly at the location where Lepidoptera were the key loss factors. As expected, no reduction in the abundance of predaceous arthropods was observed in Cry1Ab corn fields. Various species of natural enemies were recorded, particularly the earwig Doru luteipes (Scudder) (Dermaptera: Forficulidae), which was the most abundant and frequent predaceous insect. These results indicate that integration of pest management practices should be pursued to effectively minimize losses by kernel-destroying insects during corn reproductive stages when growing non-Bt or certain low-dose Bt corn cultivars for fall armyworm and corn earworm, such as those producing Cry1Ab or other Cry toxins.

Comparison of Ear Damage Caused by Caterpillar Pests in Transgenic (Bt) Maize Hybrids and Conventional Maize Hybrids

“…In general, the reduction in damage scores was, on average, of 56.3% in transgenic hybrids compared with the averages in conventional hybrids, being the Víptera and Herculex the most efficient technologies (Table 7). These results are in line with the findings of Silva et al (2018), who verified that the Cry1Ab technology reduced H.…”

“…In Brazil, it is regarded as one of the major pests, which may cause losses in yield and quality of many products. Silva et al (2018) mentioned that the presence of H. zea, S. frugiperda and Euxesta spp. was one of the main causes of maize yield losses.…”

“…is mainly intended to control fall armyworm, it can be a useful tool to control several other species such as the H. zea (Silva et al, 2018).…”

Fall Armyworm: An Emerging Threat to Agriculture-a Review

“…The braconid wasp Chelonus insularis also parasitizes eggs of FAW & controls FAW (Kumela et al, 2019;Meagher et al, 2016). Many predatory insects like ground beetle (Coleoptera: Carabidae); the striped earwig, Labidura riparia (Dermaptera: Forficulidae, Labiduridae), insidious flower bug, Orius insidiosus (Hemiptera: Anthocoridae); spined soldier bug, Podisus maculiventris are also found to be predatory against FAW (Jones et al, 1988;Sánchez-Rodríguez et al, 2010;Silva et al, 2018;Capinera, 1999). Many entomopathogenic pathogens like Bacillus thuringiensis, Metarhizium anisopliae & Beauveria bassiana were also found to be very effective against FAW (Clark et al, 2007).…”

Fall armyworm (Spodoptera frugiperda): A threat in crop production in Africa and Asia

“…Various predators like Calosoma granalatum (Prasanna et al, 2018), assasin and flower bug (Van Waddill & Whitcomb, 1982), earwigs (Romero-Sueldo et al, 2014;Silva et al, 2018)…”