Transgenic sugarcane expressing Bacillus thuringiensis Cry1Ac protein offers new possibilities for controlling the giant borer, Telchin licus (Drury), a pest difficult to control

Abstract

The giant borer, Telchin licus (Drury), is an important insect pest of sugarcane in Central and South America. This pest is difficult to control with chemical or biological control approaches due to the larvae behavior of hiding in the deepest parts of the plants. Manual scavenging and skewer killing have been the main approaches for monitoring and control of T. licus in Brazil, the world's largest sugarcane producer. Recently, Brazil launched the first commercial use of transgenic sugarcane expressing Bacillus thuringiensis (Bt) proteins to control the sugarcane borer, Diatraea saccharalis (F.), a primary insect pest of sugarcane in the Americas. In this study, five independent field/greenhouse tests were conducted to evaluate the larval survival of and plant injury by T. licus on five non-Bt and five Bt sugarcane varieties containing a single cry1Ac gene. The multiple field/greenhouse tests showed that Cry1Ac sugarcane was highly effective to control T. licus; and the high control efficiency was consistent across varieties, from immature to mature plant stages, as well as for F0 generation plants and F1 ratoons. In addition, diet-incorporated bioassays were performed to determine the susceptibility of three field-collected T. licus populations in Brazil to diet treated with purified Cry1Ac protein or with a 25-fold dilution of Cry1Ac sugarcane stalk tissue. The diet bioassays exhibited that the field T. licus populations were also susceptible to the purified Cry1Ac protein, as well as to diet treated with the 25-fold dilution of stalk tissue. The results of this study provide compelling evidence that the single-protein Cry1Ac sugarcane varieties offer new possibilities for managing the T. licus, a pest that is difficult to control with other current available technologies.