D3123: Survival and development of western bean cutworm under field-realistic Vip3A integrated refuge feeding scenarios

Western bean cutworm, Striacosta albicosta (Smith), is a destructive pest of corn (Zea mays L.), known for feeding on developing ears causing significant yield losses. Management strategies include transgenic corn hybrids that produce Bacillus thuringiensis (Bt) insecticidal proteins, with Vip3A being the only effective protein remaining. Vip3A corn is commonly planted in integrated refuge systems, where non-Vip are mixed with Vip3A plants. This study assessed the survival and development of S. albicosta larvae under integrated refuge field-realistic feeding scenarios in the lab. Neonate larvae were exposed to tassel tissues, while later instars were fed silks and kernels then kernels only. Feeding larvae with Vip3A tissues resulted in 100% mortality at the first instar. The development time ranged from 3.35 to 3.63 days, 2.62 to 3.09 days, 2.46 to 4.22 days, 2.78 to 3.75 days, and 4.79 to 5.44 days for the first, second, third, fourth, and fifth instar respectively. Only larvae not exposed to Vip3A tissues completed the sixth and seventh instar, with an average duration of 5.54 and 5.96 days, respectively. When exposed to Vip3A tissues only on the third instar, 91% of larvae reached the fourth instar, however, their development was significantly delayed; only 45% reached the fifth instar, and none reached the fifth instar. Larvae exposed to Vip3A tissues at the fifth instar reached 100% mortality before reaching the sixth instar. These findings highlight the effectiveness of the Vip3A technology in suppressing S. albicosta and explore the long-term durability in integrated refuge systems.