Corn rootworm emergence patterns, survival, and injury in transgenic short-stature corn

Short-stature corn is a recent variety predicted to soon be grown throughout the corn producing regions of the US. Therefore, understanding insect pest interactions with short-stature corn is important for the implementation of insect resistance management (IRM) strategies. The corn rootworm complex (Diabrotica spp.) contains the most economically important insect pests of corn in the US Corn Belt. Transgenic corn producing insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) is often planted to manage corn rootworm and other pests. Blended refuges, in which non-Bt plants are interspersed with Bt plants, are an IRM strategy to delay Bt resistance evolution. We studied the effects of short-stature corn and tall corn on corn rootworm emergence and survival. Three types of field plots were established for each type of corn: 1) non-Bt corn, 2) Bt corn, and 3) a 95:5 blend of Bt and non-Bt corn. Tents were placed over plots, and corn rootworm adults were collected from inside tents over the growing season. Additionally, plants were grown outside of the tents to measure rootworm feeding injury. Corn rootworm emergence was highest in non-Bt plots and peaked toward the end of July and beginning of August. Non-Bt plants received most of the feeding injury, especially non-Bt plants in the pure stand which had larger injury ratings than non-Bt plants in the blend. The results from this study will assist in the development of pest management strategies for short-stature corn.