Survivorship of Helicoverpa zea and Heliothis virescens on Cotton Plant Structures Expressing a Bacillus thuringiensis Vegetative Insecticidal Protein

Abstract

A series of tests quantified bollworm, Helicoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (F.), larval survival on plant structures of a nontransgenic cotton (Gossypium hirsutum L.), 'Coker 312', and two transgenic cottons expressing Vip3A protein or both Vip3A + CrylAb proteins (VipCot). Vegetative and reproductive structures including terminal leaves, flower bud (square) bracts, whole debracted squares, flower petals, flower anthers, and intact capsules (bolls) were harvested from plants in field plots. Each structure was infested with 2-d-old larvae from one of the two heliothine species. Larvae were allowed to feed for 96 h on fresh tissue. Survivorship at 96 h after infestation was significantly lower on all structures of Vip3A and VipCot cotton lines compared with similar structures of Coker 312. VipCot plant structures generally resulted in lower larval survivorship compared with similar structures of the Vip3A cotton line. H. zea survivorship ranged from 4 to 28% and from 1 to 18% on Vip3A and VipCot plant structures, respectively. H. virescens survivorship ranged from 10 to 43% and from 2 to 12% on Vip3A and VipCot plant structures, respectively. H. virescens survivorship was higher on VIP3A plant structures compared with that for H. zea on similar structures. These differences between species were not observed on plants from the cotton line expressing VipCot proteins. The results for these plant structures demonstrate that the combination of proteins expressed in VipCot cotton lines are more effective than Vip3A cotton lines against this heliothine complex.

Susceptibility of Helicoverpa zea and Heliothis virescens (Lepidoptera: Noctuidae) to Vip3A insecticidal protein expressed in VipCot™ cotton

“…VipCot cotton also expresses Cry1Ab, a Cry toxin. Field trials have shown that VipCot cotton provides crop protection against heliothine species comparable to that observed with other cotton cultivars that express pyramided Cry toxins (Bollgard II and WideStrike) (Bradley et al, 2004;Burd et al, 2005;Adamczyk and Mahaffey, 2008;Bommireddy and Leonard, 2008). Vip3A is derived from B. thuringiensis in the vegetative and sporulation phase and has insecticidal activity against several Lepidoptera (Estruch et al, 1996;Liao et al, 2002;Lee et al, 2003).…”

“…This trend is different from the responses observed with Cry proteins (Ali et al, 2006;Luttrell, 2007, 2009a;Sivasupramaniam et al, 2008) where H. virescens was found to be significantly more susceptible than H. zea to Cry1Ac and Cry2Ab2. Bommireddy and Leonard (2008) reported that H. virescens survivorship was higher on Vip3A plant structures than that of H. zea on similar structures. This difference in relative activity between the species could be due to different mode of actions of the Vip3A protein (Estruch et al, 1996;Yu et al, 1997;Lee et al, 2003).…”

Genetic diversity and susceptibility to Vip3Aa20 protein in Brazilian populations of <i>Helicoverpa armigera</i> and <i>Helicoverpa zea</i> (Lepidoptera: Noctuidae)

“…Also in USA, efficacy bioassays showed that both Vip3A and Cry1Ab cotton lines provided similar moderate mortality ( 60%) against H. zea (ADAMCZYK JR; MAHAFFEY, 2008). Consistently, in another study, the survivorship of H. zea ranged from 4 to 28% on Vip3A cotton plant structures (BOMMIREDDY; LEONARD, 2008). In contrast, Vip3A maize was high efficient in controlling H. zea, more than 99% of control (BURKNESS et al, 2010).…”

Heliothis virescens and Bt cotton in the United States

“…I am not denying the outstanding level of performance that Bt-cotton gives for the control of TBW; 37,38,50,70 it is without a doubt one of the most impressive technologies used again this pest. However, to give credit to all the previous IPM campaigns of the past decades, we need to consider again the fact that there is little or no consistent information regarding the status of the TBW populations over a considerable period of time before the 1980s.…”

“…However, this is only a logical supposition since there was not an accurate way to differentiate the exact host plant or geographical origin of the males captured in traps until recently. 71 In contrast to this great body of information, a few reports of larval densities present in wild hosts and other crops importantly, the use of two or more Bt toxins with unique modes of action can be critical in diminishing the development of resistance to B. thuringiensis, [46][47][48][49][50] one of the greatest challenges for the future of this technology.…”