Effect of MON 810 Bt transgenic maize diet on stored-product moths (Lepidoptera: Pyralidae)

Abstract

The transgenic hybrid MON 810-YieldGard ® was developed to protect maize against herbivorous Lepidoptera larvae in the field. Although the hybrid kernels contained 20 times less of the Cry1Ab toxin than leaves, they had been shown to be toxic to some stored product pests, indicating a protective effect of Cry1Ab during maize storage. However, the characterization of the resistance level and benefits of the Cry1Ab kernels during their storage are still incomplete. In this study, we compared the suppressive effect of the diets obtained from the MON 810-YieldGard ® hybrid to four species of stored product moths: Ephestia kuehniella, Ephestia elutella, Cadra cautella and Plodia interpunctella. The diets originated from kernels that were obtained at two different experimental fields containing the same concentration of Cry1Ab (0.35±0.056 μg g −1), and caused 100% mortality in E. ellutella, C. cautella and P. interpunctella, and 65% mortality in E. kuehniella. The comparison of LD 50 (time when 50% individuals died) and larval relative growth rate (RGR) among the tested species revealed that P. interpunctella was the most sensitive species followed by E. elutella, C. cautella and E. kuehniella. The lowest toxic concentration of Cry1Ab in the diet of E. kuehniella larvae was determined by mixing the diets from hybrid kernels containing Cry1Ab with diets from control kernels without Cry1Ab. The mortality of E. kuehniella larvae decreased with decreasing Cry1Ab concentration, and the LD 50 (concentration when 50% individuals died) was 0.20 μg Cry1A g −1 of diet. Similarly, the larval RGR decreased with decreasing logarithmically transformed concentrations of Cry 1Ab in the diet. These results show that MON 810-YieldGard ® hybrid kernels are protected during their storage against feeding by stored product moths.