Location: Pest Management ResearchTitle: Orientation of European corn borer first instar larvae to synthetic green leaf volatiles Author
Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/6/2012
Publication Date: 4/4/2013
Publication URL: http://handle.nal.usda.gov/10113/56097
Citation: Piesik, D., Rochat, D., Delaney, K.J., Marion-Poll, D. 2013. Orientation of European corn borer first instar larvae to synthetic green leaf volatiles. Journal of Applied Entomology. 137(3): 234-240. Interpretive Summary: Newly hatched European corn borer (ECB) larvae typically orient towards of corn, an important crop host, but avoid odors from spinach, a non-host. However, responses to corn were more variable, so we explore larval responses to several green leaf volatiles (common plant volatiles released after injury, e.g., causes strong smell of cut grass). We are interested in whether ECB neonate larvae have dose-dependent responses to green leaf volatiles, specifically being attracted at low concentrations but repelled by higher doses. While 1 green leaf volatile did not attract or repel ECB larvae, the other five volatiles were repellent at the highest tested dose that is comparable of levels from plants fed upon by insects or infected by pathogens. In contrast, two of the volatiles were attractive to ECB larvae at a 100-fold smaller dose, which is closer to levels emitted by uninjured and uninfected corn plants. These results suggest that ECB larvae may use green leaf volatiles as cues to avoid injured plants that may have defense responses and serve as poor hosts, and be attracted to uninjured plants with low concentrations of these volatiles. This is important because newly hatched ECB neonate larvae probably have a short window of time to find a suitable plant host or else die. There is potential for biotechnology to engineer crops like corn to increase constitutive and/or induced concentrations of compounds like green leaf volatiles. This could prove useful for management of severe crop pest species in systems like ECB with corn.
Technical Abstract: 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