Rotation of the Stylet Bundle in Southern Green Stink Bug, Nezara viridula (L.)1

Abstract

The southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae), uses a needle-like stylet bundle to feed on cotton (Gossypium hirsutum L.) bolls and other high-value crops, occasionally introducing disease-causing pathogens to developing fruit. Ongoing efforts to better understand the role of stink bug stylets in potential transmission of pathogens yielded the first evidence of a rotational aspect to the stylet bundle of the southern green stink bug. Our objective was to provide the first imagery and descriptions of observed rotation of the southern green stink bug stylet bundle. From the point of origin, a counterclockwise rotation occurs along the length of the stylet bundle in the southern green stink bug. A 90° counterclockwise rotation was observed within a span of approximately 195 µm of the stylet bundle in the insect head as the stylet bundle entered the labrum, and the rotation continued into the distal labial segments. Distally, the interlinkage between the maxillary and mandibular stylets was reduced, enabling the maxillary stylets to operate independently and possess their own rotation aspect. This report confirms and describes stylet bundle rotation in the southern green stink bug. We also added to the knowledge base by describing the degree of rotation and existence of a separate rotation aspect to the maxillary stylets distally. Additional work might be needed to determine the degree of rotation in other phytophagous stink bugs and to correlate the likelihood of pathogen transmission based on stylet bundle rotation potentially affecting feeding behavior.