Effect of intercropping of corn and sainfoin on control of the European corn borer, Ostrinia nubilalis (Lepidoptera: Crambidae), and on yield of both crops

The European corn borer, Ostrinia nubilalis Hübner, is one of the most important pests of corn. In this study, the influences of corn monoculture (C), sainfoin monoculture (S) and strip-intercropping of corn with sainfoin in the four row ratios: 2C:2S, 2C:4S, 2C:6S and 2C:8S were evaluated on the population density of the European corn borer, diversity and abundance of its natural enemies and yield of both crops in an experimental field during 2016 and 2017. Our results indicated that the densities of eggs and larvae of this pest decreased significantly in the intercrops especially in 2C: 6S and 2C: 8S compared with corn monoculture. The Shannon diversity index (H´) for predators in the intercrops was significantly greater than that in the corn monoculture. Moreover, the percentage of parasitized eggs and larvae were higher in the intercrops, especially in 2C:6S and 2C:8S, compared with the corn monoculture. Furthermore, the percentage of infested plants was also lower in 2C:6S and 2C:8S compared with the other treatments. On the other hand, high values of land equivalent ratio were found in 2C:6S (1.16 in 2016 and 1.15 in 2017) and 2C:8S (1.17 in 2016 and 1.16 in 2017). Therefore, it could be concluded that 2C:6S and 2C:8S intercrops are useful in integrated management of the European corn borer in the field.