Determining the Sensitivity of Gustatory Neurons in the Maxillary Styloconic Sensilla of Gypsy Moth Larvae

Gypsy moth larvae, Lymantria dispar (L.), are highly polyphagous and display a wide host preference, feeding on the foliage of many species, but favoring leaves of deciduous hardwood trees, such as oak, maple, and sweet gum. Gypsy moth larvae are major pest defoliators in the United States and destroy millions of acres of trees annually. These lepidopteran insects possess gustatory sensory organs located on the maxillae, namely the medial and lateral galeal styloloconic sensilla, which play an important role in host-plant selection. Using a single cell electrophysiological recording method, this study characterized the sensitivity of the receptor cells housed within each sensillum of gypsy moth larvae when exposed to a panel of selected phytochemicals by performing dose response experiments. Electrophysiological tip recordings from these sensilla revealed that medial styloconic sensilla responded to the alkaloids, strychnine and atropine, while lateral styloconic sensilla responded to aristolochic acid and atropine. In general, these different taste cells exhibited characteristic temporal firing patterns. Thus, this study provides correlative insights into the feeding behavior and taste physiology of this larval insect. It also provides a gateway to use other alkaloids in temporal and dose-response experiments as a possible means of biocontrol.