Researchers Assess the Resistance Management Strategy for Helicoverpa armigera in Bt-cotton in Xinjiang

Transgenic crops producing Bacillus thuringiensis (Bt) toxins have become crucial tools for Heliothine pest management worldwide. Nonetheless, the evolutionary capacity of pests to adapt may result in the development of resistance to Bt-toxins. The ‘‘high-dose/refuge’’ strategy for resistance management has been widely implemented and worked by introducing susceptible moths from a nearby refuge population to mate with survivors from the Bt-cotton field.

Bt-cotton is widely grown in Xinjiang which is the biggest cotton-producing area in China with more than 30% of national production of cotton fiber, but no studies have been conducted on potential refuges in this region.

Therefore, researchers assessed local crop plants and imported pigeon pea as potential refuge host plants as part of an insect resistance management (IRM) for Helicoverpa armigera in Bt-cotton in Xinjiang. Block and strip configurations of refuge crops have been widely used in Bt resistance management elsewhere, so researchers also estimated the difference in moth production between strip and plot configurations when planting potential refuge crops.

Egg and larval abundance indicated that H. armigera had a preference for chickpea, pigeon pea, and corn, over cotton, sorghum, and benne (sesame). There were no significant differences in egg or larval abundance between plot and strip configurations of these crop hosts. Researchers found that sorghum was not attractive to H. armigera, contrary to the findings in other cotton production areas. Moreover, chickpea, pigeon pea, and corn were determined to be potential refuge hosts based on egg and larval abundance over the growing season.

From the adult moth population dynamics in broad-acre and small-holder farms, the efficiency of alternative refuge crops, and local agricultural practices, researchers recommend that spring corn be grown as a strip crop as part of an IRM strategy to improve the probability of Bt-susceptible moth production and mating with resistant moths in broad-acre farms. In small-holder farms where current agricultural practices are entrenched, wheat and summer corn should be evaluated as refuge crops in the future. The result was published in Journal of Pest Science in December 2013.