Western corn rootworms (Diabrotica virgifera virgifera LeConte) are one of the most economically important pests of corn. They have been controlled using Bt (Bacillus thuringiensis Berliner) corn hybrids expressing toxic Cry proteins for over a decade, in the United States. Because they have a well-documented history of evolving resistance to control methods, US-EPA has mandated that growers of Bt corn deploy a non-Bt refuge within or adjacent to all Bt cornfields. Refuges allows larvae to develop without exposure to Cry proteins and are intended to produce many Bt-susceptible individuals. The success of refuge strategy depends, in part, on susceptible beetles from the refuge dispersing across the Bt cornfield, where they will mate with the rare, potentially-resistant, beetles from Bt corn and produce heterozygous offspring that are susceptible to Bt Cry proteins. This presentation includes mating characteristics of females collected in Bt cornfields planted in four refuge configurations (20% structured refuge, 5% structured refuge, 5% seed blend refuge and 0% refuge; 2010-2012) and laboratory pairings (2015-2016). These data reveal the proportion of females that are teneral, mated and average level of ovarian development. Multiple-mating was detected in 4.5% of the females, occurring both in short succession and more than a week apart. Multiple-matings by females were previously unrecorded in the field, though previous laboratory studies suggested they may occur more frequently. The laboratory portion of this research explored factors, such as sex ratio, population density and mating interval, which may influence the frequency of multiple-matings by females.
|Original language||English (US)|
|State||Published - 2016|