Submitted to: Environmental Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/29/2005
Publication Date: 12/20/2005
Citation: Lundgren, J.G., Wiedenmann, R.N. 2005. Tritrophic interactions among bt (cry3bb1) corn, aphid prey, and the predator Coleomegilla maculata (Coleoptera: Coccinellidae). Environmental Entomology 34(6): 1621-1625. Interpretive Summary: Insecticidal crops that target corn rootworms possess beetle-specific insecticides that could impact beetle biological control agents. One ecological pathway for these toxins to affect the predators is through aphid prey that feeds on the corn. Here we show that the transgenic corn reduces the size of aphids that feed on the corn, but that the reductions in aphid size doesn’t compromise the ladybeetle predator that feeds on them.
Technical Abstract: The ability of the transgenic corn rootworm resistant corn (Zea mays L.) hybrid, MON 863 to affect the predator Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae) through the consumption of corn-fed aphid (Rhopalosiphum spp., Homoptera: Aphididae) prey, was examined in the laboratory. Aphid weight was used as an index of prey quality. Larvae of C. maculata were reared to pupation on aphids that had consumed transgenic or non-transgenic (susceptible) corn plants. Larval duration, survivorship to pupation, post-mortem adult dry weight (taken at 30 d post-eclosion), adult mobility, and fecundity were compared for C. maculata between the treatments. Fitness parameters of C. maculata were similar between transgenic and susceptible treatments, despite a 33% reduction in the weight of aphid-prey reared on MON 863. Cry3Bb1 was detectable in the leaves of MON 863, but not in the susceptible plant, aphids or C. maculata that were fed aphids. We conclude that transgenic corn that expresses Cry3Bb1 does not inflict acute or chronic degradations in fitness on individual C. maculata through aphid prey, but these results do not necessarily apply to other natural enemies, herbivores, or insect-resistant corn hybrids.