Development of Diagnostic Concentrations for Monitoring <I>Bacillus thuringiensis</I> Resistance in European Corn Borer (Lepidoptera: Crambidae)

Comparative susceptibility of Ostrinia furnacalis, Ostrinia nubilalis and Diatraea saccharalis (Lepidoptera: Crambidae) to Bacillus thuringiensis Cry1 toxins

“…Bioassay methods were consistent for both species, and identical toxin preparations were used for all bioassays. Neonates of each species (<24 h after eclosion) were exposed to artificial diet (Marçon et al, 2000) in 128-well trays (each well 16 mm diameter, 16 mm height, CD International, Pitman, NJ). Approximately 1 ml of diet was dispensed into each well and allowed to solidify.…”

Effects of infection with Nosema pyrausta on survival and development of offspring of laboratory selected Bt-resistant and Bt-susceptible European corn borers

“…Larvae were exposed to two doses of Cry1Ab; a low, sublethal dose (3 ng/cm 2 ) and a high dose (30 ng/cm 2 ). The current diagnostic dose of Cry1Ab used to monitor resistance in field populations of O. nubilalis is 10 ng/cm 2 (Marçon et al, 2000). These doses along with a control of 0.1% Triton-X 100 were overlaid onto the diet cells using a repetitive pipetter (30 ll), and allowed to dry (see (Siegfried et al, 2001).…”

Variability in the cadherin gene in an Ostrinia nubilalis strain selected for Cry1Ab resistance

“…The colony was then divided into the Europe-S strain, which was maintained in the absence of toxin and the Europe-R strain, which was exposed to protoxin from the Bt kurstaki strain HD1-9 incorporated into rearing diet throughout larval development (Chaufaux et al, 2001). After selection for approximately 70 generations, the resistant colony was maintained by exposure to a concentration of Cry1Ab protoxin corresponding the upper end of the 95% confidence interval of the LC 99 of a susceptible population (Marçon et al, 2000) at approximately every third generation. The level of resistance to Cry1Ab toxin of the Europe-R strain at the time when this work was initiated was in excess of 1000-fold as determined by exposure to artificial diet surface-treated with Cry1Ab toxin (Marçon et al, 1999).…”