Veronica Yurchak, Vegetable Specialist, University of Maryland; vjohnso4@umd.edu
This week’s feature beneficial is the spined soldier bug (SSB), a predatory stink bug that can be found on virtually any crop or garden plant. SSBs are generalist predators that feed on a diversity of medium to large soft-bodied insects, including caterpillars, other stink bug nymphs, and beetle larvae. Using their harpoon-like beaks to inject digestive enzymes into unsuspecting prey, SSBs are able to subdue insects many times their own size.
These beneficial predators can be differentiated from other, plant-feeding stink bugs by the presence of pointed projections along the front outer margins of the prothorax, or pointed “shoulders” (Figure 1). Eggs are bronze colored with long projections circling the top of each egg (Figure 2a) and are typically laid in clusters of 20-30 eggs per egg mass. Nymphs are wingless with round, somewhat flattened bodies and distinctive orange, brown, and black markings (Figure 2b). Both nymph and adult stage SSBs are predatory.
Figure 1. SSB adult on sweet corn leaf. The white circle highlights the characteristic pointed “shoulder”
Figure 2. SSB eggs (A) and late instar nymph (B)
SSBs are native to North America and are common natural control agents of a variety of plant-feeding insect pests. They undoubtedly contribute to the regulation of various insect pest populations and have been recorded feeding on over 90 different insect species. Reported prey include the larvae of many important agricultural pests such as the European corn borer, Mexican bean beetle, diamondback moth, corn earworm, beet armyworm, Colorado potato beetle and flea beetle. One study recorded SSBs as consuming more than 100 late-instar fall armyworm larvae over the equivalent of a season, while another showed that commercial releases of SSBs, along with another species of predatory stink bug, reduced Colorado potato beetle infestations by up to 50%. Natural infestations of SSBs can be encouraged by limiting broad spectrum pesticide applications whenever possible and encouraging more diverse field habitats. SSBs are also sold commercially for release in various field and greenhouse cropping systems through several suppliers of biological control organisms.