Orientation of European corn borer first instar larvae to synthetic green leaf volatiles

European corn borer (ECB) neonate larvae are capable of orienting toward maize odors and of avoiding spinach odors. We previously reported that maize odors attraction was dependent on the stimulus regime. This led us to propose that maize odors could have a repellent or attractive effect depending on their concentration. In this work, we tested this hypothesis by evaluating attraction or avoidance of neonate ECB larvae to 4 concentrations of each of 6 single green leaf volatiles (GLVs); these are commonly found in maize and other plants. We found a dose-dependent effect for all of these GLVs with the exception of 1-hexyl acetate, which did not elicit any orientation behavior over the range of concentrations tested. These 5 GLVs were repellent at high concentrations while 2 of them were attractive at a lower concentration. These observations indicate for the first time that plant odors induce different behaviors in ECB neonate larvae depending not only on their chemical identity but also their concentration.