Digestive Enzymes and Stylet Morphology of Deraeocoris nigritulus (Uhler) (Hemiptera: Miridae) Reflect Adaptations for Predatory Habits

Deraeocoris nigritulus (Uhler) is often collected from the cones of Virginia pine, Pinus virginiana. Most species of Deraeocoris are predacious, but whether this plant bug is phytophagous or predacious is not known. To better understand the feeding adaptations of this mirid, the digestive enzymes from the salivary glands and anterior midgut were analyzed, and the mouthpart stylets were investigated with scanning electron microscopy. Evidence of a trypsin-like enzyme, a chymotrypsin-like enzyme, and pectinase were found in the salivary glands. Low levels of trypsin-like, chymotrypsin-like, elastase-like, pectinase, and (alpha)-amylase activities, as well as high levels of (alpha)-glucosidase activity, were found in the anterior midgut. The right maxillary stylet has two rows of at least seven strongly recurved teeth in front of at least three weakly recurved teeth on the inner surface, all pointing away from the head. Therefore, this insect is equipped with digestive enzymes and mouthparts mainly adapted for zoophagy.