Development and evaluation of an enzyme-linked immunosorbent assay to detect Pieris rapae remains in guts of arthropod predators

An enzyme-linked immunosorbent assay (ELISA) was developed to detect remains of Pieris rapae L. (Lepidoptera: Pieridae) immature stages in the guts of field collected arthropod predators. The assay can be used to help ascertain the relative importance of arthropod predator species in suppressing P. rapae in cabbage, Brassica oleracea var. capitata L. The ELISA is sensitive to all immature stages of P. rapae, although first and fifth instars can be detected more readily than eggs or pupae and third instars showed intermediate detectability. Assays on whole body homogenates of predators readily detected predation on P. rapae first instars by all seven of the predator species tested, although response generally declined with increasing predator size. Together the results show that the P. rapae ELISA possesses a sufficiently high level of sensitivity and specificity to be a useful tool in helping to elucidate the roles of arthropod predator species in reducing populations of P. rapae in cabbage.