Improving crop yield from agriculturally-significant plants including, among others, corn, soybean, sugarcane, rice, wheat, vegetables, and cotton, has become increasingly important. In addition to the growing need for agricultural products to feed, clothe and provide energy for a growing human population, climate-related effects and pressure from the growing population to use land other than for agricultural practices are predicted to reduce the amount of arable land available for farming. These factors have led to grim forecasts with respect to food security, particularly in the absence of major improvements in plant biotechnology and agronomic practices. In light of these pressures, environmentally sustainable improvements in technology, agricultural techniques, and pest management are vital tools to expand crop production on the limited amount of arable land available for farming.
Insects, particularly insects within the order Hemiptera, are considered a major cause of damage to field crops, thereby decreasing crop yields in infested areas. Hemipteran pest species which negatively impact agriculture include, but are not limited to, stink bug, Western tarnished plant bug and Tarnished plant bug.
Historically, the intensive application of synthetic chemical insecticides was relied upon as the pest control agent in agriculture. Concerns for the environment and human health, in addition to emerging resistance issues, stimulated the research and development of biological pesticides. This research effort led to the progressive discovery and use of various entomopathogenic microbial species, including bacteria.
The biological control paradigm shifted when the potential of entomopathogenic bacteria, especially bacteria belonging to the genus Bacillus, was discovered and developed as a biological pest control agent. Strains of the bacterium Bacillus thuringiensis (Bt) have been used as a source for insecticidal proteins since it was discovered that Bt strains show a high toxicity against specific insects. Bt strains are known to produce delta-endotoxins that are localized within parasporal crystalline inclusion bodies at the onset of sporulation and during the stationary growth phase (e.g., Cry proteins), and are also known to produce secreted insecticidal protein. Upon ingestion by a susceptible insect, delta-endotoxins as well as secreted toxins exert their effects at the surface of the midgut epithelium, disrupting the cell membrane, leading to cell disruption and death. Genes encoding insecticidal proteins have also been identified in bacterial species other than Bt, including other Bacillus and a diversity of other bacterial species, such as Brevibacillus laterosporus, Lysinibacillus sphaericus (“Ls” formerly known as Bacillus sphaericus) and Paenibacillus popilliae. 
Crystalline and secreted soluble insecticidal protein toxins are highly specific for their hosts and have gained worldwide acceptance as alternatives to chemical insecticides. For example, insecticidal toxin proteins have been employed in various agricultural applications to protect agriculturally important plants from insect infestations, decrease the need for chemical pesticide applications, and increase yields. Insecticidal toxin proteins are used to control agriculturally-relevant pests of crop plants by mechanical methods, such as spraying to disperse microbial formulations containing various bacteria strains onto plant surfaces, and by using genetic transformation techniques to produce transgenic plants and seeds expressing insecticidal toxin protein.
The use of transgenic plants expressing insecticidal proteins has been globally adopted. For example, in 2012, 26.1 million hectares were planted with transgenic crops expressing Bt toxins (James, C., Global Status of Commercialized Biotech/GM Crops: 2012. ISAAA Brief No. 44). The global use of transgenic insect-protected crops and the limited number of insecticidal proteins used in these crops has created a selection pressure for existing insect alleles that impart resistance to the currently-utilized insecticidal proteins.
Hemipteran pests injure plants by puncturing tissues with their piercing and sucking mouthparts and then extracting plant fluids. The principle damage to tissues comes from loss of plant fluids and injection of digestive enzymes. The puncture sites can be predisposed to colonization by pathogenic organisms, causing significant yield and quality loss. One family in the order of Hemiptera, Pentatomidae, has many members commonly referred to as Stink Bugs. Certain species of Stink Bugs that are agricultural pests have become difficult to control with insecticidal chemicals due to the emergence of resistant populations.
Various characteristics of Stink Bugs result in a high susceptibility to resistance emergence. For example, Stink Bugs can have multiple generations in a single growing season. Further, they can overwinter as adults almost anywhere where they can be protected (including homes), and then begin feeding on various host plants as the temperatures rise. Once development begins, Stink Bugs have two to three generations, depending on the species and host plants.
On corn, Stink Bugs are most often found feeding on young plants in late spring and early summer. Feeding at this time results in holes in the leaf, and if severe, results in deformed plants. The Brown Stink Bug is the primary Stink Bug pest for corn crops during the early vegetative stages. The Brown Marmorated Stink Bug, another corn pest, is generally found in late summer on corn usually feeding on the ear, directly destroying the kernels. This is especially a concern on sweet corn and can be quite damaging.
On soybean, most of the injury from Stink Bugs occurs during second half of the growing season when significant feeding takes place on pods and developing seed. Darkish spots will occur where the mouthparts puncture the plant tissue, although these are difficult to see. This can cause deformation and abortion of the seeds, as well as provide a route for infection by pathogenic organisms. Stink Bug feeding on soybean often results in delayed leaf maturity and foliage retention. During seed formation, seeds will become shriveled, deformed, undersized, and even be aborted. Feeding on more developed seeds will result in minor shriveling and discoloration. This not only negatively affects yield, but also will result in lower market value or inhibit the sale of produced seed.
Due to warming temperatures, stink bugs are expanding their population size and geographical range in the United States. Due to the damage on agricultural crops inflicted by stink bugs, their high susceptibility to the emergence there is a need to find new and novel insect toxins that are effective against Hemipteran insect pests such as stink bugs.