Protandry of Western Corn Rootworm (Coleoptera: Chrysomelidae) Beetle Emergence Partially Due to Earlier Egg Hatch of Males

The western corn rootworm, Diabrotica virgifera virgifera LeConte, exhibits protandry. The contribution of pre-hatch development to protandry in western corn rootworm was previously investigated with a small set of data from one population. To verify the contribution of pre-hatch development to protandry, more than 10,000 larvae from seven wild-type populations collected from across the Corn Belt were evaluated. Larvae were placed into containers on each day of egg hatch for each population and allowed to develop into adults. Duration of hatch for these populations ranged from 7 to 19 days with the percent of insects surviving to adulthood varying between 13 and 52%. For the first 25% of egg hatch, significantly more males emerge. Pre-hatch development does contribute to protandry, but overall the contribution is likely less than post-hatch development.