•  
  •  
 

Midsouth Entomologist

Abstract

The U.S. Environmental Protection Agency recently approved, for areas of the Southern U.S., a 5% seed-mixture (Refuge-In-A-Bag or RIB) combined with a 20% external structured refuge for pyramided Bt corn. In this analysis we compared the durability of a pyramided PIP (plant incorporated protectant) deployed with a 20% refuge versus a 5% RIB and an additional 20% external refuge when the larval movement proportion was varied. The results showed that when the PIP expressed a very high dose (overall mortality of susceptibles = 99.99%) and larval movement was 50% and 90%, the 20% external refuge was 38% and 52% more durable, respectively, than the external + RIB refuge strategy despite the presence of additional refuge in the latter scenario. When the PIP was a high dose (overall mortality = 99.75%) and larval movement was 50% and 90%, then the 20% block refuge was 10% and 20% more durable, respectively. Conversely, for a low dose PIP, the combined refuge strategy with 50% and 90% larval movement was 10% and 5% more durable, respectively, than the 20% external refuge. Helicoverpa zea has been shown to be highly mobile, and one should therefore proceed with caution before deploying RIBs in major cotton growing regions until a careful analysis of each PIP has been conducted.

Download

Included in

Entomology Commons

Share

COinS