A new Bacillus thuringiensis protein for Western corn rootworm control

Abstract

The Western corn rootworm (WCR) Diabrotica virgifera virgifera LeConte is one of the most economically important insect pests in North America. Since 2003, transgenic maize expressing WCR-active proteins from Bacillus thuringiensis (Bt) have been widely adopted as the main approach to controlling WCR in the U.S. However, the emergence of field resistance to the Bt proteins in current commercial products has been documented in recent years, highlighting the need to develop additional tools for controlling this devasting pest. Here we report the discovery of Vpb4Da2 (initially assigned as Vip4Da2), a new insecticidal protein highly selective against WCR, through high-throughput genome sequencing of a Bt strain sourced from grain dust samples collected in the eastern and central regions of the US. Vpb4Da2 contains a sequence and domain signature distinct from families of other WCR-active proteins. Under field conditions, transgenic maize expressing Vpb4Da2 demonstrates commercial-level (at or below NIS 0.25) root protection against WCR, and reduces WCR beetle emergence by ≥ 97%. Our studies also conclude that Vpb4Da2 controls WCR populations that are resistant to WCR-active transgenic maize expressing Cry3Bb1, Cry34Ab1/Cry35Ab1 (reassigned as Gpp34Ab1/Tpp35Ab1), or DvSnf7 RNA. Based on these findings, Vpb4Da2 represents a valuable new tool for protecting maize against WCR.

Restoration of susceptibility following removal of selection for Cry34/35Ab1 resistance documents fitness costs in resistant population of western corn rootworm, Diabrotica virgifera virgifera

“…Resistance to Cry34/35Ab1 has now been documented in WCR field populations in Iowa, 20,21 Minnesota, 22 and North Dakota based on larval survival 25 . With resistance evolving for every commercially‐available Bt trait, and new products (RNAi, Pseudomonas‐ derived toxin, novel Bt toxin 68–70 ) years away from market release, knowledge of the characteristics of resistance is paramount. We demonstrate here that Cry34/35Ab1‐resistance in WCR is associated with an adult fitness cost resulting in delayed and reduced emergence, accompanied by a decrease in adult lifespan.…”

Vegetative Insecticidal Protein (Vip): A Potential Contender From Bacillus thuringiensis for Efficient Management of Various Detrimental Agricultural Pests

“…The protein drastically reduced the beetle emergence ( > 97%) and provides root protection to maize transgenic plants in field conditions. This protein was also effective in controlling WCR populations resistant to Cry34Ab1/Cry35Ab1; DvSnf7 RNA and Cry3Bb1 resistant ( Yin et al, 2020 ).…”

Western Corn Rootworm, Plant and Microbe Interactions: A Review and Prospects for New Management Tools

“…These germplasm will be widely planted for the first time in 2022. Bayer also recently discovered an additional Bt protein [194] and a protein from Brevibacillus laterosporus [195], each with strong activity against western corn rootworm larvae and no cross resistance to current rootworm toxins. Corteva has a new transgenic maize line producing a toxin derived from Pseudomonas chlororaphis pyramided with dsRNA available [151], but the feasibility for large scale application has yet to be evaluated.…”